02/26/2013

2/19/2013

02/12/2013

02/05/2013

01/29/2013

01/22/2013

01/15/201

• 03/19/2013 Meeting to discuss EC design:

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

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

   	Requirement/Parameters	SIDIS LAEC	SIDIS FAEC	PVDIS FAEC	Note	Reference/Source
   General	(Zmin, Zmax)
   	(Rmin, Rmax)
   	# of modules
   	total surface area
   Physics	Highest electron rate (physics)			110kHz for >2GeV
   	Range of pi-/e ratio or pion rate (physics)			8MHz for >2GeV	dominated by which EC?
   	Main background type, energy range and rate range			low E pi-: 10kHz/cm^2.	dominated by which EC?
   	Physics requirement on pi rejection (and electron efficiency)			100:1	dominated by which EC?
   Trigger	Max trigger rate per module or segment			< a couple MHz
   	Minimum pi rejection
   DAQ	Per sector rate is 30kHz or below, for 30 sectors. With a safety factor of two we are looking at a total rate of 450kHz
   Shower Design	module size, shape, length, layer thickness
   	fiber density (per module or cm2)
   	fiber readout design
   	PMT readout (1/module?)
   	Max DAQ and/or trigger rate per module
   Preshower Design	segmentation size, shape, layer thickness
   	fiber density (per module)
   	fiber readout design
   	PMT readout design
   	Minimum photon rejection
   	Max DAQ and/or trigger rate per segment

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

• 03/05/2013 Meeting to discuss EC design:

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

2. Discussions on the pion pileup simulation:

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

• 02/26/2013 Meeting to discuss EC design:

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

2. Local participants: Jianping Chen
   

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

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

• 02/19/2013 Meeting to discuss EC design:

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

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

3. From Mark Jones:

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

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

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

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

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

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

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

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

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

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

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

3. From Mark Jones:

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

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

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

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

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

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

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

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

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

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

2. Local participants: Jianping Chen, Zhiwen Zhao:

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

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

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

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

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

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

4. Update on item C - Support Structure:

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

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

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

      3. What is the purpose of the "Lego" bits in the KOPIO Design (see Fig.1 in B.S. Atoian /et al/ NIM 584, 11 Jan 2008, p 291 (http://www.sciencedirect.com/science/article/pii/S0168900207021717). Won't these block light output and will we really have them? The main concern here is in how the rods through the blocks are tensioned.  One must be careful to hve either all the tension on the Lego bits or none of it there.

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

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

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

2. Local participants: Jianping Chen, Zhiwen Zhao:

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

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

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

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

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

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

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

2. Local participants: Jianping Chen, Zhiwen Zhao;

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

   1. Preshower design:

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

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

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

   2. Readout options to do:

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

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

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

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

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

           1. field resistance

           2. gain, also gain loss due to field

           3. max current capacity

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

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

   3. Support structure:

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

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

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

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

   4. Super BigBite test with HERA modules:

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

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

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

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

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

• Communication with IHEP

  1. Reply from IHEP on 2013/02/21: 2013/02/21 directory.

  2. Email we sent to IHEP on 2013/02/07: 2013/02/07 directory. Here we asked 4 questions on the support design as mentioned in the 2013/02/05 meeting.

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

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

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

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