General Meeting Summary 8/9/17

DETECTORS AT JLAB (Arthur, Richard, Andres)

SHMS AEROGEL CHERENKOV DETECTOR

• Aerogel tray has been exchanged successfully - SP-30 is now installed

• Total time was about 3 hours - faster than before due to optimization of procedure

• Tray exchange requires two techs and one expert
• pre-planning (tools, materials like black tape and o-rings, survey of tray to be installed, covers) is essential

• Two damaged bolts have to be fixed: top left and top right angle - note that design is not optimal and expect this to happen again after tray exchanges

• drilling should not affect aerogel in tray, but have to be careful

• Action item: replace two bolts

HMS AEROGEL CHERENKOV DETECTOR

• Examined SP-15 aerogel (looks fine) and SP-30 aerogel (seems less transparent than that from Bates - change?)

• Examined reflector - may consider changing to Gore

• Discussion of status of PMTs

• Two dead XP4572 PMTs remain to be removed
• Next have to remove Bates XP4500 PMTs from their cylinders (without breaking them!) and install these into the vacated HMS detector cylinders

• need to pay attention to potential removal of paint on PMTs - light leaks!

NEUTRAL PARTICLE SPECTROMETER AND PBWO4 STATUS

• 50 PMTs should be at JLab - Arthur will check - 150 more on the way

• SICCAS informs of a delay in shipment of PbWO4 crystals - target date for all 460 crystals is now end of September

• Discussion of crystal testing procedures at CUA

• Quality assurance plan discussions ongoing
• IPN-Orsay sent schedule - need to discuss together with planned work at JLab and CUA to accomplish goals

DATA ANALYSIS: DVCS (Salina)

• Discussion of observed current dependence of the dead time of the data

• for given event, trigger of interest (S2&&Cer) does not always increment - seems to indicate that event is triggered by something else. This happens every ~12 events.
• there is a variable one could look at that identifies the detector that triggered each event. More information on the DVCS trigger at this location

• Questions:

• does "Master or" consider events of all possible trigger modes (there are at least 10)?
• what does "CODA event rate" mean? - events from "s2m and CER"?

STUDIES AT CUA (Andres, Dannie)

• Structure function projections - bin optimizations ongoing

• Pulse generator

• use TTL (positive) output, which has the required specifications and convert to NIM (negative) - do that by inverting LED current, switch the legs

DETECTORS AT CERN (Rachel)

• Two highschool physics teachers from DC area participate in Quarknet program at CERN

• learn about pixel detectors and also other detectors concepts, e.g. importance of material budgets
• discussion about recruiting strategies

• Data analysis ongoing

• Shifts upcoming in October and December

• CUA lab setup will begin in late August

NEXT MEETING: WEDNESDAY 23 AUGUST AT 10:00 AM (EDT)