General Meeting Summary 6/2/16

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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)