General Meeting Summary 12/7/17

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MAGNET (Bogdan, Charles)

  • Expect main coil and yoke to arrive within next two months
  • Work ongoing for magnet assembly and test setup
  • Current test lab setup includes space for magnet assembly and testing - assumes ~1m space around setup
  • Action Item: Send space requirements sketch/info to Walt Akers before end of the year


  • Work ongoing, plan is to present options at the NPS/CPS collaboration meeting
  • Working on simulations of background, in particular for DVCS
  • Discussion about components needed (magnet, beam pipe, scattering chamber, junction scattering chamber and beam pipe)
  • Best would be to check with Hall C about status as two aspects have changed: 1) scattering chamber/beam pipe (change of O-ring) and 2) Beam pipe flared out

CRYSTALS AND PMTs (Vladimir, Arshak, Hamlet, Tanja and group at CUA)

  • Discussion about first crystal dimension measurements with the new tool
  • 20 crystals have been measured using alignment group's granite table
  • currently working on refurbishing own granite table
  • DAQ setup for prototyping and module assembly/testing
  • Anticipate electrical setup (ground etc.) done this week
  • Need to identify additional hardware, e.g. scope
  • Coordinating with Brad on computer setup once all hardware is in place
  • PMT performance analysis based on Hamamatsu data sheets
  • Some PMTs exceed dark current specification - needs to be checked
  • No information on QE provided by company, but calculated it using the blue light index that was provided. The result is on the order of 35%, which seems low - needs to be checked. Also ask company to provide QE.
  • Crystal characterization at CUA
  • Discussion of optical measurements results of ~100 crystals
  • About 20%-30% fail NPS specifications
  • Action item: setup up a range of acceptance/rejection limits
  • Out of crystals that pass the criteria there are still some that should be rejected. As an example, looking at SICCAS 5037 or 5029 in the summary table on the Wiki, one finds that both give a very high light yield. However, microscopy results show that both feature deep pits and bubbles in the bulk that artificially give such high light yields
  • Action item: perform additional microscopy and chemical analysis of outliers
  • Discussion about future plans for crystal procurement (SICCAS vs. CRYTUR)


  • General agreement on draft agenda
  • Action Items: send draft to Hall C, invite Fernando, update room on agenda (F113)

NEXT MEETING: 4 January 2018 at 9:00 AM (EST)