JEF meeting, August 7, 2020

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Meeting time and location= 9:30 am EST (JLab time) Bluejeans only


Connection instructions

We are using BlueJeans Video/Audio conferencing. Our meeting ID number is 992533564. Click "Expand" for more details.

  • Make sure you have created a BlueJeans account via your JLab CUE account using this link:
  • If connecting via Web Browser: click this link (no passcode is needed):
  • If connecting via Phone: Dial one of the following numbers and then enter the meeting ID above and hit "#" or "##"
  • If connecting via Polycom unit:
    • Dial 199.48.152.152 or bjn.vc
    • Enter meeting ID above

Agenda

Minutes

Attendees: Igal,Varun,Jane,Arshak,Jon,Zisis,Liping,Tim W.,Jared,Phil,Tim B.,Sasha,Susan,S.T.

  • Procurements (Tim W.)
    • μ-metal shields: vendor had some tooling issues, claim will send ~20 next week
    • Light guides: vendor has 10 good ones, will do 10 more, to be dropped off some time today?
      • When these arrive, Josh C. will commence construction of several modules; Tim W. offered technician help
    • Iron shields from CMU: Tim W. received 20 in March, submitted these for annealing yesterday; CMU working on 100 more
  • Sasha and Josh C. have been working on QA of recently received shipment from SICCAS
    • Check dimensions, visual inspection, laser pointer to look for bubbles. Sasha is keeping track of this in a spreadsheet.
    • Average size of face = 20.55 mm, narrow spread (~20 micron)
    • Most crystals look good, some have discoloration, one has large chip (but probably still usable)
    • Phil: can crystals with discoloration (brown/yellow) be cured with UV? Sasha: we have not tried that yet, can look into this.
    • Will hold off on light transmission measurements (apparatus in Carl Zorn's lab) due to MEDCON-5 restrictions to lab access
    • Sasha working on getting light yield setup (using Na-22 source) in TEDF, study a sub-sample of crystals
  • SICCAS currently producing remainder of first batch of crystals, time scale is ~2 weeks
    • Jane likely be allowed to travel to Shanghai in September for QA
    • New contract for construction of 450 more crystals has been signed
  • Test setup in PS arm in Hall: can study 9 crystals (actually 12, but 3 slots are occupied by NPS test modules)
    • Plan is to use the current run time to study crystal response with beam
      • Get benchmark measurements with "good" crystals, then compare with "suspicious" crystals (yellowed, etc.)
  • PMT dividers: Vlad P. has updated components and changed design to increase voltage on first dynode
    • Chris S. has new PCB layout, added switch for changing amplification (bypass or 3x)
    • Plan to install in COMCAL, use for TAC run, check linearity
    • Hope to converge on design soon
  • HV for lead tungstate crystals: HV rating for small cables might need to be addressed
  • S.T. reported that code handling insert in reconstruction and smearing is now in github master
  • Igal looked at selection criteria for η→π0γγ
    • Identified 9 variables, looked at FOM (signal to background) to set optimum cuts for each
    • Some variables provided no distinguishing power for signal relative to background: vertex cut, proton momentum cut, missing energy
    • Jared starting looking at signal PDFs for γγ invariant mass
  • Jon looked at response of FCAL2 vs FCAL1(no insert) using particle gun.
    • At 3 degrees sees drop of efficiency of FCAL2 vs FCAL1 at low photon energy: threshold problem?
    • Sasha: would be interesting to look at cluster separation for 2 photon events
    • Some interesting features seen in efficiency plot for 1 GeV photons as a function of angle
      • Drop at 5 degrees correlated with CDC endplate minimum radius?
  • Jon started implementing more realistic models for η decay distributions
    • Recommendation for π0γγ: looked at measurements from Mainz-A2: Nefkens, et al.
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