JEF meeting, August 13, 2021

Meeting time and location= 9:00 am EST (JLab time) Bluejeans only

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Agenda

• SICCAS crystals
• Module fabrication
• COMCAL tests, TAC running, etc.
• Data analysis
  • TMVA application on data (ig)
• Simulations
  • TMVA for background suppression (Chase)
  • Using MC Trajectories in simulations (Jon)
• Meeting time

Minutes

Attendees: Varun,Igal,Joanna,Zisis,Arshak,Chase,Liping,Sasha,Azizah,Bill B.,Tim B.,Jane,Jon,Phil,Olga,Susan,Jane,S.T.

• No update from SICCAS regarding test samples for production of new crystals
• Procedure for wrapping crystals has been updated (presented by Joanna(UNCW)): [1]
• Crytur confirmed can produce crystals (want to be fully loaded)
• COMCAL has been installed in the hall
  • Light monitoring system: all channels checked, some channels were unstable (drifting amplitudes, due to poor connections on PMT socket?)
    • Two channels replaced, some optical fibers reglued
  • Found problem with one of 5 thermal sensors, will operate with 4
  • About to move to platform for positioning on beam line
• Chase presented update on using TMVA for background suppression for η→π0γγ channel
  • Compared Boosted Decision Trees (BDT) to Fisher discriminants
  • 15 input variables: tested various combinations
  • BDT works better than Fisher
• Igal looked at applying BDT to simulations of signal (η→π0γγ) and background, and to 2017 data
  • Looking at γp→4γp
  • Vetoed 2π0, ηπ0 and 2η channels using 5σ cut
  • Required all photons in FCAL and a fiducial cut to avoid getting too close to beam hole
  • Monte Carlo: found large peaking background due to η→2γ
    • Not reported by previous experiments -- need to understand source
  • Using 4-vectors after kinematic fit sharpens features in mass distributions
  • Apply cut on BDT greatly reduces background below signal region
• Jon briefly showed the z-positions where conversions of photons occur as part of a presentation about using MCTrajectory information from the simulation