General Meeting Summary 3/31/16

BACKGROUND STUDIES

• Discussion about Vardan's GEANT4 simulation

• shows a background reduction, in particular for electrons, that is different from that shown in Vardan's earlier studies and also David Hamilton's GEANT4 studies.
• depending on the charged background reduction prediction may want to consider a charged particle absorber in front of the calorimeter (DVCS/HA used 10 cm of plastic - absorbs electrons up to 20 MeV)
• Action item: check implementation and also compare to previous results

UPDATE ON HV DIVIDER STUDIES

• Discussion of gain stability studies with C-W base design with PMT and APDs

• APD-based readout could be interesting if magnetic fields are too strong to shield from
• To compare to our current default active base design need to have gain stability as function of anode current for C-W bases - a double-LED setup may be advantageous to use for these tests
• may want to correlated jitter in output signal to input driver

• Follow-up to question about radiation damage to processor from Hall C January meeting

• may not be an issue as it is possible to separate digital part from calorimeter by sufficient distance - requires ribbon cables, but still not as many as with default base design

• Action item: determine linearity at high rate for C-W bases

• check against default base parameters
• include amplifier in base
• must have test with amplifier done before September 2016

MAGNET UDPATE

• Discussion about magnet budget for machining the steel (now at JLab) and coil

• machining and procurement of conductor require design drawings - ongoing activity

• Discussion about most recent design update from M. Fowler

• interferences at small angles require a specialized beam pipe - cannot complete magnet design without this
• Hall C beam line design is currently ongoing, so good time to take this into account

ITEMS FOR NEXT MEETING:

• Follow-up background study (Vardan)

• Magnet updates

• Other Action Items from list, e.g., magnetic shielding of PMTs, support structure and frame

• Other...

NEXT MEETING: THUR 21 APRIL, TIME: 9:00 AM (EDT)