General Meeting Summary 3/7/19

MAGNET (Charles, Bogdan)

• Safety and Operations documents

• OSP for mapping is being prepared - expected to be complete in week 3/11
• More detailed documents needed for ERR

• Details of mapping plan for ERR

• Planning to bring mapper to JLab in week 3/11

• Fringe fields

• Additional calculations made for downstream of magnet with passive shielding - sent this information to Jay Benesch

• Action item: redo calculations of front of HMS (snout) for ERR - this is relevant for the optics

• Paulo redid distances
• need set of kinematic positions

• Action item: determine sensitivity of experiments to up/down asymmetry due to magnetic field

• magnet horizontal field changes up/down position of detector - for measurements only matters if sensitive to up/down asymmetry
• DVCS measures up/down - need to think about and have answer for ERR
• Is the power supply reversible? - need to include in ERR

FRAME AND SIMULATIONS (Carlos, Ho San)

• Working on full prototype for tests of movable boards for PMT access

• Deciding on cable lengths and work distribution

• clarifying quotes and prices, e.g. labor and part per cable

• Testing fibers

HV DIVIDERS (Vladimir, Alex S., Fernando)

• Discussion of recent ComCal/NPS prototype results

• Best solutions for NPS HV dividers seems to either bypass amplifier or to reduce the amplification - both are practically easy to do

• slight preference to bypass the amplifier - 100uA is average anode current, peak anode current is 100mA/pulse, so have some dynamic range available --> bypass should be ok
• practically bypass means directly connect signal to output

• Planned tests with sample dividers with bypassed amplifier and reduced amplification

• idea: compare gains (e.g. 1=bypass, 2=...) and rates and choose best option experimentally
• test with beam in Hall D
• test bench either after or instead of beam tests - expect to put all together in lab in 2-3 weeks

• Planned test with 3x3 prototype and Crytur crystals

• idea: test dependence of saturation on crystals (SICCAS vs. Crytur)
• space and opportunity in Hall D

• A few notes on PMT, divider, and fADC

• R4125 is rated for 1500 V operating voltage, maximum anode current is 100 uA
• fADC dynamic range for earlier 3x3 prototype tests was 1 V
• ComCal/NPS prototype has different crystals than the 3x3 prototype
• For original HV divider design assumed 8 pe/MeV light output

CRYSTALS (Vladimir, Tanja)

• Received 160 replacement crystals from SICCAS - inspection ongoing

• [http://www.vsl.cua.edu/cua_phy/index.php/MainPage:Nuclear:NPS:PWO:CrystalLOG#JLAB_160_replacement_pieces_.282019.29_Details Some results in section JLAB 160 replacement pieces (2019) Details

• In contact with Crytur about procurement of additional crystals

ERR PREPARATION

• Created Wiki page NPS ERR for people to start filling in

NEXT MEETING: THURSDAY 21 MARCH at 9:00 AM (ET)