General Meeting Summary 6/14/18

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  • Discussion about details of assembly
  • Largest parts assembled in test lab, total assembly may be done in another location and full magnet transported back to test lab
  • Total weight is ~10t
  • Need a ~1-page document specifying tests/mapping of the magnet - check in with Charles

HV BASES (Julie)

  • Have received about half of the boards, ready to assemble
  • Have 1000 sockets at OU, still need the remaining ones
  • How many sockets are at JLab? Vladimir checked into this:
  • 36 old type sockets (machined one) in C124 office
  • 149 old type at Fernando`s laboratory F117 that sockets already mounted to HV divider circuit boards
  • 15 have been sent to Julie
  • So it is 200 total plus
  • 120 new type sockets in NPS cleanroom with PMT`s
  • In the end we got 320 sockets at Jlab
  • 35 PMTs will come from OU to JLab
  • Action Item: Send link to location where to store information on bases, data sheets etc. (Tanja)


  • Discussion about path forward - procure fewer crystals from Crytur (bid was higher pricing), procure 580 crystals from SICCAS (instead of Crytur), or a mix of 400 from SICCAS and 100 from Crytur
  • Good to check quality of Crytur crystals over a large sample - so far have only checked in single digits for rectangular crystals
  • Need to have all NPS/Hall D crystals over next few years
  • Discussion about combining crystals from different vendors in calorimeter
  • Crytur is not willing to provide crystals at less than $1900/piece at this time (original discussion was $1300/piece), Giessen U. negotiations unsuccessful
  • SICCAS is willing to replace crystals and discuss procedure to meet specifications
  • Decision to check if possible to procure 400 crystals from SICCAS and 100 crystals from Crytur. If not possible, will proceed with 580 crystals from SICCAS

NPS PROTOTYPE/COMCAL (Vladimir/Alexander)

  • Ongoing main activities
  • PMT testing - set of 200 Hamamatsu R4125 PMTs being analyzed
  • Engineering drawings
  • Assembly location details - 126, TEDF?
  • Crystal wrapping and storage
  • Monitoring system
  • PMT tests suggest good performance overall, but see relatively large fluctuations in distribution of PMT amplitudes though all within 20%, in actual experiment will gain match
  • Reflector to be used: ESR (same as VM2000 discussed in January 2018 NPS meeting by IPNO team)
  • Need sheets 17"x17" to cover 140 crystals, thickness 5um
  • Procedure for pre-shaping: anneal at about 100 degC
  • Test wrapping with dummy bar made of either stainless steel (better thermal expansion coefficient) or aluminum (easier to work with). Note error of machining is ~100 um
  • Next steps:
  • Systematic checks of PMTs
  • Update documentation of PMT tests - also link to NPS Wiki
  • Will present more details of test and assembly status in next meeting