General Meeting Summary 6/2/16

CABLE MANAGEMENT

• Discussion about optimal cable management through an SHMS "pivot-patch" cable run. This generic solution would work for NPS and also take into account the other two standalone detectors in Hall C. Main goal for NPS: assuming ~1200 NPS cables into SHMS hut, what is possible?

• Details of the generic cabling solution (note that this assumes that all connectors fit into one panel):

• patch panel at front of SHMS for 1200 cables
• cable runs want at beam-left (large angle) side of SHMS
• use penetrations into SHMS electronics hut - thre are about 6-8 inches in diameter (see page 4 of cabling slides)
• one rack a patch panel for 1200 connectors - different options for patches show on page 7 of the slides. The size of cables is important, e.g., bottom right option can only take ~400 big cables, while it could fit 1200 high density BNC cables.
• assume ~3 DAQ spaces in electronics hut for 1200 signal cables and fADCs

• Discussion about separating HV and signal cables - send HV to CH rather than to electronics hut

• General conclusion is that it is not impossible to get 1200 cables into SHMS, but it would likely require regular/smaller signal cables - consensus that RG58 cables would be ok to use

• Action items:

• check on HV main frames
• positioning of HV main frames

MAGNET UDPATE

• Discussion about the vertical gap needed for detector at 3 m from target and assuming detector dimensions 20 x 36 cm^2 of PbWO4

• current design is overdimensioned - smaller gap simplifies design
• reducing the vertical gap will prohibit placing anything between scattering chamber and magnet
• after discussion, there are no objections to reducing the vertical gap

• Update on steel machining

• two local companies can handle large steel plates

• Action item: design drawings

FRAME DESIGN

• Discussion updated design including the available rails

• Current design assumes that at a detector distance of 4 m still need one more layer of crystals. This means the smallest angle configuration is 6 degrees at 4 m from target

• Details of ongoing design work:

• working on aditional horizontal clearance with beam line
• need an estimate of distribution of crystal dimensions with wrapping
• step file available for additional work on back and cooling implementation if needed

• Discussion about installing crystals with different dimensions - how precisely need to know position of crystals inside the detector after assembling

• estimate for 3 m position of calorimeter is about 0.1 mrad, which corresponds to < 1 mm uncertainty in absolute position

• Action items:

• measure 2014/15 SICCAS crystal dimensions
• get distributions of HyCal crystal dimensions

CRYSTALS

• Tests on PbWO4 are ongoing at CUA and Orsay

• light yield and transverse transmittance mostly done
• longitudinal transmittance and irradiation starting

• Discussion about getting a few BGO crystals from L3 to test - note that this would likely require readout electronics as well

MAGNETIC SHIELDING OF PMTS

• Fringe fields at location of NPS PMTs based on field map Bogdan provided.

• field is on order 20-50 Gauss and could be shielded with mu metal around PMTs and perhaps some external soft iron shielding
• additional NPS prototype tests could be done for verification of this scheme

• Discussion about external soft iron shielding around detector

• from last meeting: transverse field at calorimeter is estimated to be 20-50 Gauss
• PMT mu metal shields out 20-50 Gauss
• Iron box around the calorimeter of wall thickness 3mm shields out any additional fields

• Action item: need the field map for polarized target

UPDATE ON RCS PROPOSAL WITH NPS FOR PAC44

• Short update on physics goals

ITEMS FOR NEXT MEETING:

• Cable management update

• Magnet updates

• PMT magnetic shielding update

• Support structure and frame

• Crytals and PMTs

• Other...

NEXT MEETING: THUR 30 JUNE, TIME: 9:00 AM (EDT)