General Meeting Summary 5/17/17

DETECTORS AT JLAB (Arthur, Tanja, Hamlet, Vardan)

• Neutral Particle Spectrometer - HV and connector plane

• HV divider design complete, finalizing design of new PCB, making prototypes for testing, component selection ongoing, procurement of larger quantities expected in next few months
• discussion about connector back plane and mechanical spacing (see these slides for illustration)

• Minimum space requirement for connectors (SHV and BNC) is 90x108 cm^2
• Interference at min angle of 6 degrees with NPS at 4m from target is 41.8 cm
• Detector frame space is about 84 cm wide when flared out to back of crystals - the 90cm required connector space may fit
• How would one flare out from smaller crystals to the larger area needed for connectors?

• Action Items:

• Check out PRIMEX HYCAL backplane
• Discuss possible options in 5/18 NPS meeting

• Discussion about Aerogel Cherenkov detectors

• SHMS detector doing fine - tray change expected at end of month
• HMS detector PMTs are dead - no obvious mechanical damage (picture of PMT photocathode), but need to check in more detail. The aerogel seems to be in good shape (Aerogel picture).

• Discussion about possible ways to mitigate risk to SHMS PMTs and also other detector PMTs in Hall C, e.g. flushing detector with dry air, helium monitors and global air handling system
• Discussion about possible ways to recover Helium-damaged PMTs through thermal treatment in vacuum chamber

• Action Item: test HMS PMTs to check for possible damage by Helium - a symptom to look for is after-pulsing

EXPERIMENTS AND R&D PROPOSALS

• Discussion about PAC45 proposals - more discussion in 5/18 NPS meeting

• Kaon tagged DIS run group proposal
• Wide Angle Compton Scattering WACS)- goes ahead as single proposal, results of recent simulations (including dose rates, power deposition/cooling, etc.) suggest that one can assume an equivalent photon flux of 1.5x10^12 photons/s for rate estimates. More information on the photon source can be found in the NPS Wiki.
• The NPS and high-intensity photon source is envisioned as one unique facility for WACS in Hall A/C and KLong in Hall D

• PbWO4 R&D proposal focus areas for FY18:

• continue crystal quality measurements including chemical analysis
• construction of a prototype to test limits of energy/position resolution, as well as investigate contributing factors to the constant term
• investigate different forms of readout including PMTs, SiPM, APDs

PBWO4 STUDIES AT CUA (Richard, Andres, Marco, Tanja)

• Crystal drawing prototype - thermal design

• three models of varying degree of technical challenge, will focus on the simplest for initial testing
• drawings of thermal design ongoing
• component identitification for temperature control and sensors, as well as weight monitoring ongoing

• CRYTUR crystal

• goal is to characterize this crystal from a later growth cycle and determine if it still meets the specifications of NPS
• this crystal has been rejected by PANDA

• Photodiode readout

• currently investigating effect of cooling on readout stability
• also testing a different pulse generator to drive LED

DETECTORS AT CERN (Rachel)

• Cosmic data with magnet on have been taken - these are important for alignment

• analysis of the data showed a misalignment - this is currently being taken care of by modifying the detector simulation, which will be used in the main data analysis

• Stable beams are expected as soon as this weekend - stay tuned for cool data at the next meeting!

• In general, much activity at CERN in preparation for the upcoming run

• tracker week ongoing
• small issue with water accumulation in CMS, which might be from condensation of cooling pipes, e.g. CO2 from the pixel detectors, but this can be dealt with

DATA ANALYSES AND SIMULATIONS (Salina, Richard, Andres, Tanja)

• DVCS-3

• Action item: contact Mongi (Ohio U.) and/or Marco about scripts for setting up the deadtime analysis

• Pion/Kaon Structure Functions - deferred until next meeting

NEXT MEETING: WED. 31 MAY at 10:00 AM (EDT)