SoLID EC Design Weekly Meeting Minutes

09/14/2017 09/07/2017 08/31/2017 08/24/2017 08/17/2017 08/10/2017 08/03/2017 07/13/2017 07/06/2017 06/29/2017
(collab mtg)
06/08/2017 06/01/2017 05/18/2017 05/11/2017 04/20/2017 04/13/2017 04/06/2017 03/30/2017 03/23/2017 03/16/2017 03/09/2017 03/05/2017
(collab mtg)
03/02/2017 02/23/2017
02/16/2017 01/26/2017 01/12/2017 01/05/2017 12/22/2016 12/15/2016 12/08/2016 12/03/2016
(collab mtg)
12/01/2016 11/11/2016 11/03/2016 10/27/2016 10/6/2016 9/22/2016
9/8/2016 8/27/2016
(collab mtg)
8/25/2016 8/18/2016 8/4/2016 7/21/2016 7/14/2016 7/7/2016 6/30/2016 6/16/2016 6/9/2016 6/2/2016 5/19/2016 5/7/2016
(collab mtg)
4/28/2016 4/21/2016 4/14/2016 4/7/2016 3/31/2016 3/24/2016 3/17/2016 3/10/2016 3/3/2016 2/25/2016 2/18/2016 2/4/2016 1/28/2016 1/13/2016
(collab mtg)
1/21/2016 1/7/2016 12/17/2015 12/10/2015 12/03/2015 11/19/2015 11/12/2015 11/05/2015 10/22/2015 10/15/2015 10/01/2015 09/24/2015 09/12/2015
(collab mtg)
08/25/2015 08/11/2015 07/21/2015 07/14/2015 07/07/2015 06/23/2015 06/16/2015 05/26/2015 05/15/2015
(collab mtg)
05/12/2015 05/05/2015 04/21/2015 03/31/2015 03/17/2015
03/10/2015 03/03/2015 02/10/2015 01/27/2015 01/20/2015 01/13/2015 01/06/2015 12/23/2014 12/16/2014 12/02/2014 11/25/2014 11/18/2014
(collab mtg)
11/04/2014 10/28/2014
10/21/2014 10/14/2014 10/07/2014 09/30/2014 09/23/2014 09/16/2014 09/09/2014 09/02/2014 08/26/2014 07/29/2014 07/22/2014 07/10/2014
(collab mtg)
05/27/2014 05/14/2014
04/23/2014 04/16/2014 04/09/2014 04/02/2014 03/26/2014 03/12/2014 03/05/2014 12/04/2013 11/09/2013
(collab mtg)
11/06/2013 10/02/2013 09/19/2013 09/11/2013 09/04/2013
08/28/2013 08/20/2013
(collab mtg)
08/13/2013 08/06/2013 07/30/2013 07/23/2013 07/16/2013 05/24/2013
(collab mtg)
05/21/2013 05/14/2013 05/07/2013 04/30/2013 04/23/2013 04/16/2013
04/09/2013 04/02/2013 03/26/2013 03/23/2013
(collab mtg)
03/19/2013 03/12/2013 03/05/2013 02/26/2013 2/19/2013 02/12/2013 02/05/2013 01/29/2013 01/22/2013 01/15/2013
(collab mtg)
(collab mtg)

List of communications with IHEP

  • A few important summaries (but only a small portion of the progress we have made)

  1. Participants:
  2. Final summary of test results on irradiated Preshower tiles:
  3. Table to summarize all prototypes we have so far:
  4. Prototype
    Reflective Material between layers
    WLS fiber type
    WLS fiber end treatment
    module side treatment
    cosmic vertical test light yield (ph.e.)
    cosmic horizontal test light yield (ph.e.)
    Other features
    Additional comments
    Kedi (original)
    US Kolgashield
    Printer paper
    no plating or painting
    final product had side-painting with TiO2
    224 (sides unpainted, wrapped losely in Tyvek); 254 (sides painted).
    48 (sides unpainted, wrapped losely in Tyvek);
    39 (sides unpainted, no Tyvek wrapping).
    front plate has holes
    (1) Details of cosmic test without side-painting see 2016/08/18 report by Ye with the PMT gain corrected; update of the vertical test with sides painted see 2016/09/22 report by Ye, done just before shipping the modules to JLab. (2) PMT gain for the cosmic test confirmed by SPD using LED signals. (3) The cosmic test for SDU1 and SDU2 modules was done without the side painting. These two modules had their sides painted with SiO2 just before shipping to JLab.
    Kedi (improved)
    Printer paper
    silver-plating (Chinese vendor)
    final product had side-painting but quality was not as good as SDU1.
    427 (sides unpainted, wrapped losely in Tyvek); 383 (sides painted).
    83 (sides unpainted, wrapped losely in Tyvek)
    front plate has no hole
    See above
    Kedi (improved)
    US Kolgashield
    Printer paper
    Y11 (Xiaochao)
    silver-plating (Chinese vendor)
    TiO2+glue (1:1) painting
    front plate has no hole
    (1) Details of cosmic test see 2017/01/05 report by Ye for the SDU group. (2) PMT gain setting is 5E6, same HV as SDU1 and SDU2.
    Kedi (original)
    mirror mylar (Yi Wang commented mirror mylar produces 20% lower yield than printer paper and Tyvek from their test).
    Y11 (Xiaochao)
    silver-painting (Italian silver shine 415001)
    TiO2(Kedi) painted
    (424.9-470), depending on trigger setup. followup: JLab test indicates the yield is 3 times lower.
    96, followup: JLab test indicates the yield is 3 times lower, see SDU Ye's report on 2017/04/20

    Details of cosmic test see 2016/09/08 report by Chendi. Gain of PMT used in the cosmic test was 2.5E6 (We questioned how this gain was determined on 9/8 but no followup). Oh here is the followup: Chendi and Prof. Wang Yi said they simply used the factor HV/gain chart, see discussion of SDU Ye's report on 2017/04/20
    Kedi (improved)

    powder paint

  5. Present evaluation about the light yield:
    1. Using the above highest MIP light yield, which is about 500 p.e./200 layers 1.5mm layers (0.3MeV MIP energy per layer or 60 MeV MIP energy total), scale up to 1 GeV electron (20% sampling factor or 200MeV energy deposit in the scintillators), we obtain (500/60*200=1666 p.e.) for 1 GeV electrons. This is 1.67 p.e./MeV, which is still factor 2-3 lower than LHCb 2.6-3.5 p.e./MeV, ALICE 4-4.4 p.e./MeV, and KOPIO 53 p.e./MeV (see May 2016 collab meeting presentation for summary -- all used Y11, KOPIO also used APD and a fancier "LEGO lock" structure. We had expected the Y11 to provide factor 2 increase, then we are equal to LHCb (which used Y11), but SDU3's result does not indicate so which is a big puzzle.
    2. With 1667 p.e./GeV electron, the energy resolution due to photon statistics will be 2.5%, adding factor of 2 for the light loss of fiber connector and clear fibers, 2.5% becomes (3.5-4.0)%. This is okay considering the intrinsic resolution is (5-6)%, bu ideally we would like to see the effect of photoelectron statistics to be negligible.
    3. Jianping isn't convinced of the energy-scaling method. The shower mechanism may not work this way. It is important to test the prototypes with a known-energy lepton beam.
  6. Possible ways to proceed:
    1. Recall on 2016/6/30 Chendi reported testing scintillators from another Chinese company that seem to provide a factor 70% higher than Kedi's new formula. Chendi will followup on this for the next (THU2) module.
  7. Beamtest data update: It turns out all runs after 420 had no GEM info due to GEM HV failure (that was never fixed). The latest run with GEM tracking is 419, whcih unfortuantely had the old threshould (-300mV) setup for the SoLID calorimeters
  8. Vince sent out some scripts, see below
    1. The first code (plot_tdcs.C) only plots the TDC channels for the various scintillators and the FASPD.
    2. The second program (plot_fadc_wtdcs.C) plots the FADC and TDC information for the three bars required for the time resolution measurement: S2 -- middle bar of the front panel; S4 -- back bar of similar type to the front bar; and S5 -- the LASPD bar.
    3. When I plot the FADC spectra, I plot it both without and with a requirement for a hit in the TDC for that particular channel. If you zoom into the figures, you can see where the discriminator threshold occurs in the FADC spectra relative to the MIP peak.
  • 09/14/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), Chendi Shen, Cunfeng Feng, Jixie Zhang, Xiaochao Zheng
  2. Report from THU (Chendi), see THU2 cosmic test results 5.pdf
    1. Focused on the PMT gain test. Measured the THU2 horizontal test at two different HV and two scintillator size settings. When the scintillator size is large (the bottom bar is 20cm long along the shashlyk, not the 10cm as shown in the slide), Npe is high. But if using small scintillators (3-5cm in size) the Npe is about 90 for the two different HV settings. This is reasonable. We did make a note that the Npe value depends on the gain measured by Beijing Hamamatsu using the SK/SP method, for which the accuracy is still being studied.
    2. We suggested that Chendi can rotate the long trigger bar by 90 degrees so the overlap between the top and the bottom bars is small, to ensure the cosmic muons pass through the shashlyk module nearly vertically.
    3. Chendi is currently studying the dependence of the trigger bar position w.r.t. the shashlyk. The result may be sensitive to the fiber reflection quality and fiber attenuation, but the effect may be too small to be seen.
  3. Cunfeng reported on SDU's PMT HV and gain study, see CR284performance_update.ppt.
    1. The SDU PMTs were also provided by the manufacturer on the SK/SP ratio. The gain was determined at SDU using the SPE method as well. However, comparison between the two methods shows that the SPE method's gain is about always a factor two higher than the factory SK/SP value. We discussed this, and we think maybe the manufacturer used a different base that affected the gain. Meantime, Chendi said when he took his PMT to Beijing hamamatsu, he was told the based used in the test is the same as the base he brought, and the gain should be the same.
    2. Cunfeng suggested Chendi to send in his PMT to SDU to determine the gain using the SPE method.
      1. First, we need to make sure SDUs SPE method is correct. We ask Cunfeng please report on the exact calculation used in the SPE method by Ang Li from a while ago.
      2. THen, for Chendi's PMT, if the SPE method gives the same gain as the SK/SP method, we can conclude that the gain from the SK/SP method for Chendi's PMTs are reliable and can be used to determine THU2 module's performance; And the reason why there is a factor two difference in SUD's PMTs may be due to using different bases in the factory vs. SDU tests.
      3. If the SPE method gives a gain that is twice the Sk/SP method for Chendi's PMT, we can conclude that something is wrong for the Sk/SP method and that we should use the gain determined from the SPE method. The SK/SP method can still be used to determine the gain vs. HV curve and extrapolate the gain at different HVs. However, this could also be because there is something wrong with the SPE method (hence we ask Cunfeng to check the calculation.)
    3. Jixie and Ye (SDU) reported that still working on the test lab tests. Data were not stable and the efficiency for good data taking is only 40%. Jixie also started checking Ye's LASPD timing analysis code and so far has not found any mistake. With the new data should be able to determine the LASPD's single-side readout timing resolution for different hit positions.
  • 09/07/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Chendi Shen, Cunfeng Feng, Seamus Riordan, Alexandre Camsonne, Jixie Zhang, Xiaochao Zheng, Paul Souder
  2. Report from THU (Chendi):
    1. Continue working on THU2 module cosmic test, see THU2 cosmic test results 4.pdf. Gain of the PMT has been determined by measuring the anode over cathode currents (SP over SK), see CR284-01.xls , but found the gain is exponential with HV (agree with our experience with HRS PMTs - JP), but the main QDC peak position from the THU2 vertical cosmic test is only linear with HV. This means the calculated Npe varies greatly with the HV applied, which does not make sense. We didn't have a chance to discuss this extensively at the meeting. Cunfeng suggested maybe the anode current is too high for our shashlyk at the high HV values applied, and cause some sort of saturation. He suggested Chendi to bring the PMT to SDU to evaluate this "range" effect.
    2. The calculation of Npe from QDC spectrum is: calculation.pdf. The "X" in this slide is the horizontal axis of all the QDC spectra in the "results 4.pdf" slides linked above. THe QDC resolution is 0.1pC/channel. The 9.4 is the attenuator used to shrink the signal so it fits into the QDC range.
  3. Report from Jixie: In the test lab, the trigger bars are both perpendicular to the LASPD, and are moved little by little to cover the full length of the LASPD.
  4. Report from Ye Tian (SDU), see 09072017_YeTian_SDU.pdf. The main progress is to determine the LASPD timing resolution with the GEM position correction applied. Explanation for each slide:
    1. SPE measurement will be delayed until all LASPD test is done.
    2. starting slide 3 are re-processed data from the "old" setup (two trigger bars only). The right plot shows the hit position from GEM on the trigger bar in mm (the bar is 5cmx30cm). The LASPD was oriented perpendicular to this trigger bar. So we are using events that hit at about 5cm length of the LASPD, at about 15cm from the narrow side.
    3. slide 4: top right was previous results of timing resolution vs. the hit position, but no position correction was made. Bottom right shows the timing of the PMT readout vs. the hit position in mm, clearly there is a linear slope. The trigger range is 5cm wide, so events below 230 and above 270 are near the edge and may not provide good fit. The plot on the left is the timing resolution of the wide side PMT with the hit position slope corrected. This is what we will achieve for events hitting the LASPD, and with single-side readout only (in this case is the wide side). Note that if the trigger bars are at the most inner side (right next to the narrow side rather than 15cm away as used here), this would have given the resolution of the worst-case senario for the actual SoLID running (events hitting narrow side, furthest from the readout PMT). For that senerio we need 150ps. We do not yet have full information on how this 156ps decompose to: contributions from PMT TTS, TDC, electronics, and GEM uncertainty, but it is promising.
    4. slide 5: same as slide 4 but now reading out from narrow side. This slide presents two problems:
      1. 1) the slope of bottom right plot is only half of the value of slide 4. This is puzzling, as the slope should represent the inverse of the speed of scintillating light traveling down the bar. (Slide 4 gives about 1E8m/s and here is about 0.5E8m/s). Simple calculation indicates that this speed should be c/n (n=1.5 here), then multiply a factor of about 2.2/3 (the cosine of the total internal reflection threshold angle, or sqrt(1-(1/n)^2)) to account for the 3D bouncing, so should be about 1.5E8 m/s.
      2. 2) the resolution is 168ps and worse than slide 5. Narrow side is closer to the hit so we expect more Npe and thus better resolution. Maybe for this particular PMT, the Npe effect doesn't dominate. It's something else that dominates the resolution and is worse than we hoped for.
    5. Will carry out the same analysis for the cosmic data that are being collected currently (since last Friday 8/31, the new data has the two trigger bars both perpendicular to the LASPD, see right side of slide 7).
  • 08/31/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Chendi Shen, Alexandre Camsonne, Jixie Zhang, Xiaochao Zheng, Paul Souder
  2. Report from THU (Chendi):
    1. Continue working on THU2 module cosmic test. However, found the prevoius way of measuring the gain is problematic because was told by his classmate (who works with the laser used) that the laser is too strong to produce only the SPE peak. Will need to take the PMT to a company (Hamamatsu Beijing, in 廊坊)to measure the gain.
    2. Tried testing the clear fiber, see the same slides THU2 cosmic test results 3.pdf (starting page 8). But because the setup was not placed in a dark box, found the ambient light affected the measurement. Tried taping the fiber end to the PMT, but this way, the coupling between the fiber and the PMT could not be reliably reproduced after cutting the fiber. Need to find a way to overcome this problem. -- Note: (a) Easiest is to place everything in a dark box. (b) the WLS fiber tests (binding radius) was not affected by this problem because (I forgot the reason...-XZ).
    3. Note from XZ: the UVa WLS fiber setup cannot be used for testing clear fibers. :(
  3. We discussed the Fermilab test:
    1. Jixie reported there are scintillator array in Hall C avaialble. It is a 20x20 array with each array covering 60x60cm of area. If including PMT the size is about 1mx1m.
    2. However, we discussed whether our status is mature enough to carry out an off-site test at Fermilab. The answer is maybe not yet. We still need to study carefully the Hall A beam test data and use them to setup new goals for the next test. (Jixie will look into the cleanest data possible and come up with a list of what we have learned, and what needs to be addressed.)
  4. Some information about the Fermilab test beam (most were answered by Mandy Rominsky at FNAL:
    1. The particle profile can be viewed at:
    2. About particle momentum: The momentum is set up by the main control room that runs the accelerator. You call them up (any time, they are there 24/7) and you request whatever momentum you want. It takes just a few minutes to switch between the different energies. There are various beamline monitors that the accelerator people use to measure the momentum they are delivering to us. We can get access to those values, but it’s not easy to put that into a data stream. We can see the momentum on the monitors though. It’s good to about 2-3%.
    3. The partile momentum can go down to about 2 GeV in the MTest beamline. At that energy it is almost all electrons and is a wide beam and not well measured. This is a secondary beamline. In MCenter, we do have a Tertiary beamline that goes down to 200 MeV. It is currently occupied. How big is your detector? It might be possible to get it in, if it’s small. Otherwise, we can accommodate you in the MCenter beamline, but we will have to think about this.
    4. The Cherenkov does not work well all the way down to the lowest range. However, we’re constructing a ToF that will hopefully cover it. We do know that the beam is about 90% electrons as you go lower. The MCenter area has beamline instrumentation. Again, it will depend on the size of your detector as to where we can put it.
    5. We still need to find out how well the beam position is monitored. If it is precise enough we may not need a hodoscope or GEM.
    6. What is their training schedule? (Though most can be done online before arrival).
  5. Ye Tian (SDU) reported study of how to find the SPE peak of PMTs, see SPE_test.pdf. This is because one way to characterize if the timing resolution of the LASPD is good enough is to determine the Npe for each PMT. (Higher Npe means better resolution). Ye tried finding the SPE of the R11102 on hand, but the pedestal is very wide. Still, the SPE is visible and may be fit with limited uncertainty.
  6. Ye Tian (Syracuse) reported on progress of the simulation, see ECAL_08312017.pdf. Basically, focused on adjusting the cuts to improve PID efficiency and to approach the preCDR values as close as possible. Found out for some kinematics the new performance is even better than the preCDR. For LAEC, the performance is worse but found out it is due to edge effect. Looks promising, though there is still work to do.
  • 08/24/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Chendi Shen, Yi Wang, Jixie Zhang, Xiaochao Zheng, Paul Souder
  2. Report from THU:
    1. May test the clear fiber this Saturday.
    2. Studied SPE peak position, as well as the SDU2 light yield position (ADC channel) for HV 1100V, 1200V, 1300V, etc, found the ADC channel position to be linear to HV but not the SPE position, see Gain of THU PMT.pdf for the SPE fitting and gain vs. HV calculation, and THU2%20cosmic%20test%20results%20(2).pdf for the main signal peak vs. HV plot. Most likely this is due to error in fitting the SPE positions, but can also be due to other reasons. Have not tried the correct SPE fitting yet. THe fitting work will have the highest priority for the upcoming week.
    3. We commented that even a double-Gaussian peak fitting may improve over previous results quite well. Depending on how the double peak fit works, may or may not need to use Chao's python code/method.
  3. Xiaochao contacted Kuraray for the fiber diameter dependence of the clear fiber attenuation loss.
    1. Here are some slides on the comparison: Loss of PS fiber.ppt. Previous communication with Kuraray data were reported on 4/13/2017. The difference in the attenuation length between 1mm and 0.5mm diameter seems to be only at the 20\% level.
    2. For quartz vs. plastic fiber, Kuraray provided the following answer: A quarts fiber will have a reasonable cost when the diameter is standard 125um, but 1000um quartz fiber will be a very expensive. A plastic fiber is very much cheaper, but the performance is very much lower in 2-3 order than a glass fiber.
  4. Report from Ye Tian (SDU):
    1. GEMs are working and have the correct current now, after replacing with two new GEMs. The GEMs are being flushed with nitrogen now and may be used for data taking soon (tomorrow maybe?);
    2. Rotated both trigger bars to be perpendicular to the LASPD. Otherwise have not studied the Npe and other items reminded in last week's meeting.
  5. Recap of fiber situation:
    1. WLS for Shower: can be either Kuraray or S.G., but S.G. costs less;
    2. WLS and clear for Preshower and FASPD: must be Kuraray because of the high radiation dose;
    3. clear fiber for Shower: S.G. costs less, but performance has not been confirmed in our THU lab; Kuraray has good customer support and detailed data to support good performance, but we have not tested those either due to lack of samples.
  6. Xiaochao also took a quick look at the Npe estimation. The current best result of 400-500 p.e. for MIP (vertical cosmic test) is about 5-8 times lower than expected, if using a 1E4 photon/1MeV scintillating efficiency (EJ200 datasheet), 50% photon propagation/absorption efficiency (Edward Cheek simulation), 5% trapping efficiency of WLS fibers (S.G. and Kuraray datasheet), and a 100mA/W PMT conversion efficiency/Q.E. (Hamamatsu R11102 datasheet). This is consistent with the fact that our light yield estimation is factor 5-8 lower than other experiments using shashlyks.
  7. Most people were away at the NStar meeting in SC to get elipsed. So we had a short meeting today.
  • 08/17/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Chendi Shen, Yi Wang, Cunfeng Feng, Jixie Zhang, Xiaochao Zheng, Zhihong Ye, Paul Souder
  2. Report from THU:
    1. didn't test the US Raytum silica fiber because those fibers have 0.5mm diameter. Xiaochao suggested testing them anyway. Xiaochao will ask Kuraray if they have data on the diameter dependence of attenuation length for clear fibers.
    2. Still running the vertical test for THU2 module.
    3. Have not yet tried re-fitting the single p.e. peak.
  3. Fermilab testing:
    1. Whether Nilanga's group will go to FNAL for the GEM testing depends on the EIC Detector R/D fund outcome of this summer. The goal of his group will be test the 2nd generation GEM for EIC, which can also be used for SoLID
    2. We (Jixie) will look into building a hodoscope using SANE/Hall C scintillators. For our test we only need sub-cm precision on the beam position. A GEM may be overkill. Also there is advantage of using our own tracking (rather than relying on a new set of GEM).
    3. Xiaochao should combine all information and see if the Npe of shashlyk from cosmic tests make sense, and use this to calibrate the simulation.
    4. Jixie and Ye will go through existing HalL A beam test data and see if the data make sense. May need to run quick rate estimation to figure out if the peak was mostly from MIP or electrons. (Xiaochao's estimate was they were all MIPs, but with some questions unanswered. See meeting minutes).
    5. Xiaochao will inquire on the Fermilab beam timeline (is it available later in the Spring? Since it's unlikely we will be fully ready by Jan-Feb'18)? and beam momentum and composition, etc.
    6. The test lab cosmic test should include the 3 shashlyk prototypes at some point, to make sure they work fine.
    7. Need well defined goals for the test and detailed run plans. For Shashlyks, Npe? dE/E? PID efficiency? prelead thickness? For SPD: Npe, timing resolution, uniformity?
    8. What is the training schedule of Fermilab? Should everyone make a separate trip to get all training done?
    9. Manpower: Any help from ANL/Fermilab? - Zhihong? Seamus? Any students?
  4. Status of the test lab (Ye Tian SDU and Jixie):
    1. GEM chambers were drawing too high current. This may indicate problem and the GEMs are off now to avoid damage to the chamber. Nilanga will be here on Friday to investigate.
    2. Still running cosmic test without the GEM. Xiaochao reminded that there are two things we can do using cosmic, that were suggested previously but never received followup results: 1) to measure Npe for LASPD, as suggested on 5/11/2017; 2) for data collected with valid GEM, instead of using GEM data to apply cut, should use the position info from GEM to look for correlation with timing and apply position correction, as suggested on 6/15/2017; also for point 1), Npe measurement, can orient both top and bottom trigger bars perpendicular to LASPD to constraint the hit position to be right next to the PMT of the narrow (or the wide) side.
  5. Ye Tian (Syracuse) presented work on the simulation:
  6. Jianping and Xiaochao met with Raytum's Steve later in the day. Possiblility for SBIR: 1) fiber connector for Shashlyk along with silica fiber bundle (maybe 200um-dia to reduce the price). The fiber connector needs to be researched (will be optical coupling); 2) any possibility of replacing the WLS fiber by something better? 3) Replace the LASPD lightguide by something with better efficiency and cost, and possible use of fiber fundle to guide the LASPD light out.
  • 08/10/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Chendi Shen, Cunfeng Feng, Sanghwa Park, Jixie Zhang, Xiaochao Zheng, Zhiwen Zhao, Paul Souder
  2. Sanghwa presented briefly status of the SPD simulation. We emphasized the focus should be to make sure current simulation is correct. Jianping mentioned Jin's simulation seemed to also suggest high pi0 background. If pi0 is signficant then there should be a correlation in the forward vs. backward energy deposits. Jianping suggested plotting pi0 photons hitting the preshower and what fraction of them scatter back? (fractional event counts? energy deposits, etc?)
  3. Beijing IHEP test beam won't be available this year. We can consider testing next year but with Fermilab testing, the Beijing test may not be necessary.
  4. Start looking into Fermilab test beam facility, see Discussions:
    1. Need to identify goal of the test: (i) to determine pion rejection of shashlyk prototype; (ii) To determine energy resolution of shashlyk prototype; (iii) To characterize SPD's at the real beam situation; ... anything else?
    2. per their website, it will take 8 weeks for test proposal to be evaluated and two weeks to get all signatures required. So we should submit beam time request at least 3 months prior to the target test date.
    3. Need to identify test beam needed. 1-7 GeV/c electrons mixed with pions? What PID is available? What is the duty factor, etc?
    4. Need to coordinate with Nilanga on concurrent GEM test
    5. Jin suggested requesting MT6.2-C for testing SoLID detectors. He mentioned the test area has a large motion table, PID+trigger detectors, and camera+temperature control, but need out own tracking (such as GEM).
    6. Jin suggested making a full cosmic test setup with trigger bars, all our prototypes, and GEM, and move the whole thing to Fermilab including all electronics and DAQ/computers. Fermilab has DAQ and computers to use as workstation, but it will waste precious beam time if we have to setup the DAQ on a new computer, etc.
    7. We will need help from nearby institutions. ANL?
    8. We need to make sure Mark JOnes with okay with taking some of the (Hall C) equipment to Fermilab.
    9. Zhiwen mentioned the EIC Calorimeter group frequently run tests at Fermilab. This time, they are planning to run test from 2/21 to 3/27/2017 (info from Craig Woody).
  5. Chendi reported on cosmic test of THU2 module, see THU2 cosmic test results_chendi shen.pdf. Discussions:
    1. besides materials, one change to THU2 is Chendi inserted all fibers one by one, rather than in groups.
    2. p.5: determination of single p.e. peak and the PMT gain. The fit seems to miss the peak. Need to fit to pedestal and SPE peak simutaneously. Zhiwen mentioned Chao Gu may have a good fitting program to use for the SPE peak. Followup: Chao Gu's python code and the paper to explain the physics of the single p.e. peak Precision Analysis of the Photomultiplier Response to Ultra Low Signals.pdf
    3. The pedestal seems to be really wide. We need to stick to R11102 for cost reasons for the main production, but JP suggested can use a better PMT for testing
    4. Current results are 232 and 673 for the horizontal and vertical tests, respectively. But missing the SPE fit might cause this number to be too large by up to 50%. If we correct this with a "2/3" fudge factor, we get 160 and 450. The vertical Npe is between SDU2 and SDU3 which is reasonable, because the materials are quite similar. THe horizontal test Npe seems to be too high and not consistent with the vertical Npe. This might be due to trigger bars too long (5x10x5cm and 5x20x5cm) and oriented along the same direction as the shashlyk, and the cosmic events are not exactly vertical. JP thinks it's not necessary to repeat the horizontal test (with rotated trigger bars). Can correct the trigger bar orientation for the next set of tests (with TiO2 coating on the side).
    5. Current test uses Tyvek wrapping around the module. Next step is to remove Tyvek and apply TiO2 painting and re-test the module.
  6. We asked Chendi if he can do the clear (Raytum) fiber test soon, before next Thursday when we meet the Raytum people. He said he will try testing on Monday or Tuesday.
  7. Ye Tian (SDU) and Jixie reported on the SPD test, see 08102017_yetian.pdf. Main change is added the GEM trigger plane with the goal of increasing rates, but this will likely not work because this trigger plane is only 3cm thick and is very big, both means the photon statistics are not as good as our dedicated trigger bars (5cm thick and 30cm long). Probably will have some results to report next week.
  8. Ye Tian (Syracuse) had some questions about implementing background into EC evaluation. (I skipped this part and will record next time.)
  9. Next week: we may have Raytum's Steve join our meeting. Sanghwa will be on vacation.
  • 08/03/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Paul Souder, Chendi Shen, Cunfeng Feng, Sanghwa Park, Jixie Zhang, Xiaochao Zheng
  2. We continued discussing Sanghwa's SPD simulation, this time focusing on the correlation shown on p.16 of last time's presentation, see spd_update_jul13.pdf. Discussions:
    1. Jianping argued this correlation might be within expectation
    2. We need to consider modifying LASPD design because now the simulation shows 120 segments to be the minimum. Options:
      1. Two LASPD, one thin and one thick;
        Use 120 segmentation but avoid the use of FMPMT. We will talk to Raytum people to see if they can design a light guide system that is better than our current design and with high photon collection efficiency.
  3. Beam test preparation: Need to figure out the available of the Beijing IHEP test beam. Jixie will look into the details of the Fermilab test beam.
  4. Chendi: doing cosmic test of THU2 module and will report next time.
  5. Ye Tian (Syracuse) reported update on the Ecal simulation, see ECAL_08032017.pdf. Last report was on 6/29 (see below). Discussions:
    1. p.5-6: showing preshower cut on electron and pion spectra. This cut can probably be optimized to increase electron efficiency.
    2. Because using the Etot/p=(mean-3*sigma) last time showed the pion rejection was not high enough to meet the 50/1 requirement, tried the (mean-2*sigma) cut this time. The pion rejection is improved and meet the 50/1 requirement for most of the momentum range, but the electron efficiency is lowered to (75-85)\%. This may still be okay but the cuts need to be optimized to raise the efficiency as much as possible.
    3. Need to understand the cause of the difference betwen the current and Jin's simulations. One cause is that Jin's did not include the aluminum support between preshower and Shower. The new simulation was repeated for no Al, which seem to help with performance, but still is significantly different from Jin's results.
    4. All results shown today are without background. Need to include the background first, then optimize cuts.
    5. After screening the prelead thickness, it appears the 2X0 is still the best value. The performance below and above 2X0 is all worse than 2X0.
    6. Jianping commented the poor performance at the low momentum edge may be mostly due to the small-angle events not covered fully by the module. Ye could add another layer of module to see if it helps.
  6. Xiaochao updated that in June, was informed by ANL that they can no longer continue the Ecal support design work because of the tight budget. Will follow up on this, the budget outlook seems to be better now.
  • 07/13/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Alexandre Camsonne, Chendi Shen, Sanghwa Park, Yi Wang, Xiaochao Zheng
  2. Sanghwa presented her SPD simulation, see spd_update_jul13.pdf. Discussions:
    1. Reviewed a few differences between Zhihong's and the new simulation. The change in the collimator does not seem to be the problem. (p.8)
    2. Zhihong used Wiser for pi0 and now Sanghwa uses Hall D generator for pi0. But Sanghwa did check what happens if using Wiser pi0 and did not see a big difference. So the pi0 generator does not seem to be the problem either.
    3. p.5, left is Zhihong's previous pion rejection vs. segmentation result and right is using Sanghwa's script to process Zhihong's simulation output file, which is similar to the left. So the difference between the two simulations is in the output files, not the processing script.
    4. p.9 is similar to p.5, which are outputs of both FASPD and LASPD with Sanghwa's script processing Zhihong's output files. There, a 240 segmentation and a 60 segmentation for the FA and the LASPD, respectively, seem to satisfy the photon rejection requirement of SIDIS.
    5. p.10 and 11 are FASPD performance with Sanghwa's latest simulation compared to Zhihong's, and the two do not agree. However, the performance of FASPD actually appear to be better with the latest simulation.
    6. p.12 is the same as p.10 and 11 but for LASPD. Now the LASPD is no longer good with 60 segments.
    7. p.6, backscattered spectrum now has the correct unit for the horizontal axis (ref. report on 7/6 above), but is still much lower than Zhihong's.
    8. We discussed what the backscattered particles are. These should mostly be photons from pi0 decay, but (Paul S.) should also have e+ and e-.
    9. p.15 backup slide: looks okay;
    10. p.16 backup slide: Zhihong's simulation (left) shows a correlation between forward and backward energy deposits, while current simulation (right) does not. (Paul S.) at high-E photons from pi0 dominate. Low E (~100MeV) should be mostly electromagnetic background. But there should not be a correlation as indicated on this page.
    11. The next step for Sanghwa is to look into the correlation on p.12, this should not be there and could be a mistake. Will also look into the radial dependence.
  3. Chendi reported that
    1. he has finished THU2 module and has sent the module to a factory to cut the fiber. Then will proceed to cosmic test of the module's light yield.
    2. Both Chendi and Yi Wang will attend the Hadron workshop in Nanjing in two weeks.
    3. Will resume the clear fiber test after the Hadron workshop. Now has clear fiber from Raytum (US), and will request 15m of S.G. clear fiber from SDU (the previous 15m-long fiber was cut for the previous test). As a reminder, the S.G. fiber was tested earlier that showed very short attenuation length. But the laser wavelength used did not match the WLS fiber's emission spectrum, thus needs to be re-tested. There is no Kuraray sample yet, as Kuraray has to wait for other customers to order this type of fiber. No free sample is available.
  • 07/06/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (Syracuse), ... Xiaochao Zheng
  2. Ye presented her simulation of the Ecal performance vs. preshower lead radiator thickness, see 07062017.pdf:
    1. p.2: updated calibration procedure. The difference between calibrated results and without calibration is small (p.6)
    2. p.7-9, the worsening of the energy resolution does seem to be proportional to the prelead thickness. Here simulation was done for prelead of 0, 0.5, 1.0, 1.5, 1.83, and 2.0 X0. None of them seem to reproduce Jin's result (p.10) but our conversation with Jin indicates that his results were from many years ago and were based on very simple setup and assumptions. So probably we should trust the latest simulation rather than his.
    3. p.11: cluster summing dependence.
    4. p.12-13: more plots on prelead thickness and angle dependence.
    5. p.14, p.15, p.20, p.23: electron efficiency and pion rejection for different prelead thickness. It looks if we adjust the cuts to reach about the same electron efficiency, thicker prelead does seem to provide better pion rejection, despite the larger energy resolution. For 2X0, the pion rejection is shown to vary between 20 at 1 GeV/c to 100 at higher momentum. However, the preCDR lists 50/1 to be the require pion rejection.
  3. Sanghwa presented update on the SPD simulation:
    1. Recap of where we are, see solid_spd_Jul62017.pdf. Bottom line is that the segmentation requirement for LASPD is different from Zhihong's result, and that the current x60 segmentation design may not be good enough to provide the required pion rejection (see p.10). There seems to be a mistake in the horizontal axis on the plot of p.8, but this has been corrected, see her updated report below.
    2. Xiaochao thinks maybe we can use two LASPD's, one thin for gamma rejection and one thick for timing resolution. Comparing to building another MRPC (~a few $M), another layer of scientillators costs much less.
  4. Chendi reported that he is working on the second THU module (THU2). No test on the clear fiber yet because he is waiting for the laser lab to be available.
  • 06/29/2017 SoLID collaboration meeting:

  1. Presentation at the SoLID collaboration meeting: SoLID_EC_June2017.pdf
  2. As a late entry, here are documents for E. Rhett Cheek's photon collection simulation work: photon_simulation_2017/
  • 06/15/2017 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Ye (SDU) reported on the 3-bar test now with LASPD as the middle bar: YeTian_06152017.pdf Comments and suggestions:
    1. GEM is fully working now.
    2. For both-side readout the LASPD seems to reach 93ps.
    3. When reading only by one side of PMT, the timing resolution is 198 and 184ps, respectively, for the wide and the narrow-side readout. However this does not yet have position correction from GEM. That is, the events all come from a ~5cm width (LASPD is perpendicular to the top and the bottom trigger bars) and the flight time varies.
    4. With adding the GEM cut, the statistics drops significantly and the timing resolution vs. hit position results seem to have very large statistical fluctuations (although the error bars are not shown in the slide.)
    5. Next step is to apply position correction properly (rather than just applying cuts on the position), and evaluate the statistical uncertainties.
  • 06/08/2017 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Ye (Syracuse) reported on the simulation of Ecal's energy resolution with a focus on understanding the large p2 term for the PVDIS configuration: YeTian_simulation_06082017.pdf Comments and suggestions:
    1. Now using separate calibration for the preshower and the shower, but the main conclusion stays the same as last week: the prelead significant affect the energy resolution. We still have ~5%/sqrt(E) and 5%/E added in quadrature. This, however, seems to be consistent with the LHCb Calorimeter TDR, Fig.3.3 (view here at the top of the webpage). For LHCb, 2X0 was chosen, but this adds sigificantly to the p2 term that may not be acceptable for SoLID.
    2. The next step is to study the pre-lead layer thickness carefully for SoLID.
  • 06/01/2017 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Ye (Syracuse) reported on the simulation of Ecal's energy resolution with a focus on understanding the large p2 term for the PVDIS configuration: YeTian_simulation_06012017.pdf Comments and suggestions:
    1. Looks like the field, the incident angle, and the 2-cm Al support between the preshower and the shower have only small effects on dE/E. But once adding the prelead the p2 term increases significantly to 4.8%. The overall dE/E is larger than Jin's result in the preCDR.
    2. One problem is that Ye is adding energy deposit in the preshower directly to the shower, without separate calibration. Will a separate calibration improve the resolution?
    3. We discussed why there is an overflow of positron's energy deposit in the Ecal. The reason is simple: the process of e+ e- annihilation means the rest mass of electrons pre-existing in the material contributes to the enery deposit. But the overflow should not be large (should simply be the electron rest mass, 0.511 MeV).
  • 05/18/2017 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Ye (SDU) reported on the three bar test: YeTian_threebar_05182017.pdfComments and suggestions:
    1. The three identical bar gives for the reference bar 82ps. This looks reasonable.
  3. Ye (Syracuse) reported on the simulation of Ecal's energy resolution: YeTian_simulation_05182017.pdf Comments and suggestions:
    1. Resolution is fit using p0 (1/sqrt(E) term), p1 (constant term), and p2 (1/E term). The fit for 100 MeV positron looks okay. However, for PVDIS configuration at 25 deg the p2 term is 4.8% which is very large. We wonder where the p2 term comes from and why we did not see this in Jin's and Rakitha's simulations earlier.
  • 05/11/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Ye Tian (Syracuse), Yi Wang, Jianping Chen, Cunfeng Feng, Jianbin Jiao, Seamus Riordan, Xiaochao Zheng.
  2. Raytum photonics sent clear fiber sample to THU for testing. These are plastic samples but Steve from Raytum said these industrial-grade fiber may still have better attenuation than Kuraray or S.G.s. He did not send glass sample because of our need of fiber bending.
  3. Ye (SDU) reported updates on the 3-bar test, see yetian_05112017_threebar.pdf. Comments and suggestions:
    1. The timing resolution is still not as good as we achieved at UVa but this is likely due to the fan-in/out module (Vince confimred that with the fan-in/out the timing would be worse. We did not use fan-in/out at UVa) and the intrinsic resolution of the electronics and DAQ (Jianping calls this "trigger problem").
    2. To move forward, we think Ye has done as much as he could on the current setup. Therefore Ye should proceed to replace the middle bar with the LASPD. The LASPD is currently equipped with the R9779.
    3. Besides timing resolution (LASPD single PMT readout combining with GEM tracking), an alternate goal that can avoid dealing with the electronics' intrinsic timing spread is to determine the photoelectron statistics. Events that hits further away from the PMT readout side will have the lowest Npe and thus the worst timing. Xiaochao did the simulation for this a while ago, see spd/SPD%20simulation%20for%20JLab%20SoLID.html, scroll down to the last figure. If the Npe for the far-end events can reach above 40 or 50, then we should be in good shape according to the simulation. But of course a direct confirmation for the timing resolution will be more assuring.
    4. Ye can position the LASPD perpendicular to the two trigger bars, so the events that cause an output in the LASPD is only in the overlapping region, within a 5cm width.
  4. We discussed what we should expect from Ye (Syracuse) simulation for the 100MeV/c and 200MeV/c (momentum) positrons and pions. Back-of-envelope calculation based on particle detector principles was done by Xiaochao a while ago, see these 4 scanned pages. Simple estimation gives (4-5)%/sqrt(E) for our shashlyk design, but simulation could give different results (any energy) and the EM shower for 100 MeV/c positions may not be the same as GeV-level electrons: ECnote1_p72, ECnote1_p73, ECnote1_p96, ECnote1_p97 (Not sure if anyone can understand these. The methods and equations are referring to two books The Physics of Particle Detectors and Particle Detectors, 2nd edition, which are Cambridge Monographs on Particle Physics, Nuclear Physics and Cosmology No.12 and 26, respectively. )
  • 04/20/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Yi Wang, Jianping Chen, Cunfeng Feng, Jianbin Jiao, Zhihong Ye, Xiaochao Zheng.
  2. Xiaochao was contacted by Raytum photonics. Will request Raytum to send samples of their glass clear fibers to THU for testing. Glass fibers have very little attenuation loss but our special size (no more than 1.02mm in diameter) may be a problem. And glass fibers probably can't be bent at the small radius as plastic fibers do.
  3. Cunfeng reported he has signed contract with a local company to produce Tyvek sheets for one module.
  4. We discussed what the new SDU module should use for the mirror reflection at the fiber ends. Looks like the only option we have so far is the silver-shine. Cunfeng will request samples from the company.
  5. Chendi reported he will be at CERN for the next month so the clear fiber test will be delayed. He confirmed that the THU laser can produce 470nm and 530nm light, which is a good news. We need to retest Saint Gobain's clear fiber, and test Kuraray's and Raytum's samples at this wavelength range (both values).
  6. Ye Tian (SDU) reported JLab test lab's status on the THU1 module: YeTian_4-20_THUmodule_edit.pdf (post-edited by Xiaochao in magenta texts). Comments and Discussions:
    1. We suspected when THU tested the THU module's light yield using cosmic events in 2016, the PMT gain was not well known. This seems to be true. Now Ye has replaced the THU PMT by the SDU#2's PMT whose gain was well characterized at SDU in 2016. The horizontal light yield of the THU module is now ~35, not 96. This has been amended in the (module overview) table above.
    2. THU's output seems to be normal from the FADC integrated spectrum. Observing the individual event, THU showed 2 double-peak events out of 25, see THU1module+SDU2PMT_testlab_screenshot.pngand SDU module showed only single-peak events, see SDU2module+SDU2PMT_testlab_screenshot.png. Both spectra were collected using the SDU#2 PMT. Note that for the SDU#2 module's output, Xiaochao thinks these are all normal signals. When the Npe is low (~50) here, it is normal to see them separated into multiple peaks due to different timing of the scintillating light generation and the speed of the WLS conversion in the fiber, but the timing separation should not be significant (at most a couple to a few ns). Also light speed through 50cm is just above 2ns so the timing separation between the light directly going towards the PMT and the light reflected by the fiber end should be less than 1 FADC channel (4ns).
    3. Xiaochao suggested rotating the shashlyk so it is perpendicular to the two trigger bars.
  7. Ye Tian (Syracuse) presented simulation of the 100 and 200 MeV/c e+, pi+ and proton, see her slides Ecal_4202017.pdf. JP and CF questioned why the electrons do not seem to lose all energy in the shashlyk, but the total energy loss of the electrons is not obvious from the 3D plot (Edep vs. z distribution). Xiaochao suggested making plots in the same form as page 12 and 13 of Rakitha's report on 2016/03/10.
  8. Xiaochao found this NIMA article on the MINOS detector:, a sampling detector made of steel and scintillators. Here, "Epon 815C resin with Epicure 3234 teta hardener (in a six to one ratio by weight, respectively) was used to bond WLS fibers into scintillator strip grooves in all modules and to bond the reflective-tape mirrors to the far ends of WLS fibers in near detector modules", and "3M 850 aluminum-coated Mylar reflective tape, 1.27 cm wide, was used to cover fibers in scintillator grooves and as mirrors to terminate the far ends of WLS fibers in near detector modules". This is something we could try. They also used clear fiber to guide the light, but did not mention the exact vendor/model info for the connector used.
  • 04/13/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Alexandre Camsonne, Xiaochao Zheng.
  2. Xiaochao requested Saint Gobain to send 15m of BCF98 multi-clad sample to THU.
  3. Chendi presented test on the WLS fiber's mirror painting and Saint Gobain BCF98 single-clad clear fiber's bending and attentuation losses:shenchendi_20170413.pdf. Comments and Discussions:
    1. The laser wavelength of 420nm does not match the Y11 or BCF91A emission peak. Ideally should use 500nm, see more discussions below.
    2. Silver shine provides 30% increase in light yield for a 50cm fiber. This is lower than expected, but better than SDU's aluminum plating.
    3. BCF98 does not show bending loss down to a bending diameter of 2.7cm. As a reference, Kuraray's website shows no bending loss for clear PSM above a diameter of (4-5)cm. -- good news for us, but we need to confirm for Kuraray's PSM.
    4. For the BCF98's attenuation length study, we questioned the uncertainty in each number, in particular the gain after the pre-amp is removed (can we trust the preamp gain to be exactly 100?). From the results on slide 22, if we take the 0.56^x from the fitted results, the attenuation length is -1/ln(0.56)=1.72m. This is much shorter than expected. In addition, there seem to be at least one problem: the first 4 points and the last 3 (5,7,9m) do not seem to follow the same log() curve, as Xiaochao reproduced here: bcf98_atten_fit.jpg (the two lines are to guide the eye, with attenuation 1.33m and 1.72m, respectively).
    5. Saint Gobain's fiber brochure shows the BCF91A emission peaks at 500nm. For BCF98, the attenuation (from a graph) is 2.1 dB/m at 400nm (2.1m), 1 dB/m at 420nm (4.3m), ~0.4 dB/m at 500nm (10.9m), and remains at about 0.3 dB/m up to 600nm (14.5m). So Chendi's result at 420nm of 1.33-1.7m is shorter than the specifications at this wavelength.
    6. As a reference, here is a spreadsheet from Kuraray on the clear fiber attenuation loss, and the attenuation length calculated from it. Here "S" stands for s-type that is supposed to have better mechanical (bending) properties below a bending diameter of 4cm, but has shorter attenuation length so we should use the non-S type: kuraray/CLEAR-PSM & MS_Loss.xls. For the Y11 emission range of 450-550nm, the attenuation length is 9m at 450nm and increase to 15m at 500nm, >20m at 550nm. These are longer than BCF98's specifications. Data are not available below 450nm but if we simply extrapolate linearly, at 420nm it could be as short as 7m. (also, our previous discussion on this was on 4/23/2014
    7. On a side note, here is an article on the Y11 WLS fiber attenuation study done at UVa by the HEP group, that shows it is 4-5m for the fast component and 9-10 for the long component, as opposed to the commonly believed number of 3m:
    8. To-do's for Chendi:
      1. If possible, setup laser at a wavelength between 450 and 550nm to match the Y11 emission peak.
      2. For bending loss test, evaluate the error of the measurement (is it sqrt of Npe? If yes, the measurement is 10% which is not precise enough). Increase laser intensity by factor 10 and repeat test, to decrease the relative uncertainty to 3%.
      3. For attenuation loss measurement, (1) need to confirm the single p.e. position without the x100 preamp. One way to do this is to repeat the 5m measurement both with and without the preamp; also (2) need to evaluate all uncertainties of the measurement (error in Npe from the fit, error in single p.e. peak, etc). For the error in the single p.e, can take multiple peaks (as on slide 2), calculate single p.e. from each pair and take the variation of the multiple results as the error. (3) Fit should be exponential: I=I0*exp(-L/L0) where L is the fiber length, I0 and L0 are the fit parameters and L0 would be the attenuation length.
      4. If after checking everything we still get less than 2m for BCF98, need to contact Saint Gobain why this is the case.
      5. Wait for Saint Gobain's multi-cladding BCF98 sample and repeat the test (from Kuraray information, no difference is expected between single- and multi-cladding for clear fibers);
      6. Wait for Kuraray's clear PSM samples and repeat the bending and the attenuation test to see if they are consistent with the vendor specifications.
  4. Jianping raised the question again why the plastic fiber's attentuation is so much worse than the glass fiber used for the polarized 3He target. Xiaochao will write to Kuraray to inquire on this.
  5. Ye (SDU) reported on the test lab status, see YeTian_sdu_4-13-2017.pdf
    1. Time-walk correction for the 3-bar test: Previously the missing correlation between TDC and FADC integral turned out to be due to a mismatch in the data stream. After correcting this, now can see the correlation and do a linear fit. However, the fit is for "TDC(top bar, left)-TDC(middle bar, left)", etc, where the "TDC middle bar, left" is used as the reference start/stop time. This does not work for the PMTs on the right. Will write to Vince to see exactly how the timewalk correction is done.
    2. Still debuggin the THU module. Switching around the PMTs, etc. Jianping suggest optimizing the test condition first (gain? threshold...) beore drawing conclusion which part of the module is problematic.
  6. Ye (Syracuse) continued working on the IHEP test beam simulation, but need to rebuild the module and tune the code.
  7. We briefly discussed the Ecal support meeting yesterday, see minutes SoLID_EC_SupportStructure.html#20170412. Based on today's discussion for reevaluating PVDIS acceptance, Xiaochao will ask Vic to do the PVDIS super module layout before the SIDIS ones. Jianping questioned again whether we can have "tapered" module for SIDIS LAEC. Need to keep this in mind.
  • 04/06/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Alexandre Camsonne, Xiaochao Zheng.
  2. SDU: available material (see MaterialList-20170406.xls) enough to assemble 2 more modules. Then need more paper. Contacting a vendor for Tyvek now. If doesn't work, will make more paper. Plan to finish the current module then assemble more in the summer.
  3. Ye (Syracuse) presented simulation for the IHEP beam test: Ecal7clusterSimu.pdf. The modules included 2cm preshower, 2cm aluminum as module endcap (between preshower and shower), followed by the shashlyk. Comments and suggestions:
    1. positron response seems to be consistent with the 20% sampling ratio;
    2. pi+ response is difficult to interpret: if I use simple dE/dx value from PDG (taking average between C and H), I got pi+ would lose 0.68MeV per layer in lead and 0.5MeV per layer in scintillator. This means 100 MeV/c pion (energy 177 MeV) will lose all its energy and 200 MeV/c pion (energy 244 MeV) will lose also just about all its energy (more so when dE/dx increases as the pi+ slows down).
    3. proton seems to be reasonable because proton likely lose all its energy in the 2-cm aluminum.
    4. Xiaochao suggested plotting Edep in all layers, including 2cm preshower, 2cm Al, and the 200 layers each of lead and scintillator, to see if they are as expected. (Positron should develop shower at about 1/3 depth of the shashlyk, pions should exhibit the Bragg peak, and protons should lose all energy in the preshower and the aluminum.
    5. Once the single-particle simulation is done we can proceed to the 1E3 electron bunch case.
  4. Ye (SDU) presented test lab status: YeTian_4-6.pdf. Comments and suggestions:
    1. GEM DAQ is still being worked on.
    2. electronics' timing resolution seems to be already ~150ps. Xiaochao thinks that's too slow. Electronic-only dt should be below 70ps (as we saw at UVa).
    3. for Timing test, TDC vs. 1/sqrt(integrated FADC) does not show any correlation. Xiaochao thinks maybe the threshold is too high; Could make 1D plot instead of 2D. Ye (SDU) thinks maybe the decoding is not correct, maybe there is a mismatch between FADC and TDC events.
    4. suggest plotting single-event FADC spectrum for the THU shashlyk module, to demonstrate multiple peaks per event that may have been the reason of too high rate during the beam test. (current slide shows 50 events per slide, can't tell which event is which).
    5. Ye (SDU) will also make scalers working to demonstrate the high rate from the THU module that we saw during the beam test.
  • 03/30/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Ye Tian (Syracuse), Jianbin Jiao, Chendi Shen, Cunfeng Feng, Jianping Chen, Alexandre Camsonne, Xiaochao Zheng.
  2. THU: could not do any laser-related test because the lab was occupied by another project.
  3. SDU purchased 500m of S.G.'s BCF98 clear fibers and will send samples to THU for testing. Xiaochao contacted Kuraray for clear PSM fiber samples, or possibly purchasing for a small amount (below their typical minimum quantity).
  4. Both THU and SDU groups have enough material for the module they are currently assembling. There are more lead layers but not enough WLS fibers or paper layers for additional modules. Both groups please check exactly how much more material is available and if there is any available funds for purchasing more material..
  5. JLab test lab status:
    1. FADC is working but time-walk correction is not. Ye (SDU) did not find any correlation between ADC and timing. Ye (Syracuse) will help looking into it.
    2. Not sure what the GEM DAQ status is.
  6. Discussion for the Bejing IHEP test facility:
    1. Both E2 and E3 seem to be suitable for testing our modules. But the June/July test period will be too soon. We hope to test the modules perhaps later this year. Need to figure out how much more material is needed to assemble additional modules (see above).
    2. Ye (Syracuse) will do simulation to study the module response for (1) E3 line: 100 and 200 MeV/c positrons, pion+'s, and protons (positron rate is high enough for testing only at these low momentum settings); and (2) E2 line: for 1000 and 2000 electrons of momentum 2.5 GeV/c incident on the module within a 10ps pulse. Not sure if the energy resolution will scale also with the number of electrons.
  7. Some detector layout discussion that we should followup: 1) need radial coverage for the updated magnet design (Zhiwen), then send this to Vic for super-module design; 2) need to make sure the clear fiber length works for both SIDIS and PVDIS.
  • 03/23/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Jianbin Jiao, Chendi Shen, Cunfeng Feng, Yi Wang, Zhihong Ye, Seamus Riordan, Xiaochao Zheng.
  2. Chendi reported the updated light yield test of BCF91A vs. Y11 and with and without silver-shine paint and SDU's aluminum plating at the end of the fiber, see his report shenchendi20170323.pdf. Notes, main conclusions, and to do's:
    1. A 420-nm filter is now added at the laser to select 420-nm light. The fiber light yield is 14 for both BCF91A and Y11, but the Npe with silver shine are only 17 and 16 for BCF91A and Y11, respectively. SDU's sample with the aluminum plating show the same result as the fibers without silver shine. Tests were also done for SDU's samples (with the Al plating) and wound about a 6-cm diameter cup, which shows Nphe=4 for BCF91A (-71% loss) and 11 for Y11 (-15% loss).
    2. The gain from silver shine is much less now, but the laser setup is almost the same as last week. This is puzzeling. Could the silver shine be sensitive for a specific wavelength range? (a quick google search found this datasheet for Italian silver shine 415001 but it does not provide reflectivity or wavelength data: silver_shine_m415001_e.pdf).
    3. Repeat of last week's minutes: note that ATLAS TDR measured the bending loss of WLS fibers, see: Fig.5.24 where the loss was measured with bending diameters of 5, 10, 15 and 20 cm.
    4. To do 1: Yi Wang suggested Chendi to polish away the aluminum plating of SDU fiber samples and retest. Meanwhile Cunfeng commented that the plating quality is really not good.
    5. To do 2: Xiaochao suggested measuring the light yield for several bending radii, from 4cm to 20cm (or large enough such that the loss is zero for BCF91A), such that we can confirm the ATLAS result but also more specific to the SoLID conditions.
  3. Ang Li reported SDU progress, see fiber_reflector_test_20170323_AngLi.pptx. Notes, main conclusions, and to do's:
    1. Re-did the preshower light yield test with the tile wrapped in Tyvek. The yield is higher than before at 27-32 for Y11 and 15-18 for BCF91A. The Y11 yield is still a factor two lower than UVa's best test. Xiaochao noted the Tyvek wrapping is still very loose. At UVa, we cut the Tyvek to hexagon shape and make sure it is flush (touching) the Preshower tile.
    2. Fiber routing in Ang LI's test is the same as UVa's: Two fibers, 2.5 turns each.
    3. Note the ADC spectra in the slides are not pedestal-subtracted and the MEAN value is not the Npe value. Ang used the known PMT gain (again, measured with an LED) and the known pedestal position to calculate the Npe for each test.
    4. Although Ang's Npe is still low, the absolute yield for the preshower isn't important in this test. Mostly, we want to confirm that for preshower, BCF91A's yield is lower than Y11's. (UVa found BCF91A yield to be about 55% of Y11, see minutes of 5/14/2014). And this is confirmed in today's and the 3/2 reports. Using today's report, compare 15-18 to 27-32 we see an average ratio of BCF91A/Y11 = 60% . This is in good agreement (within uncertainty) with the ATLAS result at the bending diameter of 9cm (see link above) which shows a ratio of ~70%.
    5. After SDU Ang Li's report on 3/2 (Preshower light yield wrapped directly in black tape), Xiaochao asked Rhett (the UVa undergrad) to run his light absorption code with the reflectivity set to zero (black tape). Rhett found the light collection dropped to 40% of the value using a refletivity of 0.90 (Tyvek). So if using UVa's best result of 90 p.e. this means we expect about 36 p.e. for the test with only the black tape. Ang's result on 3/2 was 20, lower than this. But it can be explained by other non-ideal test conditions such as extra fiber length, the use of optical grease, etc.
    6. Ang Li also tested another reflective material for the shashlyk. It's called MCPET which is a reflective paint used in lamps. It is supposed to have a higher reflectivity than Tyvek or printer paper. Using 2 shashlyk scintillator sheets and a PMT side-readout, it was found MCPET gives 13 p.e. while printer paper gives 11 p.e. This is a small increase. Also MCPET is much smoother (less friction) and may introduce assembly difficulty. So we need to look at more factors: friction coefficienty, light yield, and cost.
    7. Xiaochao noted that Rhett's simulation for the light collection, reported during the 3/5/17 collaboration meeting EC talk, shows that the gain in the light yield is at most "linear" with the increase in the material reflectivity, which means a 5% better reflectivity will result in a 5% gain or less in the light yield. This gives us a tool to judge what is the best way to increase the final light yield taking into account the limited manpower and test resources we have.
  4. Discussion about Saint Gobain vs. Kurary fiber:
    1. Received updated quote for the S.G. fibers. Now clear fiber at the shower length need is $1.25/m from S.G. vs. $1.64/m from Kuraray; WLS fiber at the shower need is $1.80/m from S.G. and $2.59/m from Kuraray.
    2. For Kuraray, the quote is 20% less than the April 2013 quote but this change is mostly due to the currency exchange rate, see JPY-USD-5y-historical.png
    3. The performance of WLS fibers has been tested extensively by ATLAS, ALICE and LHCb. Overall, Y11 has better mechanical property (less bending loss), better fiber-to-fiber consistency, and better radiation hardness (all are linked to this minutes, just to a search...). Y11 is clearly prefered performance-wise, but due to its cost, BCF91A seems to be still a better choice for the Shower.
    4. On the other hand, there has been no tests on the clear fiber because no LHC experiment needed to guide the light far away. We need to test the light transmission for clear fibers (at 2m and 5m lengths) and the bending property. Because when we route the clear fibers out of the magnet, they will be bent multiple times and we need to figure out the minimal bending radius. Xiaochao suggested Chendi to do this test because his fiber test setup can be used with minimal modification.
  5. JLab test update (by SDU Ye): GEM is being worked on and the FADC is working. Xiaochao suggested start doing the time-walk correction and see what timing resolution we can get for the 3-bar test, then can try to combine timing with GEM positioning information.
  6. At the end of the meeting we discussed the Beijing IHEP test facility.
    1. Jianbin's slides on the test facility:ihep_Hall10_testbeamInfo.docx.
    2. We are focusing on the scattered electron test beam with fixed conditions: produced at a 41-deg angle, with electron momentum 200MeV/c. There is a Cherenkov for PID and a good momentum determination. Note this is DIS with xbj=0.057 Q^2=0.245 W^2=4.951.
    3. With a 15-cm Be target, a rate of 1 event/10min is observed. A reasonable measurement of the energy resolution requires a few thousands of electrons. If we aim for such statistics within a day, we need a rate of (2-3) electrons/min. A copper or lead target can be used. However at the 15-cm thickness they will become a total bremstrahlung radiators so will it work at all?
    4. A quick calculation shows for the 15-cm Be target (0.48X0) the x-sections are: pi= 908.166 e= 177.899 pi/e=5.105.
    5. Quick calculations on the Edep in the scintillator indicates that the pions may induce a higher signal than electrons at this low momentum. It is crucial to use the Cherenkov to reject those pions and keep the contamination at an acceptable level.
    6. There are still some questions about Jianbin's slide (pion momentum not consistent with electrons) and we will continue working on that. Here is a full document (in Chinese) for the test beam: 北京中高能标准粒子试验束流装置.pdf.
  • 03/16/2017 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng (short time), Zhihong Ye, Seamus Riordan, Xiaochao Zheng.
  2. Chendi reported the light yield test of BCF91A vs. Y11 and with and without silver-shine paint at the end of the fiber, see his report shenchendi20170316.pdf. Notes, main conclusions, and to do's:
    1. The laser used is a wide-band one with wavelength 420-1100nm. This may affect the test result given the dependence of the attenuation length on the wavelength.
    2. There appears to be NO difference in the light yield between Y11 and BCF91A. This is consistent with the LHCb Calo TDR (page 10, BCF91A vs. Y11(250)MS), ours is Y11(200)MS and has slightly less absorption than the (250). Quote from LHCb: "A comparison of Y11 and BCF91A multi-clad fibers has shown that Y11(250) double-clad S-type fiber from KURARAY [18] and BCF91A from BICRON [19] give about the same light yield, but that the Y11 S-type has better mechanical properties [20]. The BCF91A fiber has less mechanical stability against bending at small radius. Also, from a comparative study it has been shown [21] that the signal from Y11(250) MC is faster than from BCF91A fibers, and that it fulfills the timing requirements. " (view this on the TDR html page here:
    3. Note that ATLAS TDR measured the bending loss of WLS fibers, see: Fig.5.24 where the loss was measured with bending diameters of 5, 10, 15 and 20 cm.
    4. The light yield with the silver shine at the end increase by about 45%. The positioning of the laser w.r.t. the fiber is shown in this file: location of laser.pdf. Because the laser is very close to the mirrored end of the fiber (compare to the 3m attentuation length), the 45% should be a good estimate of the silver shine's reflectivity itself. However, the laser wavelength is very wide so there could still be difference to expect if we repeat the test with a narrow-width laser close to the actual scintillating light
    5. To do 1: Repeat the test with a green/blue laser.
    6. To do 2: Continue testing with fiber samples from SDU (without plating and with aluminum plating at the end).
  3. Discussion about Y11 vs. BCF91A: -- note this has been updated on 3/23/2017
  4. Ye presented the test lab status: DAQ/CODA is working, but not FADC or GEM. Here is a report on the 3-bar test setup: 3-16-2017_threebar.pdf. Comments:
    1. The 3 identical-bar (3 Eljen 5x5x30cm bars from UVa) setup is working. Preliminary fitting shows ~200ps for the setup. However, Jianping questioned whether fitting only the "tip" of the peak is a valid approach. The RMS of the whole spectrum is 11 channels or 365ps (35ps/channel).
    2. The UVa cosmic test record can be found at /2015-test/SoLID EC Detector Test 2015.html#20150115, including raw "T spectrum" that shows (280-320)ps sigma value (whole spectrum sigma), which is comparable to this week's report of RMS = 11 channels.
    3. To do 1: Make FADC working and apply appropriate time-walk correction;
    4. To do 2: Make GEM working.
    5. Then can proceed to replace the middle Eljen bar by the LASPD.
  5. Still need to fix/diagnose the THU shashlyk module
  6. We also discussed briefly on the support structure. Paul and Vic asked if we can use tungsten for the preshower radiator but Jianping said it's likely to be too expensive. If we use Y11 it will have some effect as well because Y11 can have smaller bending radius (LHCb TDR showed no loss even at a bending diameter of 2.5cm). For the preshower can consider drilling a small hole at the center for mounting but the effect of the hole needs to be simulated. Jianping also mentioned Ye Tian (SYR) is taking over the simulation work from Rakitha. Once she reproduce Rakitha's latest results, can move on to the end-to-end simulation of the modules.
  7. Received updated quote for the SPDs from Eljen: Cost now is quote_SPD_Eljen_March2017.pdf$96,050.
  • 03/09/2017 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Alexandre Camsonne, Xiaochao Zheng.
  2. We talked about the status of the test-lab cosmic test:
    1. Xiaochao moved three trigger bars (Eljen 30x5x5cm) and 4x Hamamatsu R9779 (Assembly model H10570) PMTs to JLab on Sunday. Ye and Ye will try to setup the three bar test. Two more H10570 are already attached to the LASPD used in the beam test.
    2. CODA still not work. Luckily Alexandre was at the meeting. THe goal is to have Alexandre help us with the DAQ/CODA setup ASAP and hope to fix it within the week.
    3. Ye(SDU) opened the THU module and we talked about replacing the PMT. NOte: THe PMT is always attached to its corresponding base. There is a spare R11102 that can be used.
    4. Do not have (fresh) optical grease to use at JLab. Xiaochao will send some. For starters can also just run tests without the grease.
  3. Chendi talked about:
    1. Talking to a few companies (Kedi is one of them) about cutting the fiber bundle after inserting them to the shashlyk;
    2. Would like to test the silver shine paint with SDU's plating method. Cunfeng will send a few plated samples to THU (maybe after re-plating). Chendi will present the test design next week for discussions, before setting up the actual test.
    3. Have 500m S.G. BCF91A multi-cladding fibers on hand (cost was about 10WYRMB). Contacted Kuraray but no response. Xiaochao will help work out the contact information.
  4. Cunfeng mentioned the second batch of WLS fiber end plating (a company did it) didn't have as good quality as the first time. Suggest cutting/polishing the ends and sending the fibers back for re-plating.
  5. Xiaochao talked about fiber quotes. Latest was about $2/m for S.G. and $2.5/m for Kuraray. Still waiting for a full quote of clear fibers from Kuraray and an explanation from S.G. why they increased from $1 in 2014 to $2/m now. If this does not change then we'd better go with Kuraray for all our fiber needs (both WLS and clear).
  6. Jianping mentioned before writing the MIE we are asked to update the pre-CDR with the director's review responses included. This updated pCDR will be sent to the committee for review.
  • 03/05/2017 SoLID Collaboration Meeting

  1. Presentation: SoLID_EC_Mar2017.pdf
  2. Discussed with Paul R. about the support design:
    1. Vic now suggests two support planes for the shashlyk (no longer cantilevering).
    2. Front of the shashlyk needs a small hexagon aluminum (maybe 4mm) attached to the front plate of each module, which will be placed in a "swiss-cheese" like support plane.
    3. Preshower: two options - (a) glue a small hexagon 2-mm thick plastic to each preshower module and we can screw these plastic piecs to a 2mm support plane. Pro: not destructive to preshower itself; Con: need to make sure the plastic hexagon does not slide against the preshower (since they do not contact each other due to the light-tight wrapping material in between; (b) drill a small hole in the middle of each preshower and screw them to the Shashlyk's front hexagon aluminun plate. Pro: less structure; Con: destructive, may not ensure light-tightness.
    4. Paul will look into LHCb's preshower support on page of LHCb's ECal TDR.
    5. Regardless of preshower design, need to ensure support of the fiber ends out of the preshower.
    6. SPDs: need design
    7. Xiaochao will send a few fiber connectors to Paul.
    8. Short term goal: drawings for a prototype support system (6+1 cluster) for both shashlyk and preshower. Then we will figure out the funds to make this for the Fall beam test in Hall C.
  3. Discussed with Jay and Whit on the cabling/fiber route:
    1. FA-Shower/PVDIS: about 1m within the magnet, then 40-50cm across holes on the endcap; PMTs will be on the outside (downsteam in z) of the endcap.
    2. FA-Shower/SIDIS: up to 60cm across holes on the back side of the endcap; PMTs will be on the outside (downsteam in z) of the endcap.
    3. FA-Preshower/PVDIS or SIDIS: radially to the side, place PMTs on the outside (radial) of the magnet endcap.
    4. LA-Shower+Preshower/SIDIS: either upstream or downstream, PMTs will be on the outside (radial) of the magnet, total length will be 3.5m for upstream or 3.25m for downstream. For downstream cable path see page 7 of Sean's talk SoLID%20-%20March%202017%20-SEAY.pdf (light blue paths) Pro: possible larger bending radius; Con: fight with other detector cables. For upstream cable path Pros: less crowd with other detectors but possible interference with target or other parts; Con: sharp bending radius (90-deg to upstream).
    5. Hamamatsu's mu-metal shields work up to 50G (see Hamamatsu High Energy handbook). Jay assumed an upper limit of 5G which is quite safe.
  • 03/02/2017 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Sanghwa Park, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Jianbin Jiao, Ang Li, Yi Wang, Xiaochao Zheng.
  2. Ang Li reported SDU test on the Y11 vs. BCF91A fiber light yield using preshowers. see Comparison_Preshower_TwoFibers.pdf. Summary and comments:
    1. Results show Y11 yield is (50-75)% higher than BCF91A. UVa's result was Y11 is higher by about a factor two.
    2. The preshower tiles were wrapped in black tape directly (no Tyvek or paper on the surface) so the overall light yield is low, at about 20 p.e using Y11, compare to UVa's best result of 90 p.e.. With only Tyvek between the two preshowers, there can be cross talk between the two. Xiaochao suggested for the next tests, wrap each preshower individually, and wrap it allover in Tyvek or printer paper first, then wrap with black tape.
    3. The single p.e. peak was determined with an LED (not shown in slides), from which the raw data spectra were converted to Npe distribution.
  3. Chendi asked what WLS fiber should be used for the THU2 module. Answer is to use whatever he has, because the fiber is still been researched. The THU2 module will use Kedi new scintillator and powder-painted lead plates. Chendi reported he is going to study different ways of inserting the fiber. THU1 was assembled by inserting fibers in groups, this time can try inserting them individually.
  4. Sanghwa reported still working on debugging the SPD simulation code.
  5. Both Ye at JLab: need DAQ/CODA to work, also are waiting for Xiaochao's scintillator bars to setup the 3-bar timing test.
  • 02/23/2017 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Sanghwa Park, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Xiaochao Zheng.
  2. Sanghwa reported on SPD simulation status, see SPD_study2.pdf. So far, cannot reproduce the SPD segmentation result Zhihong did last year. Using Zhihong's simulated files and macros does reproduce his result, so either the simulated data are different or the macro is different. Need to debug what's going on.
  3. The two Chinese groups are just back from their winter break.
  • 02/16/2017 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Jianbin Jiao, Xiaochao Zheng.
  2. Our Chinese groups are back! Suggest SDU group to test Preshower light yields with Saint Gobain's and Kuraray's WLS fibers, and see if can reproduce UVa's results from 2014 that Y11 produces twice photoelectrons as BCF91A. One possiblity of having a different result in Preshower vs. Shower is that, the fibers are bent in the Preshower. So if Y11 has significantly better bending property than BCF91A, it could give higher light yield for Preshower but not Shower. If the bending properties are similar, though, then a higher light yield can only be explained by the fiber's intrisic light conversion (absorption and emission) efficiency.
  3. Xiaochao reported on:
    1. Estimate of the space needed for Ecal: Roughly 22cm behind Shashlyk (10cm for the support structure, 10cm for bending clear fibers, and 2cm for routing all clear fibers out). For Preshower we do not have a support design yet. Xiaochao made a sketch of preshower support: Preshower_support_sketch.pdf, will send it to Paul so he can discuss with Vic tomorrow.
    2. ECal photon-collection simulation by Rhett Cheek, see his report from last semester: PHYS_3992_report_Rhett_Cheek.pdf.
      1. The simulation starts with N of scintillating photons with random initial position and direction, track their trajectories until they are lost or absorbed by the WLS fiber.
      2. The report studied the dependence on the reflectivity of various surfaces (separately for total-internal reflection case and non-total-internal reflection case.)
      3. In the upcoming week he will work on adding the scintillator attenuation length. Attenuation length of various scintillators have been studied and recorded at the 2016/4/8 meeting. However, a closer look reveals that the attenuation length can depend on the wavelength for scintillators. We found a paper to describe this dependence: 1-s2.0-S0168900205018310-main.pdf. Rhett is using the fit from this code for his initial calculation. Of course, the fit can be easily replaced by a constant value if desired.
      4. For the longer term (1-2 months) he will study the uniformity of the light absorption efficienty. Will also make the code more user-friendly.
    3. Updated cost estimate: Cost increase by moving the production from Russia-IHEP to China is about $300k. However, the HV total cost decreased by about the same amount so hopefull overall cost will remain the same as pCDR. Xiaochao also sent out quote request for the fiber, PMT, and SPD scintillators but have not heard back from these companies yet.
    4. needs SPD simulation update from Sanghwa. At the Tuesday simulation meeting Sanghwa mentioned she will work on this early next week.
    5. One SiPM preamp has been assembled but we are holding the SiPM test for now.
  4. Ye reported on the status of the detectors: moved to test lab this week, need suggestions on how to setup the cosmic test.
    1. Xiaochao will ask VInce for a sketch of how the cosmic test at UVa was setup. Followup: sketch by Vince UVA_GEM_Test_Stand.pdf, additional pictures can be found at UVA_GEM_test/detector_stand.png, UVA_GEM_test/GEM_stand.png, and UVa's test page dated 2016/8/29.
    2. Mark is away this week. Jianping suggested waiting for Mark to come back to start connecting the cables, setting up computers, ec.
  5. We plan to run another round of beam test in Hall C in the fall. However, it is unlikely we will have any momentum selection for the particles. Meanwhile, we should try to find test beam also in China, preferrably an electron beam with known energy. Wang Yi from THU has done MRPC tests using test beams at the Chinese IHEP. We will work towards that direction for the shashlyk test. There are test beams elsewhere (Fermilab, SLAC, Mainz) but we probably do not have the manpower to work there.
  6. Jianping suggested us to continue looking for small companies for fiber development.
  7. The workshop this summer will be at Nanjing University.
  • 01/26/2017 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (SDU), Xiaochao Zheng, Jianping Chen, Seamus Riordan, Zhihong Ye, Lorenzo Zana
  2. Lorenzo reported on radiation estimate behind the ECal: zana_SoLID_EC_weekly_jan26_2017.pdf.
    1. page 2 is looking from the back of SoLID.
    2. page 3 shows the radiation in 1MeV-n-equivalent at the plane behind the shashlyk modules. Most has 10E13 1MeV-neq/cm2. LHCb tracker upgrade report tells us that for SiPM to work at this level of radiation, probably need to be cooled to -70C or -80C (see 2015/3/3 minutes for details).
    3. This result significantly disfavor the use of SiPMs.
  3. No meeting on 2/2 because Xiaochao was burned out from traveling to APS/GHP meetings. But Lorenzo sent updated radiation level estimate using better binning, see EC_PVDIS_accumulateed_1MeVnuetron_radiation.png. Most of the region has even higher level than reported on 1/26, now at about (2E+13 1MeV-neq/cm2).
  4. We had a meeting on 2/9 but no significant progress to report.
  • 01/12/2017 Meeting to discuss EC and DAQ:

  1. Participants: Chendi Shen, Ye Tian, Xiaochao Zheng, Cunfeng Feng, Jianbin Jiao, Seamus Riordan, Zhihong Ye
  2. Ye reported on SDU work on SDU#3 prototype, cosmic test done by people locally at SDU: SDU_1-12-2017.pptx. See table above for summary and comparison.
  3. Xiaochao asked Hamamatsu for a few Hamamatsu free samples, then will re-route half to SDU.
  4. Zhihong took a picture of the SiPM readout he has: SiPM_PreAmp.jpg (from left to right: Detector Group PreAmp, Hall-D PreAmp, and the S12572-100C MPPC). UVa's electronic shop can probably handle the assembly should we change the capacitor(s).
  5. Today or tomorrow, Zhihong will send to UVa: 6x of S13360-1350CS, 6x of S12572-100C (3x3mm, 100-um pixel) 2x of S12572-50P (3x3mm, 50-um pixel) both see S12572-025 series datasheet, 4x pre-assembled Hall-D PreAmps, and parts (components and PCBs) that can be used to build 10 detector-group PreAmps. Also see parts list for preamp: SiPM_PreAmp_Components.docx (for detector-group preamp); and MPPC_3MM.xlsx (for Hall D preamp but no PCB).
  6. Elton is also sending Xiaochao one Hall D 25-um SiPM along with two pre-amps.
  7. From CAEN: new product A1702 32 Channel Silicon Photomultipliers Readout Front-End Board.
  • 01/05/2017 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Chendi Shen, Ye Tian, Xiaochao Zheng, Cunfeng Feng, Zhihong Ye
  2. Cunfeng reported some cosmic test results aiming to understand why the shashlyk yield drifted during the beam test: eventRateTemp.pptx. The current conclusion is still that the yield has very little sensitivity to ambient temperature and the observed change during the best test may still be due to change in the test conditions (beam energy, target position, etc.).
  3. We focused on discussions about using SiPM for ECal readout:
    1. Xiaochao contacted Lorenzo on the radiation level behind the Ecal. Lorenzo is still on vacation, but will check when he is back.
    2. Xiaochao contacted Ardavan on his SiPM recommendations.
      1. For ECal shower readout, we expect 1200-48000 photons per pulse (here, 48000 is 2 p.e./layer obtained from cosmic MIP test, multiplied by 600 for shower/MIP scaling, then divide by 20% PMT Q.E., giving 6000 photons for electron signals, then muliply by 8 to account for further prototyping light yield improvement and a range for the electron's light yield spread; 1200 is the electrons's photon yield 6000 divide by 5 which is roughly the e/pi yield ratio obtained from simulation); the photons are roughly spreadout in 100 1-mm dia round fibers. The spread is not uniform, but it's safe to say that all photons will not be concentrated in any of the subgroup of the 100 fibers. For shower readout selection, Ardavan's answers are:
        • The key unknown is the output light’s distribution profile and how non-uniform and random it is going to be.
        • A. If the light output distribution is going to have a relatively small non-uniformity, we can simplistically normalize the output light to the fiber bundle's output area to determine the DR requirement. Since upper linearity/DR limit is determined by photon count per unit of illumination area (and not photon count alone), we have 48000 / 10x10mm = 480ph/mm^2. For a 3x3mm chip, that would be 480 x 9 = 4320ph. So, in this case, I'd recommend S13360-3025PE (3mmx3mm, 25um pixel size, see S13360 series datasheet also contains 50um and 75um's)
        • B. However, if the output light will have a relatively large non-uniformity with some small area receiving the bulk of the output photons, S12572-015P (3mmx3mm, 15um pixel size, see S12572 series datasheet) could be more suitable, considering its 15um pixel size.
        • C. Then, there’s the question of randomness of the output light’s exit angle. This pertains to how much SiPM coverage of the fiber bundle's output area would be necessary, since you’d need to devise a deterministic relationship between the SiPM output and the fiber bundle's output (as input to the SiPM) in order to find the latter based on the former using that correlation. If the randomness is relatively small and you can place the SiPM chip(s) at the right positions facing the fiber bundle’s output, you’d not need full coverage, but if the randomness is going to be relatively large, max. coverage would be preferable... alternatively, you could consider using a tapering lightguide (like a Winston cone) to focus down the fiber bundle’s output light onto the SiPM area if cost/size requirements allow that.
      2. For Preshower readout, we expect 500-6000 photons per pulse (500 is MIP result of max 90-100 p.e. divided by the 20% PMT QE; 600 is probably an estimate for electrons), distributed among 4x 1-mm dia round fibers. For preshower readout selection, Ardavan's answer is:
        • This one is quite simple. For a signal DR of 500-6000ph, S13360-3025PE (same as point A above) would be the right choice.
      3. For SiPM preamp, Ardavan's answer is:
        • We do offer modules for some MPPC products (all with 50um pixels); those come with on-board power supplies and preamps, but we unfortunately don't offer any standalone preamp for sale.
    3. Further discussions among Zhihong, Xiaochao and Cunfeng:
      1. General description of MPPC (from Zhihong): MPPC_Tech_Note.pdf
      2. Zhihong has Hamamatsu's ~50 SiPM (S13360-1350CS, 1.3x1.3mm, 50-um pixel, total 667 pixels, see S13360 series datasheet) and a few S12572-100C (3x3mm, 100-um pixel, see S12572-025 series datasheet.
      3. Zhihong also have two versions of SiPM PreAmp, one from Hall-D which give larger signal output, and one from the JLab detector group which has less noise and is good at single-photon electron detection. The Hall-D PreAmp is good for either S12572-015P/C and S12572-100P/C or any 3x3mm MCCP (with 320pF), and may work for the S13360 series (may need modification, but not sure what yet). The Detector-Group PreAmp also work for S12572-100C or any 3x3mm MPPC, and can work fine for S13360-1350CS but it would be better to replace the capacitor C6 on the PreAmp from 3.3 pF capacitor to 6 or 7pF for 1.3x1.3mm MPPCs- (Xiaochao:) all these look pretty good because it's possible we can use S12572-015P/C along with either preamp for the shashlyk module test. We can possibly use a free sample on the S13360-3025PE combined with the modified detector-group pre-amp for the preshower readout test.
      4. Powersupply needs: SiPM requires ~70V power-supplies with at least 0.1V precision, and the PreAmp requires a regular 5V low voltage PS. The 70-V PS typically cost about $400 for table-top versions that can power up to 10 SiPMs. Here are some links provided by Zhihong: PS used for the SiPM (0~100V) Digi-Key BK1787B-ND and the low-voltage PS to power the preamp: Digi-Key BK1761-ND
    4. Feedback from Carl Zorn: SiPMs these days are much better than when they purchased them for GlueX, and similar to SoLID, saved them the headache of propagating the light through light guide fibers. His suggestions are to contact Elton Smith, Zisis Papandreou (University of Regina), and Fernando Barbosa. Fernando designed most of the electronics for the SiPMs for GlueX.
      1. A quick google search found this website on the GlueX BCAL: URegina's BCal website which pointed me to BCal Readout wiki page. Lots of information there that I need more time to read and digest. -- Xiaochao
      2. From Elton Smith: the above wiki page is outdate. Here is an article smith_lasnpa.pdf that best describe the GlueX SiPM. They are using 12mmx12mm custom S12045(X) MPPCs from Hamamatsu, which is a 4×4 array of 3×3mm2 cells. Each cell is composed of 3600 50μm pixels. The article includes radiation test results. Interestingly, they found the dark current has no dependence on the operating temperature of the SiPM, contrary to what LHCb tracker upgrade described. They did find heating (annealing) the SiPM provides some recovery from the radiation damage, but does not totally reverse it.
  • 12/22/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Zhihong Ye
  2. Ye updated the status on the parasitic beam test, see slides YeTian_2016-12-22.pdf. Highlights and discussions:
    1. Performend HV scan for both the Preshower and shashlyk. The run summary is HV Scan.xlsx.
    2. For Preshowers, can see SPE peak (data included in the spreadsheet). The three preshowers THU SDU1 SDU2 have Npe at 35, 70, 40, respectively. Only the SDU1 preshower has similar Npe value as the UVa test, the other two are both lower. Then the preshower HVs were set to the original values for runs after the Preshower HV scan (after run 457).
    3. The HV scan for the Shower was also done. The 2D plots are shown on pages 4 and 5 (note: vertical is preshower, horizontal is shower, the histogram titles have these two switched). It is relatively clear now that the main peak we see are from low-energy particles and pions (MIPs), and there are very few high-E electrons. It is also clear that we need to keep the HV close to the lower range of the HV scan for future tests. (Although for THU the lowest HV setting used in this scan seems to be too low.)
    4. page 6 showers the scaler counts for cosmic and beam tests. It is clear that the tHU module has abnormal high rate. But not sure exactly what rate is here because we don't know the time. (Ye said it's 60 sec but this needs to be checked in the script.)
  3. To do list for the upcoming month:
    1. Need to run cosmic tests in January. First thing to try is to replace the PMT of the THU module. It is using too high HV and the cosmic rate is abnormal. One of the main goals of the cosmic will be to fix the THU module, so we will see if the PMT is the problem and will go from there.
    2. Xiaochao will get into the beam test data analysis on both the ecal and the SPD's timing resolution and uniformity. With help from Ye and Vince on how to analyze the data.
    3. Ye will focus on his own pion data analysis but will assist Xiaochao.
    4. The beam test setup will be moved into Hall C, possibly in Feb.. Ye will help with the move under coordination of Mark. Then we will need more of Ye's time when the Hall C beam test goes online.
  4. We waved bye-bye to Vince because this is (most likely) his last Ecal meeting. Good luck on the new job and please continue your GDH work!
  • 12/15/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Alexandre Camsonne
  2. Ye updated the status on the parasitic beam test, see slides YeTian_12-15.pdf. Highlights and discussions:
    1. Lowered the calorimeter threshold from -300mV to -150mV.
    2. GEM tracking code is working, good job! (p3, units are mm, if the event has multiple tracks then all are drawn) However, we have a few suggestions on how to make it useful for the analysis:
      1. Ask Danning how the (0,0) point is defined. If there is an opportunity during a hall access, measure how the calorimeter blocks are located w.r.t. center of GEM plane.
      2. Make the plots with cuts on the integrated FADC of each calorimeter module. This way, we can (hopefully) clearly see where each module is on this plot
      3. More questions: for multi-track events, is there at least one track that hits the calorimeter?
    3. page 4: a shift in the shashlyk peak is observed. Jianping suggest adding details such as beam energy, position, target, etc, as the shift can be caused by change in physics event (and not radiation damage).
    4. page 5+6: found out what cause the peak at 2000 for THU module (see last week's minutes). With cutting on this peak, the FADC shows pulses that are less than 10ns wide at the peak bottom. These do not look like physical events because even for scintillating lights, the pulse is about 20ns wide (see FASPD spectra). Need to understand what these are. The main peak at 5000 seems to have normal-width pulses (page 7+8), so does SDU2 (page 9+10).
    5. page 11: the structure seen for large integrated FADC values for SDU2 are caused by saturation points. THese can be easily removed when calculating the integration.
    6. We had a colorful discusson on what could be wrong with the THU module. One observation is the THU module had high rate even under cosmic conditions. But we did not have solid numbers to evaluate this. See to-do items below for further analysis of cosmic events.
  3. To-do list for Ye:
    1. Do a HV scan on all 3 shashlyks, lower the HV 50V at a time, make FADC, integrated FADC, and the 2D (PReshower vs. Shashlyk) plots for each run;
    2. Do a HV scan on all 3 preshowers, increase the HV 50V at a time, make 1D plot for Preshower's integrated FADC for each run. Ideally we should be able to see the single P.E. peak for each. Once the single P.E. peak is clearly separated from the pedestal, that's where we should set the HV from now on.
    3. When doing the integrated FADC spectrum, need to reject events that have 1 or more saturation or underflow points (I believe they are 4096 and 8192, respectively?)
    4. IF we suspect problems with the THU module, based on high cosmic rates, then need to go over cosmic runs and make a summary table for THU, SDU1, SDU2 rates. Include details of the cosmic run day/time, and threshold settings. If the HV setting was different, include them as well. This table can then be used to support statements such as "THU module's cosmic rate is high".
    5. For cosmic runs, pick a few potentially problematic runs (high rates, etc), and make FADC, integrated FADC plots for each preshower and each shashlyk module. This way we can better understand where the high rates come from.
  4. Short-term outlook: Beam will continue until next Wednesday, then comes the X'mas shutdown.
  5. Long-term outlook: There may be additional test opportunity during Hall C's spring 2017 run. Currently the lab is planning for 2 weeks of Hall B and 2 weeks of Hall C during spring 2017 to complete the 12 GeV upgrade milestones.
  6. Next week we will meet at 10am due to Xiaochao's scheduling conflict.
  • 12/08/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Alexandre Camsonne
  2. Ye updated the status on the parasitic beam test, see slides yetian_12-08.pdf. THe presentation focused on 2D plots of Preshower vs. Shower. Discussions:
    1. The HVs are adjusted such that all shashlyk modules shows an integrated FADC peak at about 500 to 6000.
    2. THU shashlyk spectrum (p4) shows a main peak at 5000 but also another higher peak at about 2000. Jianping suspects the 2000 peak is the MIP and the 5000 peak is electrons, but then the 2D spectrum shows a clear separation between MIP and electrons, and it seems to be too good to be true for the current test conditions.
    3. SDU2 module shows a recurring structure at high values. Need to understand what causes this. (followup: Ye found these are caused by 1 or 2 saturation points).
    4. Cutting on the FASPD does not seem to make a difference in the 2D plot (p9 and p10).
  3. To do list: We want to lower the threshold on the calorimeter (currently 300mV) to see if there is any MIP (assuming the main peak is electrons). We also want to increase the Preshower PMT HV to see the SPE peak (see followup below), and to do shashlyk's HV scan both ways to look for more signals. (but see next week's discussion as this will change.)
  4. Follow-up after the meeting about PMT gains and Npe estimations:
    1. Xiaochao calculates that (integrated FADC) = (Npe)*(1.6E-19C)*(Gain)*(50ohm)*(4096/1V)/(4E-9 sec)=(8E-6)*Gain*Npe. Here, we assume Ye simply adds the FADC readings together to get the integrated value. The FADC range is 1V (4096 channels) and the time-sampling is 4ns. The equation does not depend on how long Ye integrates in time, unless if the integration time is narrower than the pulse.
    2. The only PMTs for which the gains are known are for SDU1 and SDU2, both gains measured at SDU: SDU_module_HV.pdf. If we are using a 5E6 gain for both then the main peak at 5000 corresponds to Npe=122, which is likely to be MIP (1 p.e./layer yield). On the other hand, we know SDU#2 should have 80% higher yield than SDU#1 so it's puzzling why their main peak locations are both at about 5000.
    3. All preshower and SPD PMT gains were not measured at UVa. Here are gains according to Photonics' gain chart, summarized by Vince: XP2262_Beam_tests_09Dec2016.pdf. It also contains Preshower light yield results obtained at UVa.
    4. FASPD PMT gain is also unknown but Ye did an HV scan during the beam test, and the SPE peak is clearly identified. Analysis results from Vince: FASPD_HV_gain.eps, FASPD_HV_gain.png, with the location of the SPE and MIP peaks recorded in faspd_mips_HV.txt. Using the SPE location and the integrated FADC equation by Xiaochao, the FASPD PMT gain varies from 2* (at -1850V) to 1.3* (at and above -2000V) of the gain value from gain chart A.
    5. For preshowers, Vince checked the spectra obtained during the beam test. SDU1(CNCS6) and SDU2(Kedi6) preshowers do not show SPE peak see: SDU1_PSH_CNCS6_411_NPE.eps, SDU2_PSH_Kedi6_411_NPE.eps. THU preshower (CNCS5) shows a shoulder on the pedestal that could be the SPE: THU_PSH_CNCS5_411_NPE.eps. IF the THU preshower shoulder is the SPE, then the gain of the PMT is about 0.64* the value from gain chart B and Npe is about 40. A Npe of 40 is lower than UVa results (about 80) but not totally unreasonable, considering the test conditions in the hall and how the preshower was handled.
  • SoLID collaboration meeting: Ecal talk SoLID_EC_Dec2016.pdf focusing on Preshower radiation test preliminary results and the ongoing beam test of all detectors.

  • 12/01/2016 Meeting to discuss EC and DAQ:

  1. Participants: Chendi Shen, Cunfeng Feng, Ye Tian, Xiaochao Zheng, Vince Sulkosky
  2. Ye's update on the beam test: YeTian_12-01-2016.pdf.
    1. Looks like all HV are working properly now and there is no under- or overflow of FADCs.
    2. Scaler is not working and there is problem in the TDC trigger, will need an access to fix (probably on coming Tuesday).
    3. The SDU2 integrated FADC spectrum shows some wierd structure, but is not present for SDU1. See ADC_SDU1_zoomed.png and ADC_SDU2_zoomed.png. Not sure what it is.
  • 11/17/2016 Meeting to discuss EC and DAQ:

  1. Participants: Chendi Shen, Cunfeng Feng, Ye Tian, Xiaochao Zheng, Vince Sulkosky
  2. Ye's update on the beam test: YeTian_11-16-2016.pdf. Problems and to-dos:
    1. Determine HV for all detectors, especially the preshower (due to fixing the light leak) and the shashlyk (due to adding fan in/out and moving the summing module. The summing module has an integrated x4 amplifier so moving it has changed the test condition significantly);
    2. FADC spectra show a lot of abnormalty (worse than last week). Need to check FADCs urgently for all channels to make sure the saturation/overflowing is gone. If not, lower the HV. If that does not improve the spectra, need to understand the problem urgently; Follow up: For the FADC, channel 4000 is saturation (input too high) and 8000 is underflow (input too low). So we may be seeing a lot of underflows due to removing of the summing module (and the associated x4 amplifier).
    3. Check trigger rates. The three preshowers and the three shashlyk modules should show similar rates under beam conditions (except for the difference due to positioning).
    4. There will be no meeting next week (Thanksgiving break)
  • 11/11/2016 Meeting to discuss EC and DAQ:

  1. Participants: Chendi Shen, Yi Wang, Ye Tian, Xiaochao Zheng, Vince Sulkosky
  2. This week's meeting was held on Friday because there was a hall access on Thursday at our usual meeting time.
  3. Ye updated the status on the parasitic beam test, see slides YeTian_11-10-2016.pdf. There were a couple of days of beam after last Thursday's meeting, then the accelerator has been down because of a broken vacuum window on the cryomodules. Have been taking cosmic data during this time. A few problems we discussed from the slides:
    1. The HV has been adjusted for the Preshowrs, but the new data all show wierd saturation signals. These do not look like "normal" saturation signals where the signal should appear "chopped off" at the peak, but the whole event appears at channel 4096. Note that the overflow channel is 8192 so some of the previously observed saturation was actuallly overflows. Ye will try to lower futher the HV for these modules and see what happens. Meanwhile Vince will discuss with the DAQ group on what could cause the FADC to record such signals.
    2. All 3 preshower modules appear to have light leaks. Their anode current are at micro-A level, compare to the FASPD which is using the same XP2262 PMTs but shows a nA current. All 3 shashlyk modules show nA currents as well but their response to cosmics is very different from Preshowers and they also use different types of PMTs and should not be compared directly with the Preshower current. (Although, even if we ignore these differences, the microA/nA difference is probably a good indication of the Preshower lightyield IF we compare their currents with the shashlyks.) Ye will try to re-wrap all Preshowers and see if the situation improves.
    3. The THU shashlyk module is showing a much higher rate than the other modules. Not sure why.
    4. The "Calo SoLID trigger" in the scaler is recording 3x the rate of the sum of all SolID shashlyk modules, not sure why. Last week's slide showed similar numbers though the difference was only 2x. Vince will ask Mark what could be the reason behind this.
  4. Beam will probably be back on next Thursday. So we have many days of cosmic test ahead. If the beam comes back on or before Thursday, we may schedule another meeting to discuss how to best prepare for the beam test, and whether everything has been fixed.
  • 11/03/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Chendi Shen, Zhihong Ye, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Alexandre Camsonne
  2. Ye updated the status on the parasitic beam test, see slides YeTian_11-3-2016_edited.pdf. The slides included Xiaochao's post-editing in blue. Below is a to-do list:
    1. Ye mentioned adding individual modules to the TDC. There is no needto do this until we see the TDC spectra and understand them. (Ye, please email TDC spectra for all available channels. Please also note we do not need or expect good timing from detectors with WLS fiber readouts).
    2. Ye's to-do list
      1. HV for the Preshower needs to be changed: increase PS(THU), decrease PS(SDU1) -- Ye will use the Preshower spectrum to judge whether a good HV is reached
      2. When showing FADC pulses, consider drawing no more than 9 events (9 colors) in one histogram and use multiple histograms to show more events
      3. Need to post/email/discuss all available TDC spectra (Ye please clearly label on the slides what detector the plot is for, and show the TDC resolution (how many ps or ns/channel))
    3. Vince and Ye will work together on the following items -- suggested by X.Z. post-meeting
      1. A rough estimate of the light-yield of each detector. This involves knowing the PMT's approximate gain (or, the HV used combined with the HV/gain chart of each), and the resolution of the integrated FADC spectrum (how many mV/channel)?
    4. Vince will follow up with Mark on the following items:
      1. Still need to add individual modules to scalers. We thought we asked Mark to do this last week, but so far only the summed SoLID Calo is in ther. Not sure if due to miscommunication or the availability of scaler channels.
      2. Looks like the FASPD is in the trigger -- need to remove this
      3. Need to understand the module configuration for the scaler inputs "SBS calo row 1" and "SBS calo row 2". Why are their rates so different? (This will also help to understand our calo rate).
      4. Confirm the solid calo in the scaler is the sum, not a single module.
    5. For beam test, we discussed the importance of book-keeping. Ye and Danning need to make good record of the time/date of change and the run number each change affects. This should be done both in the electronic SBS logbook and a paper logsheet. Vince will design logsheets, print them, and place them in a binder for everyone to use.
    6. For the beam test also need to integrate the analysis software (TDC+FADC+scaler+GEM). Right now each is an individual software. This however is at a lower priority than understanding the data. (Of course, finishing this could facilitate the understanding of the data).
    7. Chendi updated the status at THU: received powder-painted lead sheets and will start assembling THU#2 (BCF91A fiber).
    8. Jianping will be in China for the next two weeks. Also this is the last meeting with the summer daylight saving time on the US side. Next week the meeting will start one hour earlier as viewed from China.
  • 10/27/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Chendi Shen, Zhihong Ye, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Jianbin Jiao
  2. Vince and Ye updated the status on the parasitic beam test of the SPD, preshower, and the Shower. See Ye's slides YeTian_10-27.pdf
    1. THU module arrived at JLab last Wednesday (10/19) and was prepped and installed in the hall on 10/20. Due to time limitation of the access, the 3 modules were stacked on top of each other, rather than in the 3-cluster position.
    2. Ye has been working on the FADC decoding
    3. page 2 and 3, general setup. Concerning page 3, currently the FASPD are not overlapping with the SoLID calorimeter. This needs to be changed (see items below).
    4. page 4 - trigger setup. Note the central box should be a logical "AND" not "OR". More info from Vince (post-meeting): trigger is the "AND" between the scintillator "OR" and the calorimeter modules "OR". The scintillator "OR" is between the front plane of 3 scintillator bars. For the calorimeter "OR", the SBS modules form their own sum, and the SoLID modules (PSH + SH) form their own sum. These are then combined together to form the "OR" of the SBS and SoLID modules.
    5. page 5 - trigger and scaler rates for both cosmic and beam data. Here S4 is the thick scintillator bar behind the GEM and before the SPDs. S5 is LASPD. FASPD is not in scalers yet.
    6. page 6 - rates and other setups. Note that the event rate that can be recorded is only 30Hz according to Vince, not 100k.
    7. page 7 - FADC spectra for LASPD. Looks reasonable. (JP had concern that the data shows the scintillator has a too slow rising edge).
    8. page 8 - First in-beam ADC and fADC spectra for the THU shashlyk module. Looking good!
    9. page 9 - First in-beam ADC and fADC spectra for the SDU #1 and #2 modules. The FADC for SDU#1 is similar. Looking good!
    10. page 10 - TDC spectrum. Resolution is 35ns/channel (per Vince). The spectrum looks reasonable. The "shoulders" on the sides of the main peak is due to the DAQ window and is possibly cut off at channel 4000.
    11. page 11 - to-do list. We suggested to NOT change the HV for the shashlyk modules. Need to understand better the existing data first. (See below analysis to-do list).
  3. It's great we are seeing reasonable fADC spectra from the shashlyk modules. But we summarized a few suggestions and comments on the analysis side for Ye and Vince:
    1. For the shashlyk FADC spectrum, can we clearly label the vertical resolution (in mV)?
    2. Replay more events to show their timing and height distribution.
    3. Integrate the spectrum to get a yield histogram. Equivallently can just make the regular ADC's plot for more events and with the pedestal cut off. With the integrated spectrum, hopefully we will be able to see the fraction of events that deposite all energies in the module and fraction of events that only "graze through" the side of the module.
    4. Use a rough estimate for the PMT gain (using HV) to convert the yield histogram into a "Npe" histogram (Npe="Number of photoelectrons"). This may help us to understand the light yield, as well as what type of particles are entering our detectors.
  4. We discussed a to-do list to implement immediately in the beam test using the restricted access opportunity starting today around 11am:
    1. Confirm with Mark the main trigger is an AND of scintillators and calorimeters -- followup- confirmed.
    2. Rearrange our 3 modules into a triangular 3-cluster shape.
    3. Switch the position between LASPD and FASPD. Keep LASPD still parallel to the main trigger bars (both before and immediately after the GEM). Maximize the overlapping area between the FASPD and the SoLID modules. However, the main triggers bars are not large enough to cover both SBS and SoLID calorimeter modules so part of our 3-cluster will still be outside the scintillator coverage
    4. Now all scintillators are already in the TDC. Will add "sum of 3 preshowers" and "sum of 3 shashlyks" in the TDC.
    5. Add one more scaler module so the FASPD and individual calorimeter modules can be added to the scaler reading.
    6. Followup to the two items above (post-meeting from Mark Jones): There are still a few scaler channels avaiable, will add the "OR" of the SoLID and the "OR" of the SBS calorimeter into the scalers and TDC today.
    7. In the longer term, we should try to move the SoLID modules towards the center of the main trigger scintillator so it is fully covered.
  • 10/6/2016 Meeting to discuss EC and DAQ:

  1. Participants: Alexandre Camsonne, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Jianbin Jiao
  2. For the past month we have been working on prepration for the beam test. Today Ye presented slides on the status, see test_instllation_YeTian_10-6-2016.pdf. So far we have the Preshower, LASPD, FASPD, and 2 SDU shashlyk modules in place. THU's shashlyk still has not arrived. Discussions and suggestions:
    1. page 2: picture on the right shows the fully-wrapped SDU shashlyk modules with PMTs.
    2. page 5: picture of the test stand. The detectors will be at the beam height.
    3. Today's todo's include wrapping the preshower and the SPD fibers, moving all detectors to the test stand, and hopefully start cosmic testing.
    4. Other suggested to-dos:
      1. Putting the two SDU modules on top of each other, and place them on the side of the SBS calorimeter. Also the preshower and the FASPD should cover the shashlyk.
      2. Suggest Mark to put the SBS calos towards the side so we can fit a 3-cluster later on, such that both SBS calo and our 3-cluster can be fully covered by the trigger and the GEM.
      3. Take cosmic data as soon as possible to test light tightness, noise, etc.
  3. Here is Xiaochao's reply on director's review for the EC part: Directors_Rev_Reply_EC_draft1.doc
  • (late entry) 9/22/2016 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Ye reported cosmic test results of SDU1 and SDU2 after painting the sides, see YeTian_9-22.pdf. Coating quality is different. For SDU2 the yield of vertical test decreased by 10% to 383. SDU1 the yield increased by 14% to 254.
  • 9/8/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Alexandre Camsonne, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Yi Wang, Chendi Shen
  2. Chendi presented cosmic test of the THU's shashlyk module. See chendi_shen2016_9_6.pdf or chendi_shen2016_9_6.pptx. Discussions and comments:
    1. page 2 shows a picture of the silver-paint on the fiber ends. Pushed the fibers out first, apply silver paint to both the end and a small section of the side of each fiber, then pulled the fibers back into the module.
    2. page 3: cosmic test setup. There were 3 trigger scintillators. The test was conducted using both 2-scintillator coincidence (larger solid angle) and 3-scintillator coincidence (smaller solid angle). The 3-scintillator trigger had more vertical cosmic rays.
    3. Overall, the best light yield for the vertical test is at 425 p.e. (if using 2-scintillator coincidence) or 472 (lower stat using 3-scintillator coincidence). The horizontal test gave about 96 p.e. for both types of triggers
    4. Xiaochao questioned whether it's possible to see the single p.e. peak using an LED setup like Ye did (see his 8/25 report), just to confirm the gain of the PMT.
    5. The THU module used: Kedi scintillator (old formula), Y11 fiber, mirror mylar reflector layers, lead from Beijing, TiO2 paint on the side, and silver shine on the fiber ends. The mirror mylar has comparable performance as printer paper (Yi Wang added that the THU test on print paper, tyvek and mirror mylar showed a light yield ratio of 3359:3744:2719. SDU also reported on mylar that provides only a small boost, see their report on 2016/2/4.
    6. Overall the test results are comparable to SDU module #2. Given that the Kedi's new batch of scintillator gives a factor 2 higher light yield than Kedi's old batch, I think this is a good indication that the Y11 fiber provides indeed factor of 2 higher light yield than the BCF91A fiber used in all SDU modules.
    7. Recall that on 2016/6/30 Chendi reported testing scintillators from another Chinese company that seem to provide a factor 70% higher than Kedi's new formula. THU group will follow up on this and consider making a new module with the new company's scintillator. Will also look into their cost.
  3. Vince presented slides to show how the UVa machine shop makes the Tyvek sheets, see tyvek_sheets_8Sept2016.pdf (note: file size is large, will post a compressed version later). Comments and discussions:
    1. Will ship these 400+ Tyvek sheets to SDU to be used in their 3rd module.
    2. If Tyvek sheets provide significant higher light yield than printer paper or mirror mylar, THU or SDU groups will seek manufacturers in China for future production of the Tyvek.
  4. Both SDU and THU will ship their modules to Jianping at JLab.
  5. We discussed the schedule of the beam test. Vince plans to move everything from UVa to JLab starting (or no later than?) 9/26. The closeup of the Hall will occur on 10/8. Ye already got his VISA to come and he will come during the week of 9/26. Jianping pointed out that's the same week as SPIN2016 and thus he will not be there.
  6. For planning purposes, The THU module is 80cm long including PMT. The SDu modules are 65cm long. Weight is about 15kg/module.
  • 8/25/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Alexandre Camsonne, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng
  2. We discussed about the beam-test in the fall. Detectors that will be tested parasitically during DVCS/GMp period include: GEM for SBS, light gas cherenkov from Temple, along with a common scintillator triggering system. Therefore we will have tracking and some PID information. We can form a minimal setup with: FASPD, LASPD, preshower, and shower. THe preshower and shower can be a cluster of 3 or 4 modules. Below is a to-do list:
    1. The SDU group will finish painting the two existing modules with TiO2, do a quick measurement on the light yield (both vertical and horizontal tests), and ship them to JLab.
    2. The detectors need to be installed before end of Sept./beginning October (start of DVCS run). The SDU group will look into details of the shipping (required document, process, tax, and duration) ASAP. The fall run will continue until 12/14.
    3. Do we have enough PMTs?
    4. Need to email Wang Yi at THU for shipping their modules.
    5. Xiaochao will write a short description for the test setup and the goal. THis is for Alexandre to coordinate on all detector tests.
  3. On the UVa side, the GEM/SPD cosmic test is ongoing but may still take some time before a useful result can be achieved. Vince will continue this test until the detectors are moved to JLab for the beam test.
  • 8/18/2016 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian, Xiaochao Zheng, Cunfeng Feng, Vince Sulkosky, and possibly others (this is a late entry)
  2. Ye gave an update on his analysis of the SDU prototype test see YeTian_8-18-2016.pdf or YeTian_8-18-2016.pptx. Turns out the gain used in the previous 8/4 report was too small by factor 2 and the light yield is actually higher. The 8/4 slides have been updated with this correction (but the minutes of 8/4 are kept the same, uncorrected). Other findings and discussions:
    1. THe SPE peak was obtained using an LED signal and is shown on page 9, visible and at about 27 channels above the pedestal if using the "ADC low range" setting. At the "high range" setting, the main peak of the module vertical test is at about 1500 (#2 module) or 1000 (#1 module) (see page 3). The "high range" and the "low range" differ by factor 8 so this gives about 1500/27*8=444 for the number photoelectrons, as shown on page 2. This gives about 2 p.e./layer. Scaling up 600 (MIP->Shower) gives 1200 p.e. for the actual SoLID run condition, 600 p.e. if including light loss from clear fibers and connectors, and eventually 4.1% for the energy resolution. Using Y11 instead of BCF91A potentially increase the light yield be 2 and reduce the extra dE/E to 2.9%. THat won't be too bad (except for the higher cost of the Y11).
  • 8/4/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianbin Jiao, Yi Wang, Ye Tian, Xiaochao Zheng, Vince Sulkosky,Cunfeng Feng
  2. Ye reported on the first cosmic test result of the SDU prototype, see YeTian_2016-8-4.pdf or YeTian_2016-8-4.pptx (these report files already have the factor 2 mistake corrected). Note that the original report had a factor 2 mistake in the gain used. The following findings and discussions are based on the original report:
    1. Fiber polishing was improved by using a smaller cutter, compare to reported previously.
    2. This prototype used S.G.'s BCF91A fiber, silver (mirro) paint at the end of the fiber, printer paper, Kedi's improved shashlyk scintillator, and with loose Tyvek wrapping on the module side.
    3. The vertical test gives about 218 p.e., which is consistent with or higher than the 1.5 p.e./sheet observed at UVa. (See UVa's report on 4/21/2016 report that gave 1.0-1.5 p.e./sheet). Note that UVa test used Kuraray Y11 but no silver mirror plating. Scaling the fiber efficiency found from UVa's preshower test, we expect to have (1.5 p.e. from UVa shashlyk test)*(1.4-1.5 from using new Kedi scintillator)*(1.6 due to adding silver mirror paint)*(0.5 reduction from using BCF91A instead of Y11), which gives 0.9 p.e. per sheet for the SDU module.
    4. The horizontal test gave 40 p.e., also "sort of" consistent with the estimate of 50 p.e. given in thespreadsheet linked on 4/21/2016 . (Note that the estimate assumed a 10cm vertical thickness trapassed by the cosmic ray. In reality the average height of the hexagon (placed side-ways with one side touching the ground) is (5/8)*sqrt(3)*a with a=6.25mm, which is 10.825cm so the estimate of 10cm is quite accurate so should not be the reason that the observed light yield is 40 instead of 50).
    5. With the current SDU result of 1 p.e./layer for cosmic ray (0.33MeV energy deposit), we expect the final # of p.e. for SoLID running condition to be: (1 p.e.)*(200MeV/0.33MeV)*(clear fiber and connector loss 0.5)=300 p.e., which corresponds to an energy resolution of 5.8% due to photoelectron statistics. Note that by "p.e. statistics" we are referring to the fluctuation due to limited number of p.e., not the intrinsic energy resolution due to the flucturation in EM showers. This p.e. statistics term will add to the intrinsic energy resolution. Since we hope to achieve a (5-6)% energy resolution in total, the term due to p.e. statistics should be at the 3% level or lower. Also all values here refer to 1 GeV electrons, and for higher energies scale as 1/sqrt(E).
    6. We need at least a factor 4-5 on the light yield using the same test condition. A few suggestions on improving the light yield:
      1. Use Tyvek instead of paper as reflective layers. SDU is still having trouble to punch holes on Tyvek. Xiaochao will ask UV'a machine shop to make 400 Tyvek sheets and ship to SDU. Will also take pictures on how UVa machine shop punch holes. This may provide a small factor in the light yield (UVa found maybe 10% higher).
      2. Use Y11 instead of BCF91A fibers. SDU does not have enough for one module because they used many Y11 fibers for practicing. Xiaochao will ask Vince to ship 100m more to SDU. - factor two. Note that using Y11 is a big change to the current ECal pCDR design since Y11 is factor 3 more expensive than the BCF91A currently assumed in the pCDR.
      3. Use TiO2 paint on the side of the module. LHCb publications reported that simulation shows a factor two improvement if paint is added to the module side compared to no wrapping or painting.
      4. Note that all previous shashlyk modules used bond paper (ALICE) or Tyvek type 1055B (all IHEP-made modules such as for LHCb)
      5. If all above steps are done and if everything goes ideally, we may achieve 3%/sqrt(E) due to photoelectron statistics for the mass production. However, this will incur a much higher cost ($400k more on WLS fiber). THe last hope will be a) waiting for a miracle to happen to improve the light yield; b) funding from China? or c) to use simulation to find the pion rejection factor. Maybe the pion rejection required by Physics can still be achieved even if the energy resolution does not reach the 5% (also required by Physics, but the main requirement is the pion rejection not energy resolution).
  3. There will be no EC meeting next week due to the Hadron2016 workshop.
  • 7/21/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Paul Souder, Cunfeng Feng
  2. Ye reported on testing the new batch of shashlyk sheets from Kedi. The light yield (PMT coupling to the side) is about (40-50)% higher than the previous batch, and is about 48-49 p.e. for 5 sheets. See YeTian_7-21-2016.pdf
  • 7/14/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Jianping Chen, Vince Sulkosky, Xiwei Wang, Lorenzo Zana
  2. Chendi reported that received the fiber reflective paint from Italy and will test it soon.
    1. We suggested Chendi to NOT use X-ray, but setup a simple test similar to what Ye Tian reported on 12/3/2015 on the silver plating of fiber, see Ye Tian's report here: 12-3_YeTian.pdf.
    2. If using LED, should use blue (purple LED used by Ye was okay but not at the peak of the Y11's absorption spectrum. See Kuraray WLS fiber information and the image for Y11's absorption is (unfortunately it has very low resolution). Y11 has peak absorption at 430nm and peak emmission at 478nm.
  3. Ye Tian reported testing two batches of scintillators from Kedi. The newer batch is supposed to have higher light yield. Not ready to present results yet.
  4. Vince is working on a note on the durability of optical grease, cement, and disks. Also worked on the LASPD test with GEM at UVa. Xiaochao reminded that we should also test the FASPD's light-yield uniformity with the same test.
  5. Jian-ping reminded us that we need to prepare a fall test in the hall. Xiaochao suggested Vince to pick this up and provide a to-do list/plan.
  • 7/7/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Jianping Chen
  2. Ye Tian reported on his work about cutting WLS fibers on a milling machine, see fiber_polish_YeTian_07-07-2016.pdf. There is a concern that the polished surface is not good. Suggested purchasing diamond cutters and develop a test to compare performance between the milling-machine method and other methods (such as hand-polishing or ordering fibers with diamond-cut ends directly from Kuraray).
  3. Discussed briefly on the support structure presented last week. Have question about the details. Will continue after Vic comes back from his vacation.
  4. Discussed briefly with Jianping on Rakitha's Ecal simulation with Birk's saturation reported last week. Jianping questions why this effect affects mostly pions but very little on electrons. Rakitha will make plots for the energy loss density for hadrons vs. electrons to demonstrate this. Here is the original article Birks_paper_prav64i10p874.pdf explaining how Birk's saturation works.
  • 6/30/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Xiwei Wang
  2. Chendi presented tests on different reflective materials, see chendi shen2016_6_30.pdf or chendi shen2016_6_30.pptx
    1. Pages 2-5 are intended to test the performance of 3 different scintillators (2 from Kedi and 1 from another company). Xiaochao commented that not sure the test setup on page 3 is correct. Scintillators in principle do not respond to neutral particles such as the X- or gamma-rays used here. The PMT could be simply responding to the X-ray alone or secondary particles produced when the X-ray passes through the scintillator. Therefore we can't draw conclusion from the results shown on pages 4 and 5. Suggest using cosmic ray or a beta source instead.
    2. Followup: on 7/7 Jianping commented that low-energy X-rays are dominated by photoelectron effects. So we could be seeing signals from the photoelectrons here. However the X-ray hitting PMT directly is still a concern and testing with charged particles is still a preferred and more reliable method.
    3. Page 6-10 are tests of 4 different reflective materials on the lead layer: PVC, printer paper, powder paint ( 喷塑), and Tyvek.
    4. For powder-painting,
      1. currently there is a problem that the thickness is uneven -- thicker on the edge.
      2. Powder-paint has different "patterns", for example large and small ripples.
      3. should find out the cost of powder-painting for both prototyping and mass production
    5. For Tyvek, was able to obtain 3 different samples. Xiaochao asked what type of Tyvek was available.
    6. Again, because the test used a X-ray source, we can't draw conclusion about the reflective material's performance from the results presented.
    7. For the first prototype (which used PVC), still waiting for the fiber paint. THen plan to test it at IHEP using pions or neutrons. (Xiaochao again commented should only use charged particles, so neutron beam should NOT be used.)
  3. Cunfeng reported for SDU:
    1. still working on the fibers.
    2. questioned whether the DDK connectors are our only choice (answer: no. It will be good to find something made in China!). Since the DDK connectors natually divide fibers into groups of ten, this is not that straightforward to combine with the fiber grouping scheme presented by Jianbin on 2016/6/2.
    3. hard to find 2.5mm diameter rods. Xiaochao: if 2.5-mm rods are truly hard to find, will be a problem for mass production too. Maybe for prototyping can use 3mm diameter rods.
  4. Vince reported working on: setting up the GEM for the LASPD test; reproducing preshower light yield, currently 78, should reach 94 as before. Possible explanation of the reduced light yield includes deterioration of the optical grease used (becomes yellowish, etc). Optical blue is expected to have better durability (need data or proof of spec.)). In addition, the optical grease we are using now has already expired. Will write to Saint Gobain on the durability data of various optical interfacing materials and order some new.
  5. Rakitha presented updated work on the Ecal simulation with photoelectron (light yield) effect, see ecal_pid_efficiency_6.pdf. With 400 p.e./GeV (additional 5% spread in dE/E), the pion rejection can still reach 100:1 by relaxing the cuts. THis is mostly due to Birk's saturation reducing the pion's light yield.
  6. Discussion of Ecal support:
    1. Updates from the support meeting with Vic, see 06/04/2016 email communications. Vic would like to see some of these components prototyped and tested. Not sure if either SDU or THU will do so in the short term.
    2. Xiaochao's followup slide to show which drawing is for which component: support_and_drawing_20160630.pdf.
  • 6/16/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Jianping Chen
  2. DDK connectors have arrived at THU and SDU (order by UVa). So we focused on how to use them:
    1. Vince prepared slides to show how to use these connectors, see DDK_connectors_16June2016_mod.pdf
    2. Earlier reports related to how Minerva polished the DDK connectors: see 3/17/2016 report
    3. The 2015 test at UVa using DDK connectors and clear fibers (see 2/10/2015 test page by Vince) indicated the DDK connector to retain (77-84)% of light, consistent with Minerva results. However, the clear fiber loss was reported to be (retention=)68% for a 2-m length. This is much lower than the expected 83% value reported on 04/23/2014.
    4. The 2014 test at UVa see 03/31/2014 report by Xiaochao showed a total light retention of 76% (Including two factors: the Delrin "homemade connector" which was a piece of Delrin with a 1-mm dia hole, and a 2-m long PSM clear fiber). At that time this was believed to represent a reasonable >90\% retention of the Delrin homemade connector and a 83\% retention through the 2m clear fiber.
    5. We may want to repeat the clear fiber loss test.
  3. UVa update by Vince:
    1. Started testing the irradiated preshowers. However, still working on re-storing the previous test setup. Initial test using a non-irradiated preshower tile showed the p.e. reading dropped from 90 to 50.
    2. Updated radiation dosage table for the preshower tiles. The highest dose is 189 krad. The tile in the beam dump has not been released yet.
  4. There will be no meeting next week due to the Hall A/C Collaboration meeting.
  • 6/09/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Jianping Chen
  2. Rakitha's report on Ecal simulation that now start to incorporate the light yield: ecal_pid_efficiency_5.pdf
    1. Pion rejection is much better with Birk's attenuation: "The quenching effect in scintillators where light output saturates when the energy loss density is large". For the current simulation used 0.126 mm/MeV for Birk's constant
    2. To see if this works to our favor, Xiaochao suggested adding realist photoelectron yield (such as 300 p.e./GeV; 400 p.e./GeV; 900 p.e./GeV, etc, where GeV is the incident electron energy. Maybe the pion rejection factor in the preCDR can still be achieved with a low p.e. yield.
  • 6/2/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng
  2. Jianbin reported on fiber insertion following advice from Alessandra (ALICE group):  20160602_InsertingFibers.pptx. Below are comments, discussions, and suggested to-do's
    1. great work! Y11 fibers are divided into 3 groups based on length needed. One end of the fiber is plated and inserted to the end of one module. The other end is bundled into a gland (holder) and will be coupled to a PMT.
    2. need to send the module to a company to have the PMT-end of the fiber bundle cut and polished. Here, can consult experience at THU (Chendi). THU used a diamond-mill milling machine to cut/polish the fibers at the same time.
    3. recieved BCF91A/MC fibers yesterday.
    4. To do (as shown on last slide): for the next module, will use an endplate without holes, and rely on the hand-feeling whether each fiber is pushed against the endplate.
    5. To do (suggested at the meeting): concerning the side of the module, can test the light yield without any side treatment first, then repeat the test with reflective wrrapping, and then repeat the test again with TiO2-paint. The last step is not reversible so must be treated with care.
    6. To do (suggested at the meeting): concerning the fiber connector: for future modules cna consider using DDK fiber connectors (Xiaochao ordered these in April, to ship to SDU and THU directly from Japan).
    7. To do (suggested at the meeting): Ideally, we need to fully-test a module assembled using Y11 only, and fully-test another module using BCF91A fibers only, then compare results.
    8. support prototyping, see item D below.
  3. Chendi reported:
    1. Found a reflective paint "silver shine 415001" made by the Italian, see their link here. Ordering it through a company in Shanghai now. This is also the paint reported used by COMPASS II (see an online article here).
    2. Will test the module light yield without the paint first, then paint the fiber end and repeat the test.
    3. For the fiber ends that will be coupled to the PMT, used a diamond-mill.
    4. For the fiber ends that have been inserted into the module, there is no way to mill them now since we can't retract the fibers from the module. Will try to cut the ends by a razor and hand-polish each. For the next module, should consider milling/polishing both ends of the fiber before insertion. Can use a similar method as SDU's presented above in item B.
  4. For coupling the fiber ends to the PMT, UVa group used simple stands where the PMT sits, and then used optical grease to couple. There is no mechanical holder to fix the PMT to the fiber in place, but our exprience is if we don't disturb the test setup, the PMT/fiber will remain in place very well.
  5. A to-do item for both SDU and THU groups are to prototype the latest support design, see support meeting item 4/21/2016. This design provides a solid holder for connecting the fiber connector to the endplate of the module. If SDU groups is using a different fiber connector, can modify the orange/yellow plate to accommodate. The stp file should contain all drawings. Xiaochao will contact Vic to see exactly what should be tested.
  • 5/19/2016 Meeting to discuss EC and DAQ:

  1. Participants: Jianbin Jiao, Jianping Chen, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Rakitha
  2. Jianbin: tried yesterday to insert fibers into the module, but not very successful. The BCF91A (multi-clad) fibers are coming. Will consult ALICE group on fiber insertion technique.
  3. Rakitha reported an update on ECal simulation, focusing on testing the simulation with incident muons: ecal_summary_7.pdf. Below are comments and to-do's:
    1. sampling fraction for shower, using Edep alone, for muons, changes from 0.311 w/o holes to 0.307 with holes. This ~1% change is consistent with the change in the scintillator cross section area, and the value of 0.3 is consistent with the following back-of-envelope estimation:
      • the ratio of sci/lead thickness ratio of [1.5mm*1.0g/cm^3/(43.79g/cm^2)] : [(0.5mm/5.6mm)] which gives approximately sci:lead=1.6:5.66, where 43.79 g/cm^2 and 5.6mm are radiation lengths of polysterene and lead, respectively (PDG); The average dE/dx, since it depends on the material, is about (sci):(lead)=1.5:1(read from plot in PDG). So the sampling ratio using the back-of-envelope calculation is (1.6*1.5)/(1.6*1.5+5.66*1.)=0.30.
    2. The muon results indicates there is nothign wrong with the simulation. Next will continue to electrons.
  • No meeting on 5/5 and 5/12 due to SoLID collaboration meeting. Here is Ecal presentation on 5/7. By email, Chendi reported THU group has inserted Y11 fibers into one module successfully. Zhihong cautioned people to wear gloves and be very careful while working with fiber.
  • 4/28/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Jianbin Jiao, Ang Li, Chendi Shen, Xiaochao Zheng, Jianping Chen, Ye Tian, Yi Wang
  2. SDU update on testing the scintillator (shashlyk hexagon) light yield: Scintillator test results.pptx. The basic setup used 3 sheets, with lead and with or w/o reflective layers. PMT (China-version of R11102) coupled to the side with optical grease. In average the readout shows 10 p.e./layer using the gain-calculation method. Tyvek in average give higher yield than printer paper, but using aluminum as the reflective layer does not improve over paper. The calculated Npe has large drift from day to day over a 6-week period. We provided some suggestions at the meeting:
    1. we are not so comfortable with using the gain method, especially given the large day-to-day drift, since it could be the single p.e. peak that is drifting but the gain method uses a fixed single p.e. position. Suggest to use high gain and try to get the single p.e. and the main peak to be on the same graph as a double-check. Also can do this for a few days continuously to see if both peaks drift (while the ratio --Npe-- might be stable).
    2. with the 10 p.e./layer seems to be consistent with the 1 p.e./layer from the hedgehog test at UVa, since the WLS fiber trapping efficiency is only 5% for double-clad Y11 fibers (this is the solid angle openining for total-internal reflection). Jianping suggested contacting the SBIR company that we reviewed last year since their project was to develop fibers with higher trapping efficiency (in fact, 100%).
  3. SDU has ordered a torque wrench based on Xiaochao's torque calculation from last week (see link, customized to match M2.5 threads). Chendi reported that when he used a wrench to tighten the nuts, he measured (using a force sensor) 0.3kg at approximately 30cm leverarm distance, which gives 0.9N*m for a total compression of 210kg/6. This is 50% higher than Xiaochao's larger number (calculated using friction mu=0.6), but the calculation used a lot of assumptions on the thread geometry, etc., so the difference is actually small which means the calculation is using the correct method. We will contact Yaping on the torque value used by ALICE, to use as a reference.
  4. At UVa we are moving onto Tyvek hedgehog test today.
  5. We discussed the light yield. Below is a summary Xiaochao had based on the information of Kedi from Cunfeng in an email dated 2014/11/13, and web data for US companies
    Scintillator type
    Base material
    Light yield relative to anthracene (蒽晶体)
    light emission
    decay time
    attenuation length
    index of refraction
    density (g/cm3)
    C/H ratio
    radiation hardness
    more info
    Kedi (北京科迪)

    (395,425)nm (comparable to Bicron)

    CNCS (北京核仪器厂)

    ST401(A,B,C) 苯乙烯 (sterene)
    peak at 423nm


    nearly flat below 1E3Gy gamma; reduce to 90% at 1E5Gy
    闪烁体使用说明书—北京核仪器厂.doc (note typo: " 137Cs624MeV内转换电子" -- when did 137Cs have 624MeV beta decay? Should be 0.512MeV) report says 15% dE/E for this beta source measured from a 3cm-dia by 3cm height cylinder
    二甲基苯乙烯加第一发光物对联三苯,第二发光物POPOP 60%
    peak at 432nm

    much higher cost than ST401; similar to NE102A


    peak at 390nm

    1.596 1.02

    ST1423(fast) 单体甲基苯乙烯和发光物质聚合而成的二元体系 ~55%
    peak at 375nm

    polyvinyltolunene (PVT) 64%
    peak at 425nm

    conversion 10,000 photons/1MeV electron;
    PVT can't be injection-molded
    Saint Gobain

    BC400 polyvinyltolunene (PVT)

    peak at 423nm

    peak at 408nm



    peak at 425nm

    IHEP (Russia)

    polysterene + 1.8% PTP or PPO + 0.04% POPOP


    LHCb reported BC408 produces 1.6 times the light of IHEP's, indicating a light yield of ~40% relative anthracene; But newer sci from IHEP can be as high as ~60% relative anthracene (see KOPIO report)

    PPO=C15H11NO or "2.5-diphenyloxazolyl"
    POPOP=C24H16N2O or "1,4-bis-2-(5-phenyloxazolyl)"

  • 4/21/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Jianbin Jiao, Alexandre C., Xiaochao Zheng, Jianping Chen, Ye Tian, Yi Wang (intermittent)
  2. SDU update on the module compression test: 20160421_ForceTrans2.pdf
    1. The ratio of the inner compression after vs. before transferring the force is always about 0.5, which is a good thing.
    2. suspension test now gives 2.8mm. (Last week's test was done on two tables, now the test is set on one table). This appears large, since any change in the vertical position needs to be accommodated in the support design (suspect a 2.8mm drop means we need to leave 2.8mm dead space between every module, but not sure.)
    3. Still need to figure out how to use torque wrench to get the compression. Trying to order a torque wrench, but not sure what is the range of the torque. Xiaochao calculated the torque, see torque_calc_20160421.pdf. The formula used were found at two websites: There are also pre-made charts available, for example, but have not looked into it.
  3. THU update on the temperature test: shenchendi2016421.pdf
    1. changed temperature within (-30,30)C and measured the change in compression for no washer, vs. 5 washers per screw, vs. 15 washers per screw.
    2. There were questions on how to arrange the washers (all 5 in same direction or flip every other one?).
    3. Homework: suggest to do simple calculations on how the thermal length change is absorbed in the washer, and then how many washer would be appropriate.
  4. UVa quick update on the light yield test:
    1. changed from printer paper to aluminized mylar last Friday. Quick result shows 1 p.e./layer, even lower than paper (last week reported 1.4-1.6/layer for printer paper). Next will try Tyvek, then sci+paper+lead, sci+Tyvek+lead, and sci+mylar+lead. Will also consider adding nuts to provide some compression.
    2. projection on how the light yield of hedgehog test is related to the final dE/E for SoLID and estimation of what to expect from the module horizontal cosmic test: see shashlyk_lightyield_calc.xls
      1. Jianping commented that linear projection may not work.
    3. Homework: forgot internal reflection! this might explain why previous report on that reflective layers do not improve light yield, since for thin shashlyk scintillators it requires too many time of reflection for light to reach the fiber if the angle does not satisfy total internal reflection.
  5. UVa update on calculation of extended rod length, see slides fiber_bending_20160414.pdf and the spreadsheet (first sheet only) shashlyk_fiber_bending_space_calc.xls (Xiaochao). Some explanations:
    1. if we control the light loss below 5%, the distance between the fiber connector and back of module needs to be 9cm or longer.
    2. if 9-10cm is too long for cantilevering the module, can separate the fiber connector mounting from the suspesion plane. Here are some pictures of Vic's design: SOLID-Module-ver1.pdf (PDF file contains 3D content), and some pictures under this directory.
    3. the distance to fiber connectors in turn determine the uniformity, now defined in the above spreadsheet as (max-min) of loss among all 96 fibers. This corresponds roughly to Aglobal used in LHCb's TDR, but not the same, since each event will distribute energy across the whole block, so f(x) (event yield) is some sort of average of all fiber losses weighted by how much light of the event is collected by which fiber.
    4. LHCb studied global and local uniformity as functions of the fiber density, see their ECal TDR page 20-23. Alocal varies from 0.4% (for 1/cm) to 1.2% (for 1/1.5cm), and Aglobal varies from 6% (for 1/cm) to 1% (for 1/1.5cm). Here define the respond f(x)=a*[1-Aglobal*(x-x0)2/(l0/2)2]*[1-Alocal*cos(2*pi*(x-x0)/d)] where d is the distance between fibers, x0 is center position of the tile, and l0 is the half-side of tile.
    5. But how much uniformity can be tolerated by PID?  The uniformity question will require some simulation.
  6. Xiaochao mentioned the NSF PIRE solicitation will be back this year. Should prepare to submit a publication.
  • 4/14/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Chendi Shen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Jianbin Jiao
  2. SDU update on the module suspension test, see 20160414_SuspensionTest.pdf (Jianbin):
    1. results on page 3 are in good agreement with expectations (see discussions from last week on how to calculate the change in the inner-sensor's reading).
    2. single-end suspension (page 4-5): The unsupported end sags by 2.2mm. This will affect how much clearance we need when mounting all modules together. Xiaochao will need some time to think about this result. Could it depends on how tight the rods are held against the supporting plate?
    3. Todos:
      1. Test the relationship between the pre-setting pressure and the transferred force (note: expect a constant ratio between the two) (copied from page 6)
      2. working with a vendor to upgrade the sensor to allow continuous monitoring of the compression. More module work will resume after the upgrade
      3. insert fibers and do fiber shaping, then will do cosmic test. Need to build a dark box.
      4. We discussed the cosmic setup of the module's light yield. Xiaochao commented that previous cosmic tests all used the horizontal position. At UVa we have tried the vertical setup but did not get any rate due to muons possibly not penetrating the full module and the very small solid angle of the top+bottom 2-scintillator hodoscope trigger setup. For horizontal setup, expect light yield is shown in the spreadsheet posted last week: shashlyk_fiber_bending_space_calc.xls (please also refer to last week's minutes item B-4 for how these numbers were calculated). The calculation was done assuming a vertical thickness of 10cm and if the cosmic is incident with an angle (not completely vertical) so will pass through 7.5cm of scintillator and 2.5cm of lead. If  however some of the cosmic rays are strictly vertical (within +/-0.5 deg), they could give 1/3 times higher yield due to penetrating only a single scintillator layer (10cm). Judging from the final effect on additional p.e. statistics, I think 300 p.e. from the horizontal cosmic test would be acceptable and >500 would be ideal.
      5. Still need to do the torque-wrench test. Difficulty with attaching it to the module because the wrench is too short and the rods are too long.
      6. Need to design a test stand to measure how much compression is needed for friction to balance the weight. (See upper half of mech_test_module_20160407.pdf).
  3. THU update on the module compression vs. temperature test (Chendi):
    1. the previous reflective PVC layers turn out to be too expensive. Will use printer paper next.
    2. First test of module compression: start from 200kg at 22C, no spring washer. Pressure changes to 300kg at 30C and 40kg at -30C.
  4. Discussions on the light yield (UVa): making Tyvek and aluminized mylar reflective layers now. Waiting for the machine shop. Will put together the test if they can be finished by tomorrow afternoon.
  • 4/7/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Yi Wang, Chendi Shen, Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Jianbin Jiao
  2. UVa update on measuring light yield of shashlyk scintillator layers using the hedgehog method (Vince), see Hedgehog_tests_07Apr2016.pdf
    1. the basic setup can be seen from this picture: IMG_0811.JPG. Previously we used 4 layers with paper between every layer but could not see clear signal. So the latest setup used a total of 25 layers.
    2. Xiaochao's quick estimation, using the PS light yield along with some back-of-env calculation for the light collection of WLS fibers, and if each layers is sandwiched between 2 reflectors, gives: 10 p.e./1.5mm layer (Tyvek 1055B: 95%); 6 p.e./1.5mm layer (Al Mylar: 90%), and 3 p.e./1.5mm layer (copier paper: 80%), or 0.6 p.e./1.5mm layer (no reflector, single-layer).  Note that the PS test results showed a weaker dependence on the reflectivity than the quick calculation for the PS.
    3. The latest measurement gave 39.7 p.e. for no reflector or 1.6p.e./layer, and 34 p.e. for paper reflector or 1.4p.e./layer. Note that this should NOT be compared to the 0.6p.e./layer because the calculation assumed all light hitting the surface is lost, while the test used 25 layers on top of each other, so light hitting the surface is collected by subsequent layers.
    4. A direct relation between the hedgehog test and the shashlyk module light yield, assuming 2.2MeV/cm for MIP in the cosmic hedgehog test and a 0.2 sampling fraction, is multiplying the hedgehog single-layer light yield by 600 to get the light yield for 1 GeV electrons, then multiply by the electron momentum in GeV/c. Further assuming a total 50% light loss in fiber bending, connector, and clear fibers; a +60% increase if using mirrored fiber ends; and if using BCF91A instead of Y11 (BCF91A light yield is factor 2 smaller). This spreadsheet shashlyk_fiber_bending_space_calc.xls (2nd sheet) gives the calculated light yield for SoLID running condition, effect on the energy resolution, and the # of p.e. expected if we test the Shashlyk module in the horizontal position.
    5. To do: Will try higher-reflectivity layers such as Al-mylar or Tyvek. SDU will contact Kedi on whether the light yield can be increased.
  3. Cunfeng reported for SDU on the force transfer test: 20160407_ModuleTest.pdf
    1. The new measurement shows if starting from 200kg, then after turn the nuts and release the compression, the remaining inner compression is about 120kg. This indicates that the rods indeed have elongated a little when the stack bounces back. Next step is to study whether we can achieve a consistent compression by using the torque wrench. Then for the final production we will not need inner sensors (and they are impossible to implement in every module).
    2. Calculation of the cantilvering force (Xiaochao) shows the compression should decrease by 30kg at the top edge and increase by 30kg at the bottom edge. If the sensors are mid-way between module center and the edges (as the top 2 sensors are now) the reading should decrease by 15kg. These agree well with the measurement.  Note that the calculated change in compression is determined by how much the stack compression changes due to weight, and the change in the sensor reading provides an equivalent information to this change in the compression.  In other words, the # of sensor only affects the initial reading (that the 200kg is equally divided among all sensors), but will not affect the change in the reading when cantilevered. The change in reading only depends on the vertical location of the sensor.
  4. Xiaochao checked with Vic on what he needs measured on the mechanical property of the module. The plan is show in mech_test_module_20160407.pdf
  • 3/31/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Yi Wang, Chendi Shen, Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B.
  2. Chendi reported progress from Tsinghua, see chendi shen2016_3_31.pdf 
    1. First, calculated change in length if a 50-deg temperature change occur. The total change is about 1mm which is not tolerable.
    2. Because there is no inner sensor to monitor the inner compression of the stack, now use the procedure on page 3. However, the final reading of the outer sensor (123kg total) is NOT the final inner compression. Rather it is simply the rebound height change of the stack (after compression is released) times the elastic modulus of the force sensor. The inner compression thus can be any value.
  3. Cunfeng reported progress from SDU on force transfer from compression bar to rods, see ForceTransmission.pdf
    1. the method is to add force sensors to inside the module. The module thus have only 170*2 layers (not 194*2) because the length of the rod is fixed to 50cm.
    2. using the outer sensors (between compression bar and the module end plate), after 500kg compression, reduce the compression to 200kg, then turn nuts to snug and stop immediately once the outer sensor reading starts to change.
    3. release the compression bar. Inner sensor readings now show about 200kg, indicating all forces have been transferred. This also indicates that the (effective) elastic modulus of the sci+lead stack (defined as the modulus times cross section area divided by stack height) is much smaller than for the rods.
    4. Inner sensors show small fluctuation over a (2 day?) long period, may be related to temperature fluctuation. (plot on last page missing dates on the x axis). Can't confirm due to lack of temperature record.
  4. To do for module study:
    1. THU (Yi Wang) will follow the procedure of SDU and see if can reproduce the total transfer of force from compression bar to the rods;
    2. THU will use their constant-temperature incubator (恒温箱) to measure the actual module length change due to temperature fluctuation.
    3. Will continue study of adding spring-washers to absorb the length change of the module due to temperature fluctuation.
  5. Rakitha showed updated Ecal simulation for the fiber holes, see ecal_summary_6.pdf
    1. still not sure why the Edep change in lead is about 9%. Jianping suggested contacting Jin for suggestions.
  • 3/24/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Yi Wang, Chendi Shen, Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B., Alexandre C.
  2. Chendi showed progress on THU side:  20160324/Shen-Chendi-2016_3_24.pptx
    1. compression went up to 500kg and stack height appeared stable;
    2. insert 6 rods and turn nuts to snug, stopped immediately when the force sensor reading starts to change;
    3. then released the compression plate, took module off the assemble stand.
    4. now is painting Kedi's reflective paint on the module sides.
    5. This is good progress, but XC is a little worried about adding the paint this early, since it will not allow further adjustment to the stack.
  3. Most of time we discussed on how to transfer force from the compression plate to the screw/rods.
    1. the method previously used by SDU -- tighten the nuts until the sensor reads zero -- wouldn't work because this will cause higher pressure to the stack, and because the change in the force sensor reading will not reflect the actual force from the nuts (rods and force sensor have different elastic modulus).
    2. If we tighten the nuts to snug, stop immediately when the force sensor reading start to change, and then release the compression plate, the final compression force is determined by the "k" factor of the stack vs. the rod. Xiaochao's calculation is shown here: 20160324/compression_calc_20160324.pdf. We don't know the Young's modulus for the paper (or THU's reflective material), but using some online search for the printer paper, the compression force is about 1/5 of the initial preload force (500kg). However, one can see this method is not so reliable because the actual modulus may differ from the standard values.
    3. We finally agreed somewhat on the following procedure:
      1. compress the stack with 500kg until stable;
      2. reduce the compression to 144kg=24kg/rod (this is the compression needed for the static friction to balance the weight, using a static friction coeff of 0.1). -- we may reduce this to 72kg total (12kg/rod) later given that the measured static friction of 0.2. Also we don't want to stress the rods too much;
      3. insert the rods, turn nuts to snug;
      4. release the compression plate, at the mean time use a torque wrench to tighten the screws. Set the torque to be a specific value. Need testing to find out what torque force would provide the 24kg force.
      5. Stop when the compression plate is completely released and the torque wrench reaches the set value.
      6. In the long term, we need to modify our design to have two back plates similar to the ALICE module. See Yaping's graph: 20160324/DCal_forceTransfer_forXiaochao.pdf. Right now, our primary goal perhaps should be to make a working module get an idea about what the light yield is.
  • 3/17/2016 Meeting to discuss EC and DAQ:

  1. We had a short meeting today because of the mix-up about daylight saving time change in the US.
  2. Update on fiber polishing:
    1. Here are comments from Howard Budd on the DDK connector+fiber polishing of Minerva/Fermilab experiments:
      1. "The connectors have fiber glass in them. This wears the diamonds. To reduce the wear and to make a better polish, we first cut back the connectors. We let the epoxy flow through the holes to the bottom of the connectors. Then the epoxy was polished, which polished the fibers at the same time. This reduced the diamond wear and created a better polish. The amount of connector either/or epoxy polished off has to be carefully controlled so the the spring inthe clip works to press the connectors together."
      2. Polisher for the DDK connector: DDK_Connector_Polish.pdf
      3. Procedures for adding cable boots to the connector:  boot_proc.pdf
      4. Procedure for making cables: cable_odu_proc.pdf
  • 3/10/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Xiwei Wang, Yi Wang, Zhihong Ye, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B.
  2. Update from Ye on the fiber polishing machine from JLab, see 2016.3.10_tianye_fiber_polish.pdf
    1. machine has been there for many years, not sure if it was custom-built by JLab
    2. a collection of fiber polishing article from various experiments:
      1. ALICE_fiber.pdf on the ALICE sputtering machine
      2. intro_fiber_ATLAS_Tilecal.doc
      3. D0 note 3390: Detailed_fiber_Fermi.pdf "Polishing Optical Fibers for the D0 ICD in Run II", include various polishing methods and machines, also polishing the fibers inside the DDK connector
      4. D0 note 3561, method_comparasion.pdf "Comparison of fiber-polishing techniques", compared performance among the three methods -- iceblock, teflon, and the fiberfin III machine.
  3. Update from SDU/Cunfeng: see slides  SDUreport_03102016.pptx
    1. Tried to transfer the compression from the compression bar to the six brass nuts. Need to turn the nuts 2 turns (0.45mm thread length per turn) to reach a total of 150kg of force held by the nuts. This is factor 4.5 longer than what Xiaochao calculated using Young's modulus of brass.
    2. Also one thread started stripping and can't go above 150kg. Xiaochao's calculation showed that the shear stress on nuts (2.5mm thread length, 2.5mm dia) should be 5-10 lower than the brass shear strength so not sure how this happened, unless if all stress is on only one turn of thread was engaged and not the full length (so stress is 2.5mm/0.45mm =5-6 times higher). In this case the first engaged thread would start stripping, and all other threads would fail subsequently.
    3. tried cutting a 16-fiber bundle using a mill machine. Comment: maybe the mill machine can be equipped with diamond grits to reproduce the Fermilab polishers.
  4. Update from THU: working on continuously-monitoring the pressure.
  5. Update from Rakitha on simulating the fiber holes, see ecal_summary_5.pdf
    1. previously simulated 0.34mm lead by mistake. After correcting lead thickness, now the sampling fraction increased from 0.20 (no hole) to 0.27 (with holes).
    2. The averaged Edep in lead decreased while Edep in sci increased, and the sum stays unchanged. This caused the sampling fraction to increase.
    3. The energy resolution becomes slightly better due to the larger sampling fraction.
    4. Xiaochao questioned if there is any method to understand the 7% increase intuitively. This still seem too big given that the hole volume is only 1% of lead. Also, would the energy resolution improve with larger holes?  Not saying we should make more holes to make PID better, but wondering if there is an "optimized hole size" w.r.t. energy resolution?
  6. Update from UVa:
    1. Sent 60m Y11 fiber to SDU and 100m to THU yesterday
    2. Misc info: The optical glue we use at UVa is Eljen EJ500 optical cement and the polishing set is Ocean Optics, Fiber termination kit
    3. For polishing the fibers by hand, Vince worked with Micah (a high-school student) for a total of 3-4 man-hour to polish 100 fibers.
    4. Ordered 150 sets of DDK connectors for practicing at UVa, SDU and THU.
    5. Will contact Minerva again for their fiber polishing method.
  • 3/3/2016 Meeting to discuss EC and DAQ:

  1. Participants: Chendi Shen, Cunfeng Feng, Yi Wang, Zhihong Ye, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B.
  2. Update from SDU/Cunfeng: see slides compressionTest.pdf
    1. paid 100,000RMB for 4km of fiber to Saint Gobain through a trade company, but the trade company was very slow. As a result will not have the fiber within the next few months. Xiaochao will ship 40m to SDU and 80m to THU for module assembly. These are Kuraray Y11 fibers, so will have 2-3 times higher light yield than the Saint Gobain fibers. But it's always good to have a module with Y11 for R&D;
    2. Will continue contacting Saint Gobain to have an update (the Chinese branch is hard to contact).
    3. lead plates from Kolgashield will arrive at SDU soon. Xiaochao followed up on the 220 plates Kolgashield and Kolgashield said UPS just picked it up.
    4. Now using lead plates from Yantai, printer paper, the total module length after compressing 2 days at 500kgf is 45.3cm. There is still uneven-ness of less than 1mm. Also the module length is 1cm longer than THU's (see below).
    5. Not sure how much need to turn the brass nuts to keep the compression.
    6. Continued shashlyk light yield test but using 3 layers together. Xiaochao thinks the drifting of +/-1 out of 27 p.e. over 3 days is quite normal (within statistical fluctuation) and is not really a concern. The stat. fluctuation would be higher for the single-layer result although when the actual drift is +/-2 out of 8, it becomes hard to tell if it's a systematic drift or statistical fluctuation.
  3. Update from THU/Chendi: see slides 2016.3.3_Chendi Shen.pptx
    1. Module length is 44.3cm after 200kgf compression. Both lead plates and reflective layers are from the company in Beijing. The reflective layers are pvc, witht the side facing scintillators silver-plated and the side facing lead has a grit polish (磨砂处理).
    2. The 200kg force seems to have stablized after 2 days. Not sure if need to go to 500kg. Also not sure if the tool is strong enough to apply more force. (It is already hard to turn the nuts to reach 200kgf).
    3. Ordered 500m fiber from Saint Gobain, also not sure when these will arrive.
    4. Has contacted company on the force sensor to have computerized reading. This is useful for SDU too. So far the pressure reading is done by hand, multiple times during the day.
  4. We discussed the cost of the lead plate: RMB13 from Qingdao, RMB8 from Beijing, and RMB10 from Yantai. Kolgashield's estimate for mass production is $1.22/plate, so need to make sure the Chinese vendors do not charge more than this for the mass production.
  5. Update from Vince/UVa.
    1. first measurement of the shashlyk plates' light yield: 2-3 p.e. from 4 layers. But used only reflective layers on the top and bottom of the 4 shashlyk layers, and the light coupling to the PMT is not good. Will work on this within the next two weeks.
    2. Radiation dose reading for the preshower is back, see
    3. Slides show the shashlyk setup and overview of the preshower radiation test: Detector_tests_03Mar2016.pdf
  6. We discussed about fiber cutter and polisher. JLab Hall B's machine can handle fiber bundles but is currently broken. Ye will try to visit and take some pictures next week. JLab detector group has a machine from FiberFin: FF-FF4 with base cost of $10k. We are still searching for a more economical yet powered polisher.
  7. Xiaochao will work with the support group (Vic) on tolerance on module length, tilting of the module vs. endplate, and also to figure out how much we need to turn the brass nuts to keep the necessary compression force.
  8. Rakitha showed a summary of the simulation with and w/o fiber holes: ecal_energy_leakage_1.pdf. There are two effects that still need to be studied:
    1. energy leakage increased from about 1% to 2%. Not sure what is causing this, since the change in the effective X0 is small and the leakage goes like e^{-d/X0} with d the module length. On the other hand, e^{-d/X0} is only the theoretical expectation and the real situatio always has small leakage (such as the 1% w/o holes). Could it be a change in the Molere radius?
    2. Sampling ratio increased from 20% to about 35%. This is unexpected since the holes change lead and scintillator the same way.
    3. To diagnose what's going on, suggest plot Edep vs. layer separatly for lead and for scintillators. If there is transverse leakage it should be there for all layers (and more so for where the the shower maximum). If it is leakage in the back it should also be evident from such plot.
  • 2/25/2016 Meeting to discuss EC and DAQ:

  1. Participants: Chendi Shen, Alexandre Camsonne, Cunfeng Feng, Xiaochao Zheng, Vince Sulkosky, Ye Tian.
  2. Jianping pre-update (out of town now): next Fall DVCS/GMp running will be extended.  For the dedicated run period for GMp, the DVCS calorimeter will be removed.  Alexandre
    is proposing to set up test detectors to take some low momentum data for cross-checking the hadron rates from the Hall D event generator.  (The parasitic data taking this spring will be
    biased toward higher momentum.)  It was proposed that perhaps we could place the shashlyk modules, which are being constructed by the Chinese groups, in the test set up with GEMs, and maybe even the SPD detector(s).
  3. Here is Alexandre's report on the possible parasite test setup: SBS-GMp-parasitic.pptx. Some discussions:
    1. Detectors that may be tested including the GRINCH (cherenkov for Hall A A1n) (slide 11); HCal of SBS (30x30x100cm) (slide 12), the SoLID ECal shashlyk protype and the SoLID LA and FASPD prototypes;
    2. The setup in the current DVCS calorimeter box does not have momentum information, and does not have magnets. If we want to test the energy resolution and/or if to avoid high low-E background, must use the proton in the LHRS in coincidence. (GMp will detect elastic electrons in the LHRS in the fall, so we will potentially take beam time away from GMp by reversing the HRS polarity).
    3. There is also the possibility of taking out the calorimeter box completely and use the RHRS for all parasitic tests. But the fall-run is dedicated to GMp and GMp will use both HRSs for inclusive elastic electron detection.
  4. Vince reported on the preshower radiation test:
    1. On Tuesday Radcon pulled the dosimeters and one of them reached 30krad in 1 week (total run for the spring is 10 weeks, possibly reaching 300krad). For the preshower in the beam dump, do not plan to read the dosimeter during the spring run because of the high dose.
    2. For the summer, the plan for Hall A is to replace left Q1. Fall run is scheduled to be 9 week long.
  5. SDU report by Prof. Feng:
    1. Continued testing shashlyk light yield but the results are not stable;
    2. Assembled a module using the actual scintillator but the height is not even (1cm difference between lowest/hightest corner). The reason is because all shashlyk scintillator sheets are thicker on one side, so even through the thickness is within tolerance, the difference accumulates to a large amount on that particular side.  For now, will rotate half of the scintillator sheets by 180 deg. Will discuss with Kedi on how to improve the manufacturering quality. (THU reported they had similar problem but there seems to be an order of mag. difference: THU reported 1mm difference between the lowest/hightest sides.)
  6. We discussed how to cut/polish the fibers. Ye will go visit the Hall B setup and we will investigate if there are fiber-polishing machines available from Chinese manufacturers. Xiaochao followed up with an email to the WSU group but they do not have such machines.
  • 2/18/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Ang Li, Chendi Shen, Jianping Chen, Ye Tian, Vince Sulkosky, Xiaochao Zheng
  2. SDU update: Ang Li presented updated shashlyk layer light yield, see Scintillator primary test results 2.pptx. Our main comment and concern here is the reproducibility of the test results. It looks like the results changed quite a bit before/after the Chinese new year. The absense of the optical grease could be a problem and will test the light yield again with the grease applied.
  3. UVa update by Vince:
    1. Working on setting up the hedgehog test of the shashlyk scintillator layer sheets. Holders and PMT couplers have been 3D-printed.
    2. Preshower radiation test in hall A: starting next Tuesday Radcon will start reading the dosimeters and will do so every 2 weeks. A website has been setup here that will show pictures of the preshower prototypes, does readings, etc:
      1. Jianping recommended placing the preshower at 0deg downstream but above the beam pipe, or inside the scattering chamber (but DVCS does not want any background) or inside the beam pipe using Moller electrons (but need to break the vacuum so too late to do so).
    3. Update on the LASPD test: GEM test in the hall is not happening. Mark Jone may test some calorimeter in the HRS, and if so can test the LASPD at the same time but unlikely to happen this year.  For cosmic tests, still waiting for the GEM setup to be ready at UVa.
      1. Jianping suggested we can setup our own test system with shielding+LASPD+GEM in the hall. I think that's what we were hoping to do with the GEM in-hall test but maybe Jianping meant we do not need to involve Nilanga's group?
    4. We may go back to the cosmic-only test without GEM, but need to take a long time of data to get the position resolution using Left-Right PMT information.
    5. Will probably continue hedgehog test at UVa after 2/27 (will be at JLab next week). Received 4 more preshower modules from Jianbin last month that need to be characterized too. For the longer term will consider a long-time cosmic test for the LASPD timing.
    6. The FMPMT test paper has been on arxiv for over a month, see:
  4. Xiaochao is working on her annual DOE report. Need to check Paul's R&D plan to make sure the request is consistent. (Rakitha is currently 50% time on SoLID but focusing on background, trigger, etc, UVa needs an additional 1/2 postdoc on Ecal-specific simulations.)
  5. Jianping updated us on possible development in the SoLID TOF system: MRPC+LASPD could be a backup plan ("safty net"). New development includes upgraded MRPC (Micky Chu/EIC/TOF with Jing Huang) or the LAPPD (large-area parallel plate detector). The cost will be high but could be worth it if we could get the timing down to <30ps instead of the current 100ps, can pi/k for higher momentum (current <2.5GeV/c) and to identify kaons.
  • 2/4/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Ang Li (李昂), Ye Tian, Xiaochao Zheng, Jianping Chen, Vince Sulkosky
  2. SDU update: Scintillator primary test results.pptx on preliminary test of shashlyk layer light yield (PMT side-coupling method, cosmic)
    1. paper and mylar reflective layers adds small boost to the light yield
      • the spectrum for the mylar test is strange, need to repeat.
    2. Tyvek adds about 60% to the light yield but we know Tyvek are hard to use due to a) difficult to punch  holes and b) slippery.
    3. The plan is to produce a prototype with either paper or no reflective layer and to study the light yield. If the yield is high there is no need to experiment with Tyvek.
  3. UVa update (Xiaochao): UVa_Update_20160204.pdf on the mechanical property measurement of shashlyk scintillator pieces
    1. results on the Young's (tensile) modulus and yield strength are consistent with web data.
    2. also performed the 3-point bending test. I was told this is the same as shear stress but obviously not, see Will re-process the data and report next week.
    3. for web data on polysterene mechanical  properties, see for example:
      • Material Property Data Website (or last slide of the above report)
    4. Vince has been working on
      • setting up the radiation hardness test of preshowers (7 modules prepared) in Hall A;
      • cosmic test of LASPD timing resolution combined with GEM to remove the position uncertainty.
      • For FASPD uniformity test we still plan to use the source from Nilanga.
      • After he comes back on Feb. 15th, will focus on setting up the hedgehog test of shashlyk layers. 3D-printed holders and PMT couplers are being designed by our undergrad (Andrew Coffee). For this test we will use 100 WLS fibers in the shashlyk hole, rather than the PMT side-coupling method (of SDU).
  4. Ye Tian reported:
    1. will talk to Alexandre Camsonne to be involved in DVCS. DVCS collaboration has already agreed to take inclusive trigger data once a day on the Left HRS.
    2. will start looking into online scripts and online data analysis; will take shift.
    3. (beam starts Friday 2/5 in Halls A, B, D)
  5. Jianping reported:
    1. Dan Watts from Eidinburgh and officially joined the SoLID collaboration. Xiaochao has scheduled a phone call on Monday to discuss how his expertise in CLAS12 construction can help with ECal and other work. We may want to involve him in our weekly meetings.
    2. Mickie Chu has officially joined the SoLID collaboration. His main contribution will be focused on MRPC and TOF systems.
  6. We discussed briefly the polarized 3He PVDIS idea. A separate series of meeting and minutes will be setup on this topic.
  7. Our Chinese collaborators will not call in next week due to the Chinese New Year (2/8, Monkey). Will call-in on 2/18 but probably no new result.

  • 1/28/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Chendi Shen, Jianbin Jiao, Yi Wang, Ye Tian, Xiaochao Zheng
  2. SDU update: CF2016Jan28.pdf
    1. Measured the Young's modulus using a teaching lab oscillating device. However, result is 10 times higher than web data on polysterene. Not sure why
    2. Setup multiple stands to measure light yield of the shashlyk layers by side-coupling. Xiaochao commented that need optical grease. Will try to send some to SDU.
  3. THU update by Chendi:
    1. assembled one module using actual lead, scintillator, and mylar(?)-based reflective layers.
    2. Applied 200kg total force using the compression bar and two screws. Pressure was monitored by 4 sensors. At the beginning, the 200kg force decrease with time drastically, at a rate of ~1kg/min. Adjusted the screws to make it back to 200kg every time the sensor reading drops to a sum below 180kg. On day #2, pressure seems to have stablizied.
    3. Due to lack of experience, the force wasn't uniform across the hexagon (20-30kg diff) which caused the top layer to be unleveled at the first try. Then, had to adjust carefully the two compression screws to compress the taller section further (force diff up to 70-80kg was needed to level the top).
    4. Total height after compression is about 1cm higher than the calculated 43.5cm. After discussion we determined this is due to mylar reflective layers being 0.16, not 0.12mm per layer.
    5. Asked what we should use for the side plates. Xiaochao's answer is to try 1mm Al first.
    6. Will report in details next week
  4. Xiaochao will try to use one of the 5 shashlyk samples from Jianbin to measure the Young's modulus at UVa.
  5. Meeting for Feb: 2/4 is okay, 2/11 won't work for China because of the Chinese new year, 2/18 maybe okay.
  • 1/21/2016 Meeting to discuss EC and DAQ:

  1. Participants:
  2. SDU update: CF2016Jan21.pdf
    1. module shows some deformation.
    2. p4: discussed with an IHEP colleague about stress calculation, but not sure exactly what we need.
    3. p5-6: Received 10 PMTs (R11102-equivalent), using in-house-made dividers. Initial test shows single p.e. peak except for one.
    4. p7: use SPE peak to determine gain for fixed HV (column D), and HV needed to achieve a fixed gain (columns H, K)
    5. p8-13: attempt to measure the cosmic response of shashlyk sci layers by coupling the PMT from the side. This will be different from using WLS fibers, but is a good starting point.
  3. THU update: put together the assembly stand, but the screws for the compression bar are too short. For pictures see EC Assembling_Chendi Shen_2016_1_21.pptx
  4. SDU measured the friction between the scintillator and the lead: 0.5. This is confusing because paper will make things worse in terms of friction.
  • 1/7/2016 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Yi Wang, Paul Reimer, Jianping Chen, Ye Tian, Jianbin Jiao, Vince Sulkosky, Jie Liu, Xiwei Wang, Chendi Shen
  2. Update from SDU: assembled one stack using regular plastic and lead plates from the Chinese company, see slides firstModuleReleased.pptx
    1. Used 200kg force during assembly/compression, a few 1.3-mm steel pins were used to keep the holes aligned. Compression resulted in 4-5mm of total thickness reduction;
    2. Tightened the nuts after compression, no further compression applied afterwards.
    3. Tried cantilevering from the back, module and rods seem to hold well.
    4. Checked all fiber holes, with 1mm pins there is no problem. 1.3mm pins met difficulty with some holes.
    5. Next step is to practice fiber insertion. The fibers came in spools and are hard to straighten. Need to ask Yaping how they handled the fibers.
  3. Update from TsingHua: studied the latest Russia/IHEP shashlyk module, see slides new design about ECal 2016_1_7.ppt. The design is based on the latest from IHEP, see  The main differences from our current prototype design and the advantages are:
    1. Features: all scintillator pieces had LEGO-type locks (4/layer), and lead pieces had holes. The scintillator layers snap together. No paper layer was used.
      • Advantages: Yi commented that the paper layers can be eliminated because 1) IHEP publications showed that the paper layers did not help with reflection; and 2)the LEGO locks can help holding the weight and thus eliminate the need of the  higher friction of the paper as well as the side plates, but Xiaochao is not sure about their strength.
      • To do: Need to measure friction between scintillator and lead -- Cunfeng measured this after the meeting and found 0.5. This is confusing because paper will make things worse in terms of friction. Need to discuss this at the next meeting.
    2. The rods were looped at the module front. Two nuts per rods were used from the back end of the module and compression can be adjusted there. This can save the space of the front nuts.
  4. We discussed thesis topic of Ye. Besides hadron generator study and the Ecal work, should probably do one analysis task. Besides digging up 6 GeV data on single hadron rate, we need to look into if the currently running DVCS/GMp experiments (Feb-May 2016) have hadron triggers to use (not too-prescaled). Xiaochao will talk to Vince and Alexandre on this. If there are no available data (for free), we may need to propose test runs using the facility development time (1 week long, time TBD).
  5. Scheduled a phone meeting with Vic (the ANL engineer) for this afternoon on the support structure.
  6. Need to continue with followup items from the 12/17 meeting.
  • 12/17/2015 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Chen-di Shen, Tien Ye, Xiaochao Zheng, Vince Sulkosky, Jie Liu, Jianping Chen, Rakitha
  2. Summary of email discussion on compression pressure, from Yaping Wang:
    1. 在整个压缩过程中(参见我之前发送给你们的一张模块质量监测记载表),我们用到了三种不同大小的压力:
    2. Translation of above:
      1. (1) during the first load, we used 125kgf in Wuhan. This is higher than the 110kgf from the SUBATECH (Europe) R&D value (I think this is the company that did the design for ALICE, since many drawings are authored so). We are not sure how Europe got this value. We used higher value because we found after compressing 24 hours using the 110kgf, the module deformation still has not stablize. We measured the air gap thickness between the bottom plate and the compression plate every hour. This gap thickness should stablize eventually, if the compression is appropriate.
      2. We used 60-80kgf in the second load and eventually transfer 40kgf from the compression cross bar to the final spring (integrated into the module). These values are directly from SUBATETCH, aka their empirical values.
      3. Note that values mentioned here are for each loadcell, since in the NANTES instruction for ALICE, it says "higher value -- (9.5 bar, loadcell 1070 N = 109 kgf = 242 lbs)" in the highest compression 24-hr period in step 20, and "(total load 5350 N = 545 kgf = 1210 lbs)" for the 1-2hr precompression period in step 13.
    3. Our comments: Therefore, the exact compression  in the first load should be obtained from our own assembly process/measurement. We can't copy the value from ALICE or any other shashlyk assemling procedure.
    4. Our comments: For the second load and the final load (storage), we can use the empirical values from ALICE (60-90kg/sensor for the 2nd load, 40kg/sensor for the final load, 5 sensors per module.)
  3. Summary of email discussion on drawings:
    1. Xiaochao digged out the assembly drawing file (DWG) received from WSU in July. We tried to pick it apart and understand each component
    2. Yaping also emailed out the Chinese reproduction of all drawings (all PDF format):
  4. From today's meeting, discussions and followup items:
    1. The SDU group will look for equipment that can monitor deformation (change in thickness) of the scintillator and/or lead plates. This will be useful for monitoring compression of the module during assembly. Also if it works, we can use it to measure the YOung's modulus curve of the scintillator. - this also applies to THU group if possible;
    2. The SDU group will look for companies that can measure the Young's modulus (杨氏系数)and yield strength (threshold stress between elastic and plastic deformation of the material) for the scintillator plates. - this also applies to THU group if possible;
    3. Xiaochao will email Paul Reimer to urge for engineering support on module stress calculation/design, assembly station stress calculation/design, and eventually the support design.
      1. for the support design, carbon fiber is possible. Cunfeng updated that price of 1mx1mx5mm carbon fiber sheet is 4000 RMB/m^2. But carbon fiber should not be used for the front plate because of the need of threaded holes.
    4. Xiaochao will continue designing the front/back plates and the side straps, with help from a 2nd-year EE student.
    5. Observation from ALICE is that there is no drawing for the side straps. It was made by welding steel rods to steel plates, and then screw onto the front/back plates of the module.
    6. We need to also use springs (弹簧片) to hold the compression, just like ALICE modules. ALICE modules used 5 per module.
    7. Jianping commented that the nut-rod design is more reliable (tensile stress) than using side plates to hold the compression (shear stress).
    8. Ye Tian (?) will send pictures of all components of ALICE modules.
    9. The SDU group may consider going to 华师again with more detailed questions on module design/assembly.
    10. Jianping mentioned that 华师may eventually also participate in SoLID effort.
  5. We will meet on Thursday 1/7. Happy holidays!
  • 12/10/2015 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Chen-di Shen, Tien Ye, Xiaochao Zheng, Vince Sulkosky, Jie Liu, Jianping Chen, Rakitha B. (Yi Wang is traveling)
  2. THU side:
    1. Received quote for Y11 fiber from Kuraray, about 35RMB/meter. This is factor 2 higher than SG fiber. (Since SDU already ordered 1km of SG fiber, there is no need to order more.)
    2. Need to know the thickness of the endplate. According to earlier meeting minutes, Jin simulated that 2cm Al is okay but 4cm is not good anymore.  Perhaps we can start from 1cm. (Xiaochao wanted thinner ones, such as 6mm or 8mm. But 1cm should be fine.) Jianping also pointed that it should be straghtforward to know if a certain Al thickness would be a problem for PID by simply looking at the radiation length. For example a 1.3cm Al sheet is equivalent to 0.5mm lead, so there should be no effect since it's the same as the lead sheet in the shashlyk. (Al: X0=(24.01g/cm^2)/(2.7g/cm^3)=8.89cm; Lead: X0=(6.37g/cm^2)/(18.95 g/cm^3)=0.336cm; factor 26 difference).
    3. Would like to start assembling a module as soon as possible.
  3. SDU side: Ye reported the first try of the assembly tool using regular plastic plates. See slides: YeTian_12-10.pdf
    1. Compression is applied horizontally using 4 screws (one large, 3 small) (see slide 3)
    2. slide 4:
      1. top left: stacking regular plastic plates. However, encountered the problem that when pressure is close to 200kg, all plates start to bulge up.
      2. top right: 3 sensors were used to monitor the force;
      3. bottom left: compressed existing ~10 lead and scintillator plates, no visible change is observed after 200kg force is applied and released;
      4. bottom right: closeup view of the compression screws
    3. (later Xiaochao commented that the regular plastic may have different properties from the actual scintillator, so the problem they encounter for the real ones may be very different.)
  4. General discussion on the module structure: Overall, we still don't have a good design, but we are making progress
    1. discussion on material: Robin mentioned we usually use stainless steel 304L or 316L in magnetic field. Aluminum can be used near field but we need to avoid close loops due to Eddy currents. Al can be anodized to avoid such loop. Jianping commented that Eddy currents are always a problem but we had always used Al 7075 for 3He targets and do not see why we can't use it here.
      1. ALICE used aluminum, according to their drawings: "Alcan Alplan 5083 or equivalent, manufacturer can replace by AA6082 T851 at their own risk".
    2. We should also look into carbon fiber, at least to know the cost. Can the Chinese groups look into local companies that can do carbon fiber and get an idea of how the cost compare to aluminum?
    3. Last week Xiaochao hoped to use side plates to hold the compression pressure, but it doesn't look possible. Now it looks like we can use endplates+rods to hold a certain pressure, and the purpose of the side plates are to hold the weight and avoid sagging. But ALICE instruction showed the high pressure was maintained after the module was assembled. Xiaochao will continue to try understanding and calculating the stress on the components of the module during and after assembling.
    4. Xiaochao suggests the Chinese groups to read the ALICE assembling instruction thoroughly. It is a very complicated procedure. Even if our prototype assembling can be a "short cut" of the final version, we should be patient and do not start stacking the real components until we understand each step of the ALICE instruction. Otherwise I suspect the module will fail, or worse, there will be safety problems.   (In fact, I suggest that the SDU group to not rush and try the current assembly tool because of the reason above.)
    5. We need to understand how the compression is determined for each step. I already emailed Yaping. Will also go through WSU side to see if I can find more information.
    6. The ALICE assembling procedure involved 5 load cells, compression plates/bars, a pneumatic piston, and aluminum shims of various thicknesses. Can the Chinese group research on these components?  I can do basic calculations now, but to develop the full assembling procedure I need to know how each component works.
    7. Xiaochao will email her department colleagues and from JLab engineers to find out if there are local companies offering material testing services. We need the mechanical data for the scintillators.
  • 12/03/2015 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng, Yi Wang, Chen-di Shen, Xiwei Wang, Tien Ye, Xiaochao Zheng, Vince Sulkosky, Jie Liu, Jianping Chen, Rakitha B.
  2. THU side:
    1. Found another company (北京佳腾机械科技发展有限公司) for making the lead plate, Xiwei has checked the quality, so far pretty good and the price is only 7 RMB/piece (Qingdao company now estimates 12-13 RMB/piece). Some pictures are posted here: lead_plate1.jpg  lead_plate2.jpg  lead_plate3.jpg
    2. Received scintillator plates from 科迪(Kedi). Kedi can't make the mold and must contract it out. Below are pictures of the mold-produced scintillators from two companies:
      1. company #1: pictures: 1.jpg   2.jpg   3.jpg
      2. company #2: pictures: 1'.jpg  2'.jpg  3'.jpg
      3. However, both companies made the scintailltor with the hole directions opposite to that of the drawing. Cunfeng has asked the company to flip their mold.
    3. Xiwei has done measurements of the hole position for both the lead and the scintillator plates. Results are shown in this spreadsheet: shashlyk_plate_hole_quality_20151203.xls
    4. Also studied ALICE Ecal assembly procedure. Chendi designed an assembling procedure, see slides: Chendi_assembly_design_2015_12_03.pdf. Xiaochao added the notes to each slide after the meeting. Magenta texts indicate steps where modifications need to be made and are shown below:
      1. page 10: Chendi reported that the compression is determined by the height of the two white posts, but this would not work. Jianping and Xiaochao commented that each module can be different and we should make the posts a little shorter and use the pressure sensors alone to continuous monitor/adjust the compression.
      2. page 10-12: When wrapping the black tape and the side plates, the compression needs to be in place because the layers would spring back as soon as the compression is removed. There is also the question whether pre-drilled holes should be made on the side plate, and whether we should use some spring load between the last scintillator and the endplates to keep certain tension, as ALICE did?
      3. Jianping mentioned we need to calculate the center "bulging" of the endplates, since all compression is held by the side plates or the rods on the edges. This will determine the minimum thickness of the endplates, which should be simulated.
  3. SDU side, presentation from Ye Tian: 12-3_YeTian.pdf
    1. Measured the coefficient of kinetic friction between materials using two slightly different methods. The main results can be summarized as follows:
      1. between paper and scintillator: 0.22-0.23
      2. between paper and lead: 0.33-0.34
      3. between Tyvek and scintillator or Tyved and lead: 0.09-0.13, depends on method
      4. Looks like we should definitely use paper. Xiaochao will update the calculate using mu_s=0.2.
    2. Slides 5-7: measured the light yield of fiber silver-plated by a company in Yantai. The light yield is nearly doubled using silver plating and the leak from the plated side is <10% of the yield of the plated fiber.
    3. Slide 8: measured thickness of all materials already at SDU:
      1. 600 pieces 0.5mm lead plate -- Thickness: most 0.51+/-0.005mm, but some could reach0.52-0.53mm
      2. 20 pieces 1.5mm scintillator -- Thickness: 1.50+/-0.02mm
      3. given that the light yield fluctuation is mostly from the scintillator thickness, the above results should be okay. (need to confirm at next meeting).
  4. Jianping cautioned that everyone working with lead should be careful and use protective measures (gloves, face masks if lead powder is involved).
  5. Xiaochao asked the lead material data sheet for both companies. We want to know if there is any magnetic component/impurity.
  6. So far we don't have a plan yet to measure the Young's modules and yield strength of the scintillator and the lead. Need to find a way to do so.
  7. Xiaochao remade the module design and calculation. The idea now is to use metal plates to keep the compression between layers, and use rods for cantilevering the modules to the back support plate. The first version was sent around by emails but there were mistaks, so it is not posted here. To dos:
    1. look for suitable material for the endplate/sideplate/screws. Al alloys are strong but Robin said they should not be used inside a magnetic field because of Eddy currents. So we may go back to stainless steel after all.
    2. correction of the module sagging (should be 11 microns not 11mm).
    3. calculation the bulging of the hexagon center due to compression. This will require a minimum thickness of the Al endplate which in turn will affect PID performance.
  8. Other: for the Ecal pre R&D request, Xiaochao will remove the prototyping part but will add in travel support for the Chinese collaborators (Ye, Jianbin and Chendi).
    1. followup: Jianping mentioned the detector part is not the highest priority. (Highest three are simulation, magnet, and DAQ). So maybe I will wait until Feb. 2016 (my usual annual report time) to submit a supplemental request.
  9. Simulation:
    1. Rakitha did the simulation using the Hall D generator. (last reported at the 10/15/2015 meeting). The results are show in ecal_HallD_TriggerAnalysis1.pdf
      1. page 2: used radius-dependent cuts to preserve DIS electrons
      2. page 3: Backgrounds are generated using cross section weighted events from hall D generator, including pi-, pi+, and pi0, pi0-photons, other photons.
      3. page 5 and 6: tracks incident on Ecal before and after applying the 6+1 trigger
      4. page 7 and 8: event rates using Wiser vs. Hall D generator. The Hall D gen version's backgrounds are lower than the Wiser version by factor 2-3.
      5. page 12 and 13: trigger rate. These are much lower than slides 7/8 because there an be more than 1 event in each 30-ns window.
      6. Overall, the Wiser-based simulation is very close to the preCDR table (the only difference seems coming from not including the Em contribution, see below). And the Hall-D generator-based one has rates lower by factor 2-3.
      7. Next will move on to include also proton and other EM backgrounds, although the preCDR results already showed their effects are not dominant.
      8. Since now the goal for "reproducing preCDR trigger results" is nearly complete, it is time to make a more detailed plan for "integrating all detector trigger/simulation". Perhaps Zhiwen and Rakitha can make a step-by-step plan together.
    2. Zhiwen presented some work on combining all detectors of SoLID to get the triggers, see his presentation at the 10:30am simulation meeting: solid_simulation_zwzhao_20151203.pdf Some findings:
      1. ANL module layout seems incorrect, causing overlapping of modules if using 6.25cm-side hexagons as the module cross section.
  • 11/19/2015 Meeting to discuss EC and DAQ:

  1. Participants: Yi Wang, Chen-di Shen (申忱迪), Xiwei Wang, Jianbo Jiao, Tien Ye, Xiaochao Zheng, Vince Sulkosky, Jie Liu, Jianping Chen, Zhihong Ye.
  2. THU side:
    1. Received 20 lead plates from Qingdao and borrowed a testing machine to measure the hole positions. So far the positions are very good.
    2. Borrowed a tesing machine (the company name is 上海台硕, Xiweimeasured three lead plates and a film and the results are in this spreadsheet:  Xiwei_Wang_20151119.xls. Some explanations:
      1. Not every data was tested because of the time and limited conditions.
      2. The holes are arranged as the corresponding plate drawings.Each hole has its coordinate so the hole 74 means it is in row 7(transverse),fourth .There are 13 rows in total.
      3. The big holes are arranged as counterclockwise.(大孔1~大孔6)
      4. "57-66" means the distance between hole 57 and hole 66.
      5. "×" or "?" means it can't be measured or needn't to be measured.
      6. The following datas are about some distances and angle on corresponding drawings.(You can compare with drawings when seeing)
      7. Comments from XZ: big holes are okay, hole positions are okay, but the fiber hole diameters are about 1.45mm which is smaller than the specified (1.5,1.7)mm on the drawing.
    3. Also working on designing the assembling tools. The goal is to make 4 modules. (Hooray!  so now we might have 4 prototypes from SDU and 4 more from THU, enough for forming a 6+1 cluster!)
    4. Have a new master student, Chen-di Shen (申忱迪), to work on Ecal. So now THU has two master students on Ecal and both will have about 2 years. Xiwei can focus on hardware construction and testing, while Chendi has experience with GEANT4 and can help with simulation. We discussed that Chendi can start installing the SoLID simulation software on his desktop at THU and make it work (the SoLID simulation group should help with this), then generate preliminary Ecal performance.  We also should plan to have Chendi visiting JLab for 2-3 months. Wang Yi mentioned it's okay for THU to cover the flight and ~$30/day per diem, but either JLab or UVa need to look for about $30/day fund to match so the total is enough to cover living expenses.
    5. We discussed about the endplates of the module. UVa side thought about 6-mm thick aluminum but there is no reason why we can't use stainless steel.
    6. For the WLS fiber, Wang Yi was suggested by one of his colleages that Kuraray Y11 might be cheaper than Saint Gobain. UVa's experience is the opposite, so both SDU and THU should check with the Kuraray sales office in China to get a quote. The type we need is Y11(200) S-type, either single- or double cladding (double will have higher light yield but this can be something to decide during prototype testing.) SDU mentioned they ordered 300m from S.G. (average 75cm per fiber for 4 modules). Xiaochao commented that 360m will be a safer bet, and suggested THU to order 400m in case SDU needs spares later.
  3. SDU side:
    1. Assembly tools are here;
    2. Visa progress: Ye Tian interviewed today but is being checked; Jianbin went for interview on Tuesday and was told to use J- instead of B-type VISA. So far both may not be able to get the VISA by the end of this (solar) calendar year.
  4. For the record, the drawings used for prototyping are posted under this directory: drawings/cad_hexholes_v3
  5. Since both SDU and THU groups are recieving samples for the lead plate and the scintillators now, suggest measuring the coefficient of static friction between paper and lead plates, and between paper and scintillator plates. For the paper please use both regular printer paper and the bond paper sample from ALICE.
  6. In preparation for the module assembly we need to know the compressive strength of all material. SDU group has received a couple of samples from Kedi and will contact Kedi for any data they may have. If Kedi does not have data available, we will need to test this ourselves.
  7. Jianping urged again that we should get as much information as possible from WSU and 华师. Looks like both THU Xiwei) and SDU (Cunfeng) groups have already visited the华师 lab and learned some info. Below is a quick summary of what we know so far:
    1. 华师给Alice实验室组装量能器的过程: modules_assembly_procedure_150209_from_Nantes.pdf
    2. Module production logsheet: module_production_datasheet.jpg
    3. The contact person at 华师is Yaping Wang (王亚平). Some followup emails are included here:
      1. layers are stacked with a few s.s. pins inserted to keep alignment. After layers are stacked, more stainless steel pins are inserted before shipping. WLS fibers are insertted after modules are shipped to Italy/INFN.
      2. About installations, 3 pictures: L1030922_comp.JPG, L1030977_web.JPG, L1030963_web.JPG
      3. About compression: 
        1. We have 5 plunger pins to compress the compression plate for pre-compression process with 125kg press on each at Wuhan lab (this number could be different slight for different lab/location). The pre-compression lasted for around 24 hours at assembly station. After the pre-compression, we mount black papers shroud on 4 lateral sides of the module, and then mount straps. Then we set 75kg press for a long time stable compression off the assembly station.
        2. Once the compression was done, we will remove the 75kg press and transfer a 40 kg press on each plunger pin to the belleville washers which assembled inside of the compression plate of the module. The 40kg press will be kept all the time, and we adjusted every day to keep it at 40 kg before the shipment to Europe.
        3. These values are slightly different from the assembly instruction above, but are close.
    4. ALICE used "bond paper". Samples from 华师looks similar to printer paper but the surface is rough. We will keep searching for the exact material type.
  1. For the shashlyk module design, now we confirmed that the rod design will have too much load on the top rod, we need to study if the "wrapping" design is better. To do this,
    1. Xiaochao will have a quick calculation of the "plate design" and send the geometry of both the rod and the plate design to Rakitha, so Rakitha can simulate the effect on PID.
    2. Rakitha mentioned so far the spacing between modules is only a couple of mm. If we add stainless steel plates, the spacing has to be larger
  • 11/12/2015 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng (冯存峰), Jianbo Jiao (焦健斌), Tien Ye (田野), Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Rakitha B.
  2. UVa side:
    1. Vince is circulating the FMPMT test paper among all authors;
    2. preparing for LASPD timing test with GEM, probably between Thxgiving and X'mas. Plan to 3D-print PMT holders to attach to the SPD.
  3. Update from Tian Ye: got electro-plated lead samples from the Qingdao company, and tested the reflectivity, see solid_11-12_tianye.pdf.
    1. Note: the 1/3 surface area on the last page refer to the ratio of (area covered by lead)/(total surface area of preshower). So it is 0.36, or (100)/(100+100+75) for the preshower.
    2. All 4 electroplating material (page 2,6) are magnetic and can't be used.
    3. Results on the reflectivity show that the plating is far lower than Tyvek or printer paper, thus should not be used.
  4. Update from Yi Wang:
    1. May test 100-micro PVC sheets with reflective aluminum layers.
  5. Jianping asked if we have a thorough study on
    1. the reflective layers. Has anyone tried aluminized mylar? We should avoid doing R&D if other groups have already studied the same material.
    2. if we rely on static friction, will it change with radiation? (Tyvek is made of high-density polyethylene fibers and may degrade) We need to study radiation damage to both Tyvek and printer paper (and bond paper used by ALICE.)
    3. the assembling structure, now that we know the rod design may have a problem?
      1. LHCb: 100-micro thick steel tapes are welded to the steel compression matrices (= welded to "endplates")
      2. ALICE: from WSU picture 20150505/WSU/3-test.JPG, the modules used side plates screwed to endplates.
      3. ATLAS: extensive stress tests were done on the modules (shear failure test of the welded front-pate, torsional load test, front-plate bearing load test, and non-uniform loading of the mater plates).
  6. Update from Cunfeng:
    1. The Qingdao company has completed 400 lead pieces.
  7. Here is a summary of communication between Xiaochao and the U. Iowa engineer Paul Debbins:
    1. Comments on our "rod" design on 7/30/2015:
      1. I have a first order look at the shashlik for SoLID. My initial reaction is that the brass rod structure will experience significant 'sagging', even with both ends held fixed. The problem is that there is no diagonal vector which carries the force. The assembly essentially behaves as a series of heavy beads on a string, deforming into a catenary profile.
      2. I will try over the weekend to finish a more quantitative computer model. I would suggest  a thin external structure, such as a carbon fiber hexagonal tube which encases each shashlik module. This provides planar sections which are structurally sound and the resulting diagonal rigidity needed to resist the type of deformation present in this situation. This results in gaps between the active regions of each cell, so you have to consider how much such a gap will impact physics performance. 
      3. I modeled the assembly with minimal compression force between plates (thus the beads on a string analogy - allowing the plates to slip relative to each other). In reality there will be some compression and thus friction between plates, but with lead being relatively soft and the scintillator possibly fragile, I did not assume the module can be pulled together with a high degree of compression. This depends on the scintillator - if it is a fragile material (such as LYSO used in CMS shashlik proposal) compression forces are not possible. I would need to know the exact scintillator material and the lead alloy to be able to estimate how much compression is tolerable and how much structural benefit results.
      4. This situation also could benefit from the use of adhesives to bind things together, however it depends upon how much integrated radiation dose the detector will experience and if a suitable adhesive can be found to survive in the operating environment expected.
      5. (Note: lead alloy info emailed on 8/13).
    2. CMS prototype making from 5/26/2015:
      1. Here are photos of the individual and 4x4 matrix of shashlik cells (for CMS). These were constructed by hand due to the small quantity. Obviously, mass production would require robotic assembly to be designed. This type of construction has each stack of W plates and LYSO crystal individually wrapped in opaque aluminum, optically isolating and providing a mechanical skin of support. This method is generally referred to as an 'alveolar' construction. This alveolar method is one method under study using carbon fiber. Obviously in the test beam module the frame holding everything together is quite thick (made of polyester). In a detector, a thin-walled outer alveolar structure would have to be employed.
      2. I have also included 2 slides showing a 'plate and web' type of architecture. In this method, the W plate spans the full face of a 'supermodule', which is an array (5x5 in this case) of individual cells. The plates are separated by a carbon fiber webbing which spaces the plates apart and forms the side walls of pockets for each crystal.
      3. Both methods need further study and prototyping. My current thinking is a hybrid of both methods, using plate and web internally and an alveolar tube the bind the group into a supermodule.
  • 11/05/2015 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng (冯存峰), Xiaochao Zheng, Vince Sulkosky, Jie Liu
  2. UVa side: Vince is working on the FMPMT test paper.
  3. Update from Cunfeng:
    1. Ordered 300 lead plates from the Qingdao company, will arrive next week.
    2. Assembly stand: also ordered;
    3. Scintillators: production at Kedi in progress, they are using a 2nd company for quality check.
    4. Saint-Gobain fiber: discussion ongoing, can consider directly plating mirror to fiber ends, but the company is not sure how to polish it.
      1. Followup: Here is a file from Kuraray on how to cut&polish fibers: How to Polish_Kuraray.pdf. In the UVa lab, we cut the fiber using a razor blade, then polish with a fine sandpaper and then use flannel (regular sewing material) to do the final polish.
    5. About the reflective layer, the SDU machine shop made a tool and can make it with paper, but not Tyvek (too slippery). *** Can consider Al-plate the lead plates, then no need for the reflective layer.
    6. Xiaochao asked to measure the static friction coefficient between paper and scintillator, between lead and paper, and between Al-plated lead and scintillator.
  4. Followup on item D from 10/15/2015 minute:
    1. The factor 6 indeed should not be there. So the tensile stress on the top rod (after x2 for safety) is higher than the strength of brass.  We can consider using stainless steel rods, or increase the rod diameter (top rod only). Also the calculation depends on the mu_s (static friction coefficient, assumed 0.1 for now) so the final calculation can be different depending on the actual mu_s.
    2. A setback: Victor, the Argonne lead engineer, is leaving for a new job at U. of Chicago, on 12/1. We do not know if he can continue helping with the Ecal work.
  • 10/22/2015 Meeting to discuss EC and DAQ:

  1. Participants: Ye Tian (田野), Cunfeng Feng (冯存峰), Jianbo Jiao (焦健斌), Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Jie Liu
  2. Discussed briefly about the status of the simulation:
    1. Rakitha is using Seamus' remo for Moller, but the Ecal part can be migrated to GEMC if needed. Almost everyone else is using GEMC (Zhiwen, Cherenkov, and MEIC work at JLab). So far we have not decided on which one to use for SoLID. Also Jin's calosim is in GEMC.
    2. Jianping commented our near-term goal is to get the MIE/TDR ready.
    3. Rakitha's report from Monday showed the background is 2-3 times lower with the Hall D generator.
  3. UVa:
    1. Vince has almost finished the draft paper on the FMPMT test results. Will move on to proposal work (nucleon resonance PV) now.
  4. SDU group:
    1. Kolgashield has started production for the 1000 lead plates;
    2. Ordered 600 lead plates from Qingdao (青岛英太克锡业科技有限公司). Total price is 10kRMB including 8kRMB on the mold. So in average the price is 13RMB/piece but the unit price for larger amount will be significantly lower.
    3. Also met Saint-Gobain salesperson, plan to order 1km of BCF91A multiclad. The price is about $2.82/meter. Xiaochao's earlier quote from Saint-Gobain US is $2.36/m for 1km, for BCF91A single-cladding. So the price SDU got is reasonable. We discussed about EMA (extra mural absorber, see S-G catalog). We think it is not necessary since EMA is for reducing cross talks and also will reduce the light output.
  5. We talked about when to have Ye Tian in the US. The SDU group has about 15kRMB to spent by the end of the year, so Jianping will start the paper work now. We hope Ye will join us at JLab in early December for at least 6 months to work on the pion background work.
  6. Jianping:
    1. discussed with Haiyan on the plan to ask Tim Hallman to visit China. Probably Beijing in mid December. Will visit the Chinese NSF, 科技部, and will also have a meeting with the Chinese SoLID collaborators. The meeting with the collaborators will probably be hosted by Tsinghua U.. The SDU group should join this meeting.
    2. mentioned that Thia said the pre R&D request of Ecal will have to go to DOE because the JLab resources have been spent on the magnet and elsewhere.
    3. May start working part-time from China, for a few years starting 2017. This is mostly to lead the SoLID effort from the Chinese side (973 application).
  7. We won't meet next week due to the DNP meeting. And Jianping will be in Europe on Nov. 5th.
  • 10/15/2015 Meeting to discuss EC and DAQ:

  1. Participants: Yi Wang (王义), Xiwei Wang (王溪葳), Ye Tian (田野), Cunfeng Feng (冯存峰), Jianbo Jiao (焦健斌), Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Alexandre Camsonne, Rakitha B.
  2. Tsinghua U. group:
    1. Planning to make one module.
    2. For lead plates, found many companies in China but quality is a concern. (tooling cost is >~$7k USD) -- but see SDU report below.
  3. SDU group:
    1. Already ordered 1000 lead plates from Kolgashield.
    2. Also found a company in Qingdao (青岛英太克锡业科技有限公司) with a price of (estimate) RMB13-30/piece. The "model" (i.e. tooling) will probably be RMB5000.
    3. Ye presented some tests done on the lead plate hole position and variation, see lead_plate_test_new.pdf. The results are self-explanatory. Just a few notes:
      1. The equipment is called 光栅尺(displacement sensor)using 莫尔条纹(Moire patterns). The position resolution is supposed to be 1 um(micrometer).
      2. page 5, results on the hole position/distance need to be updated with the latest calibration of the equipment itself.
    4. Overall, we believe the quality of this company is pretty good. Tsinghua U. group can contact this company for their lead plate need.
  4. Here is the calculation of the module supporting rods if all modules are cantilevered from the back with Xiaochao's notes hand-written on the side. However, Xiaochao is still checking the calculation. There may be a factor of 6 off on the last page, for the stress on the rod. If that's the case then the rod won't hold.
  5. Jianping asked what reflective layers did other experiments use?
    1. ATLAS: wrapping material is described in the tile calorimeter TDR, see p199-202 pdf. Tyvek 1055B was used with masks printed to keep the light collection uniformity <5%.
    2. LHCb: this is described in lhcb-2000-043-note1-ecal-design-and-construction.pdf: "White reflecting 120 μ thickness paper ( TYVEK )". Also, "Tile edges are chemically mat ( thus providing the diffusive reflection ) in order to improve light collection efficiency, transverse uniformity [5] and prevent tile-to-tile light crosstalk. Alternatively the tile edges could be aluminized (HERA-B solution) with the technique of Al evaporation in vacuum by HV-induced explosion. With this lattermethod one obtains ∼ 10% worse reflection efficiency, compared to the mat coating".
    3. ALICE: from their NIM paper: "white, acid free, bond paper serves as a diffuse reflector on the scintillator surfaces and provides friction between layers. The scintillator edges are treated with TiO2 loaded reflector to improve the transverse optical uniformity within a single tower and to provide tower to tower optical isolation better than 99%". Their drawing shows material "20 WT bond paper 0.1mm".
  6. While I am at it, I also checked the scintillator composition:
    1. LHCb: The tile is produced of polystyrene-based PSM-115 scintillator with the 2.5% p-terphenyl and 0.01% POPOP admixtures. The concentration of scintillating dopants is chosen so, that the scintillator light is almost saturated, and is tuned for the scintillatoremission spectrum to match the absorption spectrum of WLS fiber.
    2. ALICE: Polystyrene (BASF143E+1.5%pTP+0.04%POPOP).
  7. Rakitha reported his work on PID: ecal_pid_efficiency_4.pdf
    1. Background only includes (Wiser) pions for today. DIS pions are also based on Wiser.
    2. Still using Wiser for pions this time, but is working on the Hall D generator in the meantime.
    3. slide 9 compare to slide 10: without and with backgrounds. With background, after tweaking the cuts slightly the electron efficiencies hardly changed and is even higher for some regions. This is due to background raising the signal amplitudes.
    4. slides 11-12: pion efficiencies without and with backgrounds.
    5. Jin's results are on p.14. We believe Jin used fixed cuts but plotted the efficiencies for different radius.
    6. Jianping commented that cuts should be adjusted after adding the background. For example now Rakitha's e efficiency is higher than Jin's but pion rejection is lower.
    7. We reviewed the goal of Rakitha's work: first we want to reproduce preCDR results (he is almost there), then upgrade to HalL D generator, then need to integrate Ecal and Cherenkov simulation to produce combined results on the offline PID and triggering.
  8. Jianping suggested Xiaochao to think about what processing can be done to reduce data volume on the L3 farm (online), this is more important than offline PID.
  9. At last, the 2015 NSAC Long Range Plan is out today! See SoLID is mentioned on
    1. page 12 (PVDIS electroweak)
    2. page 15 (PVDIS proton)
    3. page 18: "Finally, the proposed multipurpose SoLID detector (see Figure 2.6) would realize the full potential of the upgraded CEBAF"
    4. page 75 on electroweak physics: "New projects, SoLID at JLab and P2 at Mainz, Germany, are planned to limit or discover such contributions in a manner complementary to MOLLER and collider experiments. SoLID, whose design also enables a multi-faceted hadron physics program, will measure the variation of θW in a regime where a previous experiment, NuTeV, found an unexpected discrepancy. SoLID has unique sensitivity to new quark-quark neutral weak forces in an energy regime that is challenging to isolate in other PVES and collider experiments. Indeed, modelindependent considerations show that the projected sensitivity of all three PVES proposals match, and in some cases exceed, the direct reach of the next phaseof the LHC, besides being mutually complementary..." (also page 77)
    5. page 89: "While the currently envisioned program includes both high rate capability and large acceptance devices, there is no single device that is capable of handling high luminosity (1036–1039 cm-2s-1) over a large acceptance as needed to fully exploit the 12-GeV Upgrade. The SoLID (Solenoidal Large Intensity Device) program is designed to fulfill this need. SoLID is made possible by developments in both detector technology as well as simulation accuracy and detail that were not availablein the early stages of planning for the 12-GeV program."
    6. page 101: about Chinese participation in SoLID.
  • 10/01/2015 Meeting to discuss EC and DAQ:

  1. Participants: Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Seamus Riordan, Alexandre Camsonne, Paul Reimer, Rakitha B., (Ole Hensen, Steve Wood joined at 10am as part of the simulation meeting)
  2. Paul R.: Will talk to Victor on Ecal engineering design/calculation at 9:30am tomorrow.
  3. Vince reported on FMPMT test, see Finemesh_PMT_01Oct2015.pdf. A summary is as follows:
    1. The main goal of the test is an absolute determination of the FMPMT's timing resolution using the "3-bar" method. Along with the high-field test on the gain and the timing, this concludes all tests we need to do on the FMPMT.
    2. The timing resolution results are as expected.
    3. It is difficult to determine the single-photoelectron peak for this FMPMT.
  4. Xinzhan's work on SPD simulation: see phase_1.pdf. A quick summary and comments are as follows:
    1. Tried to reproduce Zhihong's simulation for SPD rate, photon rejection, segmentation, with backgrounds.
    2. Slides 2-3 are simulation results from GEMC.
    3. Slide 11: used a cut of 0.2 MIP. Xiaochao commented that we probably will use 0.5MIP because the MIP signal for the current design is already very low, and we need to keep the threshold no lower than 20mV, above the noise level.Jianping commented that we need to use simulation to determine on the best threshold.
    4. Slide 12: Rates for LA and FASPD. Jianping suspects the rates for the two are switched. Need to check.
    5. Slide 13: What's plotted here are energy deposition of daughter particles. The particle type labeled on the plot is for the mother particle. Question about the sharp drop at 1keV, too high as ionization threshold and too low as pair production threshold. Need to understand its physical cause instead of trusting GEMC as a black box.
  • 9/24/2015 Meeting to discuss EC and DAQ:

  1. Participants: Cunfeng Feng (冯存峰), Jianbin Jiao (焦健斌), Ye Tian (田野), Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Seamus Riordan, Paul Souder
  2. Prototype production:
    1. SDU: order for the lead plate from Kolgashield is ongoing;
    2. SDU: molding for the scintillators is being produced.
    3. UVa: received also quotes from VolcanGMS, price for 4-5 modules is similar to Kolgashield. Also they can attach reflective layers directly to the lead plates and eliminate the need of reflective paper layers. However, two question: 1) will the price for the full production be as competitive? 2) they currently use mylar which is very slippery and may not be suitable if we cantilever the modules. For quotes see this directory.
  3. Xiaochao continues discussion with Paul Reimer and Victor Guarino (ANL engineer) on checking the cantilever force calculation, and also a general plan for what Vic would do for SoLID. Will send out a writeup soon about the calculation.
  4. Vince continues working on the FMPMT test, focusing on the absolute measurement of its timing resolution using the 3-bar method.
  5. We discuss the PhD work planned for Ye Tian on the hadron generator, which for SoLID is mostly for background estimation.
    1. Wiser code works up to factor of two for p>1GeV, which is okay (reasonable), see previous summary memo memo46-wiser.pdf. But for p<1GeV/c Wiser never had data and may be wrong by orders of magnitude. Need to replace Wiser by the Hall D photoproduction generator and check with data.
    2. A relevant presentation is the simulation by Rakitha at the SoLID meeting, see link here. He has incorporated the Hall D photoproduction generator into SoLID simulation and produced good agreement with the PDG photon data, works particularly well for low energy below 1 GeV. He has also incorporated the EPA (equivalent photon approximation) into SoLID simulation.
    3. We need to use the Hall D code, plus EPA, and cross-check with existing 6 GeV data. Need to dig out pion data (both below and above 1 GeV) from 6 GeV experiments using radiators. All these experiments ran with both radiator in and out, both are a mixture of photon and electron beams. (Radiator-in runs produces more photoproduction and radiator-out is mostly electroproduction). This will be a good thesis work for Ye Tian.
    4. A summary in the table form is below. Red "todo"s are possible work for Ye Tian.
    5. Code
      pion momentum p < 1 GeV
      pion momentum p > 1 GeV

      compare to data
      compare to data
      Wiser + EPA or Mo&Tsai for electroproduction
      do not expect the code to work (Wiser did not have data < 1 GeV)
      do not expect the code to work (Wiser did not have data < 1 GeV)
      done for PVDIS and 3He experiments (see memo46 above)
      Hall D code for photoproduction
      done (by Eugene from Hall D)
      ongoing (see e.g. Rakitha's presentation above, for PDG data only)
      Todo: compare with JLab 6 GeV photoproduction data
      done (by Eugene from Hall D) ongoing (see e.g. Rakitha's presentation above, for PDG data only)
      Todo: compare with JLab 6 GeV photoproduction data
      Hall D code + EPA or Mo&Tsai for electroproduction
      ongoing for SoLID (see e.g. Rakitha's presentation above) Todo:
      - compare with JLab 6 GeV electroproduction data
      ongoing for SoLID (see e.g. Rakitha's presentation above) Todo:
      - compare with existing JLab 6 GeV data (PVDIS, 3He experiments, see memo46)
      - compare with more JLab 6 GeV electroproduction data
      Based on the table, a general plan for Ye Tian is:
      1. While at SDU, learn the physics, copy and compile the Hall D code and make it run;
      2. Get information from JLab on which other 6 GeV experiments may have single pion rate information, with a focus on experiments using radiators.
      3. Visit JLab, during which the focus should be to extract pion rates from JLab 6 GeV experiments (in addition to the PVDIS and the 3He experiments we already did), for both photo- and electro-productions. This could be intensive work as it involved making some old database and analyzer to run.
      4. Compare Hall D + EPA/Mo&Tsai calculation with data

  • 9/1/2015 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Alexandre Camsonne, Rakitha B., Xinzhan Bai, Zhihong Ye, Xiaochao Zheng, Vince Sulkosky, Jie Liu
  2. We discussed about the SBIR proposal from [Paradigm – The Polymer Division of INCOM Inc.] (basics on SBIR: phase I is 9 months, up to $150k; phase II is up to $1M)
  3. Hall A ep device is available for taking. Should look into what we can use for lab testing here. (scintillators, PMTs, electronics, power supplies, etc)
  4. Should we schedule bi-weekly meeting for Thursday 9am to accommodate Chinese collaborators?
  • 8/25/2015 Meeting to discuss EC and DAQ:

  1. Participants: Seamus Riordan, Rakitha B., Jianping Chen, Alexandre Camsonne, Yuxiang Zhao, Xiaochao Zheng, Vince Sulkosky
  2. We discussed what the SDU student would do: one suggestion is hadron physics generator for the SoLID simulation package. Could be based on both Wiser and the Hall D photoproduction code (by Eugene). The other option is Ecal simulation itself where we definitely can use some help.
  3. Xinzhan has started working on SoLID, focusing on SPD and MRPC simulation for SIDIS;
  4. We discussed the manpower issue: Rakitha is looking for jobs (being 3rd year with Syrucus), Zhihong is going to ANL...
  5. We discussed the SoLID plan: DOE requested a research management plan. This will be discussed at the 9/11-12 collaboration meeting. In November, plan to meet DOE for the preR&D plan.
  6. We discussed what is most needed to progress from pCDR to TDR/MIE. The conclusion is that simulation is the weakest point.
  7. Rakitha presented work on PID, see ecal_summary_3.pdf. Comments:
    1. p.4 shows dE/E we can achieve if we can measure Edep in lead. This of course is not a realistic condition but just showing what is the "most intrinsic" resolution we can get.
    2. p.5 updated dE/E, again agree with Jin's within half-percent.
    3. p.13 and on-ward: now using Edep normalized by momentum p, studying pion rejection with the Wiser-pions.
    4. p.15, when calculating E/p, should consider that tracking precision on the momentum adds to 1% of uncertainty.
    5. p.15, there seems to be a high cut on E(tot)/p, which should be removed
    6. next step is to incorporate low-energy background and study PID.
  8. Jianping mentioned the recent progress on MRPC front-end electronics, which uses "MCP PMT" which is  not sensitive to high field at all. Xi-an research institute of opt. physics is researching on this. Here is a presentation from USTC: NNVT_MCP-PMT-intro_2015.pptx (sorry, in Chinese. Also the slides showed nothing about performance under high B-field?)
  9. We discussed what to be done at the next SoLID collaboration meeting (9/11 and 9/12):
    1. pre R&D plan will be the focus of the meeting.
    2. prepare for Science review (T.H. did not want to set a fixed date, need to wait for the Oct LRP announcement. Could be early 2016)
    3. prepare for MIE/TDR
  • 8/11/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Alexandre Camsonne, Ardavan Ghassemi (Hamamatsu), Rakitha B., Xiaochao Zheng.
  2. Today we will have Ardavan Ghassemi from Hamamatsu join our meeting.
  3. Vince has completed the high-field fine-mesh PMT test. Click here for his report. As a comparison, we summarized previous test results at the 10/07/2014 meeting. Overall, our results on the gain is consistent with both INFN and the USC results. But we still need to understand the 300-400ps timing resolution measured in our test since it does not look consistent with TTS/sqrt(nphe) unless our nphe is only 2-3.
  4. Rakitha reported on PID results (no background): see ecal_pid_efficiency_3.pdf. Overall the pion and the electron efficiency results look promising. Suggestions:
    1. use momentum-normalized preshower and shower Edep, replace the shower cut by the 2D shower+preshower cut.
    2. adjust cuts as a function of momentum, keep the overall electron efficiency >95% and study the pion rejection.
  5. Xiaochao visited SDU and Tsinghua University for the Shashlyk collaboration work. SDU is already working with a lead fabrication company (there could be difficulty in getting high-quality fabrication). Also discussed with Prof. Cunfeng Feng and Prof. Zuotang Liang on how to get the funding needed for the remaining 4 modules (about 20k RMB).  Tsinghua U. (Prof. Yi Wang) also showed interest but there is no funding available for the EMCal work. Yi is planning to look for more funding opportunities.
  6. This week Xiaochao has worked on making the EMCal drawings suitable for fabrication. These are based on the ALICE module drawings received from WSU. Xinzhan mentioned his Solidwork license has expired and it may take a couple of weeks to get the new license approved and receive the disk.
  • 7/14/2015 Meeting to discuss EC and DAQ:

  1. Participants: Alexandre Camsonne, Xiaochao Zheng, Jianping Chen, Zhiwen Zhao
  2. Vince is busy with the FMPMT high-field test today and won't be at the meeting.
  3. Xiaochao showed a couple of 3D-printed scintillator samples, include two for the Preshower module.
  4. Xiaochao updated the JLab pre-R&D request with updates on the SDU funding.
  • 7/14/2015 Meeting to discuss EC and DAQ:

  1. Participants: Vince Sulkosky, Xiaochao Zheng, Alexandre Camsonne, Jianping Chen.
  2. Xiaochao: last week's EIC detector R&D meeting went well (only gave a 10-min presentation, and nobody can fail such a short one). The committee only prioritized the projects and provided recommendations by the end of the meeting. Detailed funding allocation will be determined by the BNL physics division sometime this week.
  3. caliper, or alignment group
  4. Vince:
    1. high field test plan, will come to JLab on 7/17 to start the test.
  5. SDU has located 200k RMB Yuan that has to be spent ***within this week***(???). The plan is to order the scintillator plates, the lead plates, and the paper inserts, enough for making 4 modules, total estimate is Y133k for 3 modules *4/3 \approx Y177k or about USD$30k. However, this means we need immediate engineering help to make sure the layer design is okay.  Later one, there will be more funds which can be used to purchase/fabricate an assembly stand, which also need to be designed by the JLab engineer but it will require more time and have to wait pending the engineer's schedule. Question: Where should we assemble these modules?
  6. Discussion with Robin/Whit on 7/15:
    1. Goal: Go through the prototype design and start some calculations.
    2. drawings made by XinZhan Bai, for 0.5mm lead. Drawing for the 1.5mm scintillator and the 6mm aluminum endcaps will be the same.
      1. The 1.2mm-dia holes are for threading 1.0mm dia WLS fibers. All position tolerance is +/- 0.025mm.
      2. The 2.7mm-dia holes are for the supporting rods.
    3. structure of module: alternating layers of 0.5mm-thick lead, 0.12mm-thick paper, 1.5-mm thick scintillator, 0.12-mm thick paper. Total 200 layers lead, 200 layers scintillator, 400 layers paper.
    4. the layers will be held together with two 6mm-thick aluminum endcaps, six supporting rods. Outside the endcap the rods are fixed with nuts.
    5. total weight about 15kg (~150N) for one single module. (scintillator density about 1.0 g/cc).
    6. cross section of module: 100 cm^2; length of module: about 44.8 cm.
    7. Calculations to be made (short-term)
      1. will six 2.5mm-diameter brass rods be sufficient to support the weight of the module? Any suggestion for other non-magnetic material?
      2. stress that the nuts can hold. (which will determine the compression we can apply to the layers).
      3. suggestions for prethreaded rods and nuts. Also need vendor information if available.
    8. Calculations needed (longer term):
      1. what compression force we should apply to the layers during assembly?
    9. Will wait until September for the design of the assembly stand.
  7. Other information related to the prototype design:
    1. supporting rods: plan to use 2.5mm dia brass rods from McMasterCarr, use 2.5mm dies to make thread and use Brass hex nut (M2.5 x 0.45). The reason is the smallest die they have for making threads is 2.5mm, but other companies may carry different sizes. Jianping commented we should look for pre-made threaded rods first. (Al might know). Vince said we might want to use brass or bronze instead of stainless steel.
    2. endcaps: plan to use 6mm aluminum piece and machine in the UVa shop. A 24"x24" (61cmx61cm) plate cost $426.54, can be cut to make 16 endcaps. Machine shop estimate is $1300 for 20 or $450 for 4. (Note can also use 8mm aluminum, in particular for the back endcap.)
    3. Note: this has to wait for Septembter...Assembly: It is desired to have a proper assembly stand, for which we need the engineer's help and will take some effort. Parts can be made at UVa shop. The pictures from WSU's stands can be found in this directory. From what I was told, it looks like the procedure at WSU is as follows (some info came from the 7/23 email).
      1. layers of lead and scintillators are stacked on the assembly stand. There are motorized units to raise alignment pins as more layers are stacked. (We could use 1mm dia stainless steel rods.). The ALICE module had 36 holes per plate, 4 plates form a module (so 144 holes). Among the 144 holes, 12 holes had alignment pins (on the corner).
      2. Alignment pins were removed. The layers are compressed by 500kg of force, for up to 5 times.
      3. WLS fibers are cut, polished, aluminum-sputtered, then shaped.
      4. It looks like WLS fibers were inserted into the compressed module, but there is no picture.  No optical grease or glue was used but "light yield was sufficient so didn't bother".
      5. Aluminum sheets are taped/screwed to the side of the module, PMT attached, etc.
      6. Received WSU drawing for their paper and scintillator plates (in PDF), and assembly module (but in dwg format and I have problem opening it.)
  • 7/7/2015 Meeting to discuss EC and DAQ:

  1. Participants: Vince Sulkosky, Jianping Chen, Xiaochao Zheng
  2. Vince talked to Nilanga and Mark Jones about using GEM for the SPD test. The idea is to use GEM for the in-beam test of LASPD's timing resolution, and also at UVa for the cosmic/source test of the FASPD's uniformity. Jianping commented that we should always start from the simplest case (cosmic) to learn GEM. May also help to start the LASPD timing test with source/cosmic and GEM at UVa before moving into the hall.
  3. Vince is planning for the FMPMT high-field test. We emphasized that the focus would be the operating condition (1.5T, 35 deg of PMT axis w.r.t. field). Should have finer samplings around this condition, extend to wider values if there is enough time. (The extended range would be approximiately 0-3T for the field and 0-60 deg for the angle.) Should collect data on both gain and timing resolution.
  • 6/23/2015 Meeting to discuss EC and DAQ:

  1. Participants: Vince Sulkosky, Jianping Chen, Xiaochao Zheng, Zhihong Ye, Alexandre Camsonne, Rakitha B., Yuxiang Zhao
  2. Vince tried using a source to test the FASPD uniformity. The source is a 1microCurie Sr-90 beta emitter with an endpoint energy of 0.546 MeV, but its daughter nucleus (Yttrium-90) producesbetas with endpoint energies at 2.283 MeV.
    1. Added a 1.5mm-thick 1in sq. scintillator in coincidence witht the FASPD to distinguish between the source and cosmics.  But with the FASPD on top of the 1in sq scintillator, did not see any rate increase due to source (should be due to not enough energy to penetrate the 5mm FASPD). With the 1in sq on top of the FASPD the rate seems to change from 0.05Hz (no source) to 0.06Hz (with source). The source contribution is thus very low mostly due to the low beta end-point energy.
    2. Alexandre suggested asking Nilanga for his GEM/(cosmic) test setup. This way will get the position too.
    3. Jianping suggested that can just use cosmic and by moving the 1-in sq. piece around for the position. It will be slow but we can get the data this way.
  3. Vince is also working on preparation for the following tests:
    1. FMPMT high field test (end of July)
    2. Preshower and fiber radiation test (in Hall A beam dump, possibly this fall but better next spring). Need more preshower samples from China.
    3. LASPD timing resolution test, parasitic test in Hall A is possible.
  4. Jianping: last week reported the SoLID pre R&D list to JLab, got the following comments:
    1. pre R&D funded by JLab should be generic with general purposes. For example the DAQ high-rate capacity study.
    2. EC: should update the document from last year (which was generic).
    3. Probably JLab can contribute the engineering+material need, while will have to ask DOE for manpower needs.
  5. Jianping: for the EIC detector R&D, it could be useful for improving the SoLID physics case if we can make projective-shape modules. This is particularly true for SIDIS, which will help to fill in the angle gap between the LAEC and the FAEC.
  6. Todos:
    1. Xiaochao needs to followup on last week's todos.
    2. Need to figure out a 3D projective design for the modules. (undergrad project? Or JLab engineering project?)
  • 6/16/2015 Meeting to discuss EC and DAQ:

  1. Participants: Greg Kibilko (CAEN), Gianni Di Maio (CAEN Italy), Brad Sawasky, Jianping Chen, Xiaochao Zheng, Zhihong Ye, Alexandre Camsonne, Vince Sulkosky
  2. Greg and Gianni provided an update from CAEN on the HV power supplies.
    1. We planned on the SY4527B main frame and the A1535N modules for EC HV power supplies. These are the (12ch)/24ch single-width 52-pin connector modules, 3.5kV/3mA.
    2. CAEN now has a new module A7030 which is 12/24/48ch, cost about $2500 for the 12ch SHV version ($2400 if with 8% discount). The capacity is 3kV/1mA (1.5W) [note that the website shows the original design which was for 0.5mA max. This has increased following subsequent testing.]
    3. For prototyping test we should consider A7030 ($2400) and the low cost SY5527LC main frame (4 slot ~$3700, max 400W), Hall C already have the A1535N and work well so we may not need to test its prototype.
    4. Control type: non-low-cost main frames can have either 1) touch screen control or 2) wifi/ethernet and controlled by a PC/tablet; the low-cost version only have the wifi/ethernet+PC/tablet control.
    5. here is a picture of the whiteboard.
  3. We discussed the radiation level in the hall:
    1. The CAEN modules have mini-PC chips, so are susceptible to radiation like PCs.
    2. PREX had the electronics behind green walls at the backward angle, still not enough shielding, PCs needed rebooting every 12 hours
    3. For SoLID we will need a real "bunker"/concrete wall to shield the electronics from radiation.
  4. Here is the EIC generic detector R&D proposal Xiaochao submitted as part of RD1.
  5. To dos:
    1. Xiaochao will calculate the current draw of H12445-100MOD and followup with the detector group on the R11102 base current.
    2. Xiaochao will followup with the detector group on the H12445-100MOD's preamp power needs (low voltage).
  • 5/26/2015 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha B., Jianping Chen, Xiaochao Zheng, Zhihong Ye, Alexandre Camsonne, Zhiwen Zhao
  2. Rakitha's update: ecal_summary_1.pdf
    1. page 6: energy resolution for half-thickness double-layer design: 5.0%/sqrt(E), compare to 5.8%/sqrt(E) for the original thickness (page 4)
    2. will continue pion rej analysis with background.
  3. Jianping emphasized we need the revised R&D plan done.
  • 5/12/2015 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha B., Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Zhihong Ye, Alexandre Camsonne.
  2. Rakitha's update: ecal_summary_1.pdf which is a summary of resolution analysis and a preliminary intrinsic PID analysis. Comments:
    1. Resolution now agrees with Jin's to <1%.
    2. The pion rejection is obtained from two 1D cuts, should add a 2D PS+Shower cut and maybe also make it momentum dependent (and thus 3D).
    3. The preCDR plots on pion rej in the slide are with background (not intrinsic).
  3. EC R&D draft: RD_EC_draft.pdf
  • 5/5/2015 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha B., Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Zhihong Ye, Alexandre Camsonne.
  2. Evening update by Rakitha: See ecal_energy_resolution_6.pdf: main comments:
    1. The worsening in dE/E from full-ecal to 6+1 is now less than 1%, and the 6+1 results agree with Jin's to 0.7%! (The changes that caused these significant improvement are shown on the last two slides).
    2. With the new results, the 20% energy loss tail for the 6+1 cluster is also gone.
  3. Rakitha posted ecal_clustering_update_2.pdf for the energy/block distribution:
    1. slide 5 vs 8: 5 is the # of unique blocks for all clusters above threshold. In slide 8, applied a 1MeV cut on Edep. The # of blocks has reduced by about 25%. So recording 2 clusters/14 blocks (instead of 20 blocks) should be enough.
    2. slide 11 vs. 13 is the same but for pions.
    3. slide 17 vs 18, 19 vs. 20, 21 vs. 22: unique-block's x/y distribution for individual electron event, unweighted (slide 17) and energy-weighted (slide 18).  Does look bad at all. The energy-weighted distribution clearly shows only one dominant cluster.
    4. rest of slides: individual pion events. The x/y distribution is wider than that for electrons.
    5. Xiaochao's comment: still don't understand why the energy resolution is affected so much by the 6+1 cluster. Let's go back to the 3/10 report (ecal_energy_resolution_5.pdf), for example.
      1. If the worsening of dE/E comes only from the energy loss beyond the cluster, then even a 20% loss for all event should increase dE/E only by 10%, which is much smaller than what we see.
      2. The 1/sqrt(E) dependence seems to be completely lost when going from full-ecal to 6+1, as shown by the 2D plots on slide 8, causing the large constant term. I think this is the main reason why dE/E worsened (not the 20% energy loss). How does this happen?
      3. How are the error bars of dE/E determined?  If it's only determined by the intrinsic property of the ecal, why did Jin's 6+1 result have smaller error bars?
      4. Maybe we should look more into how to get the dE/E from clustering energy, and understand it better.
  4. Xiaochao: draft for EC R&D, need to add costs
  5. Xiaochao:
    1. had a phone discussion with Tom Cormier last Friday. Here are some notes:
    2. WSU built 16,000 modules for ALICE, forming 4,000 towers (4 mod/tower). It took 3 years although most of the construction was done within two years. At the peak the lab had 10 people working. These are partly technicians (more experience, hired "from the street"), and partly graduate students (both Phys and engineering, both MS and PhD, some were willing to work full-time at minimal wage $10/hr for a full semester or a full year). The important factor is most of people should be full-time since the whole procedure is like a factory-assembly line. They had 10 assembly stations at $20k cost each. Tom had one Russian/IHEP person who had been working with him for a long time and it really helped. Some of the techs are from Russia too.
    3. Fiber density was 100/tower. The shape is semi-projective.
    4. They obtained scintillator tiles from a Russian company (had also a Russian contractor to oversee the production and quality control). Used injection molding with fixed shape/size. Upon receiving the scintillator tiles WSU machined them down to 76 different sizes to form the projective shape of the module.
    5. They used Vulcan GMS ( for the lead sheets. Lead sheets were produced at 76 different sizes directly using an adjustable die. (the hole positions were fixed but the outer size of the die can be adjusted).
    6. Fiber mirrors: after inserting of fibers, fibers were gathered and diamond-polished, then were inserted into a sputtering machine (1000 at a time) for sputtering with aluminum. The finish is "rugged" so can't be easily peeled off or damaged. Can't use thermal evaporation of aluminum because it's not structurally solid enough. I asked about attaching a single mirror to the module end. Answer is that's possible. Can also just neglect mirrors but the longitudinal (energy) nonlinearity may increase.  Can use cosmic or source tests to easily characterize the energy linearity (ray hits transversely through the module, and moving the source along the module to see the variation in response).
    7. Engineering support is partly from LBL (paid) and partly from other collaborators (free). The biggest concern was for the projective shape of the ATLAS hcal, all modules had to be supported ONLY from the back and nothing from the front. This was all designed by contracted engineers and built at WSU.  ALICE was the only experiment that has shashlyk modules within the solenoid, in contrast to fixed target experiments where one can support the modules from both front and back.
    8. All modules were cosmic-tested to provide the starting HV, which turned out to be good to 2-3%.  With the cosmic test, pi0 appeared right away without further tuning.
    9. The directory here contains many pictures Tom sent me, and the ALICE Ecal NIM paper.
    10. The WSU group is now involved in a new project and the calo lab is not used.  Xiaochao will try to contact them, maybe even salvage some equipment.
  • 04/21/2015 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha B., Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Zhihong Ye, Alexandre Camsonne.
  2. Vince reported
    1. FASPD (5-mm thick Eljen) test:
      1. For the 232 mm long bar, the configuration included one 1-mm diameter fiber of length 208 cm and three windings inside the scintillator. The total length of fiber embedded is 168 cm.
      2. For the 232 mm long bar, the timing resolution was determined to be about 2.5 ns.
      3. The measured number of photoelectrons was about 9.5.
      4. For the 444 mm long bar, the configuration included two 1-mm diameter fibers of length 240 mm and each fiber had two turns. The total length of fiber embedded is 440 cm.
      5. For the 444 mm long bar, the number of photoelectrons is 9.2, though this is probably
        underestimated due to the SPE being on the tail of the MIP peak.
      6. Xiaochao's estimation is 9.3 p.e. for the outer radius tile, 2-turn each, double-fiber configuration, at the WLS output.
      7. May need to double-check with detector group on the pre-amp design.
    2. Next step is to test the uniformity (after DIS meeting, with a source).
    3. Worked on the high-field test plan for the fine-mesh FMPMT. And studied how to mount the mu-metal shield to the PMT. (???) Other people doing the test include for example Yodanka from USC (EIC, regular PMT?).
  3. Rakitha reported on EC cluster study: ecal_clustering_update_1.pdf.
    1. # of blocks indicate information needed to record in the data stream. So need to record as many as 21 blocks. This is much higher than we planned. Also energy loss from the primary 6+1 cluster is as high as 20%.
    2. Jianping suggested looking into "projective" or "slanted" Ecal design. Both will require the front of the module to be smaller than the back side. Also, may have difficulty switching between PVDIS and SIDIS.
    3. Xiaochao asked for 3D (or equivalent) plots on the blocks, with the third dimension edep and also the z-position (so two separate 3D-like plots).
  • 03/31/2015 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha B., Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Zhihong Ye, Ziheng Chen, Zhiwen Zhao, Alexandre Camsonne.
  2. Vince reported that
    1. he tested 4 Kedi and 2 CNCS preshower prototypes and they all give >80 p.e. light yield.  He is working on the remaining 2 CNCS preshower tiles and also put together a summary of the test results to be sent to SDU.  Then he will proceed to testing FASPDs.
    2. has met with GURT(?) collaboration and discussed the high field test plan, scheduled to be likely in July.
  3. Rakitha reported on EC simulation, focusing on PID this time, see ecal_pid_efficiency_1.pdf. Comments are:
    1. Suggest removing the +2.5sigma cut on E/p;
    2. As three weeks ago, suggest revising the preshower calibration so the method is the same as what can be achieved in the data analysis (i.e. do not use simulated lead energy deposit, can simply use a constant term for it);
    3. next step: incorporate background, triggering study.
    4. What do we do with the clustering and energy resolution?
  4. Ziheng reported on his updated comparison between PB and DIS code,
    1. comparison between PB cross section and data is very good (slides 4-9), but rate comparison between PB and DIS is not good (slide 12 and beyond).
    2. for slides starting page 12, suggest plotting cross section first, then rate.  Jianping suspected missing phase space factor.

  • 03/17/2015 Meeting to discuss EC and DAQ:

  1. Participants: Xiaochao Zheng, Vince Sulkosky, Jianping Chen, Zhihong Ye, Zhiwen Zhao, Ziheng Chen, Alexandre Camsonne.
  2. Xiaochao
    1. Received detectors from China: 4 preshower hexagons from CNCS; 4 preshower hexagons from Kedi; 2 pieces LASPD, 1 piece 1mm-thick scintillator from Kedi.
    2. Reading supporting notes for the LHCb Calo TDR
    3. Discussion with Craig Woody on 3/12:
      1. EIC detector R&D accepts new proposals twice a year, assign funding once a year, next would be July 2015 and the meeting may be at JLab. For EIC there will be three ecals, described below:
      2. Central Ecal, which is now sPHENIX barrel ECal, need to be very compace, currently choice is W-SciFi (PHENIX barrel ecal length is 13cm with 0.7cm X0), fully projective for PHENIX but does not need to for EIC, energy resolution about 12%/sqrt(E);
      3. Forward (electron direction) ECal, which is now backward (electron) for sPHENIX: need 1-2%/sqrt(E), currently crystal-based; however 5-6% may be acceptable with very good tracking. A UCLA group (O.Tsai) is looking into 5%/sqrt(E) SciFi (0.4mmW).
      4. Backward (hadron direction) ECal, which is now forward (hadron) for sPHENIX: need only 12-15%/sqrt(E), can be a sampling device, currently nobody is looking into it because nobody expects challenges.
      5. Three suggestions for UVa to get into ECal:
        1. look into sPHENIX forward (hadron direction) ECal, which can be either SciFi or shashlyk, 12-15%/sqrt(E). sPHENIX has some R&D funds and hoping to get CD1 this year (2015); This will be the backward ECal for eRHIC.
        2. look into 5%/sqrt(E) for eRHIC forward ECal (useful if good tracking is available).
        3. look into 12%/sqrt(E) for eRHIC central ECal (currently top choice is W-power SciFi, but shashlyk is possible).
      6. Also discussed neutron radiation background test.
      7. Jin added that the hadron-direction and electron-direction EMCals are not part of sPHENIX, but for plans beyond sPHENIX in the 2020+ time scale.
    4. Jianping commented that we don't want to be tied to a particular detector, but a generic shashlyk for either sPHENIX or eRHIC. Xiaochao will compile an overview table of requirement of all these detectors.
  3. At the duality meeting last Friday at UVa, Wally expressed interested in resonance PV data we can get from SoLID. He recommended mapping the whole resonance region at about Q^2=1 or below.  Vince will look into this (first need a plot of expected stat uncertainty vs. Q2 and W).
  4. Ziheng Chen reported on comparison between PDF and Peter Bosted's fit for the cross section calculation, see his report.
  • 03/10/2015 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Alexandre Camsonne, Rakitha.
  2. We discussed the SiPM and EC calibration which are reported under last week's minutes below.
  3. Rakitha updated on EC simulation, see ecal_energy_resolution_5.pdf. Summary of findings:
    1. As suggested by Jin, now reduced illumination range of angle (page 3 vs. 4; this is to avoid energy leak);
    2. x,y,z distribution seem to agree with expectation (page 5). Suggest improving the binning in the z-spectrum to observe the Pb layers;
    3. "calibration" of shower and preshower energy (scintillator energy deposit vs. full energy) is done on page 6 and 7. Suggest revising the preshower calibration so the method is the same as what can be achieved in the data analysis (i.e. do not use simulated lead energy deposit, can simply use a constant term for it);
    4. page 8 shows energy vs. momentum. Some events may lose as much as half of the energy. This will have an impact on data recording. Alexandre commented that currently we are planning to readout only clusters above the trigger threshold. To avoid losing too much energy, we can either read out two clusters (with the highest two energy sum), or summing over more than 7 modules (such as 9 or 10, I assume they are along the outward radial direction of the main 6+1 cluster).
    5. page 9: energy resolution is close to 5%/sqrt(E) for the full-detector summing, but constant term increases signficantly for the 6+1 cluster case. This is probably due to energy leak shown on page 8. Suggest improvidng the trigger/summing algorithm, or increase the cluster size. Xiaochao commented that we may not need to add the whole "ring-shape" layer, since the direction of the particle's motion is roughly known. For example, can use a "elliptical" cluster shape, elongated in the radial direction;
    6. Also suggest:
      1. simulate for thinner layer thicknesses (but keep Pb/sci ratio and total geometrical thickness unchanged) for DVCS;
      2. simulate pion rejection.
  • 03/03/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Vince Sulkosky, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne
  2. At UVa:
    1. Update on the fiber connector: the quote indicates: (about $10/set). For the 100-pin connector the option is to stack ten together, which Fujikura did for the Fermilab experiment.
    2. We shipped 100m of WLS Y11 fiber to China.
  3. Discussion on the report from director's review. Items related to EC:
    1. full simulation needed, see R&D plan below.
    2. SiPM
      1. see LHCb tracker upgrade or this link for the latest development on SiPM and its radiation damage (section 3.5). The tests were done in the LHCb cavern, the neutron irradiation facility at Ljubljana, and with a Pu-Be neutron source. The neutron energy spectrum was simulated to mimic the LHCb running condition, with a peak at 2MeV. 
        1. The noise of SiPM comes from: dark current, pixel cross-talk and after pulsing. The dark count rate (DCR, measured above 0.5 photoelectron) increases strongly after irradiation and is the only radiation damage observed at the level of irradiation required for LHCb. The cross-talk and after-pulsing depend strongly on the detector technology. After-pulsing only occurs after >10ns (pixel recovery time) and is significantly reduced in the latested technology and contributes only a minor fraction to the total noise. (Thus I deduce that the DCR increase is dominated by dark current and cross-talk). Cross-talking can be reduced for new detectors with have so-called "trenches" between pixels.
        2. Both Hamamatsu and KEKEK have developed customized detectors for LHCb's scifi tracker: trenched, with specific light yield, active area, area efficiency, etc, to fit the SciFi.
        3. The increase of the DCR was found to depend linearly on the total fluence. For Hamamatsu "no trench" multi-channel arrays (Fig.3.23 left), DCR reaches an increase of factor 20 at 6E11 neq/cm2.
        4. Effect of cooling (Fig.3.23 right): cooling by each 10C reduce DCR by factor two. There data were given for fully annealed detectors after slow annealing one week at +40C.
        5. Comparison between no annealing with with annealing (Fig.3.24 left): DCR with no annealing is about twice the current with slow annealing (one week at +40C), and with fast annealing (80 minutes at +80C) is about mid-way between the two. The effect of annealing is the same for new and standard technology devices.
        6. Comparison between new and standard technology (Fig.3.24 right): At -40C, trenched detectors have about half DCR of standard detectors.
        7. They need to run at -40C for the SiPM to last the whole duration, at a neutron background of close to 1E12/cm2. So if SoLID is 2E12 neq/cm2, cooling to -50C might work, 4E12-> -60C might work, 8E12-> -70C, 1.6E13 -> -80C, etc. Note that the detector unit must be designed to increase the temperature to 40C for slow annealing or 80C for fast annealing.
      2. Craig Woody's talk on EIC eRD1, Jan 2015, shows:
        1. SiPM tested up to 0.3E9 n/cm^2 at BNL (14MeV neutrons), DCR increases by factor 10-50 (10-20 for Hamamatsu, 45 for SensL, 45-50 for KETEK), pixel-size-dependent, with Hamamatsu 15um shows the least increase;
        2. tested up to 7E10 n/cm^2 (>6MeV neutrons) at LANCE, DCR increases by 100-1000, can reach milli-Amp, also observed some loss of pixels.
      3. Also gathered information from Carl Zorn and Ardarvan from Hamamatsu. Ardavan referred to Carl as the expert, and below is Carl's reply:
        1. Carl: "The estimated high energy fluence for Hall D is 3 x 10^8 n/cm^2 for 1 MeV equivalent.  At that level, the noise would rise to unacceptable levels within 3-4 years (dark rate increases by a factor of x10).  By cooling down the SiPMs to 5°C during operation, the lifetime is expected to be the full 10 years of GlueX.  (The dark rate is reduced by x1/3 during cooling.)"
      4. CMS (talked to Brad Cox): CMS calorimeter upgrade will use W (inactive) +LSO (active), very small size (the module is about the size of a finger). The advantage of the small size is the small attenuation in the optical elements, so with radiation damage the damage in the signal is not severe. For readout, the background next to the calo is about 1E14-E15 but the SiPM is located far away, "get down to about 1E12". Is also studying galium-based PM (larger gap than silicon). He had some experience with FMPMT, some tests found that the residual gas in the tube gets ionized and the ions deposited on the cathod, causing the gain to drop by 15-50% over ~2 years of period.
    3. contact other groups (LHCb, ALICE, CMS) for shashlyk construction. Suggest Prof. Onel from U. of Iowa. Xiaochao already contacted him and will  have a phone meeting with his engineering team.
    4. software -- need estimate of FTE for EC.
    5. Calibration plan, here is a draft:
      1. Cosmic test, LED test -- before beam -- this should be good to 10-20%.
      2. A rough fit based on the fact that the energy deposit should be smooth function of R and should be repetitive in phi -- with beam, fast, can be done with only EC running
      3. Using MIP at very low beam current -- If set electron max at 1.5V, MIP peak (60MeV) should be seen at around 40mV with dE/E=20% or +/- 8mV.  The FADC full scale is 2 V and 12 bit, so resolution is 2/4096=0.5mV which correspond to +/-16 bins, plenty for a clear identificiation (if we are not messed up by very low-E background) -- with beam, not so fast, can be done with only EC running -- could be good to 2-5%;
      4. Using elastic electrons at low beam energy -- with beam, commissioning, slow, coverage in momentum and angle won't be large (probably can only use 2.2 GeV beam), precision will be high if done with tracking, can be done with only EC running but then precision limited by the knowledge of scattering angle (EC position resolution divided by drift distance, also lack of vertex position);
      5. Using electrons with known tracking/momentum -- with beam, commissioning, slow, must be done with GEM, high precision.
      6. Other possibility: pi0 reconstruction? (Need to read HERA-B note 00-103); Alexandre mentioned can setup 2-cluster triggers -- with beam, can be done with EC only, advantages include: can be done continuously and non-intrusive, can potentially reach high precision.
    6. Can we do 3%/sqrt(E) for DVCS?
      1. To get 3% we need thinner Pb layers. To keep the total radiation length unchanged, must use thinner scintillator layers as well. However, this will require a fiber density higher than 1/cm^2 (for lateral uniformity) and the cost would go up significantly.  Also Jin pointed out there exist some suspicion about the 3% value reported by KOPIO.
    7. A full R&D plan. Here is a draft
      1. Full simulation, including effect of stainless steel rods, WLS fiber attenuation, radiation damage (see LHCb LHCb tracker upgrade or this link for a modeling of the damage to the fiber), layer thickness tolerance, etc. Note LHCb report used the unit of Gy, and rad is 100 times larger. Light yield show reduction at 0.5kGy or 50krad, and drops by factor two at roughly 2-3kGy or 200-300krad. These are plastic fibers where radiation damage affects mostly the clarity (attentuation length) and the scintillating efficiency and the two are similar. Thus damage is expected to be more visible for longer fibers. For WLS fibers, there can be additional damage to the WLS dye/fluor that is not applicable to the LHCb scifi tracker.
      2. Preshower: parallel testing between SDU/China;
      3. LASPD:
        1. in-field test of FMPMT. JLab detector group is considering tests at Argonne (both NP and HEP) and UVa (medical).
        2. study of SiPM under ionization and neutron irradiation.
        3. possible customized Hamamatsu PMT with special windows -- reply from Ardavan "I discussed your concerns with Hamamatsu Japan; they can offer H6614-70 (FM-PMT assembly) with synthetic silica or alternatively UV glass windows." (3/6/15 email).
      4. FASPD:
        1. prototype testing, charactrization of light yield for 5mm thickness, surface uniformity study with a source.
        2. further design of fiber grooves.
      5. Shower:
        1. design of assembly stand and procedure (possible collaboration with China, possible advice/help from Prof. Onel).
        2. design of quality control procedure.
        3. prototype construction
        4. prototype testing - comic, in-beam
        5. radiation damage.
      6. Radiation hardness:
        1. WLS fiber performance under ionization dose, measure change in attenuation length. Can use LED or a beta source (such as 90Sr), see LHCb tracker upgrade for test results on scintillating fibers (and 4 models to extrapolate the results!).
        2. scintillator performance under ionization dose, measure relative light yield. Cosmic rays would be sufficient
      7. Fiber connectors, in-house design and prototyping for 100-pin connector.
      8. LED system design and testing
      9. Software development
    8. Other comments: DOE encouraged us to make generic detector R&D. Will contact EIC detector R&D (Jin followup: contact Craig Woody who is leading the eRD1 on calorimetry. See for their latest report).
  • 02/10/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Vince Sulkosky, Rakitha, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne
  2. At UVa:
    1. Vince reproduced ~71 p.e. on the Preshower tile, then conducted tests on the SDU square 3mm and 5mm tiles. With 3mm tile and ~1.5 turns fiber the MIP peak is barely seen, probably around 2 p.e.. For 5mm tile and 2.5 turns the MIP is located at around 11 p.e. This confirms that the light collection is proportional to the # of fiber turns.
    2. Xiaochao estimated that for FASPD, 3mm thickness with 2 turns of fiber will give 2.4 p.e. at the PMT which is not high enough for cutting on half MIP.  A 5mm thickness with 4 turns total double file will give 6.0 p.e. at the PMT which is marginal. Xiaochao will proceed to order a 5mm prototype.
    3. Vince tested the DDK fiber connector. A grease-coupling run gave about 0.77 light efficiency, which is 0.10 lower than the 0.87 from Minerva. Will try to optically cement the fiber in the connector next.  Xiaochao also contacted Fujikura for possiblly making the 4-4 and the 100-100 connectors.
    4. Xiaochao asked SDU for the design of the Shashlyk assembly stand that SDU obtained from 华中师范大学's group, but was told they need approval. Xiaochao will try to contact the华中师范大学's group directly.
  3. Zhihong updated on FASPD segmentation study.  Previously made a mistake of dividing the # of segmentations twice.  After correcting this mistake, now the photon rejection is nearly independent of the thickness.  Click here for plots: 3mm 5mm 10mm result.
  4. We (Rakitha, Jin, Xiaochao) continued debugging the Shower simulation.
  • 01/27/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Vince Sulkosky, Rakitha, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne
  2. Rakitha updated on the EC simulation, see ecal_energy_resolution_4.pdf.
    1. slide 5 is from two weeks ago. To pin down the problem, now removed Preshower (in the simulation), and simulated the EC only (slide 7).  Still, the resolution is off-charge disagreeing with Jin's (slide 8, 6+1 cluster).  Adding the Preshower will only raise the resolution.
    2. Vince will help to investigate the difference between the two simulations.
    3. discussed with Jin last week on what other problem we might have.  Found out when adding preshower to shower energy, should apply energy calibration first.  Will implement this in the code in the upcoming week.
  3. Vince udpated on the LASPD test, see his Jan. 15 summary:
    1. After optimizing the time-walk correction, now have reached ~60ps on the test bars (see run 1484 of Jan 6-9 summary), and ~(100-115)ps on LASPD (with 55-deg light guide cemented, run 1507), where the variation depends on the QDC cut.  This is better than the straight lightguide (run 1511) due to a better light collection of the light guide.  
    2. The (100-115)ps value is the convolution of both end outputs, so if we read out only one end, the one-end timing resolution should be the two-end value multiplied by at most sqrt(2). which is close to the 140ps requirement of SIDIS. (The factor sqrt(2) is not as simple as half light collection. If the event is at the far end, the far end resolution will be so much better due to large light output, but the two-end average would be dominated by the poor end, so the poor-end resolution would be the two-end resolution.  If the event is in the middle of the bar, both ends have similar resolution so in this case the one-end would be the two-end times sqrt(2). So sqrt(2) would be the worst-case scienerio and provides a safer estimate).
    3. Would be nice to run an in-beam test of the one-end readout with position correction. Cosmic is not going to work (need years to get the statistics).  If using the hut is not going to be parasitic (need to talk to Bogdan). Can also combine with GEM test if possible.
  4. Zhihong updated on the FASPD simulation, see segmentation slide here. Looks good if using 30ns coincidence window. However, we haven't seem to finalized the FASPD thickness. Plan:
    1. Zhihong will run the rejection simulation for 5mm, 10mm and 20mm thickness
    2. Vince will run test on the 3mm and 5mm SDU square tiles with the WLS fiber (we tested only the direct light output so far), to see how much light we can get.
    3. Xiaochao will look into light output and PMT choice again to make sure we have enough signal to cut at half MIP.
    4. We don't care about timing resolution of FASPD -- just emphasize again!
    5. By next week we should be able to decide on what type of FASPD prototype to purchase.
  5. Other?  Jianping is having the flu.  Get well!
  • 01/13/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Vince Sulkosky, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne
  2. Zhihong updated on the SPD simulation. Here he used Edep directly instead of the conversion of photons. Also, found a problem with previous work: the huge energy
  • 01/13/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Vince Sulkosky, Rakitha, Xiaochao Zheng, Zhiwen Zhao
  2. Zhihong updated on the SPD simulation. Here he used Edep directly instead of the conversion of photons. Also, found a problem with previous work: the huge energy deposit seems to come from a binning effect, where all events without interaction end up in the 1st bin with a bin center of 0.05MeV (see slides 4 and 5).   After removing this effect, now the segmentation looks much more reasonable, see slide 6 for the 20cm thick LASPD bar.
    1. Comment 1: The result has a stronger "step function" shape than Jin's (see pCDR), which calls for more "safety factor" in the simulation. It also depends strongly on the coincidence window width.  Assuming we can use 30ns window and a safety factor of two, a segmentation of 60 seems quite reasonable.
    2. Comment 2: The result looks in general better than Jin's (which used 50ns window and 5mm thickness).  Is it reasonable that it is better, given a 4 times thicker thickness?
    3. For Jin's result see here for the segmentation plot in pCDR.
    4. Next step:
      1. use gamma-conversion instead of using Edep directly.
      2. will add backscattering from the EC.
      3. will add light collection efficiency (but this is the same for both signal and background, right?).
        1. Kai's result on the light collection can be found in this table file. The efficiency here is defined as fraction of scintillating photons that are collected at the edge. Scintillator attenuation, loss due to nonperfect internal reflection are considered. No light guide efficiency is included. Tables 5 and 6 are for LASPD with direct PMT coupling on the outer edge (60 segmentation). Tables 7 through 14 are for FASPD with embeded WLS fibers (240 segmentation).
      4. Alexandre asked for a summary table of all sources of time jitter for SPD and EC (Shower only), to see if the 30ns window assumption is feasable.
  3. UVa update:
    1. Vince used the new R9779 PMTs and conducted the 3-bar test (bar size 5x5x30cm). The resolution obtained was about 78ps. For details see his 2015/1/6 summary here.   Note the bar size is very similar to the CLAS12 TOF test of USC, which had a ~40ps resolution and was completed dominated by the TDC. Our TDC resolution was determined to be ~33ps. So the expectation is about 40ps as well. The 78ps result is about twice the expected value, and is comparable to the (90-100)ps using the XP2262s. This has to be better, given that the R9779s are expected to be much faster than the XP2262s.
    2. Last week, swapped the middle test bar with the LASPD bar.  First result is about 170ps. For details see his 2015/1/9 summary here. Note that the 30cm long trigger (test) bars are only half as long as the LASPD, so can only test half of the LASPD bar at a time.  When the event is on the side of the bar, expect that the resolution of the near end to be better than the far end, say t3 and t4. However, the 3-bar method cannot separately determine t3 and t4's resolution. The "T" formed is only sensitive to (delta t3)^2+(delta t4)^2. So if dt3<<dt4, the result from this method, which treat dt3=dt4 and characterize the resolution as sqrt{[(delta t3)^2+(delta t4)^2]/2}, needs to be multiplied by sqrt(2) to obtain the worst-case resolution (event hitting inner radius of the bar, since the signal readout is from the outer edge only). In other words, a 150ps requirement means we need to reach 100ps resolution in our test.
    3. Simultion shows if we readout both ends of LASPD in the above 3-bar setup, assuming 0.5 light collection efficiency at the end, the value of sqrt{[(delta t3)^2+(delta t4)^2]/2} is between 80 and 98ps (depending on hit position). So the 178ps result is again about twice the expectation.
    4. So far the time-walk correction applied was a global one, individually for t1, t2, ... t6. Next step is to apply position-dependent time-walk correction.  Slicing the bar will likely not work since it will require a lot of statistics to have enough events hitting each mm-wide slice (1cm <-> 50ps, 1mm <-> 5ps).  Will try 2D fit in TDC vs ADC and (t1-t2)/2 for bar 1; and equivalently (t3-t4)/2 for bar 2, etc.  Here the (t1-t2)/2 provides the hit position. However, since t1 is used as the common stop for the TDC, need to think about what variable the TDC should be correlated to.
  4. Rakitha: see report
    1. Removed target radiation effect. Results are on page 9. Resolution still higher than Jin's 6+1 cluster values (slide 10).
    2. Will contact Jin to pin down the problem.
  • 01/06/2015 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Vince Sulkosky, Rakitha, Xiaochao Zheng, Zhiwen Zhao
  2. UVa update:
    1. Vince will use the new PMTs R9779 and repeat the LASPD timing test of last month.
  3. Rakitha: see ecal_energy_resolution_2_update_1.pdf.
    1. Added preshower, use ionization energy only (slide 12)
    2. Use total energy deposit: (slides 14 and 15) 6+1 and Preshower+Shower gives 8.6%.
    3. Important: in the simulation had radiation loss in the target, so results here are not the intrinsic resolution. Did Jin's simulation for pion rejection include the target radiation?
    4. Compare to Jin's (slide 16), which is 6+1 and Preshower+Shower, 5.2%:
    5. Next step: remove target radiation effect
  • 12/23/2014 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Jianping Chen, Zhiwen Zhao, Yuxiang Zhao, Xiaochao Zheng
  2. UVa update:
    1. Vince completed a preliminary test of the TOF test bars (5x5x30cm), using 6 XP2262 PMTs placed next to the both ends of all 3 bars. We used these old XP2262s because the new R9779s have not arrived. We could not attach the PMT to the bar because the PMT bases are not isolated and the HV power is carried by the al-mylar wrapping from one PMT to the other.  The preliminary timing resolution is 90-110ps, after time-walk correction, depending on the QDC threshould.  The # of photoelectrons summed over both ends is about 800-900 p.e.. See the test page for details.   The simulated result is 60ps for events generated at the end of the bar and 80ps for event hitting the middle of the bar.  The discrepancy can be partially explained by the (non-) optical coupling between the bar and the PMT. The TTS spread of XP2262 used in the simulation is from an early CLAS test, sigma=1.60ns, which is twice the value of the catalog specification.
    2. We have received the R9779 PMTs and will repeat the test in January.  Then we will test the LASPD timing resolution.
    3. Should also test the DDK fiber connector in January.
  3. We finished a note on the Wiser code, including comparison with data for the 6 GeV transversity and PVDIS experiment. We should add more data, especially for the nucleon resonance kinematics since comparison to the PVDIS resonance pion rates was not conclusive.
    1. Jianping commented that
      1. for Mo&Tsai we should use only 1* internal radiator since only the before-interaction counts. The after-interaction radiator will produce pions but there is a reduction in phase space (only fraction of the electron beam becomes scattered electrons and cause the after-vertex pion production). In other words, all electrons in the beam produce photons due to bremsstrahlung and photo-produce pions, but only electrons that scatter produce photons after the interaction.
        • working with some numbers, also explain why the 6 GeV PVDIS pion asymmetry is only a fraction of the electron asymmetry:  Suppose we have a 100uA beam which is 1E15 Hz incident electrons. The ~5% radiator means the bremstrahlung photons are about 1E13Hz.  Photoproduction of pions typically is at the microbarn level, while electroproduction is at 10-100nanobarn level. So overall photo- to electro-production is (5%)*microbarn/(10-100)nanobar ~ (0.5-5), maybe larger depending on the exact cross section ratio. -- this is an important fact, relevant for the PVDIS long paper writing.
      2. Mo&Tsai formula works only for (e,e') and should not be used for our case. (This we already knew but should make it clear in the note);
      3. The HRS acceptance used in the simulation is much larger than the actual value (see Xin's thesis, page 217 2D plots).  THis may be close to a factor of 2 which means Wiser should work pretty well, but still overestimating.
      4. Calculation of N* decay giving pion would not apply for our case. For our case, the main process is DIS where photons hit quark and fragment to pions directly.
      5. Wiser and isospin symmetry would not work well for resonance, which may explains why it doesn't work well for RES I and II of PVDIS; But this is of a less concern for SoLID since the SoLID e' kinematics is far from resonances. 
      6. What concerns us more is the pion with E'<1GeV from Ebeam=11 GeV, where Wiser would not work but this is a significant contribution of our background. We need to think about some test runs with HRS and the 11 GeV beam in spring 2015. (Yuxiang, Alexandre and Zhihong are working on this).
  4. EC update: We have received supporting email from 华 中师范大学. Cunfeng from SDU will work with them on the EC module and assembly engineering design.  At some point this should be coordinated with the EC support engineering design at ANL, but probably not at the prototyping stage. We should also follow up with Thia on the prototyping funding request.
  5. Update on disk: we need $15k to replace the old PVDIS disk.
  • 12/16/2014 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Zhiwen Zhao, Zhihong Ye, YuXiang Zhao, Vince Sulkosky, Xiaochao Zheng
  2. UVa update:
    1. We received Eljen TOF test bars and 3x LASPD 2cm-thick bars.  Setting up the TOF test this week.
    2. Should also test the DDK fiber connector in January.
  3. Jianping: 华中师范大学's group is involved in ALICE shashlyk construction. We will contact them for support.
  4. Zhihong update:
    1. described how to simulation SPD:
      1. First, get the conversion: start from a uniform distribution Egamma=from 0.3MeV to 11 GeV, calculate conversion for different SPD thickness. Define conversion as photon-> at least one electron, conversion is 40% for 0.3MeV 5mm, decreasing with Egamma. Should also get the electron energy profile.
      2. Simulate energy deposit of electron in SPD, now start from 0-1MeV electron to see how it looks like. Energy of the converted electron should come from step 1.
      3. Look at the background, focusing on pi0 photons (Wiser) and EM background (GEANT background simulation by Zhiwen), treat pi0 photons using results of a+b, if energy deposit is above threshold -> SPD is triggered; Then, for each photon that does not trigger SPD,  look for the EM background within the 30ns timing window and sum over the total deposit, if the total deposit is above SPD threshold, photon would trigger the SPD. (preCDR used 50ns???) This would depend on the SPD segmentation (area) and the 30ns timing window.
      4. The resulting trgger rate of c, divided by initial simulated photon, gives the photon rejection.
      5. Zhiwen said we should also look at charged particles. But (JP) in this case it is SPD charged particle trigger coincidence with the photon in EC, which should be considered in calcuating the total trigger rate.
    2. Once Zhihong get the first result, we will look at all rates and deal with charged particles. Of course the total trigger rate should be the same regardless of where we consider the effect of charged particles -- at the SPD rejection level or at the SPD+EC coincidence level.
    3. Jianping suggest talking to detector group (Drew), they have the photon detection already measured/documented (defined as energy deposit in scintillators from incident photons), needed for medical imaging research. This should summarize step (a) and (b).
  5. MAPMT: anything going on with the 16ch MAPMT test at JLab?
  • 12/02/2014 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Rakitha Beminiwattha, Alexandre Camsonne, Zhiwen Zhao, Zhihong Ye, Vince Sulkosky, Xiaochao Zheng
  2. UVa update:
    1. While being the RC for Hall A, Vince looked into the high-field magnet in the test lab. Here is a brief summary. We have ordered some magnetic shields for the tubes for the next test.
    2. Jianping mentioned Medhi has repeated the high-field test for the 64ch MAPMT because Simona's test was done on H8500 and H8500 is going to be discontinued by Hamamatsu. Medhi's test was done last week up to a few 102 Gauss. Results are to be posted later.
    3. We plan to test R11102, FMPMT (x2), the 16ch MAPMT for Preshower, and also borrow Medhi's MAPMT as a cross-check.
    4. Xiaochao sent an updated shashlyk prototype funding request to Thia on 11/22.
    5. We are planning to buy a new disk, but are waiting for reply from Sandy.
  3. Rakitha presented an ecal_edep_analysis_update_2.pdf, (slide #9), where the dE/E results have been corrected from last week. 
    1. The question still remains why the energy resolution is twice Jin's result.
    2. Suggest progressing in two directions: figure out the discrepany (point 1 above), then also develop the code for multi-dimensional cut for PID. (Zhiwen mentioned can use Jin's cut code but it's better we have an independent code or at least a thorough check of Jin's code).
  4. Zhihong:
  • 11/25/2014 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha Beminiwattha, Jianping Chen, Xiaochao Zheng, Zhihong Ye, ...?
  2.  Rakitha: ecal_edep_analysis_update_1.pdf. The energy resolution for summing all modules, no background, is about 10%/sqrt(E). This is almost twice the value Jin got. Need to check the code and/or check with Jin to see where the difference comes from. The resolutions for 6+1 and 2+1 cluster sums are even worse.
  • 11/04/2014 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha Beminiwattha, Vince Sulkosky, Xiaochao, Zhihong, Lorenzo Zana, Zhiwen Zhao, Kai Jin, Zhihong Ye
  2. Zhihong: report on SPD simulation
    1. slides 2-3: general case, for photon conversion.
    2. slides 4-5: rates shown are for the whole plane. Jianping pointed out we are missing the low-energy photon background (that should be in the GHz level).
    3. Also LASPD should have 60 segments. Shouldn't show other segmentation results (to avoid confusion).
  3. The /work/halla/e08011 disk will be relocated next Thursday-Friday and will cause a temporary outage. Sandy warned that we should monitor the aging of the disk and replace if necessary.  Perhaps we should plan to either have Hall A purchase a disk for SoLID simulation, or to purchase more from a collaborating group (don't ask Xiaochao, she doesn't have money). A 120TB disk cost $16k these days. Zhiwen mentioned the simulation takes about 7TB now (??? that small?).  Once the PVDIS long paper is accepted for publication, we can remove the 6 GeV-related files too. Another question: can someone backup all files on the silo?
  4. UVa update:
    1. Kai have updated the SPD light collection simulation:
      1. uniformity and scintillator decay for FASPD has been studied, see FASPD_decay_eff_center.dat vs. FASPD_decay_eff.dat (for uniforminty, item D1b from last week, and decay results in each file for item D1a from last week).
      2. The updated datasheet_20141104.pdf now includes figures to show FASPD efficiency with decay.
      3. Next step?
    2. Update on detector cost from various places:
      1. SDU: need confirmation, mass or prototyping?
        1. LASPD (company2) cost update: 2300 RMB per piece; (no light guide)
        2. FASPD (company2) cost update: 4 tiles, from small to large: 900, 1600, 2880, 3600 RMB per piece.
        3. LASPD (company1) cost: 900RMB plus 2300RMB lightguide per piece.
      2. Eljen:
        1. Shower scintillator plates cost: $85 ea no hole, or $116 ea with holes, for quantity of 2000, production 200/month
        2. Preshower: $77 ea no groove or $204 ea with grooves, for 1800, or $218/$414 for 3 pieces. production 100-150/month
      3. Contacted FNAL facility, but they only have the extrusion equipment, no injection molding.
      4. Need to get an updated quote from IHEP: new design for LA and FASPD, also Preshower has deeper grooves.
      5. Will Brooks replied and said "one of the campus has an injection molding equipment, one can imagine organizing some production, but won't be competitive compare to IHEP or FNAL".
      6. How to order from SDU?
      7. For Shashlyk, should we order the plates only from IHEP and do our own assembly? IHEP charges, per module, before 30% overhead: $230 for endcap and screws, $320 for assembly, and $110 for testing with a source and treating the fiber.
  • 10/28/2014 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha Beminiwattha, Vince Sulkosky, Xiaochao, Zhihong, Lorenzo Zana, Zhiwen Zhao, Kai Jin, Zhihong Ye
  2. Zhihong Ye: working on the LASPD segmentation. Had the basic code for pair production working, next step is to add the pileup. Need to correct the segmentation on slide 6.
  3. Lorenzo Zana: simulated (FLUKA) neutron background with a small shielding in front of the LASPD readout, see these slides. Background is reduced by about factor 2 and is (read from color) somewhere between 6E12 and 1E+13n/cm^2. The simulated condition was 3He target, 15uA, 3000 hours. Lorenzo suggested a factor of 3 buffer. Since the factor is close to the APD or the FMPMT limits, will carefully check SIDIS setup for a thorough simulation.
    1. We discuss the radiation limit of photodiodes. According to Hamamatsu's PMT handbook (p252, Fig.13-17), the deterioration from radiation is mostly on the transmission of the windows, which for 2mm-thick borosilica windows can be reduced as low as 20% and 70%, for 14MeV neutron flux of 2.5E+14n/cm^2 and 4.1E+13n/cm^2, respectively.  Silica and UV glass windows exhibit better performance under radiation than borosilica windows. For photon radiation (tested with 60Co), the effect is large even for 1.4E+5 roentgens. The loss can be partically recovered after storing, especially at high temperatures.
    2. For APD, some online search gives 200 kGy and 2* 10^13 neutrons/cm2, see page 4 of
    3. All SIDIS experiment have 245 PAC days: Assuming 4000h at 50muA, will have a factor (4000/3000)*(50/15)=4.4 increase compare to the slide, or at least 2E13 neutrons/cm2 (before adding the safety factor), which corresponds to ~4*10^-9 neutron/(electron * cm2)
  4. UVa updates:
    1. Kai have updated the SPD light collection simulation. See this file. The results for FASPD with WLS-fiber embedding are now plotted as figures. Next steps are:
      1. Include scintillator decay for FASPD.
      2. Study uniformity of SPD. For the next week, will focus on a comparison of "illuminating full tile" vs. "illuminiting only a small central region".
      3. For both a and b, suggest only do the 5mm, 10mm, and 20mm thicknesses.
      4. For LASPD, can do the same uniformity calculation, but can also use Xiaochao's rough simulation of efficiency.
      5. Zhiwen suggested we can combine Kai's efficiency with Zhihong's SPD simulation.  This is a big task and can be considered later.
    2. We will pause the lab test until we receive SPD prototypes.
    3. We have ordered: From Eljen: 3 test bars for setting up the timing test, one LASPD tile (6-deg segment), one straight "fishtail" lightguide and one 55-deg-tilt light guide to couple from the LASPD large arc to a 39-mm dia PMT window. Also ordered from Hamamatsu 6x R9779 assembly.
    4. Started looking into getting various components for making the shashlyk.
      1. Here is a sketch of the hexagon for both lead and scintillator sheet machining.  There will be six 2-mm diameter holes. Rough calculation shows the 2-mm stainless steel rods are good enough for the shear stress (factor five safety, using shear strength 2.5E8N/m^2), but not sure about tensile stress (LHCb EC TRR shows a compression force of 500kg, which if assuming all is on a single rod, is half of its tensile strength of 5E6N/m^2 ), and there will be a 0.3mm shear deformity (again assuming single rod). Looking at the LHCb EC TDR (p70), we will need more holes for support.  The final design has to be done by engineers.
    5. I have a rough comparison of producing each detector between different companies. Basically:
      1. For Preshower, IHEP cost ($36 EA*1.3=$47 EA) is 2-3 times less than SDU (600 RMB*1.2), mostly because SDU use machining. Have contacted SG (no response for mass quote, $550 ea for 1 prototype) and Eljen (still waiting);
      2. For SPD, Eljen's estimate for LASPD looks very good, even including the 55-deg light guide. Next is SDU, then IHEP.
      3. For Shashlyk, lead quote is comparable between IHEP and Kolgashield. Still waiting for Eljen's estimate on the scintillator sheets.
    6. Will talk to Will Brooks.
  • 10/21/2014 Meeting to discuss EC and DAQ:

  1. Participants: Wouter Deconick, Alexandre Camsonne, Zhiwen Zhao, Zhihong Ye, Kai Jin, Xiaochao Zheng, Vince Sulkosky.
  2. WM update: student is working on the 16-ch PMT.
  3. UVa updates:
    1. Put the two scintillator bars (from A.C.) to use, see this week's summary. We are still trying to reproduce the earlier result.
    2. Waiting for Eljen on light guide design. Once received, we will proceed with ordering LASPD bars, R9779s, and light guides.
    3. Started talking to Kolgashields on lead sheet prototyping. Need to make a drawing.
    4. Still taking to Hamamtsu on the S-O-R term on the FM-PMTs. Typically they give 3 months for performing the test, then need to make a decision of sale-or-return.
    5. Need to read the ATLAS ECal TDR.
    6. Kai continued with SPD light collection simulation. Here are two updated files: decay_LASPD.  This should replace his earlier file: tables.  A comparison with Xiaochao's quick code shows that the yield is higher than Xiaochao's especially for the thin tiles (5 and 10mm), but the difference is < factor 2. For 20mm the difference is smaller (maybe 40%?).  Kai will proceed to the WLS fiber simulation (with scintillator decay) for FASPD.
    7. About non-magnetic material:
      1. Al sent me this summary of non-magnetic stainless steel material, including both 315 and Nitronic 40.
        1. 1 oersted=1000/4π A/m and corresponds to 1Gauss in vacuum.
        2. 0.74 is the resistivity ρ in μΩ m.
        3. The relative permeability μr 1.003 is for for H = 5 kA/m*, where the footnote states:
           * In general, the relative magnetic permeability decreases at higher values of magnetic field strength.
        4. and here is the link for the location of the 316 table:
      2. From Joyce: 316 is considered the “most nonmagnetic” stainless steel. However, an item of 316 stainless steel which has significant welding or machining may be sufficiently magnetic to not meet your requirements for SoLID. In principle, a welded or machined component can be annealed to restore it to its nonmagnetic state, although this is not always convenient. Generally speaking, the higher the nickel content the more stable the austenitic structure and less magnetic response. So 316 stainless steel, with higher amounts of nickel, exhibits virtually no magnetism in most cases and would probably be your best bet.
      3. From one of my earlier email: "I'd like to test the magnetic property of a few stainless steel rods I got from IHEP (Russia). THe idea is that we put a magnetometer (Donal has one) in the field of 2-5T, then wave the rods around it to see if the reading changes. We'd like to see a <1E-4 change in the meter reading."
      4. Question: How does the permeability data transform to the effect on the field of SoLID?
      5. Discussion: probably need a field simulation.
    8. Xiaochao will email Jianping about asking for help from engineers.
  • 10/14/2014 Meeting to discuss EC and DAQ:

  1. Participants: Yi Qiang, Alexandre Camsonne, Rakitha Beminiwattha, Zhiwen Zhao, Xiaochao Zheng, Vince Sulkosky
  2. UVa updates:
    1. Vince brought back 3 scintillator bars from Alexandre. We will put them to test in the upcoming week.
    2. Vince also talked to people who plan to do the EIC PMT tests in the test lab. They have a 5-in bore solenoid magnet that goes up to 5T. Here are some pictures of the magnet.
    3. Simulated the timing spread caused by WLS fibers, see SPD simulation. The current conclusion is that a 8ns-decay WLS fiber (Y11) will cause a 1ns resolution if the signal contains 40 photoelectrons (roughly 2cm thick SPD). A 60ps TDC resolution as used here. The resolution is dominated by the starting time of the green (WL-shifted) photons. Using thicker scintillators will reduce the timing, but should not be considered since we all agree that for both FASPD and LASPD, photon rejection (reducing online trigger rate) is more important than timing.
    4. Also checked the consistency of the light yield between data and simulation.
    5. We already have quotes on Hamamatsu R9779/H10570 (for timing tests), bare R11102 (for detector group to test the final design of the base), Saint-Gobain on the LASPD prototype (quote for FASPD also exists but only for the 240 azimuthal segmentation, SG did not reply to my request on the light guide). SDU is discussing with their company about our LASPD and Preshower prototype, and LASPD light guide request. And we have initiated a discussion with Eljen on the LASPD + light guide. Xiaochao has to sit down and see how much funds we have left for prototyping.
    6. We have also initiated a discussion on the Shashlyk production with Wayne State.
  3. Discussions on the neutron background from the PMT's borosilicate window: Alexandre worried that neutron interacting with boron will give a large background. One other option is using quartz windows, but they are very expensive (such that Hamamatsu did not give a quote because "they are too costly for your application"). Also G0 experience is quartz windows are subject to helium poisoning so may not be a good idea.  Yi commented that "the boron should not be a problem because of the large light yield" (we expect 20-40 p.e. from LASPD), especially if comparing to the Cherenkov's MAPMTs.
  4. We also discussed where we can test the radiation hardness of all scintillators and fibers. We should ask Pavel for a radiation dose map in Hall A.
  5. JLab update: new baby!
  • 10/07/2014 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Zhiwen Zhao, Alexandre Camsonne, Yi Qiang, Jianping Chen, Xiaochao Zheng, Vince Sulkosky
  2. Discussions on FASPD timing requirement: need ~0.5ns for offline coincidence. This is based on physics requirement of rejecting background by factor 10-100, by combining timing of all 3 (SPD, EC, MRPC): roughly 0.5ns/35ns of FADC coincidence window(?). Jin commented (in a later phone discussion) that offline timing of EC can be 100ps for electrons and 200ps for hadrons (see various NIM paper). Will it reduce the requirement on the FASPD timing?
    1. Because of the long length of FASPD, direct readout from the outer edge is nearly impossible as shown in the SPD simulation. Jianping said we shouldn't change the design, i.e. still use 4 radial x 60 azimuthal segmentation with WLS fiber embedding. To proceed:
    2. Kai will simulate the light collection efficiency of WLS fibers for tile thicknesses from 0.5cm to 5cm with 0.5cm steps, with WLS fibers from 1 up to 5 turns (allowed by thickness). Here is a sketch of the 4 radial segmentation, estimated using equal aspect ratio for all 4 pieces. This may be subject to change based on equal-rate segmentation (Zhihong).
    3. Xiaochao will look into timing, maybe write another back-of-desktop simulation.
  3. Jianping updated on JLab feedback on the shashlyk prototype funding request. Initial response from the lab was positive, but had problems with the vendor. The said vendor is known to vary their quote (faster than we can follow).  We must find an alternate solution.
    1. Xiaochao started talking to Wayne State U. right after the meeting. Their high-energy nuclear physics group has a 8-station Shashlyk assembly lab with fiber treatment equipment. Here are some slides and a document on their Shashlyk detector for ALICE. However it is not clear yet how we can proceed.
  4. UVa update:
    1. Xiaochao has contacted SDU for Preshower prototyping. Previous hex tiles from SDU are not the right size (6-cm sides) and the grooves are small. This time, we want to have a direct comparison between SDU and IHEP tiles. We also plan to have parallel testing at both SDU and UVa to make sure we get identical results. For reference, here is a sketch of the IHEP tile geometry.
    2. Xiaochao has started talking to Eljen on SPD prototyping. (We already have a quote from SG, but without light guide).
    3. Xiaochao need to talk to SG on light guide design.
    4. We have quote from Hamamatsu on R9779 () and the FMPMT. Need to look into where to test FMPMT. UVa/HEP's coils have been warmed up and won't be cooled again for at least six months.
      1. Zhiwen mentioned EIC DIRC is planning to test PMTs at JLab, contact: Pawel and Kijun
      2. More collection on FMPMT test papers: INFN test on 3 FMPMTs (both gain and timing), mack.pdf(FMPMT101), FIU study on 2 FMPMTs up to 1.2T (both gain and timing). Here is a brief summary. It looks like the ideal angle is between 30 and 40 deg for R5924/H6614-01, need data for the other two FMPMT above 30 deg. Also need data above 1.2 T.

        INFN test: field uniformity ~1%, 12cm region, test signal is a Hamamatsu fast laser
        FIU test: test signal is a fast blue LED. (R5505/H6152-01 1-in and R5924/H6614-01 2in), field up to 52 deg and 1.2T.

        Data on R5924 (2-in) are shown: gain drop by 10 (theta=30 deg) to 100 (0 deg) at 1.2T, drop at theta=60 is unacceptable ( >100 at 0.2T) (inputs are laser signals equivalent to 30 p.e.) R5924/H6614-01 only: gain drop to ~0.1 at 0.7T and theta=0 deg. Gain drop is less for theta=40 deg (larger angle gives less loss), then more for theta=(40,50deg), then sharply above theta=40 deg to nearly 0 at theta>50deg..

        Rate (due to anode current)
        Data on R5505 (1-in) and R7761 (1.5-in) are shown: rate has a limit of 1E2-1E3kHz depending on size of PMT (smaller PMTs have higher tolerance, near 1E4 kHz) and field (larger field actually looks better). Here the rate is for the input laser signal whose amplitude is equivalent to 30 p.e..
        R5924/H6614-01 only: an input of 300kHz of 180-p.e.-equivalent signals (as background signals) corresponds to about 100uA in anode current. Gain varies by 30% from 0 to 100uA of background.

        Data on R5924 (2-in) are shown: for 300-p.e. signals, timing starts from <~50ps, stays nearly constant up to 0.6T, then at 1.2T rise to 100ps (theta=0) or >~50ps (theta=30deg - so nearly constant at this angle). No data on theta=60 deg. TDC was CAEN V480.
        R5505/H6152-01 (1in): about 3ns/sqrt(N) or 170ps for N=300; R5924/H6614-01: about 2.5ns/sqrt(N) or ~140ps for N=300
        With field: R5924/H6614-01 only, slowly rise from 0.28 (B=0) to 0.36ns (B=1.0T) for 28 p.e. signals, theta=0, error about +/-10%.
        With field and angle: nearly constant up to theta= 35~40deg, then rise sharply above theta=40~50 deg.
        TDC unknown.

        Other results

        Single p.e. peak is hard to observe because of the small gain at the first stage of FMPMTs. Signal is barely seen for R5924, and is nearly not present for the R5505

      3. Field strength in SoLID: plot1; plot2(log scale). At LASPD is about 1.4T.
      4. Do we need more tests given that data already exist (see item b above)?
    5. SPD simulation:
      1. For LASPD looks like 1cm-2cm thickness will fulfill requirement on both timing and light yield. Will need Zhihong's confirmation that photon rejection at 2cm is fine.

  • 09/30/2014 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Zhiwen Zhao, Alexandre Camsonne, Jianping Chen, Xiaochao Zheng, Vince Sulkosky
  2. Alexandre mentioned the <2.0ns rise time requirement on SPD is not essential.  This would be hard to reach given that most scintillators have a rise time of ~2ns.
  3. Yuxiang is in China, will be back in mid Oct. Hope to have JLab lab test update then.
  4. More discussions on the LASPD timing: 100ps if not using RF, maybe 150ps otherwise (combined with MRPC <100ps need to give a 200ps total resolution to provide the 4-sigma hadron PID.)
  5. UVa update:
    1. Preshower prototype is getting 70 photoelectrons with the IHEP tile, double 1-mm dia WLS fiber (each 2.5 turns), grease in grooves, tyvek wrapping.  Also, timing resolution of preshower output is in the 1ns range.
    2. Has been working on TDC setup and to characterize timing info of scintillators. By coupling a single fast PMT directly to the side of the Preshower tile, we hope to have some idea about the timing resolution. See 9/26 test page. So far, rise time is in the 2.5-2.7ns range.  Timing resolution is 600ps without time-walk correction. (simulation with hit position covering a full 10cmx10cm tile gives a timing resolution of about 200ps).
    3. Interested parties can check out the SPD simulation page
    4. FMPMT R5505-70: Here is the datasheet for the predecessor R5505 that shows magnetic field effect. The loss in gain looks logrithmic with field, can be as large as 1E-3 (0deg) or 1E-2(30deg) at 1.5T.
  • 09/23/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. SPD simulation update:
    1. See Zhihong's elog 99. Need to evaluate segmentation.
  3. Rakitha shows some slides on his EC simulation. Compared PS and SH energy deposit with Jin's results, seems consistent.
  4. Some info on Lorenzo's radiation study: mostly focused on radiation on the coils, and in the hall, and up to GEM, but not beyond GEM and not around the detectors.
  5. Discussion on background:
    1. Is background too high for FM-PMT? We still need to keep APD and SiPM in the picture.
    2. Zein-Eddine has experience with APD.
    3. neutron background: FA is similar to LA.
  6. We discussed beam tests of shashlyk modules. Yi mentioned the Hall D tagger area will be a good place, and Oct 2015 will be a good time (but not before). Jianping emphasized we need to improve the shashlyk cosmic test, think about what are the goals of comic vs. beam test, etc.
  7. UVa updates:
    1. We tried to maximize the Preshower output. For low fiber-turns, adding optical grease inside the grooves increased the light yield by almost 30%, see test page. We are continuing the test for higher fiber turns.
    2. Trying to do a back-of-envelope simulation for the SPD timing.
    3. We had a meeting with the Hamamatsu rep and the JLab detector group last Thursday (9/18) afternoon. Besides the fact that JLab is actively doing the base design for the R11102 (Vladimir - we may need to order 2 tubes with flexible pins for the final design of the base) and the preamp design (Jack) for the H12445-100MOD, we had some useful discussions about SPD:
      1. R9800: this is a fast tube, but the JLab-designed base focused on dealing with high rates and not particularly for fast timing (timing is still very good, it just wasn't the top priority for the base design).
      2. Long fiber may not work. In addition, using clear fibers to cover the whole outer edge will cost:
        1. Assuming 1/2 reduction in area with some light guide and $1/m clear fiber cost (note: Saint Gobain $1/m Kuraray $2/m) will cost:
        2. FASPD: outer edge area 1445 sq. cm (assuming 1cm thickness, equivalently 6 sq. cm or 0.93 sq. in if 240 segments), require 72,256 1mm dia fibers (1/2 reduction included here), 3m will cost $217k;
        3. LASPD: outer edge area 880 sq. cm (assuming 1cm thickness, equivalently 14.7 sq. cm or 2.2 sq. in if 60 segments), require 43,982 1mm dia fibers (1/2 reduction included here), 5m will cost $220k.
      3. Typically, the timing resolution Delta_t is proportional to (rise time), (amplification), and 1/(sqrt(Nphe)).
      4. If we need to read out light directly, we may want to use fine-mesh phototubes rather than APD.
        1. APDs cost a few 100$, but the gain is only a few 100 and need a very high-gain amplifier, thus is vulnerable to noise.  If we know the light input at the front face of APD and the timing profile, can run a simple simulation to figure out the S/N ratio. Ardavan sent me some info on the S8664-1010 series (used by the Heavy Photon search experiment at JLab, Stepan Stepanyan, but no timing info available) and S11625-1010 (should have similar or better timing resolution than S8664, measured to be 220ps).
        2. On the other hand, finemesh tubes are field resistant (gain drops with field, but generally okay if the field is within a certain angle of the tube axis), fast (rise time ~2ns, transit time spread ~320ps), radition-hard and have high Q.E.. The drawback is the cost: about a couple of 1000$ each.  Ardavan said he can look for field resistance data from Japan. A quick google search gives this article: that has some description of FM phototubes and performance (gain drop to 1/30 with 1T axial field, and varies with angle within 45 deg). Hall D also performed tests and showed similar results -- gain reduction and slightly worse timing resolution up to 45deg, complete deterioration above 45 deg. A search on Hamamatsu website shows two types: R5924-70 (2in) and R7761-70 (1.5in) may be suitable for us (A third type is R5505-70 1-in but typical gain is 5E5 too low and shows worse spe spectrum in the Hall D test).
      5. It is important that we order a SPD prototype and figure out the light yield and timing response. Choice of scintillators:
        1. Saint Gobain crystals BC408: rise time 0.9ns, decay time 2.1ns, light attenuation length 210cm,380cm(bulk), density 1.032g/cm3, n=1.58. Quote available!
  • 09/16/2014 Meeting to discuss EC and DAQ:

  1. Participants: Rakitha B., Zhihong Ye, Vince Sulkosky, Xiaochao Zheng, Jianping Chen, Yi Qiang, Wouter Deconick
  2. UVa updates:
    1. The old scintillator detector we found didn't work well in the test. So we moved back to the preshower test. The goal is to reach as high yield as possible. We have tried double 1-mm fiber, 2.5 turns each, minimal length, using both Tyvek and Al-mylar. The highest yield we saw was about 50. The Al-mylar so far give slightly lower yield than Tyvek (which is the opposite of our previous result).  We will do a turn-dependence test with Tyvek and fixed fiber length, then add the grease into the grooves to see if it can improve the yield.
    2. A summary of known scintillator timing resolution for references:
      Achieved timing performance
      HRS S2
      300ps per plane
      Hall A NIM and other resources

      HRS S2m
      135ps per plane, ~100ps per paddle
      Transversity data

      BigBite scintillator in electron package
      270ps per plane
      Transversity data
      it is sandwiched between preshower and shower
      CLAS12 Forward TOF counter
      Saint-Gobain BC-404, Hamamatsu R9779, see CLAS12 TOF review
      CLAS12 TOF study
      59ns with R2083, 130ps with Burle 85001 micro-channel plate photo-multiplier, 685+/-10 primary photoelectrons for 4.4MeV (2cm) MIP with R2083.

    3. Vince is picking up the neutron background simulation results. 
    4. Beam test: energy of 4GeV particles after they pass through the pion rejectors is about 500MeV, for 3GeV particles is about 350MeV. So energy-wise they are not so different. However, the poor energy resolution of the pion rejector means we can't have a good evaluation of the shashlyk's energy resolution.   We discussed again the goal of beam vs. cosmic test:
      1. XZ: The goal of such beam test is to confirm the energy resolution published by COMPASS and to setup a venue for future prototype test. Both may not be achievable if we do the test in the LHRS. Yi sugguested to use the photon tagger in Hall D (enough space, good energy resolution). But given the Hall D commissioning schedule the earliest suitable time will be October 2015.  We may want to aim for some beam test for that time period.
      2. JP: We should make the cosmic test work first for shashlyk.
  3. We will meet the Hamamatsu rep this Thursday (at JLab) and Friday (at UVa)
  4. Rakitha reported that he is working on the Preshower simulation. He already reproduced the energy deposit in both the Preshower and the Shower and they look similar to Jin's results. The next step would be to reproduce the numerical PID (pion rejection for given electron detection efficiency) both with and without background. Then will add in the 30 p.e. of PReshower light yield.
  5. Zhihong will simulate the photon rejection for SPD. But first he will double check the SIDIS requirement to find what is the photon rej for LASPD.  For FA, the MRPC will provide both timing and PID for hadrons and the SPD is a redundancy. For LA, if photon rej is not important, then we will aim for providing a good timing resolution (thicker pads).
  6. Jianping re-emphasized the timing requirement: We use SPD for online photon rejection and offline hadron PID. For forward, MRPC will provide both timing and photon rejection so the FASPD is a redundancy for both requirement. For large angle, LASPD is the only source of photon rejection and hadron PID (TOF). For hadron PID, if we use the RF signals then 400-500ps of timing resolution with <2ns rise time will be good enough. However if we do not want to use RF signals (Transversity experience -- RF for singles is not good enough and for coincidences did not use RF at all) then we need 100ps of timing resolution with <2ns rise time.   If we cannot find a balancing point between timing and PID, the for LA should we build two SPDs? -- not sure yet.
  • 09/09/2014 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Rakitha B., Zhihong Ye, Vince Sulkosky, Xiaochao Zheng, Tim Holmstrom
  2. UVa updates:
    1. First we reproduced the yield results for 6.5 turns of 1mm fiber, IHEP tile, Tyvek (37 p.e.), with the new darkbox setup. We had to polish the fiber ends.
    2. Then we did the 2-mm fiber test:
      1. The yields are much lower than we expected-- if we assume the same bending loss and attenuation length as the 1mm fiber. (For example, the test gave 25 p.e. for 5.5 turns). However, a bending loss in the 25%-per-turn range can explain the yield well. And this is consistent with the 2mm fiber being non-S type, and our grooves have 9cm diameter.
      2. Note: Kurarayonly make S-type fibers for 0.5mm and 1mm dia fibers. For 1mm fiber, S-type gives much smaller bending loss than non-S type for diameter below ~45mm, while for >50mm diameter both types are similar. The minimal bending diameter is characterized as 10cm for 1mm S-type, 20cm for 2mm S-type, and 40cm for 2mm non-S-type, thus our bending radius is way below the 40cm minimal value.
      3. It is probably safe to conclude that it's better to use double 1mm fibers rather than a single 2mm fiber. Coincidently the DDK fiber connector works only with 1mm fibers (they don't make 2mm connectors).
      4. We will repeat the 2mm fiber test with less turns to see if they give consistent bending loss results.
    3. We found an old detector that is made of a scintillator with 15 clear fibers glued to the end. See pic1, pic2 (for fiber ends). We will do a preliminary test on its light yield and timing property in the upcoming days. We have also initiated a discussion with Saint Gobain.
    4. Preparation for beam test?
      1. We were thinking about putting the shashlyk modules in the LHRS behind the pion rejectors. We have not heard back from Will Brooks about borrowing the modules. The PMTs that were used with these modules have been shipped back to Chili so we need to look for other PMT sources. We also have not heard back from Jack on the mounting of the modules behind the P.R..
      2. Latest news is that LHRS will not run above 3 GeV/c. This makes it difficult to have particles energetic enough to penetrate the pion rejector. So this fall may not be an ideal time for the beam test.
    5. Last week we gave the two MAPMTs to JLab, one for detector group for preamp design, the other for testing. These are H12445-100MOD 16-ch MAPMTs. The PMT inside are R11265-100-M16. A single-PMT is named R11265-100 and with housing is named H11934, while the 16-ch versions are called R11265-100-M16 and H12445-100MOD. Here are the datasheet of the 2 MAPMTs with serial number DA0252 and DA0254.
    6. Next set of tests includes:
      1. Maximize the preshower light yield: Using 2piece of 1mm dia fibers, cut to minimal length (20cm extra on each end for readout), polish, use optical grease for the groove and for coupling to the PMTs, use both aluminized mylar and Tyvek. Then can also add the clear fiber (two lengths) and fiber connector;
      2. Test the scintillator detector light yield and timing - pulse rise/scope and spread/TDC - use both R9800 (to get nearly only the intrinsic timing of the scintillator+fiber) and R11102 (to see effect of the slower PMT).
  3. Discussions on SPD:
    1. A quick evaluation of the timing requirement gives us two options: 1) Use clear fibers glued to the edge of the scintillator. PMT option in this case would be R9800 or low-cost counterparts; 2) Attach field-resistant diodes (such as APD) directly to the edge of SPD.
    2. We need to calculate how much timing spread the 3m fibers will give us (the solid angle acceptance of the fiber can be found on the same Kuraray webpage).
    3. We also need to calculate how much timing spread the long shape of the SPD will give us.
  4. Hamamatsu representatives will be in the area on Sept. 18-19 and we should prepare for the meeting.
  5. The EC prototype budget request is for FY15, and with possible continuing resolution.
  6. Todo:
    1. Vince will pick up the results from Lorenzo's neutron background study. Zhiwen mentioned Lorenzo's study for SIDIS at the particular places where the detector is was not finished.
    2. Zhihong will simulate the photon-rejection of SPD vs. # of segments, for 5mm, 10mm, and 20mm thicknesses;
    3. Rakitha will continue calculating the PID performance vs. # of photoelectrons from the Preshower.
  • 09/02/2014 Meeting to discuss EC and DAQ:

  1. Participants: Zhihong Ye, Zhiwen Zhao, Jian-Ping Chen, Alexandre Camsonne, Vince Sulkosky, Xiaochao Zheng, Wouter D., Rakitha B.
  2. UVa updates:
    1. We will switch from shashlyk to Preshower tests. For Shashlyk test we will think about parasitic in-beam test in Hall A in Oct/Nov., on the Left HRS. However, Vince just reported that although the TPE Compass-II blocks are still at ODU, the PMTs have been shipped back to Chili. We will need to borrow PMTs from Hall A.  Besides Hall A, we can also consider testing them at Fermilab or SLAC, or the injector at JLab (a few 10s of MeV beam).
    2. Is it possible to use R11102 and the customize bases from the detector group directly for this beam test?
    3. Here is the plan for preshower test:
      1. Continue fiber/yield optimization: We will first reproduce the prior results, then do the 2-mm fiber test (we have both 200ppm and 300ppm fibers);
      2. We will use new tiles from SDU: 20mm, 5mm, and 3mm square tiles to study the light collection in SPD. This can also provide a test for the simulation.
    4. We will move the two 16-ch MAPMT R11265-100-M16 to JLab, one for the detector group and the other for testing by Yuxiang and Wouter's student.
    5. We will pick up some polishing sand paper from JLab for the fiber work.
  3. Discussion on timing:
    1. Hadron PID require 2ns of rise time and 100ps of jitter. This can only be achieved by the SPD w/o the WLS fibers.
    2. For the EC alone, to reduce background, we require that the timing jitter to be <1ns for offline analysis. R11102 has 4.8ns of TTS jitter [divide by 1/sqrt(number of p.e.) to get the real performance]. We need the jitter from the WLS fiber light alone to be at a manageable sub-ns level (0.x ns?) and the PMT base/amplifier alone to be negligible/invisible. This probably can only be tested with the beam.
  4. Discussion on SPD:
    1. Now it's clear we might have to use SPD as the sole source of timing for LA SIDIS. Thicker scintillators give better timing resolution, but would give worse photon rejection. Some existing data:
      1. HRS S2 was 5mm and timing resolution was large. The upgraded S2m was 5cm thick and reached 100ps. BigBite scintillator is about 3cm thick and reached somewhere between 100 and 200ps.
    2. Todo: We should simulate the photon rejection for 5mm, 3cm, and 5cm thicknesses. Who?
    3. Can we do a back-of-envelope calculation for the photon rejection and the timing resolution for different thicknesses?
    4. We will talk to a couple of companies to see if they have ideas on SPD design.
  5. SoLID director's review will possibly be in November. We also discussed about the QCD town meeting.
  • 08/26/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. UVa updates:
    1. SDU's preshower test slides at the Lanzhou workshop: LanZhou SDU slides; They just sent in newer test results on the hexagon Preshower, see this file. The MIP response is 18.8 p.e. for 1 turn of fiber and 30 for 2 turns, with a 60-cm long 1.5mm dia BCF92 fiber. Correcting for the fiber diameter (/1.5) and length difference (ours are 3-m long), these results correspond to 12.5*(0.3-0.45)=3.8-5.6 and 20*(0.3-0.45)=6-9 for 1 and 2 turns, respectively. Here the first number is using a decay length of 2m and the second is using 3m. Note that even though the datasheet for Y11 shows >3m decay length, our tests showed that after folding in the circular path the actual decay length may be as small as 2m.
    2. The above results should be compared to our March 13 results: 9.5 at 1 turn and 16.4 at 2 turns with Y11 fiber. Our later tests showed that BCF92's yield is about 37% of Y11's, so we expect about 3.5 and 6.1 if using BCF92. The error is at the 10% level from determination of the spe peak. This agrees well with the SDU results.
    3. Found contact for the DDK connectors (Terry Dattilio and indirectly The connector type is MCP-10P-3 and adaptor MCP-10A. They only have this type of connector for 1mm diameter fibers. Here are the drawings: MCP-10P-3, MCP-10A. These are the ones U. of Rochester used for Minerva. The connectors are not available in the US. The company has requested 3 samples each to send to us but it will take about 6 weeks.
    4. COMPASS-II cosmic test: After various attempts (raising the threshold on the CsI to suppress background; lowering HV to avoid saturation, etc.), we see a peak that correspond to <100 p.e..  We cannot find official publication on the COMPASS-II module cosmic test or MIP test results. ODU test (Larry W.) showed similar spectrum and their tests were more sophisticated (they used a matrix of blocks and showed spectrum for a particular block only if the yield from this block is higher than those from adjacent blocks).
  3. We discussed timing requirement for EC. For SIDIS coincidence EC is the only source of timing at large angle so we need <=100ps of timing jitter and the pulse rise time needs to be <2ns. However, WLS fiber itself (Y11 and BCF91A) has a 8ns decay time and are not suitable for fast timing. So the only option is to use SPD at LA to provide the required timing info and it also means we cannot use WLS fibers for read out.
  • 07/29/2014 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Zhihong Ye, Zhiwen Zhao, Rakitha Benminiwattha, Vince Sulkosky, Yuxiang Zhao, Alexandre Camsonne, Yi Qiang
  2. Xiaochao:
    1. Kai has provided updated simulation. Note all simulation files have been moved to the spd directory.
    2. Has been talking to Cunfeng on the preshower test at SDU;
    3. Made a sketch for LAEC SPD design: click here for PDF. Kai is trying to optimize the fiber routing scheme. 
      1. Sent the design to Cunfeng, got a quote of 2500yuan/piece. Scale by area (LA: 3.99m^2; FA: 13.6m^2) and using 1:6 conversion rate, this requires $132k total for LA+FA SPD, excluding fiber. This is twice what we have budgeted for ($65k).
      2. Looking at the design, the MIP response will vary with radius. Given that the background is the highest at inner radius, must have higher MIP response at inner radius and lower at larger radius. Kai can simulate this.
    4. Begin to setup an MOU with JLab for equipment loans.
  3. Discussion about SPD (mostly Yi)
    1. possible options for FAEC: Using 240 azimuthal segments and read out light directly on the side using light guides. Light guides couple to PMT directly. Need to simulate light collection efficiency (Kai Jin).  Can also use fiber coupling at the end.
    2. LAEC still need long-distance transmission of light.
  4. YiXiang:
    1. The 64-ch H10966A MAPMT was "gone", due to dark box being opened with HV on. We should build an interlock system (Yi, Alex). Will contact Wouter to see if Hamamatsu can offer some options (free MAPMT? unlikely).
  • 07/22/2014 Meeting to discuss EC and DAQ:

  1. Participants: Xiaochao Zheng, Zhiwen Zhao, Rakitha Benminiwattha, Zhihong Ye, Vince Sulkosky.
  2. Vince: The dark box at UVa is nearly finished. Need to help Donal to setup the labview system so we can have the VME DAQ back. Xiaochao will look into getting 2 more CsI for setting up a hodoscope;
  3. Rakitha:
    1. Combined EC and Cherenkov to get the trigger rate estimate:
      1. For p>1GeV, combined EC trigger rate (pCDR) with the Cherenkov pion rej and electron efficiency to get the coincident rate for electrons and pi+, pi-. Total is 15.6kHz per sector. Zhiwen pointed out the Cherenkov PID used (as in pCDR) is still the offline performance. 
      2. To do: for p>1GeV, add the photon blocker and evaluate the coincident rate for photons and protons, both should go down;
      3. To do: find a way to estimate coin rate for p<1GeV. Not sure  how to do it yet;
      4. To do: get the accidental rate. Zhiwen mentioned it is estimated to be 18kHz per sector in the pCDR. We don't expect this to change (much?).

  • 05/21/2014 and 5/27/2014 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Yuxiang Zhao, Alexandre Camsonne, Yi Qiang, Rakitha Benminiwattha, Zhihong Ye.
  2. Xiaochao updated the UVa test results, see 2014 test summary page (Week of 5/7 and 5/22). Main conclusions:
    1. Tyvek is only 10% higher than printer paper and is not as good as aluminized mylar. Suspect the Tyvek homewrap (supposed to be 1055B) from LOWES is more for making kites than for scintific research;
    2. Using two 1.5-m long 1mm-dia fibers gave higher yield than expected. Best "fit" is a 350cm attenuation length plus 6% per turn of bending loss. Quick calculation shows using two 1mm-dia fibers give slightly higher yield than using one 2mm-dia fiber. This awaits further testing.
    3. Still waiting for 2mm-diameter fiber to arrive, and the machine shop to widen the grooves.
  3. Yixiang has been working on the test stand at JLab, see his wiki link.
    1. On 5/21, reported measurement of the gain at very low HV. This is a relative measurement (since there is not yet absolute calibration, had to fix the 1kV point to the spec), but the gain measured looks pretty good, reaching 1E3 at about 350V.
    2. Talked to detector group (Jack McKisson) on coordinating the MAPMT base design. Jack will provide an (unpopulated) PCB which serves as a connector for a group of 16 channels. Will test it using QDC and large signals first. Then move on to smaller signals and populate the PCB with amplifiers. Since it works for 16 channels, it can be used for either 10966A (using 4 PCBs) or the 16-ch H12445-100 MOD that we ordered.
    3. Todo:
      1. continue with absolute calibration of two weeks ago and see if it is truly 20% off from the QDC (CAEN V792) spec. Got some help and advice from the detector group.
      2. Will consider using LED pulse as the trigger to study timing response.
  4. Rakitha will work with Zhiwen and Jin and take over the Calo simulation (has been busy with a proposal this week).
  5. Zhihong will continue working on the radiation dose for SPDs.
  6. Xiaochao will update the preCDR, the EC part, to reflect the recent development gained from all the pre-R&D tests.
  7. Wouter and Jianping (and others) will discuss later this week on how to accommodate the coming three undergrads (one SULI/Jianping, one WM/Wouter, one WM-REU/Wouter).
  • 05/14/2014 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Jin Huang, Xiaochao Zheng, Zhiwen Zhao, Yuxiang Zhao, Alexandre Camsonne, Yi Qiang
  2. Jin reported that
    1. news: ALICE has recently assigned the shashlyk production to Wayne State University (doc uploaded to dropbox).
  3. In the upcoming weeks Rakitha will work with Zhiwen and Jin, trying to convert the previous Calor simulation package to be an integrated part of SoLID simulation. Jianping mentioned now there are two main directions: GEMC originally developed by Zhiwen, and a new "ROMO"(spelling?) package developed by Seamus. It's not clear to which package we should convert calor. Jianping commented it the decision should be made by whoever takes over.
  4. UVa lab update: Summary of the past 2-3 weeks' tests:
    1. We have tested the IHEP hexagon tile (7.5mm groove) with a 3-m long 1-mm diameter Y11 fiber, using printer paper wrapping, see 2014 test summary page (Week of 4/21-4/28). Max # p.e. is 39.6 with 6.5 turns.
    2. Using 3 identical IHEP hex tiles (5.5-mm groove), we compared the light yield of 3-m long 1-mm diameter fibers: Y11, BCF91A, and BCF92. See 2014 test summary page (Week of 4/29-5/2). We found BCF91A yield to be about 55% of Y11, and BCF92 to be 37% of Y11. The relative yield of BCF91A to Y11 is irrelevant of the number of turns, indicating that the less yield comes from the fiber conversion, but fiber bending. The finding of BCF91A seems to be different from ATLAS TDR, where it was reported BCF91A to produce similar yield as Y11 but have large bending loss at the 10-cm bending diameter (see Fig.5-24 from ATLAS TDR).
    3. Yi suggested using aluminized mylar as wrapping. We happened to find a roll in a "junk box" in the hallway, and did the mylar test, see 2014 test summary page (Week of 5/2-5/6). Max # p.e. is 41.5 with 6.5 turns.
    4. Kai Jin did a simple simulation to study the effect of fiber length decay. We found that when using L-m long fiber, it does not matter how asymmetric the fiber is inside the tile. As long as we are reading out both ends, the decay is roughly exp(-L/2/3.5m), where L is the full length of the fiber, 3.5m is the decay length.
    5. In the past week we struggled to conduct the test with tyvek wrapping:
      1.  ATLAS TDR reported using Tyvek 1055B which has 95% reflectivity. A google search found reflectivity test of various Tyvek series compared to aluminized mylar and printer paper. See 2014 test summary page (Week of 5/2-5/6) for a summary.  Xiaochao could not find Tyvek 1055B online. Consulting with UVa colleagues, she bought Tyvek homewrap from LOWES (google search easily shows Tyvek homewrap is "style 1055B". The roll from LOWES is not purely white and have Tyvek trademark on.
      2. Now we have new wrapping made from Tyvek, however, our tests first showed high background, then repeated 5.5-turn runs were not consistent. We ended up replacing the fiber (we seem to have damaged two fibers, one we have used since the beginning and the other used in the aluminized mylar runs), and now are resuming the test.  Also, an initial test from today showed slightly less yield than Al-mylar wrapping.
    6. Jianping commented that we do not need to prove that Tyvek is better than Al-mylar. Xiaochao is a bit skeptical about the Tyvek from LOWES. After this series of test she will contact IHEP about this.
  5. Xiaochao has received Hamamatsu quote on the 16- and the 64-ch MAPMTs. Will purchase one for detector group to use (pre-amp design).
  6. Yuxiang reported JLab test stand progress: see his 2014/5/14 report. Mostly:
    1. did an absolute calibration of the QDC using a function generator. The signal is basically a constant voltage, which means the QDC reading is determined by the signal voltage, the gate pulse width, and the 50ohm impedance. The calibration is about 10% off. Jianping suggested using pulse signals narrower than the gate, since it is not clear how precise the integration time of the QDC is related to the gate width.
    2. Working on some signal reflection problem.
  7. Zhihong did some SPD simulation, in order to determine its exact radiation dose etc.
  8. (Not reported directly) Xiaochao checked Zhiwen's rate calculation, with radial dependence. The conclusion is that although it is slightly different from the dose value (Jin's result, averaged over the whole detector) used in the previous calculations, it does not affect our design specification on the PMT readout (divider and pre-amps).
  9. Updated todo list:
    1. UVa will focus on optimizing the Preshower fiber embedding:
      1. continue with Tyvek test. After it is done, will test the (homemade) connector, adding grease into the groove, and adding clear fibers, to see how much it affects the readout.
      2. Xiaochao will ask for 2-mm diameter fibers for testing.
      3. continue setting up the TDC;
      4. continue building the vertical dark box;
      5. Kai Jin is working on a simulation of the fiber embedding. If it agrees with the measurement, it will prove to be useful for SPD optimization too.
    2. JLab test stand: will focus on testing the MAPMT uniformity, cross talk, etc;
    3. PMT readout design is ongoing. JLab detector group has started the work on the R11102 pre-amp+divider design. Xiaochao will order a 16-ch MAPMT H12445-100 MOD for detector group to design the 16-ch pre-amp (MOD means including tapered divider). Hamamatsu has agreed to provide uniformity data for H12445-100 MOD at the low gain we requested;
    4. Fiber connectors:
      1. Xiaochao is pursuing the DDK connector (used in Minerva, see last meeting minutes);
      2. Home-made connector doesn't look too hard to D-I-Y, but needs testing (see above)
      3. LHCb will send a couple of stuff to JLab next week (contact: Alexandre C., Pascal Perret, Magne Magili). Most need to be returned:
        1. a 64-PMT with its divider board and its adaptator for optical fibre
        2. a 32 fibre connector
        3. a bundle of 128 clear fibres (64 pairs).
    5. Rakitha (and Zhihong?) will take over the calorimeter simulation from Jin and Zhiwen. First priority is to study if 30 p.e. PReshower readout is good enough for PID.
  • 04/23/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Zhiwen: update and discussion on the rate calculation
  3. PMT related:
    1. Xiaochao is still waiting for a response from Hamamatsu on the 16-ch MAPMT quote (awaiting reply from Japan side);
    2. Discussion about the divider design has started, see PMT meeting minutes.
  4. Discussion on Minerva:
    1. From their online document they are using 64-ch, not 16-ch MAPMTs. But if we can get them for free, we can always use only 1 pixel out of 4, then effectively it will be 16-ch and the limit on the anode current is the same as the 16-ch MAPMT;
    2. Yi Qiang pointed out that Minerva used a "smart" fiber connector, called DDK connector (see arxiv1305.5199). We might want to ask R. Ransom at Rutgers for more details.
  5. General discussion:
    1. What should we use for calibration of EC?
    2. JP: why loss in clear fiber is so much? (Xiaochao later received an explanation from Kuraray). The clear PSM fiber loss data is here. Using 400dB/km for the peak WLS emission wavelength, the calculation is: 400dB/km = -10log10(I/I0)/L. So

    3. Optimize fiber embedding: Will 2-mm fibers work better, will 2x3 array work better than 1x6?
    4. Xiaochao needs to update the cost table for Jianping!
  6. UVa lab update:
    1. received 6 hex tiles from IHEP, with groove depth 5mm and 7.5mm, 3 tiles each. They are slightly bigger than the Chinese tile. The drawing is here. We started the 7.5mm groove test yesterday with a 3-m long 1mm-dia Y11 fiber embeded 6.5 turns. The MIP is at about 40 p.e.
    2. Will ask the student (Kai Jin) to run a simulation for the WLS fiber decay (length) loss (easy), and eventually a simulation to optimize the fiber embedding (much harder to do).
    3. just received Saint-Gobain BCF91A and BCF92 fibers.
    4. made a 1-1 fiber connector and will test it;
    5. received 2 R11102 from Hamamatsu, will send one to Alexandre C. and test one here; Along with this PMT test will also test the R9800 from Hall D.
    6. material for the dark box is all ready and "construction" will begin!
  • 04/16/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Zhiwen has preliminary results on the low-E photon energy deposit in the Preshower for different radius. Need: How does this compare to Jin's rad dose simulation plots in the pCDR (this is a sanity check);
  3. Xiaochao will update the cost table assuming we use 16-ch or 64-ch MAPMTs. But first she needs a quote from Hamamatsu.
  4. We discussed about the 1-1 fiber connector and Jianping preferred the connector to splicing, such that we keep one more flexibility for SIDIS/PVDIS changeover;
  5. Xiaochao will send a Chinese tile to JLab for YuXiang to test.
  • 04/09/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Update on last week's to-do list
  3. UVa Updates
    1. fiber connector test: see 2014 test summary page (Week of 3/31-4/9)
    2. Starting to build vertical dark box
    3. Will have R9800 from Yi/Hall D and test it.
    4. Xiaochao has asked Hamamatsu for life time data beyond 1000 hours. (Technically, <1000 hrs is called "drifts", beyond 1000 hrs is called lifetime) -- update: Hamamatsu does not have data beyond 1000 hours. They sent us some "extrapolated data" which use the 1000-hr data (but everyone can extrapolate!).
    5. Xiaochao got updated cost for square-shape modules: Shower $990/module square vs. $1270/module hex. For details see updated table in 03/26/2014 minutes.
  4. Yi has located some fiber fusion equipment from MSU/UConn. We might think about ordering one ourselves eventually.
  5. Yuxiang has the test setup at JLab working, can start testing something.
  6. Updated todo list:
    1. Wouter will look into buying a MAROC.
    2. Yi will borrow a H8500 assembly from JLab detector group and test its cross talk and uniformity with Yuxiang. Xiaochao suggested making a hole-mounting but Yi prefers a continous scanning device for the uniformity study.
    3. Zhihong has an AutoCAD design for mounting 64 fibers to a H8500. Will send it around. Xiaochao will use it as a starting point for the Shower and PS PMT mounting design.
    4. Xiaochao will ask Fermilab for fiber fusion samples.  Yi will talk to MSU to see if they can build another fuser.
    5. PMT base design meeting (A.C., XZ, Drew W.) is being planned. Base design on the UVa side will await for this meeting results.
    6. Zhiwen will continue the radiation dose evaluation with radial dependence (MAPMT can still be used if a significant amount of modules have 100 times less than the most inner module used for the calculation above)
    7. We are still waiting (Jin) to see if 30 p.e. from Preshower is too low for PID;
  • 04/02/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Update on last week's to-do list
    1. Alexandre C. got the LV board quote from CAEN. The price per board is similar to HV and it has only 8 channels. Power-wise (50W/ch) it could power up to 80 PMTs/channel (compare to HV 24ch/board), but then the cost saving on power supply is about $1.5M*30%=$450k and the cost increase on CW-base is about ($250-$80) per channel or $680k total. We cannot save on cost this way unless if we go with customized and lower-cost HV and CW bases;
    2. Xiaochao got info from Dinko that a customized HV cost about $50 per channel. This could save over $1M on total power supply, which will compensate for the CW-base cost increase.
    3. Zhiwen got the tools from Jin but has not completed the simulation yet. Xiaochao in a followup email also asked for radial dependence of MIP and electron rates (for PMT base design study).
    4. Zhiwen will followup also on the 30 p.e. simulation;
  3. Xiaochao updated on PMT quotes. Got recommendation of two tubes from Electron Tubes Inc: 9125B for Shower and 9142B for SPD/PS. Single-order cost matches Hamamatsu. Both have HV dividers (the C637 series, single $110, volume $75). The 9125B can be equipped with a CW base (HV3020CN or HV3020AN, single $340, volume $250). Xiaochao will order some for testing once decide on the spec. May order more for Alexandre C to study at JLab.  For ET element datasheets see this directory
  4. Zhiwen reminded that SPD design has 240+60 channels (Xiaochao mistakenly used 120+30 in the estimation).
  5. Zhihong mentioned he is doing some SiPM study for Hall B. He might find some experience of UVa faculty useful.
  6. Todo list:
    1. Continue with last week's todo list
    2. Wouter will look into purchasing a MAROC unit to test with the MAPMT. Zhihong may conduct the same test at JLab (also need to buy a MAROC unit).
  • 03/26/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. We discussed anode current and signal height calculation for SPD/PS/Shower, Xiaochao's notes are summarized as follows:
    1. Detector
      SPD w/ regular PMT
      Preshowr w/16-ch MAPMT
      Preshower w/ 64-ch MAPMT
      PMT options (Hamamatsu) all files
      PMT base commercial options (Hamamatsu) N/A
      N/A N/A E2183-501
      PMT options (Electron Tubes) all files 9142B

      N/A 9142B 9125B
      PMT base commercial options (Electron Tubes) C637

      N/A C637 C637 or CW types: HV3020AN or HV3020CN
      Radiation dose (averaged)
      2E3 rad/mon
      1E4 rad/mon 1E4 rad/mon 1E4 rad/mon
      5E3 rad/mon
      average Ianode with G the PMT gain
      inner FA: 0.0466m^2/pad, I = G*(2E-11A/ch)
      200g/tile, I = G*(3.5E-12A/ch) 200g/tile, I = G*(3.5E-12A/ch) 200g/tile, I = G*(3.5E-12A/ch)
      20 layers (300g), I = (G*5E-11A/ch)
      PMT gain to keep Ia(node) < 1/10 of max spec (see below)
      5E5 for
      (2)E4 for Ia<10uA/16 = (0.62)uA (5)E3 for Ia<10uA/64 = (0.17)uA
      for Ia<10uA
      (2)E5 for Ia<10uA
      MIP energy
      MIP # p.e. using 1E4 p.e./GeV
      10 p.e.
      40 p.e. (use 30 to be conservative)
      40 p.e. (use 30 to be conservative)
      40 p.e.(use 30 to be conservative)
      600 p.e.
      MIP pulse current assuming 30ns triangular pulse; G: PMT gain G*0.1nA = 50uA G*0.32nA = 6.4uA G*0.32nA = 1.6uA G*0.32nA = 100uA G*6.2nA = 1.28mA
      MIP rate (pi+ and pi- only, per 100cm^2 module)
      400kHz average, 50kHz inner, 1.2MHz outer
      400kHz average, 50kHz inner, 1.2MHz outer 400kHz average, 50kHz inner, 1.2MHz outer 400kHz average, 50kHz inner, 1.2MHz outer 400kHz average, 50kHz inner, 1.2MHz outer
      MIP pulse height assuming 30ns triangular pulse 2.5mV 0.32mV
      80microV 5.0mV 64mV
      electron energy (max)

      electron # p.e. (max) using 1E4 p.e./GeV N/A 1200 1200 1200 20000
      electron rate (from pCDR, averaged over whole detector)
      up to 300Hz per module
      up to 300Hz per module up to 300Hz per module up to 300Hz per module up to 300Hz per module
      electron max pulse current assuming 30ns triangular pulse N/A 256uA
      electron max pulse height assuming 30ns triangular pulse
      N/A 12.8mV
      Preamp gain needed (somewhat flexible)
      10 to keep MIP at 25mV so we can cut at half MIP
      (160 if we use 16-ch MAPMT)
      ~40 to fill 0.5V range of FADC ~150 to fill 0.5V range of FADC
      2.5 to fill 0.5V range of FADC, no again is okay since we want to cut just above MIP
      none needed, may use 1E5 gain to keep within range
      Other requirement
      prefer using 1 HV output for 2-3 PMTs

      prefer using 1 HV output for 2-3 PMTs prefer using 1 HV output for 2-3 PMTs
      Comment: All calculation is based on average dose. Actual dose will vary with radius, causing inner modules to be limited to even smaller PMT gains and thus smaller electron and MIP signals.
      HV board is planned to be CAEN 1535A floating 3.5kV/3mA(8W)
      1. We would like to keep average anode current below 1/10 of max spec to avoid significant aging (Typically running at 1/10 of max current leads to significant drop in gain (about 10%) within 10000 hours of continuous running. Max spec is usually 100uA
      2. SPD area: FA inner (R=85-127cm, 60 azimuthal) 0.0466m^2; FA outer (R=127-240cm, 60 azimuthal) 0.217m^2; LA (R=80-140cm, 30 azimuthal): 0.138m^2; total volume using 5mm: 0.1m^3.
      3. The conversion factor of 1E4p.e./GeV seems to be reasonable according to the UVa test: We used 2cm scintillator and saw max of 33 p.e. (dEdx~(1.8-2)MeV/gcm^-2, d=2g/cm^2, So dE=(3.6-4) MeV which gives (36-40) p.e.
      4. Physics-wise, the 1E4p.e./GeV conversion factor includes: scintillation efficiency of the scientilator (about 1E-3 in order of magnitude), PMT Q.E (typically 18-20%), WLS fiber collection efficiency (typically 5% for double-clad and 3% for single-clad -- from Kuraray email), light loss due to air gap between WLS fiber and scintillator groove wall, light loss due to fiber length, light loss at the PMT entrance window. From the 1E4 p.e./GeV value we can deduce that the scintillation efficiency to be 4E-3.
  3. We discussed PMT selection, see Xiaochao's spreadsheet (focus on first sheet "HEP guide screened").
    1. Hamamatsu recommended 4 types of tubes: R1166, R8619, R11102, R3998-02. We have added R9800 to the list because it's readily available from Hall D and has very fast response. Upon screening their spec and lifetime data, we decided to use R11102 and R8619 as the starting point. Their specs are: R11102 datasheet, R8619 datasheet.
    2. We will test R11102 (bought) with R9800 (borrowed from Hall D) and study also their timing response. R8619 for Preshower is bought but no divider available; The different selection for PS/SPD vs. Shower is due to cost and timing response. Alexandre C. mentioned that we would like to have anode rise time <2ns and TTS sigma <0.5ns. The TTS sigma in spec. is for single p.e., which should be scaled by 1/sqrt(Npe) for multiple p.e.'s. So the timing constraint on Shower is nearly a non-constraint due to large Npe, while for PS (Npe=30 for MIP) and SPD (Npe=10 for MIP) the TTS sigma needs to be smaller than 0.5ns/sqrt(Npe).
  4. Summary of Preshower tile test using 1.0-mm diameter Y11 fiber, click here. The # of fiber embeding turns seems to be optimized between 5 and 6 turns, giving about 32 p.e., although 36p.e. can be achieved from 7 turns.
  5. Cost estimate update: received IHEP estimate; PMT: using R11102 for Shower and R8619 for SPD/PS;
    Item cost total
    Item breakdown

    IHEP Preshower (cost nearly tripled compared to 2013 estimate)
    ($167/module + 30% = $217/module)
    IHEP Preshower material+production
    $300k + 30% overhead
    IHEP Shower (cost increased by 50%-87% compared to 2013 estimate upper and lower values, respectively)

    ($1,270/module w/o overhead;

    2013 value w/o overhead: $620-$780/module Shower only, or $680-$845/module PS+Shower)

    IHEP Shower material+production $1,098k + 30% overhead
    IHEP Shower structure+assembly
    $990k + 30% overhead
    IHEP Shower fiber cutting_mirros
    $126k + 30% overhead
    IHEP Shower testing (not included in 2013 estimate)
    $72k + 30% overhead
    IHEP SPD $65k
    IHEP SPD material+production
    $50k + 30% overhead: $10k material, $10k machining+polishing; $30k machining grooves.
    WLS fiber


    WLS fiber Preshower (Kuraray)
    WLS fiber Shower (Bicron)
    WLS fiber SPD (Kuraray)
    clear fiber


    clear fiber FA Preshower (Kuraray) $11k
    clear fiber FA Shower (Bicron) $288k
    clear fiber FA SPD (Kuraray) $1k
    clear fiber LA Preshower (Kuraray)
    clear fiber LA Shower (Bicron)
    clear fiber LA SPD (Kuraray)
    Fiber connector etc


    Fiber connector 100-100
    Fiber connector 1-1
    Fiber tubing
    Fiber connector to PMT
    Fiber connector to MAPMT
    $80*123 (incl. 10% spare)=$10k
    PMTs with bases


    PMTs ($175 PMT plus assuming $65 base), Shower
    $240x1890 (including spare)=$454k
    PMTs ($300 for $225 PMT plus base), SPD
    $300x(300+5% spare)=$95k
    MAPMT (using $3200 PMT including base), PS
    $3200x(1800/16+5% spare)=$380k
    Shipping 50k

    Total not including HV, labor, lab material & supply: $5,513k

    PMT power supply
    HV power supply (CAEN)
    $613k for 1800 ch (including spare) + 300ch SPD+(1800/16) ch Preshower = $754k

    LV power supply for PMT base (CAEN)

    HV cable boxes $270k
    Total not including labor, lab material & supply:

    Pre R&D y1
    Pre R&D y2
    1 undergrad, 2.5 grad, 1.3 postdoc, 30% technician, 0.1 physicist, 0.1 engineer
    1 undergrad, 2.5 grad, 1.3 postdoc, 30% technician, 0.1 physicist, 0.15 engineer
    1 undergrad, 1.5 postdoc, 3 grad, 0.5 technician, 0.2 physicist, 0.25 engineer
    1 undergrad, 1.5 postdoc, 3 grad, 0.5 technician, 0.4 physicist, 0.3 engineer 1 undergrad, 1.5 postdoc, 3 grad, 0.5 technician, 0.4 physicist, 0.15 engineer
    prototyping, travel, material+supply
    $45k $45k

  6. Todo:
    1. Yi will look into Crockroft-Walton base and see if it's good enough for our use (Hall D ECAL is using a BNL design for C-W bases, we need to add preamp);
    2. Yi will get the assembled R9800 unit from Hall D;
    3. Alexandre C. will talk to Thia about getting help on PMT base design;
    4. Alexandre C. will look into low voltage power supply cost in case of C-W bases;
    5. Zhiwen will talk to Jin about calculating the radiation dose for PS/SPD for outer radius modules. Better to get the continuous radial dependence. MAPMT can still be used if a significant amount of modules have 100 times less than the most inner module used for the calculation above;
    6. We are still waiting (Jin) to see if 30 p.e. from Preshower is too low for PID;
    7. Xiaochao will update the pCDR appendix and cost estimate. Will also look into PMT base design at UVa.
  • 03/12/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Xiaochao reported:
    1. HV quote:
      1. finalized to use 3.5kV/3mA common floating boards. (1mA boards cost the same). The CAEN quotes are quote 4055(3mA multi-pin), quote 4055R1 (3mA SHV), quote 4056(1mA multi-pin) and quote 4056R1 (1mA SHV).
      2. Will investigate the cost of cables for the multi-pin vs. SHV output options. The electronics group recently made connector boxes for Hall B, see pic1, pic2. We could use the same.
    2. Working with Leoni on fiber connector order
    3. PMT study:
      1. Spreadsheet for all Hamamatsu head-on PMTs.
      2. JLab Hall D PMT base with active amplifier: about $50 each, soldered PCBs to the PMT socket in-house.
    1. Preshower Test:
      1. Updated summary of Preshower test in February-March 2014: click here;
      2. Tile output is proportional to fiber volume. Will test 1mm-dia fibers up to 8 turns.
  • 03/05/2014 Meeting to discuss EC and DAQ:

  1. Participants:
  2. Preshower Test:
    1. Summary of Preshower test in December 2013: click here;
    2. Summary of Preshower test in February 2014: click here;
    3. Xiaochao has asked Jin if 30 p.e. for Preshower is good enough.
    4. Plan:
      1. Test 0.5-mm diameter fibers, with varying turns. Goal: See if using 2-mm fibers or wider grooves (doubling the # of turn) will help with p.e. yield;
      2. Build a dark box for testing vertical shashlyk modules;
      3. Waiting for BCF92 fibers and IHEP tiles;
  3. Fiber connectors: Xiaochao emailed Leoni, no reply yet.
  4. HV quote from CAEN, for 1800 channels plus spare:
    1. 3.5kV/3mA common ground, single-width, compact (24ch), with adapters; quote 4050
    2. 3.5kV/3mA common ground, double-width, SHV connectors: quote 4054
    3. 3kV/1mA common ground, single-width, compact (32ch), with adapters: quote 4053
    4. HV comments:
      1. Current determination: Jin used radiation dose for Shower and estimated 100uA/channel if using 1E6 gain (note Zhiwen estimated 1E5 gain would be enough);
      2. If we use 1mA instead of 3mA modules, cost could be lower because of higher density (32ch/module, not 24 for 3mA);
      3. Cables for Radiall->SHV are expensive. In fact more than saving on the mainframe.
      4. Note on "common ground" vs. "floating return" boards: "CAEN recently introduced the common ground family of HV boards (notated with the prefix "AG" rather than "A").  The common ground ("AG") HV boards differ from the common floating return boards in one way.  They lack three front-panel jumpers that the common floating return boards have which allow you to ground at the detector for enhanced noise protection."
      5. Conclusion: will ask for non-compact boards, also switch to floating return boards.
  5. Xiaochao has asked Vladimir for an updated cost estimate. Is higher now that we are using hexagon and possibly deeper grooves on the PReshower tiles than LHCb.
  6. Some sketch for support design.
  7. Xiaochao will ask for the stainless steel rods that were sent to ANL, and test their magnetic properties at UVa.
  • Some misc records during Dec13-Feb14
  1. Front support structure (between PS and Shower): 
    1. Jin: 2cm is okay for PID, 4cm PID is not good anymore
    2. Will consider carbon fiber, or the more expensive but stronger Al7570 (usual Al is 6xxx, common but less strong)
  2. Jin: 2cm is okay for PID, 4cm PID is not good anymore
  • 12/04/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Jin Huang, Mehdi Meziani, Yuxiang Zhao
  2. SIDIS rate update:
    1. singles e- rate is 250kHz overall (~100kHz DIS e-, 50kHZ pi0 conversion, 50kHz others), giving 200kHz for FAEC and about another 50kHz for LAEC, and probably very little room for further reduction. Coincidence with pi-/MIP rate gives about 200kHz coincidence rate (pi- doesn't provide too much reduction). DAQ limit is 100kHz. Need factor of two;
    2. We looked at Wiser part in EICcode. It uses isospin symmetry for the neutron (Wiser code is for proton only) which JP commented that won't work too good for real photons. We also checked radiation length used.
    3. The next step is for Zhiwen to continue using the EIC code and compare with available data to see how well it works. Maybe we will find a factor of two overestimation somewhere.

  • 11/06/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Jin Huang, Mehdi Meziani, Yi Qiang, Yuxiang Zhao, Paul Souder
  2. Alexandre reported (also followup from last week):
    1. lab space at JLab is a problem, considered moving MAPMT test to W&M, but JP objected and said JLab should find some space;
  3. Jin reported
    1. Simulation for the support structure thickness has been running for a few weeks now. Will have results for 0.5, 1, 2-cm thick Al support with high background before the Friday collaboration meeting;
    2. The same simulation will produce cluster distribution, which will serve as inputs to trigger simulation of Yi/Yuxiang;
    3. Now working on SIDIS performance with realistic background and real collimators;
      1. For the writeup, the PVDIS performance use all-real baffles, blockers and background; SIDIS used "blackhole" collimators;
    4. Also working on SIDIS output for Alexandre to design DAQ/readout. Not sure if we need waveform-recording yet. (We decided to use waveform for PVDIS long time ago);
    5. For background embedding used 30ns. To be consistent with waveform-recording, should use 4ns instead. Alexandre commented that we don't need to run the 4ns simulation now since the result will be better and can serve as a safety margin.
  4. Zhiwen reported on Preshower and SPD signal estimation, see
    1. Comments: should understand why LHCb test on the MIP changed from 100 to 22 photoelectrons;
    2. For PS, need maybe 10^6 gain. SPD gain needs to be 10 times higher;
  5. Cunfeng Feng from Shandong U. sent us two files summarizing specifications of Hamamatsu MAPMTs. See Zhiwen's page above.
  6. Zhiwen made a list of equipment needed for MAPMT testing, see
  7. No reply from IHEP on our request of some SPD pads for testing; Also no reply from W. Brooks on possible collaborating on EC.
  • 10/01/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Jin Huang, Mehdi Meziani, Rakitha Beminiwattha
  2. Jianping mentioned Zhiwen should continue optimizing the background/baffle system;
  3. Jianping will be visiting Shandong Univ. from 10/24-11/?
  4. We mostly discussed things to do for the EC work. Hardware-centered work include:
    1. MAPMT: Things to test include: dark current; cross-talk; HV setting/dynamic range; gain; gain-matching.
      1. We can have parallel tests at Shandong U. and at JLab. JLab will focus more on FADC gain-matching. THere is a BigBite XY test table we can borrow;
      2. In the long term UVa could setup something too.
      3. People in charge: JLab will be Alexandre C. with W&M group.
      4. The cherenkov test is documented in arXiv:1306.6277
    2. How to embed WLS fibers in Preshower tiles?
      1. XZ will contact IHEP and see if we can have some LHCb preshowers shipped to us for testing/training. To test, we can couple a PMT directly to the scintillator first, then use the same PMT to read fiber output and compare. We can either use a source or cosmic ray;
      2. If there is no LHCb tiles readily available, we can order some. In that case, we can consider order either hexagon shape, or square shape and somehow cut it, or test the square shape directly.
      3. Jin commented that we should characterize # of photo-electrons per MIP. This can be done with cosmics. Also need to test uniformity of the readout with a source moving around the surface of the tile.
    3. How to embed WLS fibers in SPD? - same as above.
    4. Genearl fiber testing:  need to meausure a) fiber light loss; b) radiation hardness;
       the following writeup might be helpful:
  5. Simulation-centered work for FAEC:
    1. Effect of the support structure on PID?
      1. Jin previously did only 2-cm support for SIDIS with low statistics. Once add both p0 and p1 term, it's not clear if the PID really degraded at a significant level (see 09/04/2013 slides from Jin)
      2. The plan is Jin will do simulation with PVDIS setting with a 2-cm support.
      3. If there is time left, Jin will run SIDIS 2cm with high statistics.
      4. More simulation such as for 1-cm is desirable, which Jin can proceed to do. Thinner values won't be realistic based on how much weight it has to support.
    2. Position of MRPC vs. SPD? SPD segmentation, performance and supporting structure?
      1. Jin's simulation on SPD was without cherenkov mirrors in the front. Further simulation should include:
      2. MRPC in front of SPD, photon rejection performance;
      3. SPD in front of MRPC, include C mirrors in the simulation, photon rejection performance and MRPC timing resolution.
      4. Jianping commented that we can leave these to Haiyan/Zhihong.
    3. PS design: segmentation (or fiber-grouping) and performance for SIDIS situation. Again can leave to Haiyan/Zhihong;
  6. Simulation-centered work for LAEC:
    1. How to maximize coverage, both at the small and the large angle side?
      • need Paul R.'s layout for LAEC before continuing
    2. supporting structure design
      • we mostly need Paul R.'s inputs here;
  7. General/Other:
    1.  fiber connection and routing; - some testing can be combined with fiber testing above.
    2.  cable routing;
    3.  switch-over between PVDIS and SIDIS;
  • 09/19/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Jin Huang, Paul Souder, Rakitha Beminiwattha
  2. Jin's slides
    1. Now using background with photon blocks.
    2. page 5, comparison of last time (More1) and new (More1+block). However, the left seems to be the kryptonic baffle and the right is the lead baffle, so not the correct comparison here.
    3. page 11: background rate simulation for 30ns windows, probability is 9/60k = 1.5E-4 for this particular radius;
    4. next page: total background rate. Roughly, we take the probability, divide it by 30ns to give the bg rate per block, then multiply by # of modules to get the total background rate per sector (or per EC). Total rate is about 0.1MHz.
  3. We will try to finish up the writeup by Thursday night;
  4. We should start discussing all tests that need to be done on the EC. An initial list is as follows:
    1. MAPMT -- gain? cross talk? HV setting? dynamic range?  For testing purposes we can borrow one. Haiyan now has one and Zein-Eddine has two;
    2. Preshower fiber routing -- how to rout it within the scintillator? What is a realistic bending radius for routing the fiber out to the wall of the Solenoid?
    3. SPD fiber routing, similar to Preshower one;
    4. fiber testing: performance/light loss, radiation hardness?
    5. WLS-> clear fiber connector: light loss?
  • 09/11/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Jin Huang, Paul Souder
  2. Jin's slides:
    1. as discussed last week, Jin has done PID and trigger simulations with the new "More1" background and the lead baffles. The new photon blocks (see below) are not included.
    2. page 12 vs page 16: off-line PID performance for kryptonic (page 12) vs. lead (page 16) baffles. The pion rejection at low p changed from ~14:1 on p12 to ~(9-10):1 on p16. A few previous pages show similar comparison of the two baffles.
    3. page 17-18: new trigger turn-on curves for low and high-radiation phi slices (ignore "4th update as reference" on page 18, these two pages are both for the "5th update-More1 background").
    4. page 19: trigger rate calculation strategy. The idea is that the trigger turn-on curve method (right) is good for single particles, but do not take into account high-rate pileups. The background embedding method (left) is good for high rate background pileup, but not for DIS electrons. As indicated at the bottom, the best method is to use bg-embedding for p<1GeV, and trigger turn-on curves for p>1GeV (where pileup is small).
  3. Zhiwen's slides
    1. tried adding lead blocks to block photon slices. Each block starts from 2.2 deg in phi of each sector and with a width of 2.5 deg. Used the current trigger turn-on curve from Jin (no photon blocks) in these slides;
    2. page 6 vs. 7: photon and pi0 background is reduced significantly.
    3. page 14 vs. 15: trigger rate for without (p14) and with (p15) photon blocks. 
    4. page  9: without photon blocks, the trigger rate of EC coin with CC is about the same size as the DAQ limit (and leave no room for error). With photon blocks, the trigger rate of EC coin with CC is about half of the DAQ limit. 
    5. Paul S. pointed out the old trigger turn-on curves are used here. With the photon blocks the curves will be lower, which will further reduce the trigger rate.
  4. Plan:
    1. Jin will add photon blocks and update the trigger turn-on curve;
    2. Zhiwen will use the new turn-on curve in his rate calculation and get a consistent version of trigger rates and backgrounds;
    3. Zhiwen will look at DIS electron rates and dA/A with the "More1 + photon block" background;
    4. We also need inputs from Paul R. on the support structure (see last week's minutes);
    5. Then we should be able to finalize a "working version" for the writeup;

  • 09/04/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Mike Paolone, Jin Huang, Paul Reimer, Paul Souder,
  2. Recap of meeting yesterday, Zhiwen's talk.
    1. page 12: went back to BaBa baffle with modification ("More1"), reduced most background by almost one order of magnitude (see comparison of middle and right columns). Top half of the table are new background rates before the EC and bottom half are EC trigger rates with the old trigger turn-on curve. We need to redo all PID and trigger-turn-on simulations with this background. Photons: can be treated as electrons, but mostly blocked by preshower lead; protons: not a problem since the rate is so low.
    2. The bottom table is the input to the DAQ section.
    3. Once we have the new trigger turn-on curve from Jin, Zhiwen will redo the bottom table.
  3. Jin's simulation with the 2-cm Al plate support between Preshower and Shower:
    1. page 2: Now using 2-cm Al plate between Preshower and Shower, and a 4-cm Al plate after Shower.
    2. page 3: change in energy resolution is 4.5%/sqrt(E) -> 5.1%/sqrt(E);
    3. page 4: adjust cuts to get the same electron efficiency (right) as before, look at how much pion rej changes (left). The change is about 20% worse at the low momentum range;
    4. Trigger turn-on curve won't change much because triggering is based on cutting the shower energy, although a slight broadening is also expected. So lowering the threshold a little will compenstate for the effect of the Al plate and we do not expect too much change in the trigger turn-on curve.
    5. Both Pauls commented that the support structure should not worsen the performance this much. Paul R. will ask ANL engineers to see if 0.5-cm or 1-cm Al support will be sufficient.
  4. Todo:
    1. Jin will do simulation of performance with the new background;
    2. For the writeup, will also include the two figures (e rate, pi/e ratio) from last week's Zhiwen's report, also the background rate table from Zhiwen's slide #12 (see above).
    3. Need support section for the writeup.
    4. SPD: we changed SPD to before MRPC sometime this past summer. It turns out this may not be acceptable because it will worsen the MRPC timing resolution. For the writeup we will keep it at the current configuration, but need to 1) place SPD after MRPC and immediately before Preshower and simulate its photon rejection; or 2) keep SPD before MRPC but simulate MRPC timing resolutions. The MRPC performance so far are based on simple estimation, not full simulations.
  • 08/28/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Mehdi Meziani, Jin Huang, Paul Reimer, Paul Souder, Todd Averett, Joe Kaditch
  2. Recap of meeting with GEP-V (for record, not discussed at today's meeting):
    1. Deadline for SoLID writeup: freeze for editing by Sept. 7/8, then one week for editing. Hoping to review in 2 months
    2. (JP) Only after SoLID CD0 will it be an important part of the GEP5 EC MRI;
    3. GEP5: ~2018; need about 400 hexagon bars, but no Preshower.
    4. Will touch base one month before the MRI deadline (Jan 2014);
  3. Recap of the Aug collaboration meeting (since Xiaochao missed it): EC trigger pion rate is 100 MHz (whole EC) or 3MHz per sector. CC trigger rate is 5MHz (see Aug collab CC talk). This leads to 3MHz*5MHz*20ns=300kHz of random coincidences, that is one order of magnitude higher than what the DAQ can handle (total DAQ trigger rate 60kHz/sector minus useful electron rate).
    1. for EC pion rate see slide 3 of ZW's talk;
    2. for pi/e ratio vs. theta and E' see slide 15 of ZW's talk;
    3. Compare to the 100:1 pi/e ratio for E'~2GeV, now we are dealing with about 1000:1 ratio at E'~1GeV. These low-E pions do pass baffles and trigger EC.
  4. Alexandre presented a few things that might help reducing the background rate:
    1. Can study the energy ratio of 3-block over 6+1 block clusters to see if that ratio can be used to reject pions;
    2. more segmentation of shower modules (using half-length WLS fibers);
  5. We discussed support system for the EC:
    1. (PR) currently we use a 2-cm thick aluminum plate before Preshower and a 4-cm thick Al plate after the Shower to support EC;
    2. If we separate Preshower and Shower modules, must add a 2-cm thick Al plate between Preshower and Shower;
    3. We ask Jin to simulate how the 2-cm plate between PS and Shower affect PID, but the feeling (of JP and PR) is it should not affect PID much. Jin will do this simulation after he comes back to the US this Friday;
    4. Collaboration with GEP5 also requires making separate PS and Shower modules.
  6. We also discussed Preshower segmentation.
    1. To faciliate design, manufacturing, the supporting system, and to ensure easy swapping between PVDIS and SIDIS, we should still use hexagon modules for Preshowers. (JP questioned whether we should use bigger PS modules but the answer is no);
    2. Jin suggested grouping fibers from outer ring of PReshower to save on readout cost (this was suggested earlier, thanks for reminding us today!). Between PVDIS and SIDIS we can change these fiber groupings;
    3. SPD is there for both LAEC and FAEC for SIDIS.
  7. Plan:
    1. We need a "brand-new" baffle!
    2. Finish writeup!
  • 08/13/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Yuxiang Zhao, Jin Huang, Paul Reimer, Paul Souder
  2. Jin will try to get the writeup this week (simulation part), Paul R. volunteered for the support section, Xiaochao will update the design and the cost; JP said the deadline is "now".
  3. For next week's collaboration meeting, Zhiwen will give the talk on EC and background. JP said there will probably be lot of discussions on the EC, background and DAQ.
  4. Zhiwen's udpate on background: slides;
    1. page 2: left: old, with a tungstun absorber (black); right: removed the absorber and enlarged beam pipe;
    2. page 3: with the old configuration, 4-cm radius beam pipe, showing position/vertex of photon events that hit the EC;
      1. top: radius vs. z; bottom: projection to z;
      2. In the z-projection can clearly see the target windows (thin spikes at -10 and +30), the peak at +40cm is the first baffle (but JP said it could also be the beampipe window). At -15cm there is an additional spike from the scattering chamber window that should be removed;
    3. page 4: new configuration, 4-cm radius beam pipe; too low statistics, but don't seem to make a big difference.
    4. page 5: new config, 6-cm radius beam pipe;
    5. when doing the above changes, ZW not only "cut away" the baffle material but also optimized the following baffles.
    6. page 6: comparison in photon flux, vs. z, among different configurations. Main conclusion:
      1. from 2cm to 4cm beam pipe there is a big improvement;
      2. from 4cm to 5 or 6cm beam pipe the improvement is less but still significant.
      3. between settings also enlarged EC acceptance to smaller radius to "see what's there". That's why the yellow/blue/green extend to smaller radius.
    7. JP commented this is what Rich found: the majority of the photon background comes from the 1st baffle, so reducing the baffle (and make the beamline bigger) helps the most.
    8. JP suggested ZW to do one change at a time, so we know which change causes more/less problems.
    9. ZW will look into how these changes affect DIS electron rates.
  5. Mike talked about CC results, using 5cm for 1st baffle radius and took out the tungstun absorber, trigger rate is 5MHz per sector. (JP said this is in good shape b/c the DAQ can handle this rate).
  6. Jin reported on the EC response to the new background.
    1. 6+1 cluster cut is 2.1 and 1.6 GeV for shower, which correspond to 2.5 and 2.0 GeV trigger turn-on threshold shown here.
    2. The figure shows we should use R-dependent threshold. At 190cm (middle of EC) should use 2.5 GeV, for example.
    3. ZW commented that he looked at DIS electrons, reported in the May collab meeting. Using R-dependent thresholds increase the Asym error on the low x corner but not middle or large x.
  • 08/06/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Mehdi Meziani, Yuxiang Zhao, Jin Huang, Paul Reimer, Michael Paolone, Paul Souder
  2. JP mentioned we got an invitation to MENU to talk about SoLID. MENU will be held in Rome, Italy this year, in late September.
  3. Paul Reimer has a complete CAD drawing for the EC support.
  4. JP said Mott wrote to CLEO about the magnet and CLEO replied favorably (so that part is done) (it's a good news);
  5. Zhiwen;
  6. Paul Reimer has a complete CAD drawing for the EC support.
  • 07/30/2013 Meeting to discuss EC and DAQ:

  1. Participants: Xiaochao Zheng, Zhiwen Zhao, Alexandre Camsonne, Mehdi Meziani, Yuxiang Zhao, Jin Huang, Paul Souder
  2. not much updates today.
  • 07/23/2013 Meeting to discuss EC and DAQ:

  1. Participants: Xiaochao Zheng, Rakitha B., Zhiwen Zhao, Alexandre Camsonne, Mehdi Meziani, Bob Michaels, Yuxiang Zhao, Jin Huang, Paul Reimer, Bob Michaels, Todd Averett, Paul Souder
  2. Alexandre C. reported on the DAQ test stand: PDF slides;
    1. input signals will be random pulsers; slide 7 additional hardware is for SIDIS trigger only.
  3. Zhiwen: clear fiber cutting tool pictures.
  4. Jin: PID with new background completed. Will wait for final background to do sophisticated fitting of PID as functions of phi, momentum and angle.
  • 07/16/2013 Meeting to discuss EC and DAQ:

  1. Participants: Xiaochao Zheng, Rakitha B., Zhiwen Zhao, Paul Souder, Alexandre Camsonne, Mehdi Meziani, Bob Michaels, Yuxiang Zhao, Jin Huang, 

  2. Summary of the past 6 weeks:
    1. Background (Jin&Zhiwen): starting from the baffles of 5/23 meeting, Zhiwen increased the inner radius of the first baffle, as a result the chance of the background triggering blocks is reduced by 20-30%, will continue to the effect on trigger rates and PID.
    2. DAQ (Alex C.): checked with electronics group, can probably read out only the cluster signals and not all blocks, which means we CAN run 60kHz/segment (60kHz was the goal we tried to fit the PID into, see slide #23 from 5/23 report), but still need to work on L3 triggers to reduce data size.
    3. CC with background: Mike is waiting for Maurizio's coding of optical process.
    4. MAPMT: next step was bench-testing, no progress so far; Alex C. will write a test plan with required equipment ***
    5. PMT: cost update? customized bases? smaller PMTs? - no update.
  3. Paul S. summarized what Rich found for the background:
    1. one source is the beam pipe being too narrow and that could be optimized.
    2. for the high-E photons, to study the effect need to know how many convert to electrons, which depends on knowing all material/thickness on the photon passage. One question is the exact material/thickness of Cherenkov mirrors. The values from the last writeup may not be final.
    3. need to shield the high-phi stripes, 2-cm tungstun? (PVDIS only)
  4. Zhiwen updated on the available space for EC (slides): heavy gas Cherenkov asked for 10 cm, so EC modules need to be moved back by 10cm, causing 10cm less for the readout. Currently EC has 80cm room and a rough study of the readout space tell us it's possible to reduce it to 70cm (slide 3). Another option, which may be pursued when further room is needed, is to elongate the yoke. Slide 4 shows the effect of the field change (difference between current and the elongated yoke version) for "20cm longer yoke". Only positive values are drawn. The difference is <100G within the endcap, compared to the nominal 100-1000G in the detector region. Effect on detectors needs to be studied, but probably the most prominent for CC and not for EC or GEM.
  5. Xiaochao on IHEP reply on 2013/6/2:
    1. they can make the SPD, rough cost estimate between $40k and $70k for both LA and FA of SIDIS.
    2. they propose to order fibers in spools and need 10-15% spare fibers.
    3. cutting, polishing and production of mirrors on fiber was $0.5/piece 3 years ago and now may have gone up by 20-30%, and not more.
  6. Plan:
    1. beampipe: Zhiwen will look into optimizing it and will work with Rich;
    2. Rakitha is looking into pion backgrounds and may have something to report soon;
    3. Tungstun shielding for high background phi-slices: start from simulation work, then support and space. Can wait for next week to ask Jin to start.
    4. Design MAPMT test -- Alex. C;
    5. clear fiber cutting: figure out how much time is needed to cut all our fibers;
    6. others: detailed fiber-wiring scheme for SPD?
  • 05/21/2013 Meeting to discuss EC and DAQ:

  1. Participants: Zhiwen Zhao, Xiaochao Zheng, Paul Souder, Alexandre Camsonne, Mehdi Meziani, Rakitha B., Bob Michaels,

  2. Zhiwen had sent new background to Jin, see Jin's slides:
    1. page 3: new background is called "3rd update CLEO background";
    2. page 4: For radiation dose, high phi slide, the dose changed from 30krad/month (top of this page or see 4/30 report) to about 40krad, so changes are not significant.
    3. pages 5-7: Other updates on EC.
    4. Update on PID performance is still on-going.
  3. Zhiwen reported on the baffles, see his slides.
    1. page 3: The previous discrepancy from Seamus' version was solved. Other changes include using precise calculation for Apv (not just ~80ppm*Q2) -> see numbers on top of this page. In general error bars are smaller in Zhiwen's version. These are still for "large Z" baffles which means interfering with detectors;
    2. page 4: comparison of "small Z" Zhiwen and "large Z" Zhiwen baffles. "Small Z" version no longer interfere with detectors. Rates are similar.
  • 05/14/2013 Meeting to discuss EC and DAQ:

  1. Participants: Jianping Chen, Zhiwen Zhao, Xiaochao Zheng, Paul Souder, Alexandre Camsonne, Mehdi Meziani, Robert Michaels, Wouter Deconinck, YuXiang Zhao, Yi Qiang.

  2. Zhiwen talked briefly on the baffles: There is a small discrepancy between Zhiwen's and Seamus' baffle DIS rates, due to using different luminosities. Will track down the problem. Other than this, ZW's baffles seems to have 50% higher pi+ and similar photon rates;
  3. Wouter talked briefly on the MAPMT. It's clear that we should do complete FADC-based triggering and waveform recording, rather than forming digital triggers in front-end electronics;
  4. YuXiang presented a plan for trigger simulation, see his slides. We questioned what the goals are for the trigger simulation?  Bob commented that for 6 GeV PVDIS we did have a simple trigger simulation before running, although later it was replaced by a more sophisticated full-scale trigger simulation;
  5. Alexandre talked about DAQ, see his slides.
  6. We also talked about calibration of EC channels. This will require embedding LEDs in both PS and Shower. Questions include radiation damage to the LEDs, and how to embed LEDs for the Shower since the front side of the Shower fibers have integrated mirrors.  An option is to have LEDs in front of the PMTs only.
  7. Just to clarify on the triggers:
    1. EC trigger for electrons can be cut at 1.6 GeV for 6+1 cluster sum, and for pions can be at 400MeV for 6+1 cluster sum;
    2. electron triggers would be formed by the AND of EC (>1.6 GeV) and CC.
    3. pion triggers would be formed by the AND of EC (>400MeV) and .not.CC.  For p>4 GeV this reduces to EC only but it's okay, since pion events can be selected offline by waveform+tracking/momentum analysis.
  • 05/07/2013 Meeting to discuss EC design:

  1. Participants: Jianping Chen, Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Richard Holmes, Alexandre Camsonne, Mehdi Meziani, Paul Reimer, Robert Michaels(?)

  2. Jin reported on the simulations: talk,
    1. page 4: tried removing DC component in the background (caused by the purple photon spectrum)
    2. page 4-5: PID update with DC component removed. Not much change in the results (?).
    3. page 6: trigger simulation w/o background, comparison of Shower (6+1 cluster cut only, requiring >1.6GeV as before) and that with Preshower cut added (only cutting on the central block of the 6+1 cluster, requiring it to be >1 MIP+1 sigma):
      SH 6+1 > 1.6GeV
      (left panel of page 6)
      SH 6+1>1.6 GeV and PS central block > 1 MIP+1 sigma
      (right panel of page 6)
      pion eff
      pion rej (=1/eff)
      electron efficiency

      1. Comment from JP: why only cutting on the central block? - Alexandre: CTP can easily implement either single-block or sum-of-cluster cut.
      2. Comment #2: electron efficiency too low (already)?
    4. page 7: trigger simulation with background, same SH+PS cut as page 6:

      mid R, high gamma phi band
      pion eff
      pion rej (=1/eff)
      electron eff
      inner R, high gamma phi band
      pion eff
      pion rej (=1/eff)
      electron eff
      1. Comments #1 from Jianping: Should increase electron efficiency. But this will require some momentum-dependent cut and A.C. commented that this is not possible at level-1 trigger.
      2. Comments #2/general discussion/decision: Level 1 trigger probably should only have Shower from EC, to keep electron efficiency >99%
        1. below 4 GeV, can have CC only in the L1 trigger. CC probably provides good PID here.
        2. above 4 GeV (which is the threshold of CC for PVDIS), CC will stop working and can have EC Shower only in the L1 trigger. 3:1 pion rejection is probably OK.
    5. page 8: studied possible pion triggers by a low EC cut at 0.75 MIP, total rate is close to 2MHz (too high for making a trigger!)
      1. JP: for PVDIS no separate pion trigger is necessary in EC. Can use EC (Shower only) trigger, then add CC to get electron trigger and require .not.CC and apply a prescale to get the pion samples.
      2. Doesn't this mean below 4GeV we still need the Shower in the trigger?
    6. page 9: Estimate of effect of light loss on PID: Assuming 50% loss, effect is minimal as long as we calibrate the photon yield online. -- GOOD!
  3. Alexandre C. reported on DAQ, see his talk:
    1. page 6: propose a method to use accidentals to make pion triggers, just try to look for them in a 80ns window using FADC waveform analysis.
    2. page 7: Estimate of data rate using 20 samples (80ns). Note there is a typo: Both Shower ("Calorimeter") and Preshower should have 7 channels for 7 blocks, not 6.  The data rate is now comparable to GEM (see page 8);
    3. JP commented that we don't need 80~ns (too much data to transfer), and we don't need to use accidentals to make pion triggers -> 30% less data rate?
    4. page 8: GEM data rate estimate;
    5. page 9-11: A quick estimate of the tape cost. Propose that we need a reduction of 30 in data to keep the tape cost at the level of $2M. Possible ways of reduction: a) extract amplitude and time from waveform: factor of 13(52ns)->2, or factor of 5; b) safty margin can use 2 not 4 as on slide.
      1. JP commented that we don't need to worry about the tape cost now, it should be part of the JLab operation budget, not part of SoLID.
  4. Other updates: Alexandre C. is considering the IHEP workshop, to be held from 6/22 to 6/23.
  5. Discussions on how close we are to the final design: 
    1. The biggest problem is the baffle. So far, the baffle used in the background simulation is Seamus' version, which does NOT fit into SoLID. To fit it into SoLID in GEANT Zhiwen had to cut the iron return and other stuff as well. This is not physically possible. So the highest priority now is to adjust baffles to make it (1) fit into SoLID without cutting other detectors or the iron; and (2) Keep the electron acceptance as close to Seamus' version as possible. Whatever that means for the low-E background we just need to deal with it (example: factor of 2 worse in background -> slight degrade in PID, etc..)
    2. Still need to combine all rates and pion rej from CC and EC.

  • 04/30/2013 Meeting to discuss EC design:

  1. Participants: Jianping Chen, Zhiwen Zhao, Wouter Deconinck, Jin Huang, Xiaochao Zheng, Paul Souder, Alexandre Camsonne

  2. Jin reported on the simulations: talk,
    1. Still using PVDIS background with Seamus' baffle and CLEO magnet.
    2. page 4: update on the radiation dose including some phi-dependence.
      1. Top: using Babar magnet, Bottom: Using CLEO magnet. 1st layer is Preshower. Based on the phi dependence of Zhiwen's background simulation (see this plot), within each sector of 12 deg, can divide into 2 regions of 6 deg each.
      2. Left bottom plot shows the higher radiation phi region, and right bottom shows the lower radiation phi region. They show doses of ~30krad and ~20krad/month respectively. Within the approved 120 PAC days of PVDIS, this will put the total dose to 120krad and 80krad respectively. This is close to the 100krad tested for the two fiber brands, which will cause 10% and 15% of light loss respectively for Kuraray and Saint Gobain.
      3. If including some safety factor it will easily exceed 100krad. For example, the two fibers were tested at 700krad which showed respectively 30% and 50% of light loss.
      4. Jin commented that light loss is not a problem for Shower, but will likely be fore Preshower.
    3. page 5: PVDIS PID now including pi+ and photon backgrounds. Bottom plots: blue = DIS electrons; red = DIS pions; others = backgrounds.
    4. page 6 through 8: calculations of PID at mid -radius (1.9 m) for the high radiation phi 6 deg slice, while the results of last meeting was at the smallest R (worse PID).
      1. page 6: PID with only pi- background, no pi+ and no photon;
      2. page 7: PID with pi+ but no photon: degradation isn't too bad, maybe a factor of 2 worse at low momentum.
      3. page 8: PID with photons and pi+: shows large deterioration in PID. Now pion rej varies from ~10:1 at 2.5 GeV/c, to ~50:1 at 5.5 GeV/c, to ~100:1 at 7 GeV/c.
    5. page 9: same condition as page 8, but now look at smaller R (1.2-1.4m) and larger R (2.4-2.6m), and high and low phi radiation slices separately. The biggest difference is in the low momentum (2.5 GeV/c), which is now about 7:1 for smaller R and high phi dose slice.
  3. We discussed on the above PID simulation affect the whole EC design:
    1. Using the pi/e ratio on page 29 of last collaboration meeting's CC talk, the low theta/low momentum region - 20 deg, 2GeV/c - has pi/e as high as 200:1. Pion rej from CC is about 1000:1 in this range (see previous slide of the same talk), and EC now shows 10:1 rej. So overall the pion contamination on electron samples, even in the offline analysis, will be 2%. Adding background to CC PID simulation will only make things worse.
    2. Can we live with 2% pion contaminations?  If the SoLID is already built then the answer is we can, but now we should try everything to improve PID.
    3. Main conclusion 1: Using 6+1 cluster sum alone isn't enough. One must store all waveforms on tape. Waveform analysis off-line will potentially improve PID by a factor of 10 (estimated using 4ns vs. 50ns timing);
    4. Main conclusion 2: We must have a sophisticated pion trigger and pion sample analysis. If the contamination is 5%, then we must measure pion asymmetry to 1% level in order to control the systematic uncertainty to below 0.05% (1/10 of the statistical error). This means pion samples can be as high as 1/4 of the electron samples. Perhaps we should aim for equal amount of pion and electron events, for offline analysis.
  4. Zhiwen also commented that the soft photon rate (as seen in this plot) might be too high for GEM layer 1 as well. Paul S. commented that he has Rich H. looking at the photons, in order to understand where they come from and how to stop them (if possible).  All baffle plots can be found at
  5. To do list:
    1. Zhiwen will continue optimizing the baffles, focusing on reducing the photons. However, must pay attention to not reduce e- rates;
    2. Jin will do simple simulation of how 10%, 15%, 30%, and 50% light loss will affect Preshower PID. These % are chosen to reflect the light loss of Kuraray@100krad, S.G.@100krad, Kuraray@700krad and S.G.@700krad.
    3. Jin will continue to trigger simulation, now including all backgrounds.
    4. Alexandre will work on DAQ, to accomodate the recording of all waveforms. This will likely double the DAQ cost and add $1M.
    5. Jin will work with Alexandre on designing the pion triggers. Similar PID analysis/simulation as for electrons must be done for pions as well. (For example, a large electron contamination in pion triggers will significantly increase the error on the measured pion asymmetry).
    6. Jin will think about additional EC methods to improve PID.
    7. Xiaochao received pi/e ratio table and CC performance table from M.P., will try to work on the files. Also will need to make sure CC simulations include backgrounds as well.
  • 04/23/2013 Meeting to discuss EC design:

  1. Participants: Todd Averett, Wouter Deconinck, Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Mehdi Meziani, Paul Souder, Alexandre Camsonne

  2. Jin reported on the simulations: talk,
    1. Now using PVDIS background with Seamus' baffle and CLEO magnet.
    2. How pileup is treated: If a background signal comes in within the 50ns window, its whole amplitude is added to the signal.
    3. slide 2-5: PVDIS background and offline pion rejection. Only e- and pi- background used. Electron efficiency is 94% or above and pion rej is 30:1 at 2 GeV to 100:1 at higher momentum.
    4. slide 6: trigger simulation using Shower alone. Cut on 6+1 cluster > 1.6 GeV (correponds to 2 GeV electrons). Electron eff is 99%+ (not drawn), pion rej is 10:1 at 2 GeV to 2:1 for 5-7 GeV. But low momentum pions dominate the background.
    5. slides 7-8: review of radiation dose for EC. Sc and fiber are both plastic so doses are similar: about 10krad/month. Times this by 1 PAC year gives 100krad. Compare to dose tolerance:
      1. Scintillator varies from 100krad to 1Mrad (Jin email 4/22/13), but need to consider if they all match the WLS fiber spectrum etc.
      2. WLS fiber dose is more of a problem: Kuraray shows 10% loss in light output at 100krad, Saint Gobain is 15% loss at 100krad. Preshower will have this level of light loss after 1 PAC year of running (Paul said we are not approved for that long anyway).
    6. Todo for Jin & Zhiwen:
      1. double check why pi+ background is twice that of pi- using baffles;
      2. Should include photons and pi+ in the PID analysis for both trigger and offline levels;
      3. For radiation dose should consider phi-variations and see how bad the dose is where the photons hit the most. (probably both phi- and R-variations should be included). How many modules are in these high-photon strips? If it's bad, how to avoid it?
        1. Adding lead strips?
        2. Route WLS fibers to get around it?
        3. Make more PS modules to make it easily replacable? - probably the best method.
      4. Shower alone is not enough for PID at the trigger level. Should include Preshower in the trigger. Algorithm can be the same as for Shower.
      5. Should come up with a functional form (or tables) for theta and momentum dependence of pi rej, for both trigger and offline levels;
  3. Discussion on triggers
    1. Alexandre showed some slides on the basic PVDIS trigger idea and we discussed the following:
    2. Trigger rate limit is about 60kHz/sector (total 30 sectors). This limit does not depend on how many detectors are in the trigger;
    3. Our expected DIS electron rate is 4-8kHz/sector, which leaves up to 50kHz for other stuff. Since pi/e ratio is as high as 80-100, the pion rejection must be >20:1. Also need to leave some room for pion trigger itself (assuming same rate as DIS electron which is probably an overkill).
    4. Trigger algorithm for Shower: Currently a threshold is set for each module. Once a module exceeds the threshold, an integration is done for a 48 or 52ns (must be multiples of 4ns the FADC sampling time). FADCs are 12-bit. The resulting integrations, probably 18-bits,  are:
      1. chopped to 13 bits and are sent along with 3-bit timing information to CTP (Crate Trigger Processor) to form triggers. Summing of 6+1 clusters are done at CTP. An 8-ns coincidence is required for summing.
      2. saved to tape, along with timing info, for offline analysis.
    5. Same trigger mechanism can be done for the Preshower. And similar trigger mechanism can be done for the CC. These 3 can be combined in the CTP in coincidence to form triggers.
    6. CC trigger requirement: >98-99% electron efficiency, study what pi rej would be.
  4. Discussions on MAPMT
    1.  following the trigger discussion we talked about MAPMT algorithm.
      1. For SPD, similar method as LHCb can be used for out trigger: use different thresholds for each channel and no gain correction is applied. The FE electronics produce digitial triggers only. We could use the same: just put a threshold on each of our SPD sectors.
      2. Jin commented that for SPD we need to have the FADC data on tape.
      3. Our SPD contains 30 sectors for SIDIS LAEC and 120 (60 in phi and 2 in R) sectors for FAEC.
      4. For Preshower, LHCb used FE electronics to do a) analog gain-matching; and b) analog pileup corrections using DAC. LHCb explicitly stated that gain-matching is too slow for them at the trigger level. Alexandre mentioned gain correction can be done in the CTP, but not sure about the speed.
    2. To do:
      1. Xiaochao will make a short list of our trigger requirement on the MAPMT and send it to Todd.
      2. Alex will look into whether gain matching using CTP is fast enough.
  5. Other to-do's:
    1. Put together (p,theta) tables for: electron rate, pion rate, pi/e ratio, CC pi rej (both trigger and offline), EC pi rej (both trigger and offline).
    2. Start thinking about pion triggers. Jin suggested that a single Shower threshold on the MIP will do, CC and Preshower can be added at the offline level. Details?
  • 04/16/2013 Meeting to discuss EC design:

  1. Participants: Jianping Chen, Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Mehdi Meziani, Paul Souder

  2. Jin mentioned SBB will use MAPMT for readout, as for the front-end electronics only Bogdan knows the details;
  3. Jin reported on the simulations: talk
    1. SIDIS LAEC offline PID and trigger simulations are both done. PID looks good: pion rejection with background is worse than w/o, but is still at the 100:1 level;
    2. Also did SIDIS photon rejection using SPD: 45 segments will provide 10:1 rejection. Jianping commented that 30 segments with 8:1 rejection will probably be good enough, and the 30 segments can match that of GEM and other detectors.
    3. PVDIS offline-level PID is done using the old Babar baffle design and ignoring both photon and pi+ backgrounds. Pion rejection is at the level of 30:1.  It is questionable whether this meets the physics requirement. Trigger simulation hasn't been done yet.
  4. Quote updates:
    1. Fiber with diamond-tool-finishing: Saint-Gobain; DTF is about $1.1-$1.3 per piece;
    2. Kuraray fiber quote, they do not provide diamond-cut or polishing at this large quantity. Shipping cost (see Zhiwen's email on 9/19/2013) is
      1. To U.S. JPY 1,150,000- ($11545 based on today's currency exchange rate)
      2. To Russia JPY 1,300,000- ($13050 based on today's currency exchange rate)
    3. PMTs:
  5. Todo:
    1. Jin will continue PVDIS trigger simulation using the old Babar baffle design;
    2. Jin will provide more information on the PVDIS offline pion rejection. More specifically: A plot/matrix of pion rej factor vs. momentum and theta, like page 29 of last collaboration meeting's CC talk.  It will be even nicer if the same binning can be used.
    3. Upon receiving the above result from Jin, Xiaochao will put together the CC and the EC rejections and see if it meets the physics requirement of PVDIS that pion contamination should be <=1E-3;
    4. Someone will need to discuss with Bogdan on the status of the MAPMT electronics - Jin? Maybe Todd?
    5. Zhiwen will continue with the baffle design, but focusing on
      1. making the negative particle's acceptance correct and make sure the final electron statistics meet the PVDIS proposal goal (Fig. 2.6 on page 20 of the PVDIS 2009 proposal), or at least a comparison of the statistics to Seamus' last results. Care must be taken to use exactly the same Q2/x binning for these comparisons. Paul S.  mentioned at most 10% reduction in statistics can be tolerated.
      2. If keeping high electron acceptance means some photons or pi+ will be accepted, we will have to deal with it through PID.
    6. Paul S. will look into the PVDIS requirement on the trigger PID. The max trigger rate was provided in the DAQ talk of March 22 meeting.
  • 04/09/2013 Meeting to discuss EC design:

  1. Participants: Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Paul Reimer,  Mehdi Meziani, Paul Souder, Todd Averett, Wouter Deconinck

  2. Todd and Wouter presented a writeup on the Multi-anode PMT study. This is a possible route but clearly there is significant electronics work involved;
  3. Photon-rejecting Scintillator Pad (PRSP) segmentation: it will cover from 85cm to 240cm (Zhiwen) and the equal-rate segmentation should be at 127cm (Jin). Xiaochao sent this to IHEP and asked for a quote for the PRSP (go to IHEP 2013/04/06 directory).
  4. Zhiwen worked more on the baffle design and is hoping to get a working version in two days from now;  Then he will send the background to Jin for PVDIS PID and trigger simulation.
  5. Xiaochao emailed IHEP again to question on: a) if IHEP would like to have full spools of fibers shipped to them or have the fibers cut by the fiber company; b) If they can do 100-100 fiber connectors; c) if IHEP also like to have clear fibers shipped to them; d) cost of mirrors. (go to IHEP 2013/04/09 directory).
  6. Zhiwen is still working on PMT quotes;
  7. Update on fiber quotes: KURARAY; Saint Gobain.
  • 04/02/2013 Meeting to discuss EC design:

  1. Participants: Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Paul Reimer,  Mehdi Meziani

  2. Paul updated that he recieved the stainless steel rods from CERN/IHEP and will test their magnetic properties.
  3. Jin will send the Scintillator segmentation to Xiaochao this afternoon (see last week's meeting);
  4. Zhiwen reported briefly on the baffle design (click here for his report for this afternoon). The current design has multiple problems in addition to direct line of sight for photons. Tried straight-slit design, neutral acceptance is low but positive acceptance is high.
  5. Jin will continue with SIDIS LAEC simulation. For PVDIS simulation will try both: a) old baffle with direct photons removed; and b) straight baffles that have positive charged particles.
  6. Zhiwen received new quotes from Kuraray on the fibers, now with PS fibers quantity updated.
  7. Zhiwen is working on the PMT quotes;
  8. Wouter and Todd aren't be able to call in today and will report next week.
  9. Xiaochao will summarize to Will Brooks and have 1-2 COMPASS module shipped to ANL, for the engineers there to study its structure and to design the EC support.

  • 03/26/2013 Meeting to discuss EC design:

  1. Participants: Jianping Chen, Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Paul Reimer,  Mehdi Meziani, Todd Averett

  2. The EC talk at last week's SoLID collaboration meeting can be found here.
  3. We have identified a few things to work on, from short- (a couple of days) to long-term (2 weeks):
    1. Jin - Need to finalize the photon-rej Scintillator segmentation. We decided on 120 segments but the radial segmentation has to be determined using equal-rates;
    2. Jin - Need to estimate how much we can bundle the Preshower readout, again using equal-rates;
    3. Xiaochao - Once we have the two above, Xiaochao will contact IHEP to discuss the design and to update the cost estimate (mostly on the new photon-rej Sc);
    4. Zhiwen - get a formal quote for 1700 (or whatever) times 2 regular PMTs, rather than using the rough estimate of $600 each.
    5. The above items are relatively short-term - to be completed in 2-3 days; and the items below are somewhat "long" term - to be completed in 2 weeks.
    6. Todd, Zhiwen - To reduce the cost of PMTs for the Preshower, one stand-alone project is to study the performance of multi-anode PMTs, and how LHCb did the gain-matching. This can potentially save the cost of Preshower PMTs by factor of 6 (from $1.02M to ~$200k). Todd has agreed to spend a few hours on this in the next couple of weeks. Zhiwen will send him the references.
    7. For now we assume all PMTs, regular or multi-anode, will be located outside the field;
    8. Paul - We need to look into the support of the Preshower and the photon-rej Scintillator, and how much space (both radial and in z) is needed to guide all fibers out. For the writeup, can we have a nice figure to show the general layout and the support structure?
    9. Jin - will continue simulation with background for SIDIS LAEC and PVDIS;
    10. Xiaochao - need a semi-final fiber quote from Zhiwen and Mehdi. This of course will depend on the Preshower final design.
  4. Todd mentioned he will have a summer student that can be put on SoLID. We should think about a stand-alone project suitable for a new student.
  5. Jian-ping will be in China for the next two weeks. He will bring back yummy things for our next meeting.
  • 03/19/2013 Meeting to discuss EC design:

  1. Participants: Jianping Chen, Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Paul Reimer,  Mehdi Meziani, Todd Averett

  2. We should have a summary table for all requirements and current known facts of EC. From the top of my head I think it should be presented in the form of:

    General - by Xiaochao
    (Zmin, Zmax) (cm)
    (-65, -5)
    (405, 465)

    2012/12/06 writeup

    Polar angle (deg)

    2012/12/06 writeup

    (Rmin, Rmax) (cm)

    2012/12/06 writeup

    # of modules

    total surface area (m^2)

    2012/12/06 writeup

    Physics requirement on pi rejection

    (50-100):1 desired, 50:1 achieved

    Electron detection efficiency

    95% desired, 94% achieved.

    Energy resolution

    10%/sqrt(E) desired, 4%/sqrt(E) achieved

    Timing resolution

    <300ps desired, 100ps achieved

    Radiation resistance

    500krad desired

    Position resolution

    <~1cm desired, ~1cm achieved.

    Physics - PVDIS by Xiaochao, SIDIS by Jin
    Highest electron rate (physics)

    110kHz for >2GeV

    PVDIS 2009 proposal Table 3.3 on page 40

    Range of pi-/e ratio or pion rate (physics)

    8MHz for >2GeV
    dominated by which EC?
    PVDIS 2009 proposal Table 3.3

    Main background type, energy range and rate range

    low E pi-: 10kHz/cm^2.
    dominated by which EC? PVDIS 2009 proposal Table 3.3

    dominated by which EC?

    Trigger - Jin/Alex/Yi
    Max trigger rate per module or segment

    < a couple MHz

    Minimum pi rejection

    DAQ - Jin/Alex/Yi Per sector rate is 30kHz or below, for 30 sectors. With a safety factor of two we are looking at a total rate of 450kHz

    Shower Design - Xiaochao from current writeup
    module size, shape, length, layer thickness
    6.25cm-side hexagon (about 100cm2 area), 0.5mm Pb, 1.5mm "STYRON 637" plastic scintillator, total length: 18X0 (43.4cm), 195 layers.

    2012/12/06 writeup

    fiber density (per module or cm2)
    2012/12/06 writeup

    fiber readout design
    WLS fiber connected to clear fiber (1-1) using Leoni fiber connector plates.

    2012/12/06 writeup

    PMT readout (1/module?)
    fine-mesh or multi-anode

    Jin/Alex/Yi Max DAQ and/or trigger rate per module

    Preshower Design - Jin upon further study
    segmentation size, shape, layer thickness

    fiber density (per module)

    fiber readout design

    PMT readout design

    Minimum photon rejection

    Jin/Alex/Yi Max DAQ and/or trigger rate per segment

  3. Jin presented some slides on the design. See SOLID elog #31.
    1. Simulated PID for the hexagon shape, with a cluster size of 1+6. The pion rejection is similar to square size with a cluster size between 4x4 and 9x9, and is above 100:1 for e efficiency 94% (slide #3)
    2. Then, also included background. Coincidence is required between the Shower 1+6 hex cluster and (10cm)^2 of preshower area.  Slide #5 is shown with (10cm)^2 of preshower closest to the beam pipe which has the highest rates. Background pileup chance is 14% for 50ns windows.  Still fine-tuning the cuts but it is obvious that background pileup (mostly low E electrons and pi-) raise the pion signal and cause worse pion rejection. Gamma background still needs to be checked because current baffle condition allows direct photon sight and this is not reflected in Zhiwen's background output (input to Jin's study).
    3. Simulated photon rejection for the scintillators, have preliminary number on this vs. sector size (slide #10). We should focus on low E photons which has a rej of ~10 for 240 sectors, (6-7):1 for 120 sectors; and ~3:1 for 60 sectors.
    4. Geometry of Preshower: With 60 sectors we are looking at an inner width of 10cm (at R=100cm) and an outer width of 20-30cm.
    5. With 60 sectors: rate is about 4MHz. Alexandre mentioned he would be happy with a hit rate of a few (or a couple) of MHz. So 60 sectors is likely to be our starting point. The required photon rejection will determine # of sectors.
  4. Other catchups: Xiaochao will ask Will Brooks if it's okay to send a COMPASS module to ANL for support design purpose.
  5. Plan for the 3/22-23 Collaboration Meeting:
    1. Updates on the Shower Design
      1. Hexagon shape, PID performace with and w/o background (can be based on today's slide from Jin).
    2. Updates on the Preshower Design
      1. Overview
      2. Sector size determination - photon rej simulation and requirement, rate and DAQ and/or trigger requirement.
      3. Pion rejection factor in coincidence with Shower
    3. Updates on readouts:
      1. current status is that we are debating between fine-mesh and multi-anode PMTs. (last update see 1/15 meeting).
      2. Jin mentioned LHCb is using 64 channel multi-anodes which could be a significant cost saver. Zhiwen commented that it would be hard for gain matching. LHCb used some electronics to achieve gain matching, perhaps this can be studied independently (by Todd?);
      3. Field resisitance of multi-anode PMTs was presented by Simona at the last collaboration meeting which showed that up to a few 100 of Gauss is OK. This is good enough for EC.
    4. Updates on fibers:
      1. Comparson betwen Saint Gobain and Kuraray. We have not heard anything from S.G. on their fiber quality control (see 2/21 meeting).
      2. No conclusion on radiation dosage. This is likely to be part of our own test program for 2014.
    5. Updates on cost estimate:
      1. Need to ask IHEP.
    6. Remaining todo: discussion on trigger integration (PS in trigger or not?). etc.
  • 03/05/2013 Meeting to discuss EC design:

  1. Participants: Jianping Chen, Zhiwen Zhao, Jin Huang, Xiaochao Zheng, Paul Reimer, Diancheng Wang

  2. Discussions on the pion pileup simulation:

    1. Inputs would be:
      1. electron, pion, and photon energy distribution from Jin;
      2. rate information from Zhiwen;
      3. pulse shape for typical sampling EC modules, one example is from Zhiwen's COMPASS module picture (see last week's minutes);
    2. Outputs needed:
      1. Amount of pions mis-identified as electrons;
      2. Total rate (e+pi) at the triggering level;
      3. Pion rejection factor;
    3. Tasks identified;
      1. simulate the pion pileup at the triggering level, where only one threshold on the Total Shower (TS) will be implemented at first.
      2. simulate the pion pileup at the analysis level, where both Preshower (PS) and TS cuts will be used. This will require energy correlation between PS and TS (2D energy distribution) which we don't have yet.
      3. All items above should be performed under the condition that the EC design is not final yet, in particular the size and shape of the PS. The PS module does not need to match the size of the Shower (which is now 100 cm^2), and could be much larger.
  3. Discussion on Support:
    1. Paul:
      • block size should accommodate the light-tight wrapping and production tolerance. We decided to make the modules 6.25 cm on each side, and the effective side length will be 6.395cm (see Paul's email following today's meeting);
    2. About the shorter modules designed for LAEC of SIDIS:
      • In the writeup we proposed to use 5x5 cm^2 modules with half-length to increase the angular acceptance of the LAEC. The square shape of 5x5 can easily be accommodated. However, since we are now using hexagon shapes, we should reconsider this design and might need to abandon the shorter length idea.
  4. Jianping commented that we should update the cost estimate in the writeup and also to include a support section and support cost;
  5. Jianping mentioned all upcoming workshops/conferences in Russia: 1)March workshop; 2) June workshop at IHEP; 3) mid June/July workshop at Dubna; and 4) Sept workshop at Dubna (oh my don't people ever work there???). We should send someone to one of these workshops to discuss about EC and SoLID physics.
  • 02/26/2013 Meeting to discuss EC design:

  1. Remote participants: Jin Huang, Mehdi Meziani, Xiaochao Zheng, Zhiwen Zhao, Paul Reimer

  2. Local participants: Jianping Chen

  3. From Zhiwen: no news from the Italian fiber company or Leoni yet;

  4. Discussion on Support: We got reply from IHEP on 2013/02/21:
    1. Paul:
      1. Brass is too soft;
      2. ANL engineers are already working on tension/deformation/shear/deflection simulations. Should have a presentation in 3 weeks.
      3. Current ANL design is based on hexagon with the longest diagonal length 10cm. We should modify this and match the cross-sectional area to 100cm2;
        • followup: After the meeting we calculated that the hexagon side should be 6.204cm with the longest diagonal size 12.408cm. We could use 6.25cm and 12.50cm.
    2. We should ask for a sample (samples) of the stainless steel rod from IHEP, with the same diameter but shorter length (10 inches would be plenty). Then we can measure the magnetic property (excitation curve) and so on;
    3. We should try to borrow 1 COMPASS module from ODU, ship it to Argonne for the Engineers to work with. Maybe they can measure the rod tension at ANL as well.
  5. From Jin: won't be able to work on simulation this coming week, but will do so during the period 1-2 weeks from today.
  6. We discussed on the pi/e pulse shape/pileup problem:
    1. Input from Jin:
      1. the highest pion rate is about 10k/cm2, and the total electron rate over all energies is about a few times smaller. For pulse shape analysis, we should know the electron rate vs. energy distribution and treat the low-E electrons as background as well;
      2. Energy deposit:
        • Shower pion/e is about 0.1-0.2;
        • Preshower: electron at 8 MIP, pion at 1 MIP, however both have long tails so chose to cut on 3MIP;
    2. Discussion on pulse width:
      1. Input from Zhiwen: COMPASS module had about 50ns during last year's test (click here for photo). The PMT used was fast: 1.9ns rise time and a few ns total width (here is the spec.);
      2. Input from Paul: For sampling EC like this the pulse width is dominated by the module.
    3. We should include the pulse shape simulation in the current EC simulation.
  • 02/19/2013 Meeting to discuss EC design:

  1. Remote participants: Jin Huang, Mehdi Meziani, Xiaochao Zheng, Paul Reimer

  2. Local participants: Jianping Chen, Zhiwen Zhao, Mark Jones.

  3. From Mark Jones:

    1. The 4-5%/sqrt(E) resolution of SoLID might work well for GEP-5, but will need to discuss with Charles before saying anything official. (Yay! we will get a quarter of our EC from GEP!!!)

    2. Will also ask Charles if hexagon shape works for GEP.

    3. Will setup a one-time meeting next week for discussions between SoLID and GEP-5.

  4. Not much done on the fiber or simulation. Updates:

    1. Zhiwen got some design on the fiber connector from Leoni fiber, but probably we should not circulate this to IHEP.

    2. Xiaochao will remind IHEP that they have not answered our questions on the support structure. Will also inquire the material of the steel rods (must be non-magnetic).

    3. Followup on the fiber radiation dose (Jin): fiber dose is the same as scintillator dose, still the 3krad/month stated last time.

  5. The current meeting time doesn't work well (1 hour is too short). Xiaochao will setup a doodle poll so we can schedule a new meeting time.

  • 02/12/2013 Meeting to discuss EC design:

  1. Remote participants: Jin Huang, Mehdi Meziani, Xiaochao Zheng

  2. Local participants: Jianping Chen, Zhiwen Zhao, Mark Jones.

  3. From Mark Jones:

    1. GEP5 is considering sampling calorimeter made of 380 layers, 1.5mm sc and 0.3mm lead, with energy resolution of 3%/sqrt(E). This is 50% better than our design [1.5mm+0.5mm, 4-5%/sqrt(E)]. GEP5 requires about 430, 11x11cm^2 modules and we are considering combining the effort to some extent. It will be great if we can share the same module design, such that a fraction of the EC work can be funded/completed in collaboration with GEp5.

  4. Some updates on fiber quality - by Zhiwen and Mehdi: see their report.

    1. slide 2 shows some ATLAS test data on fiber light output and radiation hardness [NIMA 453 (2000) 255, pdf]. A more detailed study from the ATLAS EC can be found here (pdf). Comments:

      1. We should request a quote from the 3rd company (Pol. Hi. Tech, Italy?), with fiber type S250-100.

      2. We should request Saint Gobain if they can control their fiber quality better (light output has an RMS of 10%, compared to the 1.8% of Kuraray).

      3. What is the actual radiation dose on the fibers alone? Jin said right now with the new PS design it is as low as 3krad/month, but could increase by factor of 10 pending more background simulation. We need to:

        • ask the LHCb people (or the fiber company) if they have smaller radiation dose test;

    2. Slide 5 shows some discussion with Saint Gobain people. Good progress on possible fiber connectors and embedding WLS fibers in scintillators (they can do groove-drilling with diamond, while Fermilab can do molding). For the record, the other fiber-embedding scintillators were/are planned to be done by: the LHCb preshower was done byUniversitat de Barcelona, and the CLAS12 hodoscope is from Univ of Edinburgh.

  • 02/05/2013 Meeting to discuss EC design and support structure:

  1. Remote participants: Jin Huang, Mehdi Meziani, Paul Reimer, Xiaochao Zheng

  2. Local participants: Jianping Chen, Zhiwen Zhao:

  3. Update on item A - Preshower Design: Jin presented preliminary simulation on the photon rejection, see his report. It was found:

    1. Radiation dose on the Preshower seems to be OK.

    2. Using 5mm scintillator for the 1st layer, the photon rejection is 7:1 for 1-7 GeV/c or 1:20 for 1-2 GeV/c, if cutting on 0.5MeV below the MIP.

      1. Backscattering from the Shower part seems to make the photon rejection lower;

      2. Jianping questioned more on the background problem which may force the raising of the cut;

      3. waiting for more background inputs from Zhiwen (pi0, etc..).

  4. Update on item C - Support Structure:

    1. We will email IHEP in order to address 4 questions from Argonne:

      1. What are the fabrication tolerances for the modules?  In other words, how much room should the supporting structure leave between    the modules?

      2. What is the tension in the rods that are used to hold the blocks together?  What are the rod diameters?  This question is getting at how rigid the modules are physically and what we can count on if we are just supporting at either one and/or both ends.

      3. What is the purpose of the "Lego" bits in the KOPIO Design (see Fig.1 in B.S. Atoian /et al/ NIM 584, 11 Jan 2008, p 291 ( Won't these block light output and will we really have them? The main concern here is in how the rods through the blocks are tensioned.  One must be careful to hve either all the tension on the Lego bits or none of it there.

      4. We are strongly considering a hexagonal shape, since the stacking in pseudo-wedges might be easier.  Are there any problems with this?

  • 01/22/2013 Meeting to discuss EC design and support structure:

  1. Remote participants: Jin Huang, Mehdi Meziani, Paul Reimer, Xiaochao Zheng

  2. Local participants: Jianping Chen, Zhiwen Zhao:

  3. Update on item A - Preshower Design: See 2nd part of Jin's report on background study, no conclusion made here.

  4. Update on item B - Readout Study: Zhiwen commented that Cherenkov is using multi-anode rather than fine-mesh PMTs is purely due to geometric reasons. Multi-anode PMTs match better with their signal output.

  5. Update on item D - HERA module test: Jin did simulation for HERA modules, see his report. It was found:

    1. Energy resolution from our simulation is consistent with their published value, about 10%/sqrt(E);

    2. Pion rejectionis (3-10) times worse than what we require. But we might study the pi/e ratio vs. radial distance, and see if there is a significant cross sectional area where the pi/e ratio is low and the HERA modules are good enough. After all, this is a great cost-saving.  Jin commented that to use two different modules, there would be some "dead zone".

  • 01/15/2013 Meeting to discuss EC design and support structure

  1. Remote participants:  Jin Huang, Mehdi Meziani, Paul Reimer, Xiaochao Zheng

  2. Local participants: Jianping Chen, Zhiwen Zhao;

  3. We identified a to-do list as follows:

    1. Preshower design:

      1. Now we will focus on using "fan"-shape Preshowers that consists of 2X0 of lead (1.2cm) followed by a 10 or 20mm-thick scintillator. We will build one for the large angle, and one for the forward angle that will be the same for PVDIS and SIDIS. We will start from 30 segments, but more segments might be necessary depending on what the simulation shows. The LA PS will consists of one Pb layer followed by one Scintillator layer mentioned above, and the FA PS will have an additional thin scintillator plane in the front for photon rejection.

      2. The readout will be the same as before: We will imbed WLS fibers in the scintillator pads, then connect them to clear fibers for going outside the fields, then readout by PMTs. Some readout R&D is still on going (see below);

      3. To do (Jin Huang): Determine the effect of using larger "fan" size and the number of segmentations, thickness Scintillator layers (10mm or 20mm for the post-Pb layer? What should be the thickness of the photon-rejection scintillator layer?). For the LA PS this will depend on 1) PID; 2) capacity of the PMT; and 3) S/N ratio; and for the FA PS this will depend on 1) PID; 2) capacity of the PMT; 3) S/N ratio; and 4) How much photon suppression we can get.

    2. Readout options to do:

      1. Zhiwen Zhao: With the new, larger fan-size, how many WLS fibers do we need per "fan pad" and how to arrange them?

      2. Zhiwen Zhao: Will using field-resistant PMTs (like the one in Cherenkov) an option for FA PS? This will depend on a) the cost saved on WLS and clear fibers as well as machining the scintillator pads; and b) the cost of field-resistant PMTs ($3k each for 2-inch PMTs - per Jin and Yi); If PMT-directly-readout is an option then possible lightguides should be looked into.

        • On 2013/1/15 JP asked why Cherenkov is not using fine-mesh PMTs.

        • Answer (Zhiwen): fine-mesh PMT has no obvious gain loss up to 1500 Gauss; price about $1500 with standard glass for 2in diameter. Gain is about 5E5, good enough for our EC. The other option is a segmentable "multi-anode" (into 4 channels) $5k PMT but is less field resistant, but >10 in gain. Also see 01/22 update.

        • At the moment both multi-anode and fine-mesh PMTs are still possible options for EC. To do for Zhiwen: study/compare their

          1. field resistance

          2. gain, also gain loss due to field

          3. max current capacity

          4. cost, including cost comparison with WLS-clear fiber readout. 50-mm square multi-anode cost $5000 each;

          5. JP questioned why we don't consider cheaper PMTs, if field only reduce the gain by "some factor", since our need for gain isn't as demanding as Cherenkov; -- to be studied.

    3. Support structure:

      1. Argonne engineers will work on this with inputs from Zhiwen. Many other people will be kept in the loop.

      2. Jin commented that we do not need to have the Preshower made at IHEP anymore.

      3. To do by Zhiwen: In our latest email with Argonne engineers we should give the flexibility of using W or Pb with Al frame for the Preshower, but we should reject stainless steel due to possible magnetism and Cu or Al alone (due to lightness). <- emailed 1/8

      4. Hexagon shape (suggested by Argonne engineers) is still an option depending on if the support is easier to design.

    4. Super BigBite test with HERA modules:

      1. Mark Jones has 10 HERA-B modules with size 11x11 cm2, about 20 X0 long, but much thicker layers (3mm Pb/6mm scintillator vs. our 0.5mmPb/1.5mm scintillator). Exact sampling and total thickness to be confirmed. Bench test of modules being setup now.

      2. HERA-B has a total of 500 middle and 1700 outer modules (see their NIM paper). (Zhiwen) inner modules had 4 readout, outer modules had 1 readout.

        • If energy resolution and pion rejection are close to what we need, could consider using these modules for both SBB and SOLID.

        • Todo for Zhiwen/Jin: Need simulation to: 1) Find out what expected performance of HERA modules is; and 2) compare with bench test to see how good our simulation is.

        • Beam test is being considered at the Fermilab electron beam test facility. JP suggested SLAC might also have some test facility.

  • Communication with IHEP

    1. Email sent to IHEP to request cost update and fiber-cutting: 2013/05/30 directory. and their reply.
    2. Email sent to IHEP on 2013/04/09 on fiber connectors and detailed fiber questions: 2013/04/09 directory.
    3. Email sent to IHEP on 2013/04/06 on the new design of the PRSP: 2013/04/06 directory.
    4. Reply from IHEP on 2013/02/21: 2013/02/21 directory.
    5. Email we sent to IHEP on 2013/02/07: 2013/02/07 directory. Here we asked 4 questions on the support design as mentioned in the 2013/02/05 meeting.

    6. Reply from IHEP on 2013/01/17: 2013/01/17 directory Here Vladimir questioned on the new Preshower design, asked for detailed design diagram for further discussion. We don't have such design yet. For fiber connectors he also asked for a design, Zhiwen has asked Leoni Fiber to see if they already have something.

    7. Email we sent to IHEP on 2013/01/08: 2013/01/07 directory. Here we modified the Preshower design significantly, following the hint from Vladimir's email below.

    8. Reply from IHEP on 2012/12/17: 2012/12/17 directory and 2012/12/20 directory. Valdimir raised many questions including some that triggered the major change of our Preshower design. And he gave preliminary detailed quote for the module production. Following this email, plus the latest fiber quote from Medhi, Xiaochao has setup a spreadsheet to show the EC cost breakdown: ods format, xls format.

    9. Original email to IHEP in late 2012 can be found in the 2012/12/15 directory, including a PDF file for our basic design.