JEF meeting, August 21, 2020
Meeting time and location= 9:30 am EST (JLab time) Bluejeans only
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:
- http://jlab.bluejeans.com (You should only need to do this once)
- 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 "##"
- Dial: 1 888 240 2560 (US or Canada only)
- or, List of International Numbers
- If connecting via Polycom unit:
- Dial 22.214.171.124 or bjn.vc
- Enter meeting ID above
- SICCAS crystals
- PS test setup
- Preparation for module fabrication
- COMCAL tests, TAC running, etc.
- Snowmass contribution
Attendees: Igal, Arshak, Varun, Jared, Phil, Zisis, Jon, Sasha, Tim W., Jane Josh, Tim B., S.T.
- Sasha and Josh had previously installed 9 "good" crystals in the PS setup in Hall-D to study light yields.
- Choose 1 as a reference for light yield comparisons to study "bad" crystals
- Swapped out 6 crystals, installed crystals showing various levels of discoloration (yellow, brown,...)
- Discolored crystals show notable degradation in light yield and energy resolution.
- The worst 2 have 25% worse amplitude and would be rejected (Sasha suggested a 20% threshold w.r.t. nominal "good" crystals)
- One crystal is right at the border (-20% amplitude) for being rejected: S.T. asked whether it was worth trying to cure this one; Sasha will consider
- Next plan to install crystals that appear to have bubbles or other internal imperfections
- Also plan to install Crytur crystals (expected to be better than SICCAS crystals, plan to use as real reference crystals)
- New light guides: quality better than previous vendor; some evidence for machine marks, could do with better polishing, but satisfactory for what we need
- PMT divider redesign: slow progress, would help if had face-to-face between Vlad P. and Sasha
- Plan to install revised version in COMCAL; had hoped to do before TAC run (very soon, if beam comes back!)
- Sasha would like to test linearity, will need to coordinate with GlueX run coordinator
- PMT/divider testing - Phil indicated interest in working on this.
- Igal continued studies of η→π0γγ channel and 3π0 background
- Optimization of selection criteria
- Switched to using DReactionFilter with kinematic fitter: χ^2 is most powerful cut
- Noticed that there was not a huge difference in signal purity between FCAL and FCAL-2 after cut optimization, although resolution got better with FCAL-2
- Question about shower threshold: S.T. indicated that it is currently the same for both FCAL lead glass blocks and insert
- Question about covariance matrix: S. T. implemented a diagonal matrix in the code for insert based on Sasha's measurements
- There is a plan to redo exercise to determine covariance matrix for FCAL, will try to learn how to do this for FCAL-2
- Jon looked at FCAL-2 efficiency with MC with material in front of FCAL-2 turned off -- efficiency looks flat at ~99% above 2 degrees
- Indicates features in previous plot due to FDC chambers and other sources of material upstream of the FCAL
- Liping has completed a draft of our contribution to the Snowmass effort.