JEF meeting, August 27, 2021
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Meeting time and location= 9:30 am EST (JLab time) Bluejeans only
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Agenda
- SICCAS crystals
- Module fabrication
- COMCAL tests, TAC running, etc.
- - Adjusting LED system for CCAL -- Sasha
- Data analysis
- - 2π0 and 2η studies -- Annika Thiel
- - \eta \to \gamma\gamma\pi^0
- Simulations
Minutes
Attendees: Bill B., Olga, Phil, Zisis, Arshak, Jon, Susan, Azizah, Igal, Annika, Liping, Sasha, Jane, S.T.
- SICCAS received shipment of new raw material, producing test crystals now; plan to wait ~2 weeks for results
- Powder from previous vendor --> poor quality crystals
- Delivery schedule is still unknown
- COMCAL has been installed on platform and re-surveyed
- Still tilted but not as badly as before
- Sasha checked out COMCAL response using LED and alpha source
- LED response using amplitudes wider distribution than expected (hoped for?)--> spread in light distribution
- Adjusted HV, checked timing --> things are starting to look good
- Light uniformity from LMS is a concern for FCAL-II; plan to use different LED colors just like done for FCAL
- Fernando has prototype for PMT divider for NPS, working on tuning design for them, then for us
- Hope to test during upcoming runs, can even be during CPP next year, but want to set a deadline for the middle of next year
- Igal gave an update on his η→π0γγ analysis
- Ran simulations for both GlueX and JEF conditions
- Observed considerable peaking background from η→2γ, probably arising from conversions/split-offs
- Looked at ways to reduce or eliminate this contamination
- Observed considerable peaking background from η→2γ, probably arising from conversions/split-offs
- Found expected number of π0γγ events to be roughly consistent with the JEF proposal
- Found the amount of beam time needed for production of 50M ηs with recoil proton required to be roughly an order of magnitude longer than the proposal estimate
- Offline discussion summary:
- Clarify the meaning of 50M tagged eta i.e. eta with a detectable recoil proton (eta can possibly not pass the selection criteria)
- Out of 50M tagged eta, 1/4 is expected to pass the selection criteria
- Expected integrated luminosity for phase IV is 315 pb-1 ie for 100 PAC days, ~ 1fb-1 should be collected
- After re-compiling all numbers, the signal observed is consistent with simulation expectation
- Offline discussion summary:
- Found that the kinematic fit is distorting the mass distributions (sometimes moving peaks away from the physical mass values)
- TMVA results briefly touched on, but signal after applying cut on BDT response seems high possibly due to a bug in DSelector that is treating g1g2 and g2g1 as two different combination
- Ran simulations for both GlueX and JEF conditions
- Annika presented some results of her γp→p2π0,p2η analysis
- Background in 2η channel is high, but reduced by imposing a π0 veto
- Handled background by looking at side-band regions in 2D
- See considerable 2π0 strength at low mass consistent with f0(500)
- We had a discussion regarding simulation of these events
- Annika currently using genr8, looked into using amptools without much success
- Use mass distributions from data?