- Participants:
- Final summary of test results on irradiated Preshower tiles:
- Table to summarize all prototypes we have so far:
Prototype
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Scintillator
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Lead
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Reflective Material between layers
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WLS fiber type
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WLS fiber end treatment
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module side treatment
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cosmic vertical test light yield (ph.e.)
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cosmic horizontal test light yield (ph.e.)
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PMT gain determined by
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Other features
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Additional comments
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UVa hedgehog test (25 layers)
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Kedi (original)
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none
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Printer paper
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Y11(200)MC
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no plating or painting
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loosely wrapped in Tyvek
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N/A
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about 1.4 p.e./layer
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SPE and MIP peaks on the same spectrum
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for details see Vince's report on 2016/4/7.
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SDU1
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Kedi (original)
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US Kolgashield
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Printer paper
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BCF91A-SC
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no plating or painting
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final product had side-painting with TiO2
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224 (sides unpainted, wrapped losely in Tyvek); 254 (sides painted).
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48 (sides unpainted, wrapped losely in Tyvek);
39 (sides unpainted, no Tyvek wrapping).
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SDU's SPE method
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front plate has holes
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(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.
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SDU2
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Kedi (improved)
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Chinese
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Printer paper
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BCF91A-SC
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silver-plating (Chinese vendor)
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final product had side-painting but quality was not as good as SDU1.
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427 (sides unpainted, wrapped losely in Tyvek); 383 (sides painted).
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83 (sides unpainted, wrapped losely in Tyvek)
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SDU's SPE method
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front plate has no hole
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See above
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SDU3
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Kedi (improved)
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US Kolgashield
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Printer paper
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Y11(200)MC (from Xiaochao)
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silver-plating (Chinese vendor)
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TiO2+glue (1:1) painting
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491 (in 2018), ~450 reported on 2019/4/11
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107
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SDU's SPE method
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front plate has no hole
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(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.
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SDU4
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Kedi (improved)
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Chinese
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powder paint (from THU)
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BCF91A-SC
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ESR with white backing, cut to small pieces and attach/tape individually to each fiber
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final: TiO2+water+glue painted twice
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~260 (no side treatment); ~345 (sides wrapped in Tyvek); 360 (side painted once with TiO2); 370 (painted twice with TiO2); 562 if fiber ends attached by individual ESR/white sheet.
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SDU PMT
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need solidify fiber end treatment/procedure for mass production.
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see 2019/4/11 and see 2019/5/16
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SDU5
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Kedi (improved, batch3)
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US
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Tyvek
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BCF91A-SC
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company polishing, ESR with white backing, a large sheet pressed against all fiber ends
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final: TiO2+water+glue painted twice
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220 (no side treatment); 270 (sides wrapped in Tyvek); 280 (sides painted with TiO2 once and twice); 398 if fiber ends also attached ESR/white large sheet.
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SDU PMT
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need solidify fiber end treatment/procedure for mass production.
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see 2019/5/16
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SDU6
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Kedi (improved)
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China
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ESR
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Y11-MC
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SDU polishing, ESR with white backing, a large sheet glued to all fiber ends
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final: TiO2+water+glue
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633 (no side treatment); 798 (loose ESR on sides); 813 or 875 (sides painted with TiO2+glue)
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SDU PMT
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thread WLS fibers through layers first, then compress
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see 2020/8/13 and 2020/9/23
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THU1
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Kedi (original)
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Chinese
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mirror mylar (Yi Wang commented mirror mylar produces 20% lower yield than printer paper and Tyvek from their test) (mirror reflection).
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Y11(200)MC (from Xiaochao)
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Italian silver shine 415001
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TiO2(Kedi) painted
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(424.9-470), depending on trigger setup. followup: JLab test indicates the yield is 3 times lower.
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96, followup: JLab test indicates the yield is 3 times lower, see SDU Ye's report on 2017/04/20
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not measured, used factory gain vs. HV curve
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Details of cosmic test see 2016/09/08 report by Chendi. Gain of PMT reported on 2017/04/20. For reflective layer test see 20160204
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THU2
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Kedi (improved)
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Chinese
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powder paint (diffusive reflection)
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BCF91A SC or MC?
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Italian silver shine 415001
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wrapped in Tyvek
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748 if using SK/SP method, *1.5 higher if using gain from IHEP SPE method. SDU retest shows 570-580.
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90 to 103 if using SK/SP method, *1.5 higher if using gain from IHEP SPE method.
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PMT gain: (1) Beijing Hamamatsu's SK/SP method, base changed but claimed to be identical base model. (2) Beijing IHEP SPE method (without changing the base) gave the gain to be 2/3 of the currently used values, which means Npe should be 3/2 of the currently reported value.
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Details of cosmic test see reports by Chendi on 2017/09/14 and 2017/09/28. Confirmation of gain measured at IHEP see Ye's report on 10/28 and 11/2. for SDU retesting.
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THU3 (in progress)
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Kedi (improved)
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Chinese
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powder paint (diffusive reflection)
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fiber?
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diamont cut + TBD
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TBD
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TBD
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TBD.
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THU4 (planned)
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Kedi (improved)
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Chinese
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Tyvek possible
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?
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TBD
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TBD
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TBD
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TBD.
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- Present evaluation about the light yield:
- Using the above highest MIP light yield, which is about 750 p.e./200 layers 1.5mm layers (at 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 (750/60*200=2500 p.e.) for 1 GeV electrons. This is 2.5 p.e./MeV, which is now comparable to LHCb 2.6-3.5 p.e./MeV, but lower than 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.
- With 2500 p.e./GeV electron, the energy resolution due to photon statistics will be 2%, adding factor of 2 for the light loss of fiber connector and clear fibers, 2% becomes 3%. This is okay considering the intrinsic resolution is (5-6)%, although ideally we would like to see the effect of photoelectron statistics to be negligible.
- 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.
- Possible ways to proceed:
- 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.
- 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
- Vince sent out some scripts, see below
- The first code (plot_tdcs.C) only plots the TDC channels for the various scintillators and the FASPD.
- 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.
- 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.
- Some old notes that should not be forgotten: see 10/07/2014 notes: "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)".
- On 4/30/2013 and 4/23/2013, Jin's work on radiation dose
- Need to do simulation of 30 p.e. as Preshower light output, and how 10%, 15%, 30%, and 50% light loss from 30 p.e. will affect Preshower PID. These % are chosen to reflect the light loss of Kuraray@100krad, S.G.@100krad, Kuraray@700krad and S.G.@700krad
- Statement in pCDR is probably based on Jin's work from early on (but no record of his exact words in this log):
The preshower would have more decreasing in gain, and the front layers of shower also have some decreasing, but back
layers have much less decreasing. The overall effect is less than 20% after 400KRad.
- Readout for FASPD may need to use regular PMTs with x10 pre-amp gain (or up to 40 to allow ease of cutting at half-MIP). 16-ch MAPMT will require a pre-amp gain of 160, not achievable.
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- Main goal are to figure out:
- Are there serious pileup problems? Need absolute gain to know MIP position.
- Need to make sure ECal at high rate can distinguish pion MIP from background (Trigger performance), and electrons from pions (PID performance)
- SIDIS hadron trigger is the most problematic. PVDIS trigger can have high threshold (1 GeV at large theta and 2-3 GeV at small theta) so less problematic -> need SPD photon rejection study
- Beam test trigger setup: we now have 3: Type1 = Sc0 .and. Sc1; Type 2 = Top PS .and. TOP SH; Type 3 = Sum_of_3_Shower; Type 253 = random pulser. Need to check threshold (ideally at half MIP).
- preCDR trigger setup:
- electron: EC 6+1 cluster .and. Cherenkov (Cherenkov = OR of multiple channel) .and. SPD (for photon rejection)
- pion: half MIP in ECal (Shower 6+1 cluster) .and. SPD (for photon rejection), plus offline cuts on Cherenkov.
- Low rate test at large angle in July-Dec 2022; High rate test at small angle in Jan-March 2023; DAQ high-rate test (VMM readout) from summer 2023 til early 2024.
- SBS lessons learned: GEM in the hall is much more noisy than GEM on the bench.
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- SDU started testing different scintillators
- Beam test prepation ongoing: receive recoated MAPMTs; setting up Duke's DAQ system; will work on Cherenkov; taking access to Hall C today to look for cables and study possible locations of the high rate test; looking for the test stand used for previous Hall C Cherenkov test (should have more than one but we cannot see any); Mark suggested using R-HRS scintillators (if UVA ones are of low quality)
- Will need to send beam test doc (redacted) to Hall C XEM spokespeople.
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- THU+SDU group (Dong Liu, Zhihong, Cunfeng, Ye Tian) presented a plan to make two super modules (14 modules total). This is funded by Zhihong.
- Slides on current thinking of the material choice: 20211020Solid Ecal Prototype material selection and assembly.pptx. We discussed two remaining uncertainties: WLS fiber Y11-SC vs. BCF91A-MC; and connection from WLS to clear fiber (one-one connector, bundling, or light guide).
- How much gap tolerance can we have? -- (1) will need Ye Tian (Syracuse U)'s simulation for when electrons enter with an angle; (2) we should also test the modules at an angle during the beam test; (3) Zhihong et al should tell us what a realistic wrapping gap and tolerance is, then we can see if the two ends can meet.
- From last time: will compare Kedi vs. Dubna scintillator performance next.
- Zheng (UIC) followed up on FTBF data analysis, now taking out 2% of beam energy spread, though there is very little change in p0 and p1, see Total_Linear_ER_Reduced.pdf. Comparing Zheng's with Jixie's analysis, now I see a difference in two aspects: (1) Jixie's seems to have a smaller dE/E than Zheng's, with the 6 GeV in particular the best point (worst in Zheng's); (2) subtracting dE/E=2% beam intrinsice energy spread from data seem to have a big impact on Jixie's result, but not on Zheng's.
- Paul Reimer gave a presentation on 9/22 and we discussed the support design. Holey front plate does not seem to be a problem.
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- Zheng Huang repeated the FTBF analysis, now with run-by-run calibration from Jixie and preshower correction, see Sep14new.pdf. The p0 and p1 from the fit are 4.6% and 10.4%, respectively. The so-called nonlinearity of preshower refer to low preshower energy deposit side, the (SH+PSH)E/p spectrum does not line up with 1.0. We suggested understanding the physics of this observation first before making any correction of it.
- After the meeting we asked Zheng if we can remove the 3 data points from 6GeV, 10GeV and 16GeV and refit. Here are the results: Sep14new_remove6,10,16GEV.pdf, and now p0 and p1 improved to 3.7% and 10.9%, respectively (so mustly p0 is improved by nearly 1%). We asked further if it is possible to remove a hypothetical 2% beam energy spread from each point. -- TBD.
- Moving forward with FTBF test, need to write a report; will try pulse deconvolution, possibly in Spring 2022 and may need a GRA on this.
- Paul Reimer gave a presentation on 9/22 and we discussed the support design. Holey front plate (see SDU design does not seem to be a problem.
- THU group is back!
- Simulated alternate design but thinner lead per layer means more layers (0.3mm lead, 220 layers) and longer module and we may not have space for this. The un-uniform design (scintillator thickness varying with depth) also do not work by definition.
- Will compare Kedi vs. Dubna scintillator performance next.
- Zhihong Ye (new to THU) will make a 7-module supermodule and test out support design. Discussion on this is ongoing.
- Some discussions on fiber aging lead to oxygen effect. Might need to test the fiber in a high-oxygen environment.
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- SULI student Ben has a basic algorithm for pulse separation but need to write a code to store the information in a Tree. Jixie will help with this.
- Zheng Huang add preshower energy deposit in his analysis, see Zheng_Huang_ECal_position_corr_Jul%2029th.pdf. The next step would be to get calibration constants from Jixie and repeat everything.
- JLab beam test discussions: Need a goal, need to look into Hall C runplan (David Flay will help), etc.
- Notes from earlier: SoLID PVDIS expects 9MHz/module above MIP in Preshower
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- Zheng Huang presented FTBF ECal data analysis with corrections for position-dependence in the energy deposit, see Zheng_Huang_ECal_position_corr_Jul%2015th.pdf. It looks like positioning correction can help reducing the extracted energy resolution.
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- Updates from SDU, see 1_Light%20loss%20at%20the%20new%20connector.pptx showing the 500x 0.5mm dia clear fiber bundle has about 40% of light loss when reading out Shashlyk signals. This is high loss but the convenience of using such fiber bundle (easy on/off) cannot be overlooked.
- Presentation on Machine Learning by Zhenyu. Jianping mentioned that several sub-groups are already using ML: (1)SoLID PID; (2) PRAD tracking (Duke) but has not started this for SoLID; (3) MRPC frontend readout; (4) Athena has something developed for tracking; (5) For DAQ there is the frontend-streaming idea that does not use trigger. It's safer (does not "lose" data) but need lot of data storage space.
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- Updates from SDU, see 1_Light%20loss%20at%20the%20new%20connector.pptx showing the 500x 0.5mm dia clear fiber bundle has about 40% of light loss when reading out Shashlyk signals. This is high loss but the convenience of using such fiber bundle (easy on/off) cannot be overlooked.
- A few of us discussed the FY22 beamtest on Monday June 14th.
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- Wrapping up FTBF data analysis. Further checking fit quality etc. does not seem to have any effect on improving energy resolution. See Jixie's slides solid_ecal_calibration_20210603.pdf
- SULI student Ben J. from UVA will work on waveform analysis of ECal signals.
- SoLID incident angle on position resolution: Ye is working on reproducing the preCDR results.
- Zhenyu checked position difference of MWPC vs. ECal, still varies with run. Several factors (calibration, moving of ECal, beam direction and energy, HV) can affect this. Not sure which one is causing the run-to-run drift.
- We need to think about what beam test we need to best characterize ECal performance. Possible tests in Fall2021-Sp2022 running.
- Jianping brought up using machine-learning for PID (used at D0, JLab/Zhiwen in the loop of this type of discussions, not CMS, maybe LHCb? MRPC and GEM of SoLID already using it to some extent) -> Zhenyu has experience with D0 and will prepare a presentation for June 17 (after collab meeting).
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- About x and y position resolutions, how are they affected in SoLID running situation where particles incident at an angle? -> Ye will look into simulations
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- Dong Liu showed detailed fits of the attentuation length of clear fibers, see summary_sdu_fiber_irradiation.pdf. Still waiting for one sample of WLS fiber and scintillators at the highest dose. Existing data look solid. Suggest be careful of uncertainties, the stdev of the 3-sample data may not be a good estimate of the uncertainty. Radiation dose is from simulation (though checked with radiation measurements for some areas), was told the uncertainty is 10% on dose.
- Zhenyu: meeting the new student this week and then will get started on simulation.
- Jixie: tried removing events with double peaks or if the peak arrives too early or too late. Width of dE/E is improved slightly though there are still events on the high-E side (tail), see solid_ecal_calibration_20210520.pdf Cutting on these events and check the pulses may help to reject them further. Also tried removing 2-3% energy spread from the measured data (old signal results, slide 11).
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- Mengjiao showed fit of attenuation length vs. log(dose) and found it to be a linear function for both PMAA and BCF98 clear fibers. THe same function also works for the relative light yield for WLS fiber and the scintillators, see her slides . There was still some confusion why the 78% light loss for the 6-m long BCF92 fiber case looks "typical" now. Suggested to plot the expected light loss as function of dose, using the fitted log(dose) dependence, to illustrate that for some cases the loss can be exponentially high.
- Chao presented waveform analysis used for Cherenkov test, see his slides Waveform.pdf. A few important points: (1) there are two codes to identify pileups: Chao's can id negative peaks; and TSpectrum can also be used; (2) neither does peak deconvolution, only identify multiple peaks by find the valley and separate the integrate by the valley position; (3) for scintillators, the peak height is less affected by pileups than peak integration, and one can use height alone for analysis. (This may not be true for ECal signals that has a Landau shape).
- Zhenyu showed slides on beam position, see yezhenyu_SoLIDECal_20210513.pdf. Updates are: (1) now added Cherenkov cut; (2) pointed out the energy leak through the gaps may make dE/E worse - page 2. The right-side plot is with a beam cut of the 3-block center (at the gap); We need some smart beam cut to reject the gap region for dE/E analysis. (3) the gap between blocks is a few mm in width - page 8, though it does vary from gap to gap (probably depending on how the blocks were positioned/pushed against each other). To do: process gain-matched ADC data once have received them.
- After the meeting, Alexandre sent slides from 2002 Hall A analysis workshop camsonne-ws2002.pdf where he had a peak deconvolution algorithm for DVCS analysis. The code is not generic yet and we might want to find someone to work on it.
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- Jixie showed a few slides on the calibrated data in 2D preshower vs. shower form, see solid_ecal_calibration_20210506.pdf. The slides include 2D and 1D calibration spectra. The 4GeV and 8GeV both are worse than 6 GeV case. We suspect event pileup to be the culprit. Will ask around for waveform analysis and/or separation algorithm.
- Zhenyu showed beam position analysis for MWPC vs. EC cluster finding algorithm, see yezhenyu_SoLIDECal_20210506.pdf. We noticed that: (1) we can see the gaps between modules; (2) the x and y resolutions extracted from taking the difference of MWPC and cluster values are about 1.3-1.5 and 0.75-0.9cm, respectively, see slides 5 or 8 or 11. The wider x value is because the beam in MT6.2 is kicked horizontally and enters the detectors with a horizontal angle; What about real SoLID situation?and (3) from the mean values of x and y can calibrate the MWPC position w.r.t. ECal. (slide 12). However, these analysis was done without Cherenkov cut and without block gain-matching. For the latter reason, cluster position may change due to HV, which is what we see between runs 1065 and 1066 (no beam position change, only HV change occurred between these runs).
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- Mengjiao showed results on attenuation length of irradiated fibers, see the attenutation length of irradiated fiber.pdf. Suggest plot these vs. dose to look for dependence.
- We continued discussion on FTBF beam test data, now including aligning preshower with shower and cross all 3 blocks, see Jixie's slides solid_ecal_calibration_20210429.pdf
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- Mengjiao reported on test results of the irradiated BCF98-SC fibers, see clear fiber (BCF98-SC) irradiation test.pptx. The results shown are for 3m and 6m fiber length and the last sample (6m at the highest radation) shows much larger loss than expected. Suggestions:
- Check results of the last test sample/point, retest if necessary;
- Try to convert the observed light loss to a shortening of the attentuation length for each of the clear fiber tested (both BCF98 and the PMMA from last week). Plot the attentiaon length vs. dose and see if there is a certain pattern.
- We discussed FTBF data analysis, with a focus on calibrating all blocks.
- Zhenyu (UIC) showed the calorimeter cluster-finding algorithm result, see yezhenyu_SoLIDECal_20210422.pdf. Shown in the top panel are "cluster x vs. MWPC projected x", "cluster y vs. MWPC projected y", "cluster - MWPC" y vs. x. Lower panel shows the 1D profile of cluster x minus MWPC x (left) and cluster y minus MWPC y (middle). At higher energies there are saturation problems that affect the cluster-finding and some double-peak feature starts to show up. Using these we can find out the offset of the MWPC (0,0) w.r.t. block center and a better way to cut on the beam position.
- We discussed the end-to-end calorimeter simulation. Ye's slides are ECAL_digitization_resource.pdf. The photon absorption calculation code, completed by Edward Rhett Cheek in 2017, can be found from 6/29/2017 minutes.
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- Mengjiao reported on test results of the irradiated PMMA (from CHunhui) fibers, see clear fiber (PMMA) irradiation test.pptx. The results show up to 5% light loss for 2-m long fiber with 3.7E+13 MeV/cm^2 (neutron equivalent).
- We discussed FTBF data analysis, with a focus on calibrating all blocks. See Jixie's slides solid_ecal_calibration_20210415.pdf (nice calibration plots for 6 GeV with 2cm beam radius cut)
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- SDU: received more fibers that had been irradiated at IMP. Will test in the upcoming week.
- We discussed FTBF data analysis, with a focus on calibrating all shower blocks. Calibration data at 4, 8, and 16 GeV (lowest energy of each HV setting) seem to be the best. Higher energies all have some saturation issue (issue varies with energy).
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- Discussed FTBF data analysis, see Jixie's slides: solid_ecal_test_status_update_20210401.pdf; Slides 11-12 shows nice calibration spectra, while slide 18-19 shows significant pileups for 8 GeV.
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- We shifted the meeting to Thursday (permanently) to avoid conflict with SoLID Cherenkov meeting.
- Participants: Mengjiao, Ye Tian (SDU), Ye Tian (Syracuse), Dong Liu, Cunfeng, Jianping, Jixie, David Flay, Xiaochao Zheng; From THU: Chendi Shen, Kai Sun, Linmao Li, YuLei Li
- Mengjiao presented the scintillator radiation test, see 1_fiber irradiation test.pptx, using cosmic passing through 6 scintillators sandwiched with 5 lead layers. Some highlightes:
- light yield loss is about 1.5+/-0.7% for 4.5 krad and 9.2krad, and 5+/-0.7% for 121 krad.
- Ye presented updated simulation for the beam test, see ECAL_beamtest_03182021.pdf:
- Found a bug in the pion simulation and it looks much more reasonable now.
- Effect of beam size on the one-module data is quite small (after adding preshower to shower energy);
- Jixie presented progress on FTBF data analysis. Focused on pedastals, see solid_ecal_test_status_update_20210318.pdf. Notes:
- Developed 3 algorithms to extract the pedastal. Note that previous week, the method of "profiling" (averaging over all events for a channel) using the "before pulse" window was used. This can lead to pedestal too high because of possible noise signals in that window. Now have: (1) slide 5: using the "before pulse" window of each channel's profile with a high cut (to reject noise peaks) and do a constant fit. However this is affected by whether there is background noise during that window, and is time consuming; (2) slide 6: do a y-projection of the "before pulse" window, followed by a Gaussian fit. This is probably the most precise way (and should be identical to the old-time QDC method). It also shows a high-peak tail which could be the source of error for the profiling (without cut) method used previously. (3) do a y-projection and choose the bin with max content. However this is subjected to digitization error, since the real pedestal is a real number.
- We agree method 2 is the best. However when Jixie process the data for pedestal subtraction, he rounded the fitted peak position to integers (slide 10). This should be corrected for the next round of the analysis if the effect is found large. The run-to-run pedastal values fluctuate by +/-1 (slide 1) but it could have been smaller had the number not been rounded.
- Again on slide 10 one can see the change in pedastal from the old to the new method. Most channel had 0 or 1 change but some had change at 3 or 5. This can be significant since the FADC signal is integrated over 12 samples, so a shift of 3 leads to a fhit of 36 in the MIP, which can be the reason why previously when the MIPs are aligned among 3 blocks, the main peaks are not for some of the calibration energies.
- Currently, re-processing the data with the new pedestal determination. This can take 30-50 hours. Then will do calibration again.
- We discussed with THU group (Chendi et al.): Chendi and students can probably help to understand the FTBF test data. We also asked if it's possible to test the next batch of new modules at the facility where the THU group test the NICA modules. CHendi will look into this.
- We will meet in two weeks, on April 1st, due to the A1n/d2n collaboration meeting on March 25th.
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- We shifted the meeting time this week by one day to avoid conflict with the SoLID Science Review.
- Participants: Mengjiao, Ye Tian (Syracuse), Cunfeng, Jianping, Jixie, Alexandre C, Paul Reimer, David Flay, Xiaochao Zheng
- Cunfeng gave a quick update from SDU side: (1) still testing irradiated fibers; (2)contacting Chunhui for the connector design and testing plan, and possibly design for fiber to PMT coonector; (3) will also look into LED monitoring system design.
- Ye (Syracuse) presented simulation for the test data, see ECAL_beamtest_03112021.pdf. Notes:
- Setup includes 3 Scintillator planes in size 10x10x0.645cm;
- pion spectra do not look right;
- with R=4cm beam the energy resolution is 7%/sqrt(E) plus 0.5% plus 4%/E in quadrature when beam hits center of 3 modules;
- Effect of beam size: with beam hitting center of one module, for beam size R=4cm to 6cm, dE/E increases by 3% absolute. Will provide more results next week.
- Jixie presented progress on FTBF test data analysis, see solid_ecal_test_status_update_20210311.pdf that includes MWPC cluster finding and module calibration. Notes:
- SHould we use MIP or electron peak to calibrate the shashlyks? Answer (JP): MIP is the one we should algin. electron peak has all compliications (energy leak onthe side/back, beam size, etc).
- Could add Cherenkov cut to select only pions for calibrating the preshowers (since MIP peaks there are more spread out by electron energy deposit);
- Once E is higher than 6GeV, energy leak in the back of module becomes significant and not easy to calibrate or analyze.
- When aligning MIPs, main peaks are not aligned. This indicates error in pedastal determination. Need to look into this. Unfortunately we did not take any "cosmic" data (triggering by FTBF Scintillators only);
- Discussed algorithm for MWPC cluster identification, recommend selecting only the "cleanest" event to analyze and do not waste time to select "gems" from the sea of multi-cluster events.
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- Participants: Mengjiao, Ye Tian (SDU), Ye Tian (Syracuse), Cunfeng, Jianping, Jixie, David Flay, Dong Liu, Xiaochao Zheng
- Mengjiao presented the fiber radiation test, see 1_fiber irradiation test.pptx. Some highlightes:
- clear fibers are tested from E11 to E13 MeV/cm2 (neutron equivalent), BCF91A tested between E12 and E14 MeV/cm2 neutron radiation level. Note: 1-n-MeV/cm2 approx= 3.3E-11 Gy and 1Gy=100rad, see Lorenzo's talk at ...
- light yield loss is about 3% for 9.2krad, and 8% for 121 krad.
- Jixie showed calibration data from FTBF test. Beam size was about 6cm diameter. Notes:
- Rough calculation of electron Edep over MIP is factor 25, data about 14000/1000=14. Possibly energy leakage on the side (large for the large beam size) and back (small).
- It appears SDU4 is better than SDU4 and THU2, but in light yield, SDU5~THU2 both better than SDU4, so does not look like light yield is a direct factor here. Also note that for 14 times 570 (p.e. for cosmic) gives 8000 p.e. or 1.1% which is negligible.
- Noted the beam energy itself has a 3% spread, or 1.5% for smaller beam sizes.
- Need comparison with simulation for the exact same condition, need adding preshower to shower, need cutting on beam position -> next week.
- We discussed other things for optional RandD, including LED system (ref CLAS12).
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- Participants: Alexandre Camsonne, Chao Peng, Jixie Zhang, Zhiwen Zhao, Xiaochao Zheng
- Chao presented basic info on the Hall C Cherenkov Test from 2020 d2n run:
- Used HERA-B blocks, some 11x11 some are 1/4 small. These blocks are gain-matched but not calibrated;
- low rate test had 15kHz/cm^2 and high rate at 200 kHz/cm^2 single p.e. rates. These correspond to 4.8 MHz/PMT, dominated possibly by low-E electrons. SoLID SIDIS will have threshold cut below MIP for hadron trigger and expect 2-4MHz per PMT rate. Thus the rates are comparable but particle type may not be.
- For small angle test, scintillators were completely useless (they are about 1in wide and 2ft? long so smaller than our SPDs). Not sure where the ECal trigger threshold was set but it was higher for the small angle run.
- Zhiwen: ECal high rate more a problem for SIDIS (needs hadron trigger). For PVDIS or electron trigger, will trigger at 1 GeV at large theta and 3-4 GeV at small theta so not as problematic.
- Discussion of possible high rate effects (Chao):
- non-linear response to energy deposit -- this is possible if PMT power supply can't provide the high current needed. For Hycal (PRAD) for example, 12C runs had the linearity problem because the current booster was not working well. Heard Hall C calorimeter had similar problem -- nee follow up.
- Radiation damage
- pile-ups -- this is where Hall C test can be useful, provided the backgrounds are similar to SoLID. From the event Chao showed, there wasn't serious pileup problem.
- Immediate to dos from today:
- Zhiwen will provide simulation of the particles (rate, energy, type) for the front face of ECal for Hall C test and compare with SoLID test;
- We noted there were random trigger data at small angle (i.e. not all data had ECal high-threshold triggering), Chao will look into that data;
- Could we find rough calculation of FADC amplitude -> Npe? (rough gain would be sufficient) -- Chao
- From Chao: Can we have PRAD 12C rates (and what particle type), HyCal size and PMT and HV module type, so we can look into nonlinearity problem?
- Discussed also about FTBF test
- position of hit can be calculated as the block center weighted by signal amplitude. This should provide a rough cut to help with MWPC tracking.
- Chao has a generic cluster recon script that could be useful
- Here are slides from Jixie: solid_ecal_test_status_update_20210217.pdf that contains TDC hit patterns of MWPC (some indicates the typical chamber behavior which is multiple wire hits), and scope snapshots of both preshower and shower signals.
- Bucket list for R and D:
- need digitization of GEMC outputs to simulate FADC spectra (Hall B has a template, see https://github.com/gemc/source/blob/master/hitprocess/clas12/ecal_hitprocess.cc and https://github.com/gemc/source/blob/master/hitprocess/clas12/ft_cal_hitprocess.cc
- The above may be particularly useful for SPDs (FASPD has very low light yield) and preshower.
- need MAPMT and PMT base design, prototyping, and tests - can start after Science review (CD0);
- need a practical shashlyk module support, and need design for Preshower and SPD mounting/suppport system; need integrating all to SoLID structure.
- need design for LED monitoring system;
- need to develop calibration procedure;
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- Participants: David Flay, Jianping Chen, Alexandre Camsonne, Ye Tian (Syracuse), Jixie Zhang, Xiaochao Zheng
- Some progress on the analysis following last week's to do list, see slides solid_ecal_test_status_update_20210211.pdf.
- Looked at CHerenkov integrated spectra again. Jianping suggested the multiple peaks are either the real single, double, photoelectron peaks, etc, or could be reflection of the single p.e. peak. Regardless, we don't need to dive too much into this detail. Out of the 3 channels, 1 seems to be working well. The other two do not. Suspect we lowered the N2 pressure too much. Jianping's estimation is that 3psia is ideal for 16 GeV pi/e separation. We changed from 5 psia to 0.8 psia for the Up chamber and left the Down chamber at 0.2 psia. The 0.8 psia seems to be the only good channel. The 0.2 psia probably only gives 2 p.e. for electrons (need exact calculation if we want to be sure, but not important now). Note: The GC is 3.5m long (total of two chambers), each 1.8m long, the Up chamber has one PMT and the Down chamber has two PMTs.
- No progress on cluster-finding or track-finding algorithm.
- To do list for analysis:
- Ask for the exact TDC module (?ns/channel)
- check if the 3 Cherenkov channels are swapped; look at the run before we changed the pressure and compare all 3 channels. This should tell us if we labeled the channels incorrectly.
- look at the run before we changed the pressure and compare all 3 channels. This should tell us if the Up chammber had more photoelectrons before we lowered the pressure.
- Change the cut when studying Cherenkov signals to: cut on two Cherenkov channels and look for the spectrum in the 3rd. Do this for all 3 channels. For ch3 the cut can be at 250. For the other two, need to cut just above the one-photon peak or even rejecting only the zeros (cutting just above half of the single photon peak, for example).
- plot MWPC events (the cluster pattern) and see if there is a clear strategy for track-finding.
- For above, can even try cutting on the Ecal total sum to see if it helps with cleaning up background or noises.
- For calibration, Jixie mentioned need Ye's simulation to study the absolute calibration from FADC channel to GeV. But as a first step can simply align the main peak from all 3 blocks (i.e. soft gain-matching). Keep in mind even when the beam hits the center, the energy absorption is not 100%.
- To address the high-rate ECal performance comments form the Director's review, we will need to check the 2016 Hall A data (open floor during DVCS, no prelead), and the HERA shashlyk data during the 2020 Hall C Cherenkov test run. IF these data are not enough then we need to plan for a high rate test, but it will be very difficult to do during SBS.
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- Participants: David Flay, Paul Reimer, Alexandre Camsonne, Ye Tian (Syracuse), Jixie Zhang, Xiaochao Zheng
- Beam test using the Fermilab Test Beam Facility (FTBF) was successfully carried out from Jan. 13th to 27th. Summary of electron trigger statistics is given in SoLID elog3864653 (this does not include the last day's of 120GeV proton beam data). Pictures and daily reports can be found at https://redmine.jlab.org/projects/solid-ecal/wiki/Daily_Reports. A one-slider showing the FTBF MT6.2 setup was made by David: ecal-setup_ftbf.pdf.
- Jixie presented summary and current decoder status, see solid_ecal_test_summary.pdf. Notes:
- Regardless of trigger intensity given on the FTBF website, actual trigger rates if using MWPC never exceeded 15k/spill (1 spill per minute). Need to take this into considration for future test planning.
- Found and fixed a problem in MWPC decoder that shifts one event from one spill to the next.
- TDC spectra of MWPC wires have double peaks. Paul suspect these are from two differnet buckets (19ns apart), but hard to tell without knowing TDC channel unit (they look 24 channels apart). -- to be solved.
- MWPC1 typically has 5 hits in x and 5 hits in y, MWPC2 typically has 2 hits each in x and y. Some cluster finding algorithm is needed to find the track and clean up background. - Jixie will contact Evan and other groups using FTBF to see if there exists something we can use.
- The integrated FADC amplitude spectra need some understanding. Scintillator, preshower and shower channels look fine, but the trigger and the 3 Cherenkov channels have multiple peaks that appears from digitization (they do not look like single, 2-, and 3-photoelectron peaks.) - to be solved.
- Comparison of ECal and MWPC DAQ event count shows ECal is always missing events. 2-3 events for some runs and about half events for some others.
- To dos: Jixie will collect more info on MWPC TDC spectra shape (and input file format and usage) and cluster-finding algorithm; Alexandre will look into ECal DAQ event decoder to find the missing events. Once we know more what we can already use, we can start dividing the tasks more specifically. We will regroup at 12noon (eastern) on Thursday Feb. 11 and go from there.
- We also discussed preshower mounting, how to guide out and protect the fragile WLS fiber, etc. ZHiwen pointed out that: clas12 forward tagger hodoscope use WLS fiber in scitilator. It solves similar problem in a much small size. see page 72 of their 2012 TDR
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- Participants: Yimin Hu, Steven Lu, Xiaochao Zheng
- suggestions: liquid light guide? Some company may be willing to develop large-diameter ones for SoLID.
- DDK connector/fiber polishing: very time-consuming work. Need to revisit manpower need/cost.
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- Participants: Dong Liu, Xiaochao Zheng, and others
- Discussed a plan to use X-ray machine to test radiation hardness of PMMA fibers, see Attenuation%20length%20of%20the%20Nanjing%20clear%20fiber%20and%20the%20irradiation%20test%20plan.pdf. The method may not work though, because the emission of the X-ray is very narrow and it also may not represent the radiation of SoLID.
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- Participants: Dong Liu, David Flay, JP, Jixie, Paul R., Ye Tian, A. Camsonne, Xiaochao Zheng
- Mengjiao showed more fiber connector test results, see Fiber connector light loss test and BCF91A fiber.pdf. The relative loss for low Npe values plateaus at ~33% for Chunhui's polishing and ~22% for SDU polishing. These values are still on the high side compare to published losses by Minerva.
- SDU received the BCF91A-MC fiber replacement from S.G. (and shipped from UVA). Testing shows 25% higher light yield than BCF91A-SC fibers. The new fibers have diameter 1.06mm (vs. 1.00 mm of old MC or SC fibers) but this should not be a problem for module assembling.
- Jixie on test lab status: vertical test of shashlyk is fully setup. DAQ is still being worked on by A. C., shashlyk modules are all fine, but 2 of the preshowers appear to be very noisy - will replace PMT by new ones provided by the techn when available; lead bricks are still not received (XZ will inquire); XZ brought two more preshower modules and some new Y11 fibers, polishing papers from UVA, can use to repair the preshower or use as backups;
- Discussion of FTBF: how do we match events between MWPC and our DAQ? Paul mentioned they use synchronized "spill#" and "Event#". SHould we send our DAQ trigger back to MWPC DAQ for recording the event #? How is Cherenkov signal provided by FTBF? Are our trainings complete and sufficient for the January visit? Do we need to prepare for 2-person operation (for setting up the DAQ)?
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- Participants: ??
- Update from SDU, see 20201108 update from SDU.pdf. Tested light loss of fiber connector for different Npe. Observe a linear decrease in relative loss vs. Npe. This can be problematic because our actual light per fiber is only a few Npe. Need to test loss for low Npe values
- We discussed the module support structure because SDU woul dlike the next module to be used for the actual SoLID setup. Xiaochao sent the meeting minutes to Dong for reading.
- Also discussed a plan to test PMAA clear fiber's radiation hardness using a X-ray machine at SDU. Xiaochao will send radiation dose of SoLID to Dong Liu.
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- Participants: Dong Liu (SDU), Mengjiao Li, Cunfeng Feng, Jianping Chen, Xiaochao Zheng, Jixie Zhang, plus others
- Discussed test lab ECal setup status: Jixie fixed the scintillator (one side glue is broken), see this pic; still waiting for hardware to set up the DAQ.
- Regarding FTBF test, how do we use their Cherenkov?
- Mengjiao showed more of fiber connector test results, see fiber connector.pdf
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- Participants: ??
- SDU update from Mengjiao: fiber%20connector%20light%20loss%20test.pdf
- Re-tested fiber connectors with optical grease, DDK connector showed 24-32% loss, only about 5% better than without grease (see last week). This is still large. The fibers were polished by CHunhui company and may not be high quality. Polishing by machine at SDU showed comparable loss. Suggest polishing "by hand".
- S.G. team informed me they will ship replacement fibers.
- Note that other experiments: Minerva, CMS HCAL (see this CERN document hep-ex/0102031.pdf) used clear fibers (BCF98 from S.G. or the Kuraray fibers), which were measured to have attentuation length of 4-5m (SG) or 8m (K).
- Note: The Minera DDK test results were for combined loss of DDK connector and fiber attenuation. They also used optical cement (not grease). Vince's test from 2016 also showed ~30% loss for optical grease but smaller (~20%) loss for optical cement.
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- Participants: ??
- SDU update from Mengjiao/Ye/Liping: SDU6_fiber_connector.pdf
- SDU6 test result: Npe=811-833 (PMT HV dependent), used Y11-MC, Kedi enchance, ESR film for both layers and fiber ends, TiO2+glue for side coating. These have been added to the table above.
- Tested fiber connectors: DDK connector showed 29%-36% loss. This is large. The test did not use any optical grease and may be the reason for high loss. The commercial connectors show 25% loss. Will retest with optical grease.
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- Participants: Jianping Chen, Linmao Li, Cunfeng Feng, Paul Reimer, Jixie Zhang, Ye Tian (SDU), Xiaochao Zheng
- SDU update from Mengjiao: studied the PMAA-core clear fiber from Chunhui, see SDU_fibertest_20200909.pptx and the company website http://www.china-light-guides.com/product/17.html. Preliminary test using a 5-m sample shows attenuation length greater than 20m. This is promising, and we should look into testing it with the prototype module and a price quote for mass production.
- Xiaochao: much have happened on communications with Saint Gobain: met with S.G team (4-5 people) on 8/19, and followed up by emails. Latest responses are:
- While the shipment was found to be MC fibers, latest check with quality control found that batch of MC fibers did not meet the quality standard and should not have been shipped to customers.
- It is normal to not see two "peelings" under the miscroscope for S.G's MC fibers, because they used a different process from Kuraray.
- S.G. agreed the attentuation length of clear BCF98 is at 4m level. They pointed out that the latest product manual/brochure no longer list the 10m or the dB/m graph we used to inferred the 10m attenuation length.
- S.G. mentioned they are willing to with with customers on the cost of their fibers, and we can provide a "target price" based on our budget.
- S.G. has suggested we use PMAA-core clear fibers in place of BCF98 (note PMAA is the same material Chunui is using). Still working on this.
- Still working on getting replacement fibers for BCF91A-MC.
- Xiaochao on FNAL test:
- Received email from FNAL that we are given one week from Dec. 9-17, for our ECal test. Working with DAQ group (A.C.) on getting the DAQ sytem needed. The idea is to get the current SoLID Cherenkov test DAQ from Hall C as soon as the run is completed, set it up in the test lab, test out the full system (3 preshower, 4 shashly), and move to FNAL at least one week in advance of the test to set up there. Nilanga has agreed to help (Xinzhan will contribute if he gets OPT in time), and Kondo may help too.
- Need prelead layers - X has contacted D.Higinbotham, also FNAL.
- Need to work on paper work.
- No update from Paul R. yet on the supporting design.
- We discussed about next prototype, SDU7, can use BCF91A-MC (with the correct quality), and with PMT directly coupled first, then connect to 4m of PMMA-core fiber and test light yield again.
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- Participants: Jianping Chen, Linmao Li, Paul Riemer, Jixie Zhang, Wang Yi, Yancheng Yu, Ye Tian (SDU), Ye Tian (Syracuse), Xiaochao Zheng
- Yi mentioned the NICA Ecal module production has now started at THU. These are 4x4cm square modules with 0.3mm lead, ?? mm scintillator, readout is by 6 Y11-MC fibers of 1.2mm diameter. Tests using 1-5 GeV electron beams showed Npe~4000 at 1GeV. Not sure what Npe for cosmic is (need ask Chendi). We (SoLID Ecal group) would like to hear a full presentation on this from THU: NICA ECal design, performance/test results, and simulation. Yi mentioned Linmao's ECal simulation includes also light propagation and trapping and we need to learn how this is done. A postdoc (Huang Yan) is more involved in the NICA physics simulation.
- We discussed ECal simulation and decided 3 to do items:
- Linmao sends simulation code to Ye (Syracuse), and Ye will study how light propagation is done and give a report;
- Ye (Syracus) will send her SoLID ECal modular code to Linmao and see if she can improve it.
- We would like to know Linmao's simulation results for the NICA Ecal module and a comparison with THU's test results, for both cosmic and electron beam tests.
- Ye (SDU) reported preliminary cosmic test for SDU6 prototype, see SDU6_pre_Ye.pdf which shows a preliminary cosmic response of Npe=813 or 875 (PMT HV dependent, need further checking). This is the highest yield of all SDU prototype modules! Also showed a simple calculation to estimate electron response (same as what Xiaochao did) using a SoLID ECal sampling ratio of 0.24. Latest sampling ratio from Ye Tian (Syracuse)'s simulation is 0.2284. Some reference on ESR reflector can be found under today's subdir.
- Xiaochao checked emails from last year and found from Kuraray, a comparison of Y11 vs. BCF91A performance: 190822 Reference for SoLID Jlab.pdf and a quote (under the same subdir). Discussions:
- These data suggest Y11-SC is better than BCF91A-MC and that the initial light yield of Y11-MC is only 20% higher than Y11-SC (rather than 5% vs. 3% based on trapping efficiency). Contacted Kuraray again to inquire why Y11-MC has similar light yield as Y11-SC, as well as if they have data on BCF91A-SC and clear fibers. Have not heard back from them.
- Ye Tian (SDU) commented that his test results show Y11-MC to be 40% higher than BCF91A-SC. THis is not inconsistent with the Kuraray data though there is no direct comparison.
- Xiaochao will talk to Saint Gobain people (with their technical team) to discuss these findings on the fiber. Had hoped to have scheduled the meeting by now but have not heard a set time yet. Will use the new slides from Ye: MC_fiber_problem_Ye_new.pptx
- We will change ECal meeting to 8:30am US EDT on Wednesdays starting next week.
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- Participants:
- Ye reported checking the fiber cladding under a microscope and did not find double cladding, see MC_fiber_problem_Ye.pdf
- Ye reported latest results on attenuation length, see Fiber_attenuation_length_Ye_07302020.pdf. It is still ~4m for BCF98. Results for BCF91A-SC shows ~3m and is only slightly shorter than the brochure specification. Also reported SDU6 is fully assembled and being tested; Found a commercial fiber fuser and may try it out.
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- Participants: Ran Wang (SDU 王冉), Cunfeng Feng, Mengjiao Li, Jixie Zhang, Ye Tian (SDU), Jianping Chen, Xiaochao Zheng
- Ye reported more on fiber tests, this time in a latex report, see YeTian_07162020_fiber_test.pdf
- For testing light yield, the results are not affected by the PMT/fiber gap as long as it is less than 3mm.
- Table 2 on fiber polishing is based on BCF91A-SC. Will test the other fibers next.
- Fig.4: the polishing reported in this figure used the 1um diamond abrasive paper (see Fig.3).
- For LED+WLS fiber test, need to know wavelength of the LED.
- FIg.7: need to add wether these are tests on SC or MC fibeers (though it may not be important now, see below)
- Table 4 and Fig.8: It appears the test results for both preshower light yield and the attenuation length are similar for BCF91A-SC and BCF91A-MC. Need to look into whether the new MC fiberes are actually MC or SC under a microscope.
- Discussion on materials: Cunfeng commented the ESR is very difficult to use for the reflective layers in the shashlyk, because it's easy to tear. But okay to use for wrapping shashlyks if double-layered.
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- Participants: Ran Wang (SDU 王冉),Ye Tian (SDU), Jianping Chen, Paul Reimer, Alexandre Camsonne, Xiaochao Zheng
- Ran reported on restarting clear fiber attenuation test, see fiber%20attenuation%20length%20test%207-2-2020.xlsx. The first 2-3 points are promising (they seem to indicate long attenuation length), but the rest of the data points show large decay that do not follow the expected exponential loss behavior. We suggested debugging the measurement to see where the problem is. We also asked to keep a record of the WLS fiber lengh that is connected to the clear fiber, and what type and length of fiber was used for the LED stability monitoring.
- Paul reported having received all drawings from Vic. Has been sorting these drawings in preparation for handing them over to the engineering team at MEP.
- Ye presented a plan for the next SDU module: 1) The WLS fiber will be Y11-MC (from Xiaochao some years ago). Although we just shipped some BCF91A-MC to China, these WLS fibers were prepared a long time ago so we will use the prepared Y11-MC this time, and leave the BCF91A-MC next module; 2) The fiber end reflector will be a full sheet of ESR reflector glued to the fiber ends prior to inserting and compressing. Ye showed a picture where the WLS fibers ar already glued to a few layers of scintillators. 3) The reflective layer between lead and scintillator will be ESR sheets. Although the ESR is expensive for this prototype, earlier tests from 9/5/2019 showed it can provide 2/3 higher light yield than power-painted lead sheets. If the light yield from the new prototype (SDU6) is indeed higher, then we can look into lowering the price of ESR for mass production.
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- Participants: Cunfeng Feng, Jixie Zhang, Ye Tian (SDU), Chendi Shen, Xiaochao Zheng
- Ye reported on THU2 test results with both THU PMT and SDU PMT, see THU2.xlsx. Trust more the later test results using SDU PMT, Npe is about 570-580. Gain of PMT is tested by Jinan studen Hong Yuan, may have covered only center of PMT area but center/edge difference should be only a few percent. Prevous results using THU PMT was about 750. In this test found THU PMT not in good condition (HV divider is not stable?).
- XZ: Looks like there is not a lot of progress in solving the Npe difference between all SDU and THU modules. Next, will ship multi-cladding Saint Gobain fibers to SDU and THU and assemble more prototypes, as well as testing performance of the multi-cladding clear fiber (attenuation length, light loss when connecting WLS Multiclad to clear multiclad fibers through the Fujikura connector; readout of Npe with all 100 WLS fibers connected to 100 clear fibers).
- Also SoLID group is planning to test the LGC prototype in Hall C in early 2020. We should consider adding 3 shashlyk modules. SDU2 module and the preshowers should still be at JLab. (SDU1 is at Argonne and THU1 is back in China). We should ship 2 or 3 newer prototype shashlyks to JLab soon.
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- Participants: Cunfeng Feng, Jianping Chen, Jixie Zhang, Ye Tian (SDU), Chendi Shen, Xiaochao Zheng
- Ye reported on THU2 testing results, see SDU_EC_09192019.pdf. Npe seems to vary between 600 and 900 depending on which PMT is used. Will continue testing/studying.
- Xiaochao ordered Saint Gobain MC fibers using this quote: QUO-51694-L2G8F2.pdf.
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- Participants: Cunfeng Feng, Jianping Chen, Jixie Zhang, Ye Tian (SDU), Chendi Shen, Xiaochao Zheng
- Chendi: sent THU2 module to SDU, SDU has just received it.
- Ye reported on clear fier test (BCF98 SC), see resuls here: EC_09052019_SDU.pdf
- Tested ESR vs. powerpainted lead layer. ESR seems to be much better (2/3 higher)
- WLS bending test: Y11-MC shows visible (1%) loss at bending diameter 7cm, but not much more at larger diameters. BCF91A shows large 5% loss at 10cm and 7% at 6cm. Not a terrible loss overall.
- Clear fiber loss test: about 2.3m. (Need to record type of fiber).
- Need to repeat bending loss on clear fiber first (length too long and is mixing bending with attenuation losses;
- (JP) fiber end coupling needs to be stable and careful.
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- Participants: ??? Chendi Shen, Ye Tian (SDU), Liping Wang, ianping Chen, Jixie Zhang, Xiaochao Zheng
- Xiaochao collected information on fiber focusing on single- vs multi-clad. Here is a quick summary:
- Saint Gobain fiber: SC trapping 3.44%, MC trapping 5.6%.
- Kuraray Y11 fiber: SC trapping 3.1% with cladding wall thickness T=3% of D (diameter) for round fibers; MC trapping 5.4% with cladding 3%+3% of D.
- Kuraray clear fiber is called clear PSM, not sure if it's available in SC or MC type.
- The above means if we connect multi-cladding WLS fibers to single-cladding clear fibers, there can be loss due to different trapping efficiency (~40% loss). XZ emailed Kuraray to confirm this, and also requested quote for 520km of MC BCF98 clear fiber from Saint Gobain. Need to test connector quality for WLS-MC to clear-SC vs. WLS-MC to clear-MC.
- Existing fibers at UVa: (known) ordered S.G. BCF91A and BCF92 in Jan 2014 cost $2049.62, need to find the quote or purchase record though; ordered Y11(200)MC 500m (min order quantity) cost $3,490.00. Shipped most of Y11 to China for module assembly. Used Y11 for preshower module and hedgehog study at UVa in 2013-2014. Need to check: (1) did we have clear PSM fiber samples from Kuraray? (2) type of fiber used for connector tests in 2014?
- Existing fibers at SDU: 2016 order should be BCF91A-SC, should also have Y11(200)MC from Xiaochao. Need to check what were used in the recent fiber connector and clear fiber attenuation test.
- Existing fibers at THU: should have 20m of BCF98-MC sample from S.G. that Xiaochao requested to be sent to THU in 2017; need to check what was used for THU shower prototypes. Need to check what were used in the clear fiber attenuation test in 2017.
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- Participants: Chendi Shen, Ye Tian (SDU), Liping Wang, ianping Chen, Jixie Zhang, Xiaochao Zheng
- Liping presented test of light loss in DDK fiber connectors using silicon grease, see her slides: light loss from green fiber to white 7-11-2019.pdf. Some notes on the slides:
- With grease the loss appears to be reduced by 20% (relative) compare to air gap only coupling (see last meeting).
- The DDK connector has 10 holes and all have fibers in. However, fiber in hole #7 is broken and results are not reported in the table. (IN other words, results for fibers 7,8,9 should correspond to hole #8,9,10).
- There is large variation from fiber to fiber. This is probably due to quality control of fiber polishing and how the connector is handled. I will post some references from 2016 in the next line.
- Chendi: Finished testing THU2 module and can reproduce previous results (Npe about 740). Chendi talked about optimizing the wrapping material (currently using Tyvek) but we objected it. This is because the goal of re-testing THU2 is to compare the test setup between THU and SDU (it is still puzzeling why all SDU modules have 50% less light yield than THU2 module). Thus we suggest Chendi ship/send the THU2 module to SDU without any modification.
- Reference on DDK connector handling and performance, from earlier EC meetings:
- See 2016/6/16 meeting minutes for documents prepared by Vince S. on how he used the DDK connectors at UVa. For earlier notes see 2016/3/17 minutes for notes (though less clear) from Howard Budd on how the connectors were polished/used for the Minerva/Fermilab experiments.
- To do items:
- SDU group (Liping and Ye) will study the references (above) and see if can improve fiber+connector polishing procedure and connection quality.
- Chendi will send THU2 module to SDU for testing.
- Xiaochao will contact WSU group to learn their recent development. (construction, fiber polishing, calibration, tuning, monitoring, etc.)
- Next we will meet on Thursday July 25th.
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- Participants: Chendi Shen, Ye Tian (SDU), Liping Wang, Cunfeng Feng, Jianping Chen, Jixie Zhang, Xiaochao Zheng
- Liping presented test of light loss in DDK fiber connectors. No coupling material was used ("air gap" coupling), see her slides:fiber light decay 6-13-2019.pdf. Some notes on the slides:
- On page 2, the WLS fiber length used is 0.6m, clear fiber about 0.4m.
- When testing the long clear fibers (1-3m), the fiber is not straight in the dark box (but the bending radius is large too).
- The main results are: attenuation length of clear fiber is determined to be about 4m, the loss of connector+clear fiber is about 36%. The loss due to connector itself appears to be about 29% (very high).
- Chendi: Still testing THU2 module. May send it to SDU next time
- We will not have a meeting on July 4th. Next meeting will be July 11th.
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- Participants: Chendi Shen, Ye Tian (SDU)), Liping Wang, Cunfeng Feng, Jianping Chen, Jixie Zhang, Xiaochao Zheng
- Cunfeng: no news about the CHinese funding application (so probably not a good news).
- Xiaochao: Asked Prof. An at IHEP again, here is his reply: "今年试验束估计得下半年（10月以后）开机了，开机前我会通知您和冯老师。"
- Chendi: Since we asked to test THU2 at SDU lab, chendi is testing THU2 again at THU. IF the previous result is reproducted then will send THU2 to SDU for testing.
- For next meeting: see notes below table above, another company for scintillators (Chendi)??
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- Participants: Seamus Riordan, Chendi Shen, Liping Wang, Ye Tian (SDU), Chendi Shen, Jianping Chen, Jixie Zhang, Xiaochao Zheng
- Report from SDU group on the test results for SDU4 and SDU5 and fiber end reflectors. The best material for fiber end coating is called "ESR white tape" and has been applied to both modules, see EC_05-16-2019_SDU.pdf. With the module sides painted and fiber ends also coated, the yield is about 563 for SDU4. SDU5 has fiber ends coated but sides only wrapped in 1 sheet of reflector, which now gives 398. Overall these are within expectation, and only THU2 seems to give a yield (750 or above 1000 depending on which PMT gain we trust) that is much higher than modules using similar (or nearly identical) materials and technique. THe module "master table" has been updated accordingly.
- Seamus sent out his estimate on the ECal support frame, see CostEstimate-ver1.xlsx and ecsupport_estimate_may2019.xls. Some numbers are estimated using the expected coverage area (the cost simply scales with area, to the 0th order). These are just in time for the WBS cost estimate.
- Chendi reminded us that silver tape is much better than silver shine from his tests.
- Need to get an update on the Beijing IHEP test beam status.
- Among all modules, only THU2 seem to have much higher yield than others. We would like to see what the light yield would be if THU2 module is tested in the SDU lab. (So we can be sure that the problem with the PMT gain is out of the picture).
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- Participants: Seamus Riordan, Chendi Shen, Ye Tian (Syr), Jixie Zhang, Xiaochao Zheng
- No report today.
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- Participants: Jianping Chen, Ye Tian (SDU), Cunfeng Feng, Ye Tian (Syr), Liping Wang, Yu Bo (SDU), Jixie Zhang, Xiaochao Zheng
- Yu Bo (an undergrad who just joined the SDU test group) reported updates from the SDU group, see SDU_Updates_041119.pdf. First, re-blued PMT-fiber for SDU3, but found it didnot affect light yield. So the 10% drop from last year is still not understood. Then reported results on SDU4: about 250-260 with no side treatment, and about 350 with sides wrapped loosely in Tyvek. Fiber ends had no treatment for both numbers, thus these numbers can be compared directly with SDU1 performance (original Kedi scintillator, Npe=224 with sides wrapped in Tyvek) and is consistent with scintillator light yield improved by 60% from the original to the current/improvement batch. Next step is to test SDU5, replace fiber with fibers with mirror plating, paint the sides, and do horizontal test of SDU3/4/5 together. Stay tuned!
- Jianping reported briefly on SoLID status: JLab is now occupied by other projects. SoLID review possible in June but mostly we are awaiting for lab scheduling, collab mtg will be one month prior; we need to keep up-to-date on the support design; engineering design needs to be finished within the first 2 of 5 total years.
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- No meeting last month due to Chinese new year/winter break; Also a few of us were occupied by the funding proposal work (submitted!).
- Participants: Ye Tian (SDU), Cunfeng Feng, Ye Tian (Syr), Liping Wang, Chendi Shen, Xiaochao Zheng
- Liping reported initial cosmic tests on SDU modules. First step is to determine what shreshold to use for the DAQ and to reproduce previous SDU3 test results. See her report threshold%203-28-2019.pptx. Main conclusion is SDU3 is found to have Npe=450 at 4 different HV values (good!), while previously was tested to give 490 (we could claim consistency, though light yield is 10% lower). Threshold was determined for all modules: SDU3, SDU4, and SDU5.
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- Participants: Jianping Chen, Ye Tian (SDU), Cunfeng Feng, Ye Tian (Syr), Liping Wang, Seamus Riordan, Xiaochao Zheng
- Seamus reported meeting with Vic and Paul last Thursday, discussed how to come up with a rough cost for PS/SPD support;
- Next round of Chinese funding proposal application is due by end of Feb. 国际合作is the only thing we can fit in, but chace is very small based on prior experience.
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- Participants: Ye Tian (SDU), Cunfeng Feng, Ye Tian (Syr), Liping Wang (王利苹), Xiaochao Zheng
- Ye an Liping Wang (SDU) reported working on SDU4 and SDU5, see EC_01102019_SDU.pdf. In particular, reported on a reflective tape 3M ESR, reflectivity tested to be above 90%.
- Chendi reported preparing for new THU module. Plan to us silver tape for fiber end.
- We discussed whether it's possible to use front plates with holes. With holes, the tapes can be added after inserting the fiber. chendi suggested we could have double-plate design. Need to think about this more.
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- Meeting shifted to Wednesday so we don't have to work during X'mas break.
- last week's meeting cancelled due to snow in Virginia.
- Participants:
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- Participants: Ye Tian (SDU), Cunfeng Feng, Seamus Riordan, Yelei Lee, Chendi Shen, Botao Wang, Jianping Chen, Xiaochao Zheng
- Ye (SDU) reported on fiber end tests: FiberMirror_Ye_12062018.pdf
- Shanghai's silver painting has been retested and results good, but cost ~50RMB/fiber, prohibitive.
- Yantai's cost (600-700)RMB/50 fibers, too high! And results are not uniform among samples: batch 1 (48-62)%, batch 2A (63-78)%, batch 2B NG, batch 3 NG
- Overall, we concluded we should not pursue factory-processing of the fiber end: either the cost is prohibitive (shanghai), or is lower but results are not good. Should focus on DIY from now on (such as Italian silver shine or other material, painted on fibers by hand).
- We discussed what to do with the Chinese funding proposal. We suggested Prof. Feng to talk to Prof. Liang Zuotang and find out what happened in the previous year. If we don't gain extra knowledge then we shouldn't waste time to re-work it.
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- Participants: Ye Tian (SDU), Cunfeng Feng, Yelei Lee, Jixie Zhang, Botan Wang, Chendi Shen, Jianping Chen, Xiaochao Zheng
- Reply from Beijing IHEP on beam status: "高能所试验束最近一年在做激光康普顿背散射改造，所以一直未提供用户实验，如果顺利的话，明年6-7月左右可以提供用户实验，到时候我会提前通知用户，谢谢！
祝好！"
安广朋 (11/19/2018)
- Botan Wang (THU) reported on reflective layer test: 20181129_Botan%20Wang.pdf
- THU3 and SDU4 will use "new smooth" and THU2 used "old smooth", but this company in Beijing may close soon. Plan to use the Nanjing company. The samples labeled "Nanjing thin" and "thick" gave results as good as "new smooth" and "old smooth".
- need better thickness data for "Nanjing thin sheet". The samples received were done by hand and not so uniform;
- need to test thin Tyvek too. "thick Tyvek" is too thick.
- need cost
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- Participants: Ye Tian (SDU), Seamus Riordan, Yelei Lee, Ye Tian (Syr), Jixie Zhang, Chendi Shen, Xiaochao Zheng
- Chendi: received power-painted lead plates, waiting for SDU to send fibers, then will assemble two modules, one with
- Ye (SDU): reported on the new silver-mirror for fiber ends using a factory in Shanghai and compare to the already-used factory in YanTai, see EC_fiber_mirror_11012018_Ye.pdf
- Shanghai: Quality is really good (light yield increases by about 90% from test 1 and 70% from test 2) but cost is very high. Ye mentioned he reported on this for only 3 fibers about 2 years ago.
- Also tested the other company used before (in YanTai), using test method 2, it has lower reflectivity than the Shanghai fibers.
- Using method 2 the results for Shanghai fiber is only 70%, 20% lower than method 1 (just after fibers are plated). COuld this be due to different methods being used, or due to oxidation of silver???
- As a comparison, Chinese SDU quote includes only 100 CNY per module for silver plating.
- We suggested: (1) repeat test (method 1) for both types of fibers; (2) repeat test (method 2) for both types of fibers and with a focus on repetivity; (3) contact Shanghai factory to reduce cost and to avoid oxidation; (4) contact Yantai factory to improve performance (both reflectivity and adhesiveness).
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- Participants: Ye Tian (SDU), Alexandre Camsonne, Ye Tian (Syr), Jixie Zhang, Chendi Shen, Xiaochao Zheng
- In the past two weeks we discussed possible cost-saving for SoLID (in general, related to SPD and EC). Given that MRPC will not happen, Xiaochao will come up with a quick design of a second FASPD for TOF purpose. We need TOF resolution to be similar to LASPD.
- Chendi reported on test of fiber end reflectivity, see 20181018_shenchendi to repeat/confirm Ye's work previously reported on 2018/09/20. Materials being tested are silver paint, TiO2+glue, and the 3M tape (that Xiaochao bought from US and shipped to Ye at SDU). Found the 3M tape to be very good, need to find ways to fix it in position (Xiaochao mentioned Minerva exp glued the tape to their fibers -- optical glue of course).
- Ye (SDU) reported the group has moved the lab/equipment from Jinan to Qingdao, setting up the new lab now. Also reported the bulk polishing received from the vendor shows very good fiber end polishing quality.
- We need to followup on the beam status of Beijing IHEP.
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- Participants: Cunfeng Feng, Alexandre Camsonne, Ye Tian (Syr), Jixie Zhang, Chendi Shen, Yulei Lee (Li), Yan Huang (黄彦），Xiaochao Zheng
- Yulei reported test results on various reflective layers (for lead plates), see The Reflectivity Test of Different Material on Lead FilmSurfaces.pdf. Some explanations:
- on page 5, the "silver plated paper" was used for module THU1, "old smooth surface" was used for THU2 and SDU4, "new smooth surface" is being planned for THU3, and "thin Tyvek" will possibly be used for SDU5 and THU4. The "waterborne" material is a power paint material and is "水性材料" in Chinese.
- page 6, the think Tyvek reflectivity (0.80) was taking from a paper which describes the value 0.80 for 150um-thick Tyvek. Here the 0.80 number is simply used as a reference of comparison. The reflectivity of other material is assumed to be linearly proportional to the light yield. All tests here used the same set of WLS fibers. The connection betwen the fiber end and the PMT are untouched throughout the test. We asked whether threading the fibers through holes can damage the fiber, the answer is unlikely. Also in this table, the "lead only" data were collected first and the "black reflective paper" was taken the last. Both gave very low outcome.
- Chendi will followup with SDU to get more think Tyvek from them for assembling THU4.
- We discussed the evaluation of light yield using the "voltage only" method and using ADC+analyzing Npe. Chendi said the amplitude was so low that using ADC could hardly get a reliable measurement of the Npe. The voltage only method used here is much faster and easier, and should provide a reliable estimation of the actual reflectivity performance.
- Info for the beta source used is included in the slide, in case anyone want to cross check the voltage reading.
- Xiaochao will email Beijing IHEP to get an update on the test beam status.
- Ye Tian (Syr) mentioned she is doing simulation study of combining 3 module outputs into one readout (PMT), for the LAEC and the outer modules of the FAEC. This will reduce the cost possibly by a lot, but we have to wait for her results to see if it is feasible and how many channels we can save.
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- Participants: Ye Tian (SDU), Seamus Riordan, Jixie Zhang, Chendi Shen, Xiaochao Zheng
- Ye reported on tests/comparisons of different fiber end painting/plating technique, see EC_Ye_09202018.pdf. A few comments and summary:
- Batch 2 and 3 of the scintillator has similiar quality.
- For the four methods listed to polish the fiber ends (slide 4), #1 (top left) is the best but the cost is high (4RMB/fiber end), so won't be practical to use. #1 and #4 (bottom right) are the same company but the difference is #1 is to polish individual fibers and #4 is to polish fibers in bundles. The clear fiber of #4 in the picture is for illustration and is from another project.
- slide 4 (still): methods #2 and #3 are not good at all.
- slide 5 is the 4 methods for plating/painting: from left to right and top to bottom: "3M tape", some paint, silver metaling painting ink, and aluminum sputtering mirror. Top left (silver polyester film tape) was purchased from the US and the method is similar to the one used by Minerva (see prev mtg minutes), but no glue has been used yet; #2 and #3 are not good; #4 should be good (this is the method used by Fermilab) but not good here for whatever reason.
- slide 6 and 7, reflectivity test and results. The fiber length is about 10cm. The polishing methods are the above #1, #2, and #3. (#4 isn't available for WLS fibers yet). Some details that are important: For the 3M tape method, Ye tested the light yield without the tape first, then added the tape to the fiber end without removing the fiber from the holder, and then repeated the test. However for the fibers with silver painting, he tested multiple fibers first (such as fiber #5,6,7) for the "fiber company polished fiber", take all out, painted the ends by dipping them into the metaling ink, then put them back one by one to repeat the light yield measurement. We discussed this and most of us think this removal of the fiber from the holder adds large uncertainties. We suggested Ye to repeat the tests with the silver metaling painting ink without removing the fiber. The ink can be applied with a small brush.
- Besides repeating the test, we think that so far data show the tape and the metaling ink methods are the best for painting/plating, and the fiber company's bundled polishing is the most promising for module production. We need to wait for more data to confirm this.
- Chendi reported the following:
- Sent out lead plates for powder painting. (Ye asked to change the layer thickness of the powder painting since that seems to improve the reflectivity). Xiaochao asked for the exact thickness used by all existing modules (THU2 was 0.08mm "wavy" surfaces, then newer plates have 0.05mm smooth layers) and the upcoming modules. We should be able to accommodate 0.06mm (see simulation paper thickness).
- Next week, Yulei will report on powder painting results.
and suggested the following:
- To avoid scraping off the mirror ends of the fiber, the front end plate of the module needs to have fiber holes. The fibers then can be inserted from the front end. -- this will affect the support design (not the support plate itself though).
- Can we try TiO2+glue for the fiber end? - Ye already tested it, need to check minutes
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- Participants: Cunfeng Feng, Seamus Riordan, Jixie Zhang, Jianping Chen, Ye Tian (Syr), Ye Tian (SDU), Xiaochao Zheng
- Ye (SDU): found a company in Nanjing to polish 100 fiber ends at one time. So far the result is very good. Will report details next time.
- Jianping mostly talked about the request to reduce SoLID overall cost. For example what would be the outcome if the module size is increased 50%?
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- Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Jianping Chen, Jixie Zhang, Xiaochao Zheng
- No update from THU: waiting for lead plates. Chendi will also test THU1 within the month.
- Ye (SDU) reported that he has assembled module SDU5. Material used are listed in the table above. The module is now being compressed and WLS fibers will be inserted next. This module still use the flat front plate design.
- Xiaochao reported a meeting with Seamus, Paul R., and Vic from ANL, also with Jixie and Jianping, at 3:30pm on 8/15. We discussed the modification to the support plane and Vic agreed to make new drawings within the next 2-3 weeks. To do items:
- load analysis (Vic): what are the allowed ranges of the length for the empty space between the rod and the back support plane, and for the new spacer design? (see minutes from 7/31 for explanation).
- We will discuss with SDU group on the minimal clearance needed to assemble the module into the support structure. (this is determined by how much the fibers can be bent -- very little -- and how much the rods stick out from the front plate of the module)
- Jianping gave us an overview of the DOE SoLID review, held on 7/13. Important notes:
- ECal reconstruction should start now. We suggest Jixie look into this and develop a plan and a FTE estimate.
- Among R/D items, MAPMT for the preshower should be tested. We will talk to SDU group about this.
- We need to make sure the space needed for ECal support and readout exist (to do for Jixie with Whit).
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- Participants: Ye Tian (SDU), Cunfeng Feng, Jianbin Jiao, Jixie Zhang, Xiaochao Zheng
- The SDU group made a "mockup" module with the proper front plate and we tried fitting it in the support. Here are some pictures:
- module front plate: IMG_0022.JPG
- module back plate(s): IMG_0024.JPG
- fitting into the support structure (back): IMG_0025.JPG IMG_0029.JPG
- fitting into the support structure (front): IMG_0027.JPG
- fitting into the support structure (sideview): IMG_0028.JPG
- We proposed a few modifications:
- item 5 (backplate of module) in SOLID Module 3-22-2018.pdf: need to be flat on both sides, such that nuts can be tightened against this piece to keep the compression. (Right now there is no nut holding the compression against this plate. And if nuts are added to the rod directly, before the spacer, there is no way to tighten them after compressing the module because the wrench does not fit into the small space to turn the nut. Or have to use longer, custumized nuts and will increase cost). See for example IMG_0030.JPG IMG_0033.JPG for the current (not working) design.
- item 8 (spacer) in SOLID Module 3-22-2018.pdf: i.d. needs to be smaller to fit snug on the rods (dia 2.5mm).
- This is major: in order to mount the module in the horizontal (SoLID) position, we propose:
- Modules are assembled, compressed, and with nuts holding compression against plates 1 and 5. WLS fibers are cut to proper length and fitted to one side of the fiber connector, to be later fitted into item 7.
- Supporting front and back plates are in position first;
- Each module is lowered into the support structure, with module close to horizontal. Modules can be held by thin ribbons. Module front plate is inserted into the front support plate first (which will require the front end to be lowered first, below the backend, to allow space for the fiber). WLS fibers are carefuly routed and stick out from the holes on the back support plane.
- Then a spacer (hollow rod with inner thread) is inserted from the other side of the back support plate to thread around the rods (that stick out of the module).
- Nuts are added to the back of the spacer to hold it against the support plane
- Here is a sketch: (apologize for the sub-eng-standard illustration): mod_fitting.png
- In this case, item 6 is not necessary and will be replaced by the back support plane.
- We need a load analysis to make sure it is okay to transfer the module weight from the rod to the new spacer. What is the range of the new spacer length (blue item in sketch) and the distance between the end of the rod (green item) and the back support plane? (Vic?)
- Vic got quotes for the large support plane, see PO 18808.pdf and 040918 Module 1 Details.pdf
- We then talked about the possibility of 3D-printing some of the parts at ANL so the ANL group can better discuss/design the thing.
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- Participants: Chendi Shen, Ye Tian (SDU), Cunfeng Feng, Seamus Riordan, Jixie Zhang, Jianping Chen, Xiaochao Zheng
- The SDU group made the 7-module support structure, yay! Here is a presentation from Ye on the first trial of mounting the SDU4 module in the structure. Beam_test_support_SDU_ye.pdf. We discussed a few problems/questions. Clearly these all need careful or thorough study:
- The rod length of SDU4 is too short to fit in the support -- not a big problem for the beam test but for future modules (to use for the SoLID production), the rod length needs to match the support design. Or, if cannot find the proper rod length, needs to modify the support design.
- The support design includes the design for the module front plate, which should be used for the production. So far all prototypes are not using this design. -- not a big problem for the modules already assembled. But for future prototype modules should consider making them with Vic's front plate design so we can learn how well it works.
- Current there is a gap if mounting more than one module in the structure, between the modules. However, the SDU4 has not been wrapped. We need to know how much gapping should be designed into the support and the tolerance with the wrapped modules. This has to be from the SDU/THU group based on their measurement of the module lateral size after wrapping.
- What is the mounting procedure? -- please see minutes from the 7/17 meeting with Vic below.
- Xiaochao will arrange a meeting with Vic at ANL to figure out details of the support design before leaving for China.
- the meeting occured on Tuesday 7/17 (Participants: Vic, Paul R., Seamus, Xiaochao, Jianping). Discussions are as follows:
- First, Vic appreciates that we have made the support for the 7-module design. We can learn a lot from this process
- The basic mounting procedure that Vic envisioned is as follows: (1) the front support plate is laid horizontally. It should be supported from the corners (to not block any holes) and elevated from the ground. (2) Then modules (in the vertical position) are placed on top of the support plate one by one. The middle extrusion of the module front plate should go directly into the center hole. The six rods are inserted into the six smallholes. Then 6 nuts are added from below the support plane and are tightened. (3) Once all modules are mounted on the front support plane, spacers are added to the rods and the back support plane is mounted on all modules.
- We raised a significant problem with step (3): It will be difficult to align all rods from all modules with the holes in the back support plane at one time. (For the beam test there are 42 holes. For the final SoLID production, there will be 360 holes for each 12-deg wedge. THis is something we need to continue working on.
- Jianping really would like to use some kind of adjustable (not fixed-length) spacers. This will allow a larger tolerance on the module length. (Right now Vic is suggesting shims.) THis doesn't seem to be a big problem, though it requires some modification of the spacer.
- Jianping would like to see the modules mounted horizontally one by one. THis means both the front and the back support planes need to be in position first. However, this means we cannot use single-piece rods to go into the holes in both planes. BUt for others at the meeting this seems to be a significant concern, since the shear load will be very different if the rods terminate short (outside the back support plane) and are held only indirectly (such as rod supported by spacers, then spacers supported by the holes on the support plane).
- We confirmed that the lateral spacing between the modules and its tolerance is something the THU/SDU groups need to provide as inputs. ANL now has only SDU1 which is not enough to study this tolerance (by measuring the outside size of the wrapped module alone).
- Overall, we think the main problem so far with the support design is the need to mount the back plate at one time after all modules are mounted on the front plate. Aligning all 360 holes will be nearly impossible. WE asked Vic to think if there is any way to mount the modules one by one using adjustable spacers. Whether the rods have to be shortened is a separate question to be investigated next.
- Xiaochao will send Vic some information on how other experiments mount their shashlyk modules.
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- Participants: Chendi Shen, Ye Tian (SDU), Cunfeng Feng, Seamus Riordan, Jixie Zhang, Jianping Chen, Xiaochao Zheng
- Chendi presented tests on the fiber reflectivity, see 20180614_shenchendi.pdf. Basically, there is a 40% improvement on the signal yield if the fiber end is coated with sliver shine. Will continue this test with TiO2 painting and a different radioactive source.
- We discussed the possibility of making 7 modules for the beam test, if time allows. This requires each of THU and SDU to make two more modules.
- We discussed the possibility for SDU group to construct the 7-module support using ANL design. Prof. Feng said he would try his best. The manpower to mount the modules to the support may be a problem. (while cost is less of a problem).
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- Participants: Chendi Shen, Ye Tian (SDU), Jixie Zhang, Jianping Chen, Xiaochao Zheng
- all previous meetings in May were either cancelled or did not have substantial reports to log.
- Chendi: doing fiber reflectivity tests now. Will report next week.
- Ye (SDU): presented 3 material tests, see 05-31-2018_Ye_SDU.pdf. Some findings and comments:
- Powder paint test: on page 2, top row are for the older THU powder painted lead tile samples, bottom row are for the newer THU samples that are currently being used for SDU#4. The two plots on the left are the original test results (top was from earlier). To avoid possible confusion due to using different PMTs, the samples are now tested using the same PMT+electronics, shown on the right. Looks like the two sets of samples have about the same performance. (Chendi: the two sets of samples were made by two different factories).
- New Kedi scintillator test: these are the same formula as previous "Kedi improved" in SDU2, SDU3 and THU1, but were produced just now. On page 4 and 5 Ye tried to compare the previous scintillator with the current batches. However, tests of Ch0 (left, new batch) and CH1 (right, older sample) are using different PMTs. It's not clear if the 10-20% difference seen here is due to scintillator quality or PMT. Also, difference between page 4 and 5 are due to using different samples from the same batch. Therefore within each batch there can be up to 10% variation.
- We suggest: switch the PMTs used for CH0 and CH1 and repeat the test. On the other hand, the performance of the new batch is likely the same as (or no worse than) the previous one.
- Fiber-end reflectivity test: Fiber length used was about 60cm (same as for module assembling). New results show there is very small improvement between using silver-shine or TiO2 paint compare to no end-coating at all. Cannot reproduce the previous 70% improvement result. Chendi commented that he saw a 40% improvement for silver shine, not too different from the value reported here. We discussed that the fiber ends have to be cut and polished to high quality, but it's not clear how we can improve the fiber end reflectivity otherwise.
- Xiaochao mentioned none of the prototype modules used/are using Tyvek between tiles. We should plan to have at least one prototype using Tyvek, since Tyvek is found to still provide the best between-tile reflectivity of all material (see THU's report on 20160204. Ye (SDU) said they have enough Tyvek sheets (with holes) at SDU for one module assembly, and will think about using it for SDU5.
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- Participants: Chendi Shen, Jixie Zhang, Jianping Chen, Yulei Lee, Seamus Riordan, Xiaochao Zheng
- Chendi: plan for THU3: fiber from SDU, THU will buy 1000 new scintillator tiles. THU2 used tyvek wrapping on the module side. For THU3, plan to paint THU3 with TiO2. Also plan to paint fiber ends with TiO2 (not silver shine). ***We suggested testing reflectivity first***.
- Chendi reported that Ye (SDU) also plan to buy 400 scintillator tiles.
- For Tyvek Chendi mentioned there are different thicknesses. The 500micron Tyvek has better reflectivity than the 200micron ones, for example.
- Seamus reported some findings aobut SDU1 module which was shipped to ANL. The rods are no longer tensioned. The two end plates are not parallel and not vertical when the module is horizontal, etc. The module however stays rigid and seems still compressed.
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- Participants: Chendi Shen, Ye Tian (SDU), Ye Tian (Syracuse), Jixie Zhang, Jianping Chen, Yulei Lee (THU new PhD student with Prof. Wang), Xiaochao Zheng
- Ye (SDU): still preparing material for SDU4. Fiber will be BCF91A. Will report on reflectivity of the powder-painted lead next week. Xiaochao suggested Ye start asking for samples of the silver shine from the vendor.
- We discussed where to find the 3rd module for the IHEP beam test. Chendi reported at THU there is not enough scintillators. We will follow up on this by email.
- We discussed what is the next goal for ECal simulation. Doesn't look like we have urgent things to do. We could think about effect of the wrapping between modules but eh effect is probably minor. For now, Ye (Syracuse) can focus on other SoLID simulation tasks.
- Jixie has been helping to integrate the Hall D generator into SoLID simulation package.
- General update on SoLID from Jianping:
- met with lab management to discuss having the science review in 2018. Pushing SoLID in parallel with Moller.
- Moller: have CD0, plan to start construction (CD3) in 2020 and it will last 4 years;
- SoLID: if we can get the science review and CD0 in 2018 then CD3 can be in 2021, followed by 4 years of construction.
- On scheduling the science review: we are ready! Plan to meet with DOE on June 21/22, and will schedule the review then.
- General discussion on SoLID priority tasks from Jianping:
- DAQ limit?
- Cherenkov R+D? What is the rate limite?
- Any request from ECal? -- ANL group is requesting a 30-deg wedge of the full-size support to be constructed during the R+D stage. After the IHEP beam test we should also run a 7-module test at Fermilab. Will need funding support for that test (travel, DAQ/electronic cost, etc).
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- Participants: Chendi Shen, Ye Tian (SDU), Ye Tian (Syracuse), Jixie Zhang, Cunfeng Feng, Xiaochao Zheng
- Chendi:
- Here is the datasheet for the TiO2 powder paint that will be used for module SDU4: power painting.pdf. THU2 used a similar paint but that factory has been closed.
- Ye: received the powder-painted lead plates from THU and will start working on SDU4 assembly.
- We talked about material planned for SDU4. Will use Kedi's improved scintillators, Chinese lead plates. The only uncertainty is the fiber end reflectivity, whether the Italian silver shine should be used or a TiO2 painting, or other different methods. Xiaochao made a sketch for how possibly avoid the silver shine + glue to become a huge bulb at the end of the fiber: method_paint_fiber_end.pdf
- Discussed about what to do with the Ecal simulation. Jixie has been working on integrating the Hall D generator into SoLID. Ye asked if we should model the fiber holes and/or what the next step of simulation should be. We suggested Ye check Rakitha's latest results first (Hall D generator, fiber hole, Birk's effect, etc.)
- Need to follow up on Ecal support structure design and prototyping.
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- Participants: Chendi Shen, Ye Tian (SDU), Ye Tian (Syracuse), Jixie Zhang, Cunfeng Feng, Seamus Riordan, Alexandre Camsonne, Xiaochao Zheng
- (last week's meeting cancelled due to snow days)
- Chendi:
- reported the company for powder painting claimed to have a new material (instead of TiO2). We ask Chendi to find out the detailed composition.
- asked if he should test the timing resolution, The answer is yes, if it is convenient to do with the cosmic (vertical) test. We do require certain timing resolution from the ECal.
- Jixie reported the shipping of the two modules, THU1 (along with SDU1 PMT) to China and SDU1 (w/o PMT) to ANL is going smoothly.
- Ye Tian (Syracuse) presented simulations for the beam test, now with a beam radius of 3cm and with 0.12mm mylar(Tylar?) replaced by 0.07mm TiO2. See beamtest_update_03292018.pdf
- The new results show larger energy deposit in the reflective layers, nearly the same as the deposit in the scintillators. If this is true then it is a concern, because we don't want to lower the sampling factor (which determines the light yield). Looking at the numbers, TiO2 is 4.23 g/cm3 in density and mylar is 1.38g/cm3. So the total (thickness*density) is 1.79 times higher in TiO2 than mylar. On the other hand, the new THU module does show higher light yield with the TiO2 powder painting. At this moment, Chendi reminded us that the TiO2 powder painting layer may not be pure TiO2, but a mixture of TiO2 and a bonding/glue material. Again we ask Chendi to find out the exact composition of the TiO2 paint used by the company.
- Overall the results look promising. There are differences in the electron vs. pion signals for the full Ecal setup configuration. The beam size does not seem to introduce a big effect. Looks like both 3- and 7-module settings give similar results.
- We need to discuss what to do on the support design. (ANL group has committed to continue the design work).
- Xiaochao asked Vic at ANL to design a small support system for 7 modules for the beam test. Here are some drawings: SOLID%20Module%203-22-2018.pdf, Test%20Module%203-23-2018.pdf, Test%20module%20assembly.pdf.
- We discussed the necessity for the Chinese groups to adopt the support as soon as possible. This is mostly due to the ANL group needs inputs from the module assembling group: The most important is how much tolerance we need to accommodate the wrapping of the module, the straightness of the module, and possibly the length of the module.
- Looking at the drawings alone both THU and SDU groups' concern is that the rods they are using are 50cm long (total). Minus the module length (45-46cm for SDU including 0.6cmx2 Al plates, and 42-43cm plus 2cm of Al plates for THU), there are only 3-4cm extra length left for mounting. But while this may seem difficult, 3cm is probably still do-able.
- The other concern is how to fit all 7 modules into the 6x7 holes all together. But this is exactly where the tolerance become important and should be worked on.
- To move forward, Xiaochao will ask Vic for some detailed drawings for the individual pieces.
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- Participants: Ye Tian (Syracuse), Paul Souder, Ye Tian (SDU), Alexandre Camsonne, Jixie Zhang, Jianping Chen, Seamus Riordan, Chendi Shen, Xiaochao Zheng
- We had a long pause due to low activity/Chinese new year + winter vacation
- Chendi inquired if it is okay to 3D-print endplates for the module. The answer is NO. 3D-printed plastics will not have the strength and the radiation hardness needed by the project (both prototyping and production).
- Ye (Syracuse) presented simulation work on the planned Beijing IHEP beamtest. Her slides can be found at beamtest_update_03082018.pdf
- Overview of the presentation: focused on studying the single-, 3-, and 7-module cluster outputs for very small beam size, incident perpendicular to the module's front face. For the 3-module setup the beam is shifted by 1cm in both x and y to avoid the hole between the 3 modules. There are 4 configurations: (1)Shower only; (2) shower plus preshower scintillator; (3) shower plus preshower scintillator and pre-lead (this is full config minus Al support plate); and (4) full ECAL (with 2cm Al support between preshower and shower).
- Looks like the full ECAL configuration (#4) can have some 2D separation of electrons from pions, although not great (but this is part of the nature for this low momentum). Config.#3 is similar but we note that there is always Al due to the endplate of the shower module (which now is not in the simulation, see suggested revision below).
- Suggested revisions: (a) need to replace 0.12mm myler by 0.07mm thick TiO2, which is the new powder paint material on the lead plates. For TiO2's density and radiation length can use weighted average of the 2 elements (Ti and O). (b) need to know the exact thickness of the aluminum frontplate that is universal for all modules (SDU Tian YE said it's 6mm). (For SoLID running simulation, this front plate thickness of 6mm is integrated into the support structure of 2cm Al between the preshower and Shower, so no need to modify the SoLID simulation); (c) add actual beam size (5cm-7cm full width).
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- Participants: Jianping Chen, Jianbin Jiao, Seamus Riordan, Chendi Shen, Alexandre Camsonne, Jixie Zhang, Cunfeng Feng, Ye Tian (SDU), Ye Tian (Syracuse), Yi Wang, Xiaochao Zheng
- Chendi presented updated analysis on the THU2 test, see 20180201_chendi%20shen.pdf Both 800 and 700V test still show double peaks and the middle peak position does not seem to change with the HV value, and it is always there (even when checking subsets of data). Chendi suspects a pedestal shift, Jianping said it's probably an equipment grounding problem, and Yi Wang suggested correcting this off-line. Xiaochao also suggested using finer bins (if statistics is high enough). Overall, the current preliminary result is that SDU2 vertical result is about 700.
- Ye Tian (SDU) presented work on 3 topics, see the updated file yetian_02012018.pdf. Some comments:
- First is the linearity test for the SDU PMT used by Chendi's tests for THU2 module. Observed that if we define nonlinearity to be larger than 5%, then nonlinearity occurs at: Npe=300 at 1100V, 550 at 1000V, 1100 at 900V. THe peak currents are 20mA, 24mA, and 26mA for the 3 HV values. We note that the LED pulse shape is not exactly known, and if it is different from the shashlyk signal (square vs. triangular shape, or if a different width), then the equivalent Npe that causes saturation of the anode peak current would be different. The shashlyk output signal shape was previously reported by Ye on 1/11/2018, which was found to be a triangular pulse with the full width (at the bottom of the triangle) being 40ns. This means the shashlyk would have the same saturation Npe if the LED pulse being used this time is a square or triangular pulse with the FWHM being 20ns. (Note that Chendi's slides today shows saturation clearly at 1100V. Whether there is saturation at 1050V is difficult to say because of the large error bars in Chendi's results).
- The second is testing the reflectivity of the THU's powder-painted lead sheet. The PMT is directly coupled to the side of several layers of lead and scintillators. Results indicate the powder paint increase the reflectivity by about 50% compare to Tyvek. (NOte that this does not mean the reflectivity itself is 50% higher. Only the effective increase due to reflectivity is 50% higher). This is consistent with the shashlyk module test if we simply assume the same factor applies to the full module vertical test situlation (Npe~700 from THU2 vs. Npe=480 to 500 from SDU2 and SDU3).
- The third test is to examine the signal from the 3 modules at JLab under the cosmic ray condition. The SDU2 and SDU3 labels are switched. From the FADC channel reading, and using 50ohm coupling, 4ns timing resolution, 1V/4000 channel resolution, we can calculate that Npe for the bottom picture (should be SDU1, not the SDU2 as labeled) is 2000*(1V/4000)/(50ohm)*4ns = 4E-11C. Dividing the PMT gain 5E6 and then by 1.6E-19 we get Npe=50, exactly the same as the cosmic horizontal test done earlier in China. (Similary, the top plot shows SDU2 to have Npe~75).
- The THU1 module on the other hand does not seem to provide reasonable signal at all. We suspect fiber inside is broken or obscured or the coupling to the PMT failed. We suggested shipping this module back to the THU group for inspection and repair.
- Overall this is great progress.
- Ye Tian (Syracuse) presented the beam test simulation with 1 vs. 3 vs 7 modules, see beamtest_modulecheck_20180201_YeTIanSyr.pdf. The resolution looks reasonable. We raised some questions and comments:
- No prelead due to the very low energy of the beam. This means we can't test the prelead thickness.
- overall conditions are: 2cm preshower, 2cm Al support, and the shashlyk.
- The calibration constants (slide 2 and beyond) were obtained with the prelead and at 1 GeV. These should be re-done using the lower beam energy here and without the prelead. For today's report ignore all "reconstructed energy" obtained this way.
- The 100MeV/c pi+ simulation for preshower doesn't seem correct. Pions should deposit MIP (4.4MeV or slightly more in the 2cm preshower scintillator, and only one peak). The 200 MeV/c pion spectrum looks reasonable.
- As the next step, after fixing the problems above, is to add in a real beam size. communication with the Beijing IHEP indicates a beam size of 5-6cm (either square as determined by the sensitive area of the TOF, or a 6cm-diameter circle as determined by the beam pipe).
- Additional comments: can plot preshowr vs. shower (2D) plot of pions and electrons, (e and pi on the same plot with different colors will be better, but separate plots are fine too as the first stage). One possible concern is that the two may overlap significant, which will require a very good Cherenkov detector to separate the electrons.
- We continue communicating the IHEP. We are told (after the meeting) that the tracking detector there is too old to use. We need to bring our own tracking detector if needed. (Note that the detector advantage of IHEP vs. Fermilab is not only the tracking, but also the PID detector. At IHEP a gas Cherenkov can be used for e/pi PID (IHEP's TOF is for pi, proton PID), while at Fermilab for low momentum there is only a TOF which is still being commissioned.
- We discussed the preparation of the beam test:
- We still prefer to determine Npe from the JLab hall test (preferably) and see whether the main signals were electrons or MIPs.
- Tian Ye's presentation today indicates that SDU1 and SDU2 are good for beam test, but not THU1. As of now, there are 4 working modules: SDU1, SDU2, SDU3, and THU2, two of these are in China and two are in the US. If we avoid shipping SDU1 and SDU2 back to China, then we need 6 more modules to be assembled from China. SDU group has enough material to make SDU4 and SDU5 (will need to send the lead to THU for powder painting). We will ask Prof. Wang at THU to make 4 more modules.
- If no precision positioning detector is available at Beijing IHEP, then it will not be possible to test LASPD timing. In this case, our main goal of the beam test should be:
- For shashlyks, form a 3-cluster or a 7-cluster and to determine 1) Npe and 2) energy resolution for electrons of known momentum; 3) Combine with other PID detector (TOF or Cherenkov) to determine PID performance; 4) note that we can't study the prelead thickness as noted above.
- We can test the FASPD with the goal being to determine Npe and its uniformity by moving the beam across the detector. But FASPD is quite fragile and shipping will be a problem. Also the coupling to the PMT is non-trivial because the Npe is expected to be about only 10. We do need to know the precise gain of the PMT but that's not a problem with SDU group's expertise.
- Probably no LASPD beam test.
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- Participants: Cunfeng Feng, Xiaochao Zheng, Ye Tian (SDU), Ye Tian (Syracuse), Jixie Zhang, Seamus Riordan, Sanghwa Park, Jianping Chen.
- Ye (SDU) reported that:
- tested SDU3 with higher voltages and results still seem to be linear. Will present next time.
- analyzed JLab data on the shashlyks. Found reasonable results on Npe vs. hit position for SDU1 and SDU2, but for THU2 couldnot get a good signal. Will make slides next week.
- Measured gain for the SDU PMT used by Chendi (for THU2 cosmic test), which Chendi already used in his report below.
- Can test the saturation current for this PMT, so that we know for sure which HVs used for THU2 had saturated.
- Chendi presented progress on the THU2 test, see slides 20180125_chendi_shen.pdf. Looks like the THU2 light yield is about 700-800. But we need Chendi to do more careful analysis (He had only a short time to go through the data after receiving the gain results from Ye). For example:/li>
- The 1050V and 1100V results (Npe=622 and 680) may be in the saturated region (estimated using PMT gain and estimed Npe (assuming PMT saturates at a peak current of 25mA), see calculation shown on 12/14/2017 below.
- The 1000V and 900V results (Npe=700-750) may not saturate but the plots do not show the pedestal properly.
- The 800V (Npe=858) has a double peak. Seamus questioned maybe this is due to HV instability. Can divide the data into smaller chunks to pin down if the 2nd peak existed only during a certain time.
- The 700V analysis still needs to be done.
- Sanghwa: presented progress on SPD photon simulation, see spd_sim_check_012518.pdf. The main progress is simuation for photon timing spread for the higher yields (5E3 and 1E4 scintillating photons/MeV rather than 1E3 photons/MeV reported on 1/11/2018). Observations, comments and suggestions:
- These spreads are only due to photon propagation, no extra timing spread from the PMT, TDC, or other readout components.
- The "average" delta t from reading only the narrow-side PMT and only the wide-side PMT are 186 and 214ps, respectively. (the hit is very close to the narrow side). This is larger than expected. We provided the following suggestions:
- The initial beam spot has 5cm diameter and the hit position is not corrected. We suggest that 1) simulate for only a tiny beam spot size (1mm); 2) simulate for a 1cm dia beam spot (Jixie used 1cm cuts in his timing analysis so this can be compared to his results); and next can 3) use the 5cm spot simulated data and study how the arrival time correlate with the hit position, and correct for it in the simulated data. The results can be compared to 1) and 2). No.4) would be to continue incorporate scintillating photons that do not satisfy the total internal reflection. But all 4 items need to be done separately in order to separate different factors.
- Ye (Syracus) will report next week on the simulation.
- Jianbin wrote to Beijing IHEP and was informed that the ongoing beamline modification/upgrade will complete by June. Announcement will be made in May (one month before beam turn-on) to users.
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- Participants: Chendi Shen, Ye Tian (SDU), Ye Tian (Syracuse), Jianbin Jiao, Jixie Zhang, JP Chen, Sanghwa Park, Xiaochao Zheng
- Chendi reported that he finished all data taking for THU2 module and had sent the PMT back to SDU for measuring the gain. (recall that this is the SDU PMT for which the gain was measured at 1050V or above using the SPE method, and now we need the gain for below 1000 V to determine the THU2 light yield from the latest data).
- We discussed the possibility of building more prototype modules. SDU has enough lead, scintillator, paper, and fiber for two more (SDU4, SDU5), THU has fiber for another module but not scintillators and lead. Also SDU's lead does not have powder painting, which may provide better performance (as shown by the higher light yield of THU2). We will keep discussing this in future meetings.
- We discussed the minimal number of modules needed for the inital beam test. Using 7 modules is idea, 3 modules would be okay, and 1 module is TBD. We suggested Ye (Syracuse) to simulate the signal if using only 3 or 1 modules for the 100MeV/c and 200MeV/c electron or positron beam.
- Xiaochao presented a spreadsheet to compare Fermilab's MTest and Mcenter with Beijing IHEP's E2 and E3 lines: beamtest_facility_comparison_20180118.xlsx. Discussions below:
- The Beijing IHEP facility provides much more superior detector conditions. This is a big factor because for any detector we bring, both the difficulty and the overhead time go up. For Fermilab we need to bring our own tracking and scintillator arrays and also none of the groups is local, so the cost of running a test there while bringing two extra detector systems (along with electronics and DAQ) is nearly impossible from cost factors alone.
- An update on TOF at Fermilab: it is being commissioned now and should be ready to use. (Recall: the only PID detector at Fermilab is a Cherenkov which does not work for the low momentum range -- a few GeV -- that we are interested in.)
- IHEP E3 line provides 100 MeV/c and 200 MeV/c electron or positron beams, and to achieve a high enough rate we need to study the use of thick targets. But overall it is do-able. Ye's simulation (using sum of 7 modules, reported on 4/6/2017, showed that the energy resolution is as expected -- about 10% for 200 MeV/c and 15% for 100 MeV/c, which gives about 4.2 or 4.5% resolution for 1 GeV beam.). The only thing missing is the signal/resolution if summing over less modules, see above.
- We will email IHEP to see their beam availability in 2018.
- We ask the two Chinese groups (SDU, THU) to think over the decision to conduct the first test at Beijing IHEP and we will continue the discussion next week. Besides electronics and DAQ, the test also require building a stand that can move the modules in a 2D plane perpendicular to the beam.
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- Participants: Chendi Shen, Ye Tian (SDU), Cunfeng Feng, Ye Tian (Syracuse), Sanghwa Park, Alexandre Camsonne, Jixie Zhang, Seamus Riordan, Xiaochao Zheng
- Chendi completed THU2 test with the SDU PMT at 800V and is now doing 700V. Plan to send the PMT back to SDU afterwards for measuremnt of the PMT gain.
- Ye (SDU) reported on cosmic test of SDU3, see 01112018_yetian_SDU3.pdf. Note that previous report on SDU3 was on 1/5/2017 where the PMT gain was fixed at 5E6. We suspected this would cause the PMT anode current to saturate. Ye reported the following:
- Upgraded from QDC to FADC. This allows a precise determination of the pulse shape (page 2). Note that the observed pulse has a full width of ~40ns so our previous assumption (40ns-full-width triangular pulse) was very close.
- Did vertical tests at 900, 950 and 1000V (page 4). The total charge for the main peak at 1000V is up to 300pC, which for a 40ns-full-wid triangular pulse gives a peak current of 15mA. This is lower than the 26mA limit reported on 12/14/2017 which means the PMT should not saturate at these 3 HV values.
- The gain of the PMT was measured using the SPE method from ~900V to 1200V (page 5), and the gain vs. HV can be fitted well (although the error bars seem to be problematic). The gains for the cosmic signal were determined to be between 1.35E6 (900V) and 2.93E6 (1000V). Note that these are lower than the 5E6 used previously.
- The final Npe value was found to be about 490 for all 3 HV values. The results seem to be consistent. This also shows that the Jan 2015 test (by Ang Li and reported by Ye Tian) was accurate wnd was not affected by saturation. This is because the Npe is lower than 600 (see report from 12/14/2017).
- To do for Ye: still need evaluation of all 3 shashlyk module signals from the JLab test-lab cosmic test. See minutes from 12/14/2017.
- Now that the Npe for SDU3 has been re-measured and proven to be accurate, it is quite puzzeling why THU2 almost produce twice the light yield as SDU3. The powder paint on lead and the silver paint at the end of the fiber can certainly boost the light yield, but a factor two is unlikely. Because of this, we will wait for the THU2 test to be completed, gain measured at SDU, then crunch numbers again. If THU2 is comfirmed to give Npe=1000, it will be desired to ship the THU2 module to SDU and the test repeated by Ye, using exactly the same PMT and the setup as SDU3.
- Sanghwa reported on simulation of LASPD, now focusing on post-GEMC simulation of photon propagation and yield, see spd_sim_011118.pdf
- Initial results reported here look promising. The Npe value and the timing spread are in the right order of magnitude as the data.
- The main uncertainty can be in the original photon yield. Online catalog shows 1E4 photon/MeV deposit energy. Xiaochao looked into this a couple of years ago, see SPD simulation page. Note that at the top of page, we found the preshower light yield indicates the photon yield for the Preshower (polysterene, which is known to give only 2/3 of the yield of PVT, which is what EJ-200 or BC material are made of) is 4E3 photons/MeV. If we trust this then we expect the catalog value can be too high by 50%. But in the worst case the yield for EJ-200 or BC-408 etc is still about 6E3/MeV. Somewhere down on that SPD page, Xiaochao used 1E3 photons/MeV for her work. This now looks like a big underestimation. The strongest support for the 1E3/MeV is from CLAS12 TOF test, but we don't have enough information for the TOF detector geometry, coupling etc, to account for all possible light loss. Overall, Xiaochao thinks using a light yield of 1E4 to 5E3/MeV may be better for Sanghwa's current work. The 1E3 photons/MeV value should still be included/continued if it does not cause too much extra work, so that we can study how the timing resolution, dominated by the difference in the photon propagation path in Sanghwa's simulation, varies with Npe. Is it statistically or not?
- Xiaochao suggested adding other mechanisms to the light propagation: 1) light not subject to total internal reflection can still be reflected by the mylar wrapping. Can use a reflectivity between 0.8 and 0.9 for these photons; 2) The light guide used in our LASPD is not ideal and can cause a loss of up to factor 2 (in particular for the wide-side light guide, which bends the light by 55 deg).
- Other to dos: Xiaochao will make a comparison of pro's and con's for carrying out beam test at Fermilab vs. Beijing IHEP, then we will decide which one.
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- Participants: Chendi Shen, Ye Tian, Cunfeng Feng, Ye Tian (Syracuse), Jianbin Jiao, Alexandre Camsonne, Jixie Zhang, Seamus Riordan, Xiaochao Zheng
- Chendi completed THU2 test with the SDU PMT at 900V and 1000V. Plan to send the PMT back to SDU. But we asked Chendi to repeat the test at 800V to make sure the results are free from saturation. Chendi will do this over the winter break, and will report on all THU2 tests in January.
- Xiaochao will make a comparison of pro's and con's for carrying out beam test at Fermilab vs. Beijing IHEP, then we will decide which one.
- Ye (SDU) reported on linearity test of the two PMTs on hand, as well as some results on the JLab cosmic test of SDU2 module. See yetian_12142017.pdf.
- Performed linearity tests for two PMTs at a fixed gain of 4E5 and found them saturating at about 50mA (slide 1). Tests at 1000V, 1100V and 1200V found the PMT saturating at above about 26mA (slides 3-5). If assuming the shashlyk signal is a 40ns-full-width triangular pulse, the observated maximum anode current will allow a measurement of the Npe only up to 600 if the gain is fixed at 5E6. So all SDU prototype cosmic tests need to be repeated (this is already in the plan, but it's good to confirm the max pulse current from the linearity test).
- We reminded everyone that for SoLID running condition, the high radiation level require running the PMT at a gain of about 2E5 (this is to keep the background anode current at 1/10 of the max 100uA level specified by Hamamatsu). See previous report on 2014/3/26. For cosmic test of the modules, we should stay within the E5 range for the gain.
- page 8: SDU2 signal vs. GEM position. It looks reasonable that the closer the hit is to the PMT end, the larger signal. For the next step, suggest Ye to: (1) convert the integrated FADC amplitude to Npe, if the PMT gain is known, and (2) look into more data on SDU1 and THU1.
- After the break, Ye will report on SDU3 cosmic test (previous results were affected by PMT saturation). Will also report on further analysis of all 3 shashlyk module signals obtained with the JLab test-lab cosmic test. Then we need to evaluate if all 3 shashlyks are good for beam test.
- We will have our next meeting on in January 2018.
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- Participants: Chendi Shen, Ye Tian, Cunfeng Feng, Ye Tian (Syracuse), Jianping Chen, Jixie Zhang, Seamus Riordan, Xiaochao Zheng
- Nobody had work to report this week so we focused on making plans. We will have one more meeting before the winter break. At the next meeting, we will discuss the following:
- Chendi will report THU2 cosmic test results performed with the SDU PMTs. Hopefully results are free of PMT saturation and other ambiguities.
- Xiaochao will make a comparison of pro's and con's for carrying out beam test at Fermilab vs. Beijing IHEP, then we will decide which one.
- Ye (SDU) will report on SDU3 cosmic test (previous results were affected by PMT saturation). Will also report on the status of all 3 shashlyk module signals (THU1, SDU1 and SDU2) obtained with the JLab test-lab cosmic test. Then we need to evaluate if all 3 shashlyks are good for beam test.
- We need to move detectors from the test lab. The SPD and scintillators can go back to UVa. For shashslyks need to see what the next step should be.
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- Participants: Chendi Shen, Ye Tian, Ye Tian (Syracuse), Jianping Chen, Jixie Zhang, Jianbin Jiao, Seamus Riordan, Xiaochao Zheng
- Chendi finished 900V setting for THU2 module and is testing the 1000V setting now.
- Jixie reported LASPD timing analysis, see Jixie_LASPD_TimeResolution_Update_20171130.pdf. Focused on a multi-dimensional fit (X, Y dependence along with a 2nd-order polynomial for the time-walk of PMTs). Results are better than last week. Need need to fine-tune further the fit, but since the results are approaching 150ps, the main focus next will be to finish quickly the tuning of the fit and then apply to all data sets. Eventually will also need to write a technical note to summarize the method for SoLID use.
- Ye (Syracuse) reported work on the EC simulation, see ECAL_SIDIS_1130207.pdf, which focused on the SIDIS PID performance.
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- Participants: Chendi Shen, Ye Tian, Cunfeng Feng, Ye Tian (Syracuse), Jianping Chen, Jixie Zhang, Sanghwa Park, Seamus Riordan, Xiaochao Zheng
- Chendi tested THU2 (vertical setting) performance using Ye's PMT. See report THU cosmic test with SDU PMT.pdf. The PMT base *mount* had to be replaced to fit the tHU setup but otherwise the test used the SDU PMT+base combination and we believe the PMT gain measured at Beijing IHEP to be the correct value to use. Some observations and comments:
- The SDU PMT gain was measured with IHEP SPE method only at 1050 and 1100 V, where the PMT is known to be saturated if fed the signal from vertical tests. We need SDU to send Chendi data on PMT's current ratio vs. HV (or similar data), to estimate the gain at lower HV values.
- We suggest Chendi to continue taking more data sets at lower HV values, for example 900 V and 1000V.
- The good news is that the Npe value measured at 1050 and 1100 V are both very close to the results tested using SDU's PMT (if using gain values measured at Beijing IHEP).
- We will wait for lower HV results. But it's quite promising that THU2 reaches 1000 pe for the vertical setup.
- For SDU group/Ye: Need to look up HV values used for all SDU modules' cosmic tests: SDU1, SDU2, and SDU3. If the HV was too high, the Npe results would not be reliable, and need to be re-tested. Ye can start re-testing SDU3 module right away.
- Jixie did more analysis on the LASPD timing, see Jixie_LASPD_TimeResolution_Update_20171116.pdf. See summary and plan below:
- Stopped taking data in test lab at Monday(Nov. 12), 9 AM.
- Tried new calibration method to data set E. Still not considering x-y dependence in calibration yet. Previous method is fit 1st-order-polynomial in time-walk calibration. This new method fits 5th-order-polynomial. The result is worse than the previous result. We think using a 5th polynominal is over fitting. Reasons include: A) over correct the values; B) pick more noise|unwanted events; C) have unpredicted behavious in fitting boundary which requires careful adjustments in cut from PMT to PMT. Imperfect cuts will result in bad result.
- TODOs: 1) Study the resolution of the trigger. Estimate the best resolution we can achieve theoretically.
2) Try to fit no more than 2nd-order-polinomial in time-walk calibration;
3) Developing another calibration method which will do x-y-ADC 3-D calibration. Will use data set F to try
out this new method. (Because Data set F only use 2 GEM detectors,
need to work on new tracking algorithm for this data set.)
- There will be no meeting next week because of the Thanksgiving holiday.
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- Participants: Ye Tian, Cunfeng Feng, Ye Tian (Syracuse), Jianping Chen, Jixie Zhang, Sanghwa Park, Xiaochao Zheng
- Presentation from Sanghwa on SPD photon rejection study: spd_update_10302017.pdf. Main progress is to study photon rejection for different cuts. Previously used MIP/2 cut which gave low photon rejection for the current 60-segment design. In this report, changed the cut from 3.8/2 to 2.03-2.1 (MIP is 3.8) (all are arbitrary units) and found the photon rejection can meet the 10:1 requirement. -- good news! For safety we will still request a small amount of pre RD fund for more LASPD prototyping and testing, maybe $5k for the prototype and another $5k for fibers.
- Ye Tian (SDU) presented result for testing SDU's PMT gain at Beijing IHEP (Daya Bay's group setup). Here is the report: PMT_test_SDU_IHEP.pdf. Main conclusion is that SDU's SPE method is consistent with Beijing IHEP's results, to within 5% for 4 of the 5 PMTs tested. The 5th PMT had a 15% discrepancy and is still being investigated. For next step, Ye sent SDU's PMT to Chendi at THU, so Chendi can use the SDU PMT to test THU2 module.
- Jixie presented LASPD timing resolution analysis, see Jixie_LASPD_TimeResolution_20171102.pdf. Still taking data to increase statistics.
- We will skip the meeting on 11/09, so everyone can take a break.
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- A short meeting. Chinese side updated that Ye Tian is at Beijing IHEP to measure the SDU's PMT gain using IHEPp facility. Found the gain measured by IHEP's SPE method to be within 5% of SDU's measured gains, except for one PMT where the difference is 15%. This means the THU2 module is indeed close to factor two higher in light yield than SDU3. We think this can be due to various materials used: fiber end mirror and the reflective layers. To confirm this, both THU and SDU need to make more modules. Also, Ye will leave one of SDU's PMT to Chendi so Chendi can measure the THU2 light yield with SDU's PMT, as another confirmation.
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- Presentation on EC and SPD: SoLID_EC_Oct2017.pdf
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- Participants: Ye Tian, Cunfeng Feng, Ye Tian (Syracuse), Jianping Chen, Jixie Zhang, Xiaochao Zheng, and maybe a few others
- Ye (SDU) is now back to China and reported on a plan for constructing the new SDU4 module, fiber connector test, and PMT gain test, see SDU_test_plan_10122017.pdf. Note the US lead sheets (Kolgashield) are painted, not "plated with chrome".
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- Participants: Ye Tian (Syracuse), Jianping Chen, Alexandre Camsonne, Jixie Zhang, Xiaochao Zheng
- No report from China this week because everyone is eating moon cakes.
- SDU Ye Tian is leaving tomorrow. Jixie reported on the test lab status: data taking is almost done. The gas for GEM is almost finished and there will be no more test (with GEM).
- We reminded ourselves that we still need to figure out what's the problem with the THU shashlyk module, since it seems to have problems during the beam test.
- The easiest to do for the light yield comparison is to test the THU module with the same PMT as SDU's. Jixie will do this. No GEM is needed for this test.
- Ye Tian (Syracuse) reported on progress in the simulation, see Efficiency_PVDIS_10052017.pdf. Mostly Jianping discussed with Ye and gave suggestions.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), Chendi Shen, Jianping Chen, Cunfeng Feng, Jixie Zhang, Xiaochao Zheng
- Report from Cunfeng on SDU's SPE method to determine the PMT gain: spe-introduce.pptx. The method observes the single pe peak at a high voltage, and use the current vs. HV curve to determine the gain at lower voltages (which are ultimately used for the module study.
- We found no issue in the method alone, but we need to have a detailed uncertainty analysis for each step (SPE peak position, extrapolation to lower voltages, etc).
- Jianping suggested it will be much better if we can determine the module performance with a different PMT (with very large dynamic range to show both SPE and the main production peak at the same HV). Then there will be no ambiguity from the gain. Can SDU find such a PMT?
- The other way to solve the issue is to have the SDU PMTs measured at IHEP. This may need to wait a couple of weeks because of the upcoming Chinese National Day holiday.
- Report from the test lab (Ye SDU and Jixie), see 09282017_yetian_sdu.pdf
- Did a first round of analysis for the setting where the trigger bars are perpendicular to the SPD bar. It was determined the timing resolution (t0+t3+t2+t5)/4-t4 to be 184ps (see slide 7) when reading out from the wide side with the event hitting the left-most side (similar to the SoLID condition). We take out the resolution of the trigger bars (82ps for each of the t0,t3,t2 and t4), the resolution for t4 is 170ps. Eventually this dominates the TOF for the LA particles (since the other timing for the coincidence is from MRPC which has a 60-80ps resolution depending on the rate, and is still been improved on)
- It looks like cutting on the y position can shrink the timing for the narrow-side readout to 117ps. This is interesting. we need to determine how much the y-cut improves the wide-side readout.
- Analysis for the setting where the trigger bars are parallel to the SPD bar is still ongoing. The time-walk correction is not very good and currently the correction from the perpendicular setting is being used. The timing resolutions are good though: about 178 ps reading out from the wide side and about 120ps from the narrow side (no y cut). But this is without any cut on x. I wonder what the resolution will be if we select only events hitting close to the narrow side?
- Xiaochao wondered what's the effect of statistics on the dt measurement, since it looks like there are only 500 events in each position bin? (We did not arrive at a conclusion on this, although the figure shows nearly no statistical fluctuation which indicates the stat effect is probably negligible).
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), Chendi Shen, Seamus Riordan, Alexandre Camsonne, Jixie Zhang, Xiaochao Zheng
- Report from the test lab (Ye SDU and Jixie), see 09212017_yetian_sdu.pdf
- Data taking has been smooth (no crashing). Efficiency of good events (signal in all detectors) is low, at about 1000/(100k-150k). Will finish taking data of LASPD with different trigger positions within the week. The closest distance between the trigger bar and the narrow side is 0.75" and to the wide side is 1.75" due to blocking from the light guide.
- Has continued LASPD timing analysis. Redid timing and timewalk correction for the new data (with trigger bar perp to the LASPD, while previoud data was parallel). See slide showing dt for a 5cm width. Note, here the timing definitions are: t0,t1,t2 on the left, t3,4,5 on the right. Need to divide data into 1cm bins and plot dt vs. position.
- It seems that the time-walk shown can be improved, the top plot seems to have a slight slope remaining.
- There were low FADC cuts used, see slide 6. Need to make sure these are not cutting into good signals.
- Need to subtract trigger bar resolution from the total dt. Question here is what to add back to get the final expected resolution - depend on SoLID trigger timing, what do we use to form the TOF? - will wait for next week. Does this trigger bar timing include electronics and TDC timing?
- Next Ye will do the Npe measurement for LASPD. Problem is cannot remove the PMT (UVa group glued those). The only way is to increase HV and hope to see the SPE peak. (as oppose to dismount the PMT and use an LED).
- Shashlyks have been taken data in the horizontal position as well. Jixie needs to take over Ye's code on the shashlyk analysis and see what info needs to be extracted. Probably this has to wait until Jixie take a look at all beam test data and come up with a to-do for the shashlyk modules.
- Report from THU (Chendi), see THU2 cosmic test results (6).pdf
- Did position dependence study for the THU2 module horizontal test. THe results are 103, 92, and 90, with 10cm apart. The decrease in Npe as the trigger bars are moved away from the PMT is expected, but the drop observed is larger given the long attenuation length (>3.5m for both S.G. BCF91A and Y11 fibers). It may also implies a low reflectivity at the fiber end. See calc_hor_dep.xlsx
- Found a facility at the Beijing IHEP to measure the PMT gain with the SPE method. Tested gain for 1000V and 1100V with THU's own base and found gain to be about 2/3 of the SK/SP methods. THis means the actual Npe is higher than calculated using the SP/SK gain. Also the fact that the Spe results are lower than the SK/SP method is the opposite of what was found at SDU.
- In the IHEP SPE fit, p0,1,2 are Gaussian fit to the pedestal, p5,6,7 are Gaussian fit to the SPE, and p3,4 are the two normalization factors of the two peaks. The 20x1E-15 factor is the FADC 0.02fC/ch. These are direct results from IHEP code. The x11 amplifier is already corrected when making the histogram.
- We now have the problem that THU2 may have a Npe of 30-50% higher than SDU3, despite using the same scintillators. The only way to reconcile this is to test the SDU3 module (alone) using the THU setup or testing the THU2 module (alone) using the SDU setup. Note the only thing that should be moved is the shashlyk.
- We also need to double-check SDU's SPE method of determining the PMT gain -> next week.
- Ye Tian (Syracuse) reported a summary of the SIDIS PID GEMC simulation, see ECAL_09202017.pdf. Questions:
- What to do next? Xiaochao suggested PID for PVDIS, but check with Paul first;
- How to improve edge effect? One way is to add short modules, but ANL group has stopped the layout design work so we are stuck.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), Chendi Shen, Cunfeng Feng, Jixie Zhang, Xiaochao Zheng
- Report from THU (Chendi), see THU2 cosmic test results 5.pdf
- 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.
- 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.
- 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.
- Cunfeng reported on SDU's PMT HV and gain study, see CR284performance_update.ppt.
- 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.
- Cunfeng suggested Chendi to send in his PMT to SDU to determine the gain using the SPE method.
- 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.
- 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.
- 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.)
- 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.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Chendi Shen, Cunfeng Feng, Seamus Riordan, Alexandre Camsonne, Jixie Zhang, Xiaochao Zheng, Paul Souder
- Report from THU (Chendi):
- 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.
- 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.
- 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.
- 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:
- SPE measurement will be delayed until all LASPD test is done.
- 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.
- 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.
- slide 5: same as slide 4 but now reading out from narrow side. This slide presents two problems:
- 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) 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.
- 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).
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Chendi Shen, Alexandre Camsonne, Jixie Zhang, Xiaochao Zheng, Paul Souder
- Report from THU (Chendi):
- 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.
- 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).
- Note from XZ: the UVa WLS fiber setup cannot be used for testing clear fibers. :(
- We discussed the Fermilab test:
- 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.
- 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.)
- Some information about the Fermilab test beam (most were answered by Mandy Rominsky at FNAL:
- The particle profile can be viewed at: http://ftbf.fnal.gov/particle-composition-in-mtest/
- 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%.
- 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.
- 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.
- 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.
- What is their training schedule? (Though most can be done online before arrival).
- 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.
- 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.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Chendi Shen, Yi Wang, Jixie Zhang, Xiaochao Zheng, Paul Souder
- Report from THU:
- May test the clear fiber this Saturday.
- 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.
- 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.
- Xiaochao contacted Kuraray for the fiber diameter dependence of the clear fiber attenuation loss.
- 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.
- 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.
- Report from Ye Tian (SDU):
- 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?);
- 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.
- Recap of fiber situation:
- WLS for Shower: can be either Kuraray or S.G., but S.G. costs less;
- WLS and clear for Preshower and FASPD: must be Kuraray because of the high radiation dose;
- 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.
- 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.
- Most people were away at the NStar meeting in SC to get elipsed. So we had a short meeting today.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Chendi Shen, Yi Wang, Cunfeng Feng, Jixie Zhang, Xiaochao Zheng, Zhihong Ye, Paul Souder
- Report from THU:
- 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.
- Still running the vertical test for THU2 module.
- Have not yet tried re-fitting the single p.e. peak.
- Fermilab testing:
- 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
- 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).
- Xiaochao should combine all information and see if the Npe of shashlyk from cosmic tests make sense, and use this to calibrate the simulation.
- 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).
- 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.
- The test lab cosmic test should include the 3 shashlyk prototypes at some point, to make sure they work fine.
- 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?
- What is the training schedule of Fermilab? Should everyone make a separate trip to get all training done?
- Manpower: Any help from ANL/Fermilab? - Zhihong? Seamus? Any students?
- Status of the test lab (Ye Tian SDU and Jixie):
- 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.
- 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.
- Ye Tian (Syracuse) presented work on the simulation:
- 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.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Chendi Shen, Cunfeng Feng, Sanghwa Park, Jixie Zhang, Xiaochao Zheng, Zhiwen Zhao, Paul Souder
- 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?)
- 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.
- Start looking into Fermilab test beam facility, see ftbf.fnal.gov. Discussions:
- 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?
- 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.
- Need to identify test beam needed. 1-7 GeV/c electrons mixed with pions? What PID is available? What is the duty factor, etc?
- Need to coordinate with Nilanga on concurrent GEM test
- 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).
- 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.
- We will need help from nearby institutions. ANL?
- We need to make sure Mark JOnes with okay with taking some of the (Hall C) equipment to Fermilab.
- 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).
- Chendi reported on cosmic test of THU2 module, see THU2 cosmic test results_chendi shen.pdf. Discussions:
- besides materials, one change to THU2 is Chendi inserted all fibers one by one, rather than in groups.
- 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 pav.py and the paper to explain the physics of the single p.e. peak Precision Analysis of the Photomultiplier Response to Ultra Low Signals.pdf
- 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
- 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).
- Current test uses Tyvek wrapping around the module. Next step is to remove Tyvek and apply TiO2 painting and re-test the module.
- 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.
- 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.
- Ye Tian (Syracuse) had some questions about implementing background into EC evaluation. (I skipped this part and will record next time.)
- Next week: we may have Raytum's Steve join our meeting. Sanghwa will be on vacation.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Paul Souder, Chendi Shen, Cunfeng Feng, Sanghwa Park, Jixie Zhang, Xiaochao Zheng
- 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:
- Jianping argued this correlation might be within expectation
- We need to consider modifying LASPD design because now the simulation shows 120 segments to be the minimum. Options:
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.
- 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.
- Chendi: doing cosmic test of THU2 module and will report next time.
- Ye Tian (Syracuse) reported update on the Ecal simulation, see ECAL_08032017.pdf. Last report was on 6/29 (see below). Discussions:
- p.5-6: showing preshower cut on electron and pion spectra. This cut can probably be optimized to increase electron efficiency.
- 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.
- 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.
- All results shown today are without background. Need to include the background first, then optimize cuts.
- 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.
- 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.
- 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.
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- Participants: Ye Tian (Syracuse), Ye Tian (SDU), JP, Seamus Riordan, Alexandre Camsonne, Chendi Shen, Sanghwa Park, Yi Wang, Xiaochao Zheng
- Sanghwa presented her SPD simulation, see spd_update_jul13.pdf. Discussions:
- 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)
- 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.
- 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.
- 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.
- 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.
- p.12 is the same as p.10 and 11 but for LASPD. Now the LASPD is no longer good with 60 segments.
- 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.
- We discussed what the backscattered particles are. These should mostly be photons from pi0 decay, but (Paul S.) should also have e+ and e-.
- p.15 backup slide: looks okay;
- 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.
- 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.
- Chendi reported that
- 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.
- Both Chendi and Yi Wang will attend the Hadron workshop in Nanjing in two weeks.
- 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.
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- Participants: Ye Tian (Syracuse), ... Xiaochao Zheng
- Ye presented her simulation of the Ecal performance vs. preshower lead radiator thickness, see 07062017.pdf:
- p.2: updated calibration procedure. The difference between calibrated results and without calibration is small (p.6)
- 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.
- p.11: cluster summing dependence.
- p.12-13: more plots on prelead thickness and angle dependence.
- 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.
- Sanghwa presented update on the SPD simulation:
- 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.
- 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.
- 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.
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- Presentation at the SoLID collaboration meeting: SoLID_EC_June2017.pdf
- As a late entry, here are documents for E. Rhett Cheek's photon collection simulation work: photon_simulation_2017/
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- Participants:
- Ye (SDU) reported on the 3-bar test now with LASPD as the middle bar: YeTian_06152017.pdf Comments and suggestions:
- GEM is fully working now.
- For both-side readout the LASPD seems to reach 93ps.
- 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.
- 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.)
- Next step is to apply position correction properly (rather than just applying cuts on the position), and evaluate the statistical uncertainties.
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- Participants:
- 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:
- 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.
- The next step is to study the pre-lead layer thickness carefully for SoLID.
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- Participants:
- 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:
- 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.
- 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?
- 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).
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- Participants:
- Ye (SDU) reported on the three bar test: YeTian_threebar_05182017.pdfComments and suggestions:
- The three identical bar gives for the reference bar 82ps. This looks reasonable.
- Ye (Syracuse) reported on the simulation of Ecal's energy resolution: YeTian_simulation_05182017.pdf Comments and suggestions:
- 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.
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- Participants: Ye Tian (SDU), Ye Tian (Syracuse), Yi Wang, Jianping Chen, Cunfeng Feng, Jianbin Jiao, Seamus Riordan, Xiaochao Zheng.
- 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.
- Ye (SDU) reported updates on the 3-bar test, see yetian_05112017_threebar.pdf. Comments and suggestions:
- 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").
- 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.
- 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.
- 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.
- 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. )
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- Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Yi Wang, Jianping Chen, Cunfeng Feng, Jianbin Jiao, Zhihong Ye, Xiaochao Zheng.
- 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.
- Cunfeng reported he has signed contract with a local company to produce Tyvek sheets for one module.
- 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.
- 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).
- 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:
- 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.
- 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).
- Xiaochao suggested rotating the shashlyk so it is perpendicular to the two trigger bars.
- 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.
- Xiaochao found this NIMA article on the MINOS detector: http://www.sciencedirect.com/science/article/pii/S0168900208011613, 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.
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- Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Alexandre Camsonne, Xiaochao Zheng.
- Xiaochao requested Saint Gobain to send 15m of BCF98 multi-clad sample to THU.
- 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:
- The laser wavelength of 420nm does not match the Y11 or BCF91A emission peak. Ideally should use 500nm, see more discussions below.
- Silver shine provides 30% increase in light yield for a 50cm fiber. This is lower than expected, but better than SDU's aluminum plating.
- 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.
- 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).
- 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.
- 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
- 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: https://arxiv.org/pdf/1511.06225.pdf
- To-do's for Chendi:
- If possible, setup laser at a wavelength between 450 and 550nm to match the Y11 emission peak.
- 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%.
- 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.
- If after checking everything we still get less than 2m for BCF98, need to contact Saint Gobain why this is the case.
- 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);
- 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.
- 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.
- Ye (SDU) reported on the test lab status, see YeTian_sdu_4-13-2017.pdf
- 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.
- 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.
- Ye (Syracuse) continued working on the IHEP test beam simulation, but need to rebuild the module and tune the code.
- 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.
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- Participants: Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Alexandre Camsonne, Xiaochao Zheng.
- 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.
- 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:
- positron response seems to be consistent with the 20% sampling ratio;
- 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).
- proton seems to be reasonable because proton likely lose all its energy in the 2-cm aluminum.
- 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.
- Once the single-particle simulation is done we can proceed to the 1E3 electron bunch case.
- Ye (SDU) presented test lab status: YeTian_4-6.pdf. Comments and suggestions:
- GEM DAQ is still being worked on.
- 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).
- 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.
- 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).
- Ye (SDU) will also make scalers working to demonstrate the high rate from the THU module that we saw during the beam test.
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- Participants: Ye Tian (SDU), Ye Tian (Syracuse), Jianbin Jiao, Chendi Shen, Cunfeng Feng, Jianping Chen, Alexandre Camsonne, Xiaochao Zheng.
- THU: could not do any laser-related test because the lab was occupied by another project.
- 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).
- 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..
- JLab test lab status:
- 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.
- Not sure what the GEM DAQ status is.
- Discussion for the Bejing IHEP test facility:
- 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).
- 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.
- 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.
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- Participants: Ye Tian (SDU), Jianbin Jiao, Chendi Shen, Cunfeng Feng, Yi Wang, Zhihong Ye, Seamus Riordan, Xiaochao Zheng.
- 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:
- 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).
- 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).
- 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.
- 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.
- 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.
- Ang Li reported SDU progress, see fiber_reflector_test_20170323_AngLi.pptx. Notes, main conclusions, and to do's:
- 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.
- Fiber routing in Ang LI's test is the same as UVa's: Two fibers, 2.5 turns each.
- 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.
- 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%.
- 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.
- 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.
- 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.
- Discussion about Saint Gobain vs. Kurary fiber:
- 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.
- 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
- 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.
- 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.
- 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.
- At the end of the meeting we discussed the Beijing IHEP test facility.
- Jianbin's slides on the test facility:ihep_Hall10_testbeamInfo.docx.
- 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.
- 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?
- 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.
- 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.
- 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.
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- Participants: Jianping Chen, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng (short time), Zhihong Ye, Seamus Riordan, Xiaochao Zheng.
- 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:
- 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.
- 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: http://lhcb-calo.web.cern.ch/lhcb-calo/html/TDR/calo_tdr/node14.html).
- 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.
- 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
- To do 1: Repeat the test with a green/blue laser.
- To do 2: Continue testing with fiber samples from SDU (without plating and with aluminum plating at the end).
- Discussion about Y11 vs. BCF91A: -- note this has been updated on 3/23/2017
- 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:
- 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).
- 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.
- To do 1: Make FADC working and apply appropriate time-walk correction;
- To do 2: Make GEM working.
- Then can proceed to replace the middle Eljen bar by the LASPD.
- Still need to fix/diagnose the THU shashlyk module
- 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.
- Received updated quote for the SPDs from Eljen: Cost now is quote_SPD_Eljen_March2017.pdf$96,050.
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- Participants: Jianping Chen, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Alexandre Camsonne, Xiaochao Zheng.
- We talked about the status of the test-lab cosmic test:
- 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.
- 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.
- 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.
- Do not have (fresh) optical grease to use at JLab. Xiaochao will send some. For starters can also just run tests without the grease.
- Chendi talked about:
- Talking to a few companies (Kedi is one of them) about cutting the fiber bundle after inserting them to the shashlyk;
- 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.
- 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.
- 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.
- 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).
- 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.
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- Presentation: SoLID_EC_Mar2017.pdf
- Discussed with Paul R. about the support design:
- Vic now suggests two support planes for the shashlyk (no longer cantilevering).
- 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.
- 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.
- Paul will look into LHCb's preshower support on page http://lhcb-calo.web.cern.ch/lhcb-calo/html/TDR/calo_tdr/node42.html of LHCb's ECal TDR.
- Regardless of preshower design, need to ensure support of the fiber ends out of the preshower.
- SPDs: need design
- Xiaochao will send a few fiber connectors to Paul.
- 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.
- Discussed with Jay and Whit on the cabling/fiber route:
- 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.
- 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.
- FA-Preshower/PVDIS or SIDIS: radially to the side, place PMTs on the outside (radial) of the magnet endcap.
- 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).
- 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.
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- Participants: Jianping Chen, Sanghwa Park, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Jianbin Jiao, Ang Li, Yi Wang, Xiaochao Zheng.
- Ang Li reported SDU test on the Y11 vs. BCF91A fiber light yield using preshowers. see Comparison_Preshower_TwoFibers.pdf. Summary and comments:
- Results show Y11 yield is (50-75)% higher than BCF91A. UVa's result was Y11 is higher by about a factor two.
- 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.
- 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.
- 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.
- Sanghwa reported still working on debugging the SPD simulation code.
- Both Ye at JLab: need DAQ/CODA to work, also are waiting for Xiaochao's scintillator bars to setup the 3-bar timing test.
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- Participants: Jianping Chen, Sanghwa Park, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Xiaochao Zheng.
- 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.
- The two Chinese groups are just back from their winter break.
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- Participants: Jianping Chen, Ye Tian (SDU), Ye Tian (Syracuse), Chendi Shen, Cunfeng Feng, Jianbin Jiao, Xiaochao Zheng.
- 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.
- Xiaochao reported on:
- 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.
- ECal photon-collection simulation by Rhett Cheek, see his report from last semester: PHYS_3992_report_Rhett_Cheek.pdf.
- 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.
- The report studied the dependence on the reflectivity of various surfaces (separately for total-internal reflection case and non-total-internal reflection case.)
- 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.
- 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.
- 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.
- needs SPD simulation update from Sanghwa. At the Tuesday simulation meeting Sanghwa mentioned she will work on this early next week.
- One SiPM preamp has been assembled but we are holding the SiPM test for now.
- Ye reported on the status of the detectors: moved to test lab this week, need suggestions on how to setup the cosmic test.
- 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.
- Mark is away this week. Jianping suggested waiting for Mark to come back to start connecting the cables, setting up computers, ec.
- 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.
- Jianping suggested us to continue looking for small companies for fiber development.
- The workshop this summer will be at Nanjing University.
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- Participants: Ye Tian (SDU), Xiaochao Zheng, Jianping Chen, Seamus Riordan, Zhihong Ye, Lorenzo Zana
- Lorenzo reported on radiation estimate behind the ECal: zana_SoLID_EC_weekly_jan26_2017.pdf.
- page 2 is looking from the back of SoLID.
- 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).
- This result significantly disfavor the use of SiPMs.
- 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).
- We had a meeting on 2/9 but no significant progress to report.
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- Participants: Chendi Shen, Ye Tian, Xiaochao Zheng, Cunfeng Feng, Jianbin Jiao, Seamus Riordan, Zhihong Ye
- 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.
- Xiaochao asked Hamamatsu for a few Hamamatsu free samples, then will re-route half to SDU.
- 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).
- 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).
- Elton is also sending Xiaochao one Hall D 25-um SiPM along with two pre-amps.
- From CAEN: new product A1702 32 Channel Silicon Photomultipliers Readout Front-End Board.
- Participants: Jianping Chen, Chendi Shen, Ye Tian, Xiaochao Zheng, Cunfeng Feng, Zhihong Ye
- 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.).
- We focused on discussions about using SiPM for ECal readout:
- Xiaochao contacted Lorenzo on the radiation level behind the Ecal. Lorenzo is still on vacation, but will check when he is back.
- Xiaochao contacted Ardavan on his SiPM recommendations.
- 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.
- 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.
- 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.
- Further discussions among Zhihong, Xiaochao and Cunfeng:
- General description of MPPC (from Zhihong): MPPC_Tech_Note.pdf
- 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.
- 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.
- 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
- 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.
- 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
- 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.
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- Participants: Jianping Chen, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Zhihong Ye
- Ye updated the status on the parasitic beam test, see slides YeTian_2016-12-22.pdf. Highlights and discussions:
- Performend HV scan for both the Preshower and shashlyk. The run summary is HV Scan.xlsx.
- 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).
- 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.)
- 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.)
- To do list for the upcoming month:
- 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.
- 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.
- Ye will focus on his own pion data analysis but will assist Xiaochao.
- 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.
- 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!
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- Participants: Jianping Chen, Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Alexandre Camsonne
- Ye updated the status on the parasitic beam test, see slides YeTian_12-15.pdf. Highlights and discussions:
- Lowered the calorimeter threshold from -300mV to -150mV.
- 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:
- 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.
- 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
- More questions: for multi-track events, is there at least one track that hits the calorimeter?
- 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).
- 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).
- 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.
- 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.
- To-do list for Ye:
- 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;
- 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.
- 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?)
- 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".
- 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.
- Short-term outlook: Beam will continue until next Wednesday, then comes the X'mas shutdown.
- 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.
- Next week we will meet at 10am due to Xiaochao's scheduling conflict.
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- Participants: Jianping Chen, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Alexandre Camsonne
- 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:
- The HVs are adjusted such that all shashlyk modules shows an integrated FADC peak at about 500 to 6000.
- 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.
- 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).
- Cutting on the FASPD does not seem to make a difference in the 2D plot (p9 and p10).
- 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.)
- Follow-up after the meeting about PMT gains and Npe estimations:
- 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.
- 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.
- 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.
- 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.
- 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.
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- Participants: Chendi Shen, Cunfeng Feng, Ye Tian, Xiaochao Zheng, Vince Sulkosky
- Ye's update on the beam test: YeTian_12-01-2016.pdf.
- Looks like all HV are working properly now and there is no under- or overflow of FADCs.
- Scaler is not working and there is problem in the TDC trigger, will need an access to fix (probably on coming Tuesday).
- 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.
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- Participants: Chendi Shen, Cunfeng Feng, Ye Tian, Xiaochao Zheng, Vince Sulkosky
- Ye's update on the beam test: YeTian_11-16-2016.pdf. Problems and to-dos:
- 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);
- 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).
- 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).
- There will be no meeting next week (Thanksgiving break)
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- Participants: Chendi Shen, Yi Wang, Ye Tian, Xiaochao Zheng, Vince Sulkosky
- This week's meeting was held on Friday because there was a hall access on Thursday at our usual meeting time.
- 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:
- 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.
- 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.
- The THU shashlyk module is showing a much higher rate than the other modules. Not sure why.
- 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.
- 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.
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- Participants: Jianping Chen, Chendi Shen, Zhihong Ye, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Alexandre Camsonne
- 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:
- 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).
- Ye's to-do list
- 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
- When showing FADC pulses, consider drawing no more than 9 events (9 colors) in one histogram and use multiple histograms to show more events
- 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))
- Vince and Ye will work together on the following items -- suggested by X.Z. post-meeting
- 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)?
- Vince will follow up with Mark on the following items:
- 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.
- Looks like the FASPD is in the trigger -- need to remove this
- 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).
- Confirm the solid calo in the scaler is the sum, not a single module.
- 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.
- 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).
- Chendi updated the status at THU: received powder-painted lead sheets and will start assembling THU#2 (BCF91A fiber).
- 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.
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- Participants: Jianping Chen, Chendi Shen, Zhihong Ye, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Jianbin Jiao
- 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
- 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.
- Ye has been working on the FADC decoding
- 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).
- 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.
- 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.
- page 6 - rates and other setups. Note that the event rate that can be recorded is only 30Hz according to Vince, not 100k.
- page 7 - FADC spectra for LASPD. Looks reasonable. (JP had concern that the data shows the scintillator has a too slow rising edge).
- page 8 - First in-beam ADC and fADC spectra for the THU shashlyk module. Looking good!
- 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!
- 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.
- 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).
- 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:
- For the shashlyk FADC spectrum, can we clearly label the vertical resolution (in mV)?
- Replay more events to show their timing and height distribution.
- 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.
- 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.
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- We discussed a to-do list to implement immediately in the beam test using the restricted access opportunity starting today around 11am:
- Confirm with Mark the main trigger is an AND of scintillators and calorimeters -- followup- confirmed.
- Rearrange our 3 modules into a triangular 3-cluster shape.
- 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
- Now all scintillators are already in the TDC. Will add "sum of 3 preshowers" and "sum of 3 shashlyks" in the TDC.
- Add one more scaler module so the FASPD and individual calorimeter modules can be added to the scaler reading.
- 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.
- 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.
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- Participants: Alexandre Camsonne, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Jianbin Jiao
- 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:
- page 2: picture on the right shows the fully-wrapped SDU shashlyk modules with PMTs.
- page 5: picture of the test stand. The detectors will be at the beam height.
- Today's todo's include wrapping the preshower and the SPD fibers, moving all detectors to the test stand, and hopefully start cosmic testing.
- Other suggested to-dos:
- 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.
- 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.
- Take cosmic data as soon as possible to test light tightness, noise, etc.
- Here is Xiaochao's reply on director's review for the EC part: Directors_Rev_Reply_EC_draft1.doc
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- Participants:
- 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.
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- Participants: Jianping Chen, Alexandre Camsonne, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng, Yi Wang, Chendi Shen
- 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:
- 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.
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- 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:
- Will ship these 400+ Tyvek sheets to SDU to be used in their 3rd module.
- 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.
- Both SDU and THU will ship their modules to Jianping at JLab.
- 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.
- For planning purposes, The THU module is 80cm long including PMT. The SDu modules are 65cm long. Weight is about 15kg/module.
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- Participants: Jianping Chen, Alexandre Camsonne, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Cunfeng Feng
- 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:
- 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.
- 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.
- Do we have enough PMTs?
- Need to email Wang Yi at THU for shipping their modules.
- Xiaochao will write a short description for the test setup and the goal. THis is for Alexandre to coordinate on all detector tests.
- 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.
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- Participants: Ye Tian, Xiaochao Zheng, Cunfeng Feng, Vince Sulkosky, and possibly others (this is a late entry)
- 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:
- 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).
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- Participants: Jianbin Jiao, Yi Wang, Ye Tian, Xiaochao Zheng, Vince Sulkosky,Cunfeng Feng
- 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:
- Fiber polishing was improved by using a smaller cutter, compare to reported previously.
- 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.
- 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.
- 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).
- 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).
- 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:
- 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).
- 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.
- 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.
- Note that all previous shashlyk modules used bond paper (ALICE) or Tyvek type 1055B (all IHEP-made modules such as for LHCb)
- 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).
- There will be no EC meeting next week due to the Hadron2016 workshop.
|
- Participants: Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Vince Sulkosky, Paul Souder, Cunfeng Feng
- 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
|
- Participants: Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Jianping Chen, Vince Sulkosky, Xiwei Wang, Lorenzo Zana
- Chendi reported that received the fiber reflective paint from Italy and will test it soon.
- 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.
- 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 http://kuraraypsf.jp/psf/images/ws_il007.gif (unfortunately it has very low resolution). Y11 has peak absorption at 430nm and peak emmission at 478nm.
- 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.
- 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.
- 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.
|
- Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Ye Tian, Xiaochao Zheng, Jianping Chen
- 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).
- Discussed briefly on the support structure presented last week. Have question about the details. Will continue after Vic comes back from his vacation.
- 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.
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- Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Xiwei Wang
- Chendi presented tests on different reflective materials, see chendi shen2016_6_30.pdf or chendi shen2016_6_30.pptx
- 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.
- 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.
- Page 6-10 are tests of 4 different reflective materials on the lead layer: PVC, printer paper, powder paint ( 喷塑), and Tyvek.
- For powder-painting,
- currently there is a problem that the thickness is uneven -- thicker on the edge.
- Powder-paint has different "patterns", for example large and small ripples.
- should find out the cost of powder-painting for both prototyping and mass production
- For Tyvek, was able to obtain 3 different samples. Xiaochao asked what type of Tyvek was available.
- Again, because the test used a X-ray source, we can't draw conclusion about the reflective material's performance from the results presented.
- 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.)
- Cunfeng reported for SDU:
- still working on the fibers.
- 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.
- 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.
- 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.
- 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.
- Discussion of Ecal support:
- 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.
- Xiaochao's followup slide to show which drawing is for which component: support_and_drawing_20160630.pdf.
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- Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Jianping Chen
- DDK connectors have arrived at THU and SDU (order by UVa). So we focused on how to use them:
- Vince prepared slides to show how to use these connectors, see DDK_connectors_16June2016_mod.pdf
- Earlier reports related to how Minerva polished the DDK connectors: see 3/17/2016 report
- 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.
- 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.
- We may want to repeat the clear fiber loss test.
- UVa update by Vince:
- 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.
- 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.
- There will be no meeting next week due to the Hall A/C Collaboration meeting.
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- Participants: Cunfeng Feng, Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Jianping Chen
- Rakitha's report on Ecal simulation that now start to incorporate the light yield: ecal_pid_efficiency_5.pdf
- 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
- 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.
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- Participants: Jianbin Jiao, Chendi Shen, Rakitha, Ye Tian, Vince Sulkosky, Xiaochao Zheng
- Jianbin reported on fiber insertion following advice from Alessandra (ALICE group): 20160602_InsertingFibers.pptx. Below are comments, discussions, and suggested to-do's
- 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.
- 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.
- recieved BCF91A/MC fibers yesterday.
- 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.
- 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.
- 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).
- 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.
- support prototyping, see item D below.
- Chendi reported:
- Found a reflective paint "silver shine 415001" made by the Italian eptainks.com, 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).
- Will test the module light yield without the paint first, then paint the fiber end and repeat the test.
- For the fiber ends that will be coupled to the PMT, used a diamond-mill.
- 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.
- 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.
- 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.
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- Participants: Jianbin Jiao, Jianping Chen, Ye Tian, Vince Sulkosky, Xiaochao Zheng, Rakitha
- Jianbin: tried yesterday to insert fibers into the module,
but not very successful. The BCF91A (multi-clad) fibers are coming (note: in 2019 we corrected this, the BCF91A fibers ordered by SDU in 2016 should all be single-clad).
Will consult ALICE group on fiber insertion technique.
- 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:
- 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.
- The muon results indicates there is nothign wrong with the simulation. Next will continue to electrons.
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- 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.
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- Participants: Cunfeng Feng, Jianbin Jiao, Ang Li, Chendi Shen, Xiaochao Zheng, Jianping Chen, Ye Tian, Yi Wang
- 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:
- 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).
- 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%).
- SDU has ordered a torque wrench based on Xiaochao's torque
calculation from last week (see link https://item.taobao.com/item.htm?spm=a1z09.2.0.0.IQtjJy&id=44152212864&_u=rmr4u7n1f66, 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.
- At UVa we are moving onto Tyvek hedgehog test today.
- 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
Vendor
|
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)
|
HND-S2
|
|
(50-60)%
|
(395,425)nm (comparable to Bicron)
|
2.4ns
|
>2m
|
1.58
|
1.05
|
1:1.1
|
|
塑闪性能指标及图.ppt
|
CNCS (北京核仪器厂)
|
ST401(A,B,C) |
苯乙烯 (sterene)
|
40%
|
peak at 423nm
|
2.8-3ns
|
1-2m
|
1.6
|
1.05
|
1:1.104
|
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: "
137Cs的624MeV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
|
ST1421(high-yield)
|
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
|
<2.5ns
|
|
|
|
|
|
much higher cost than ST401; similar to NE102A
|
| ST1422(sub-ns) |
在快时间塑料闪烁体中加入猝灭剂
|
2.8%
|
peak at 390nm
|
0.7+/-0.1ns
|
|
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
|
<=1.7ns
|
1-1.5m
|
|
|
|
|
|
Eljen
|
EJ200
|
polyvinyltolunene (PVT) |
64%
|
peak at 425nm
|
2.1ns
|
~4m
|
1.58
|
1.023
|
4.69:5.17
|
|
conversion 10,000 photons/1MeV electron;
PVT can't be injection-molded
|
Saint Gobain
|
BC400 |
polyvinyltolunene (PVT)
|
65%
|
peak at 423nm
|
2.4ns
|
160cm
|
|
|
|
|
|
BC404
|
68%
|
peak at 408nm
|
1.8ns
|
140cm
|
1.58
|
1.032
|
1:1.1
|
|
|
BC408
|
64%
|
peak at 425nm
|
2.1ns
|
210cm
|
|
|
IHEP (Russia)
|
|
polysterene + 1.8% PTP or PPO + 0.04% POPOP
|
varies
|
|
|
|
|
|
|
|
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)"
|
|
- Participants: Cunfeng Feng, Jianbin Jiao, Alexandre C., Xiaochao Zheng, Jianping Chen, Ye Tian, Yi Wang (intermittent)
- SDU update on the module compression test: 20160421_ForceTrans2.pdf
- The ratio of the inner compression after vs. before transferring the force is always about 0.5, which is a good thing.
- 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.)
- 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: http://www.efunda.com/designstandards/screws/fasteners_intro.cfm. There are also pre-made charts available, for example http://www.repairengineering.com/bolt-torque-chart.html, but have not looked into it.
- THU update on the temperature test: shenchendi2016421.pdf
- 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.
- There were questions on how to arrange the washers (all 5 in same direction or flip every other one?).
- 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.
- UVa quick update on the light yield test:
-
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.
- 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
- Jianping commented that linear projection may not work.
- 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.
- 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:
- if we control the light loss below 5%, the distance between the fiber connector and back of module needs to be 9cm or longer.
- 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.
- 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.
- 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.
- But how much uniformity can be tolerated by
PID? The uniformity question will require some simulation.
- Xiaochao mentioned the NSF PIRE solicitation will be back this year. Should prepare to submit a publication.
|
- Participants: Cunfeng Feng, Chendi Shen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Jianbin Jiao
- SDU update on the module suspension test, see 20160414_SuspensionTest.pdf (Jianbin):
- 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).
- 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?
- Todos:
- Test the relationship between the pre-setting pressure
and the transferred force (note: expect a constant ratio between the
two) (copied from page 6)
- working with a vendor to upgrade the sensor to allow
continuous monitoring of the compression. More module work will resume
after the upgrade
- insert fibers and do fiber shaping, then will do cosmic test. Need to build a dark box.
- 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.
- 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.
- 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).
- THU update on the module compression vs. temperature test (Chendi):
- the previous reflective PVC layers turn out to be too expensive. Will use printer paper next.
- First test of module compression: start from 200kg at 22C, no spring washer. Pressure changes to 300kg at 30C and 40kg at -30C.
- 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.
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- Participants: Cunfeng Feng, Yi Wang, Chendi Shen, Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Jianbin Jiao
- UVa update on measuring light yield of shashlyk scintillator layers using the hedgehog method (Vince), see Hedgehog_tests_07Apr2016.pdf
- 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.
- 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.
- 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.
- 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.
- 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.
- Cunfeng reported for SDU on the force transfer test: 20160407_ModuleTest.pdf
- 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).
- 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.
- 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
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- Participants: Cunfeng Feng, Yi Wang, Chendi Shen, Jianping Chen, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B.
- Chendi reported progress from Tsinghua, see chendi shen2016_3_31.pdf
- First, calculated change in length if a 50-deg temperature change occur. The total change is about 1mm which is not tolerable.
- 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.
- Cunfeng reported progress from SDU on force transfer from compression bar to rods, see ForceTransmission.pdf
- 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.
- 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.
- 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.
- 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.
- To do for module study:
- 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;
- THU will use their constant-temperature incubator (恒温箱)
to measure the actual module length change due to temperature
fluctuation.
- Will continue study of adding spring-washers to absorb the length change of the module due to temperature fluctuation.
- Rakitha showed updated Ecal simulation for the fiber holes, see
ecal_summary_6.pdf
- still not sure why the Edep change in lead is about 9%. Jianping suggested contacting Jin for suggestions.
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- Participants: Cunfeng Feng, Yi Wang, Chendi Shen, Jianping Chen,
Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B., Alexandre C.
- Chendi showed progress on THU side: 20160324/Shen-Chendi-2016_3_24.pptx
- compression went up to 500kg and stack height appeared stable;
- insert 6 rods and turn nuts to snug, stopped immediately when the force sensor reading starts to change;
- then released the compression plate, took module off the assemble stand.
- now is painting Kedi's reflective paint on the module sides.
- 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.
- Most of time we discussed on how to transfer force from the compression plate to the screw/rods.
- 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).
- 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.
- We finally agreed somewhat on the following procedure:
- compress the stack with 500kg until stable;
- 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;
- insert the rods, turn nuts to snug;
- 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.
- Stop when the compression plate is completely released and the torque wrench reaches the set value.
- 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.
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- We had a short meeting today because of the mix-up about daylight saving time change in the US.
- Update on fiber polishing:
- Here are comments from Howard Budd on the DDK connector+fiber polishing of Minerva/Fermilab experiments:
- "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."
- Polisher for the DDK connector: DDK_Connector_Polish.pdf
- Procedures for adding cable boots to the connector: boot_proc.pdf
- Procedure for making cables: cable_odu_proc.pdf
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- Participants: Cunfeng Feng, Xiwei Wang, Yi Wang, Zhihong Ye, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B.
- Update from Ye on the fiber polishing machine from JLab, see 2016.3.10_tianye_fiber_polish.pdf
- machine has been there for many years, not sure if it was custom-built by JLab
- a collection of fiber polishing article from various experiments:
- ALICE_fiber.pdf on the ALICE sputtering machine
- intro_fiber_ATLAS_Tilecal.doc
- 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
- D0 note 3561, method_comparasion.pdf "Comparison
of fiber-polishing techniques", compared performance among the three
methods -- iceblock, teflon, and the fiberfin III machine.
- Update from SDU/Cunfeng: see slides SDUreport_03102016.pptx
- 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.
- 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.
- 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.
- Update from THU: working on continuously-monitoring the pressure.
- Update from Rakitha on simulating the fiber holes, see ecal_summary_5.pdf
- 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).
- The averaged Edep in lead decreased while Edep in sci
increased, and the sum stays unchanged. This caused the sampling
fraction to increase.
- The energy resolution becomes slightly better due to the larger sampling fraction.
- 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?
- Update from UVa:
- Sent 60m Y11 fiber to SDU and 100m to THU yesterday
- Misc info: The optical glue we use at UVa is Eljen EJ500 optical cement and the polishing set is Ocean Optics, Fiber termination kit
- 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.
- Ordered 150 sets of DDK connectors for practicing at UVa, SDU and THU.
- Will contact Minerva again for their fiber polishing method.
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- Participants: Chendi Shen, Cunfeng Feng, Yi Wang, Zhihong Ye, Xiaochao Zheng, Vince Sulkosky, Ye Tian, Rakitha B.
- Update from SDU/Cunfeng: see slides compressionTest.pdf
- 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;
- Will continue contacting Saint Gobain to have an update (the Chinese branch is hard to contact).
- 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.
- 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).
- Not sure how much need to turn the brass nuts to keep the compression.
- 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.
- Update from THU/Chendi: see slides 2016.3.3_Chendi Shen.pptx
- 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).
- 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).
- Ordered 500m fiber from Saint Gobain, also not sure when these will arrive.
- 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.
- 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.
- Update from Vince/UVa.
- 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.
- Radiation dose reading for the preshower is back, see http://hallaweb.jlab.org/experiment/E05-007/SoLID/EC/meetings/2014-test/2016-test/radHardness/SoLID_preshower_radhardness.html
- Slides show the shashlyk setup and overview of the preshower radiation test: Detector_tests_03Mar2016.pdf
- 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.
- 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.
- 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:
- 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?
- Sampling ratio increased from 20% to about 35%. This is unexpected since the holes change lead and scintillator the same way.
- 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.
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- Participants: Chendi Shen, Alexandre Camsonne, Cunfeng Feng, Xiaochao Zheng, Vince Sulkosky, Ye Tian.
- 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).
- Here is Alexandre's report on the possible parasite test setup: SBS-GMp-parasitic.pptx. Some discussions:
- 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;
- 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).
- 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.
- Vince reported on the preshower radiation test:
- 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.
- For the summer, the plan for Hall A is to replace left Q1. Fall run is scheduled to be 9 week long.
- SDU report by Prof. Feng:
- Continued testing shashlyk light yield but the results are not stable;
- 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.)
- 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.
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- Participants: Cunfeng Feng, Ang Li, Chendi Shen, Jianping Chen, Ye Tian, Vince Sulkosky, Xiaochao Zheng
- 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.
- UVa update by Vince:
- Working on setting up the hedgehog test of the shashlyk
scintillator layer sheets. Holders and PMT couplers have been
3D-printed.
- 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: http://hallaweb.jlab.org/experiment/E05-007/SoLID/EC/meetings/2014-test/2016-test/radHardness/SoLID_preshower_radhardness.html
- 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).
- 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.
- 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?
- 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.
- 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.
- The FMPMT test paper has been on arxiv for over a month, see: http://arxiv.org/abs/1601.01903
- 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.)
- 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.
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- Participants: Cunfeng Feng, Ang Li (李昂), Ye Tian, Xiaochao Zheng, Jianping Chen, Vince Sulkosky
- SDU update: Scintillator primary test results.pptx on preliminary test of shashlyk layer light yield (PMT side-coupling method, cosmic)
- paper and mylar reflective layers adds small boost to the light yield
- the spectrum for the mylar test is strange, need to repeat.
- 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.
- 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.
- UVa update (Xiaochao): UVa_Update_20160204.pdf on the mechanical property measurement of shashlyk scintillator pieces
- results on the Young's (tensile) modulus and yield strength are consistent with web data.
- also performed the 3-point bending test. I was told this is the same as shear stress but obviously not, see https://en.wikipedia.org/wiki/Three_point_flexural_test. Will re-process the data and report next week.
- for web data on polysterene mechanical properties, see for example:
- Material Property Data Website (or last slide of the above report)
- http://www.boedeker.com/polyst_p.htm
- 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).
- Ye Tian reported:
- 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.
- will start looking into online scripts and online data analysis; will take shift.
- (beam starts Friday 2/5 in Halls A, B, D)
- Jianping reported:
- 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.
- Mickie Chu has officially joined the SoLID collaboration. His main contribution will be focused on MRPC and TOF systems.
- We discussed briefly the polarized 3He PVDIS idea. A separate series of meeting and minutes will be setup on this topic.
- 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.
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