General Meeting Summary 4/13/17

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  • Discussion about Magnet preparation plan, e.g. general checks and assembly once coils and yoke arrive (anticipated July/August)
  • likely need support from HA/HC
  • lifting equipment available in test lab, for assembly no stand needed as currently envisioned
  • power supply to be used: HKS, can be moved between halls, will need AC power and cooling
  • magnet assembly could be done in test lab, testing magnet is more challenging due to power and cooling requirements
  • action item: check on HKS PS power and cooling requirements
  • Discussion about magnet components
  • nothing new on coils
  • Ohio yoke vendor received the steel plates


  • SICCAS crystals are on order, anticipate first ~100 to arrive in June/July
  • IPNO getting ready to test subset of the current 45 crystals
  • CUA received one rectangular crystal from Crytur from a late production cycle (rejected by PANDA) - will check is performance would be acceptable for NPS.
  • Discussion about latest pricing of Crytur crystals in context of current PANDA schedule


  • Discussion about points needed for design
  • PMT R4125-01 information:
  • R4125-01 PMTs are exactly same type PMT as R4125. Only with a small difference that R4125-01 is HP painted version. This conductive paint is connected to the photocathode and all PMT bulb will be at the same voltage

as photocathode. To avoid any electrical problems (sparking between PMT and surrounding mu-metal shield) we will cover phototube with a thin layer (~25-30 mkm) of Teflon.

  • Power dissipation by HV dividers in the detector box:
  • Based on our measurements NPS HV divider current at 1100 V is about 450 mkA, so heat deposition from each divider would be about 0.5 Watts. Note, this is about factor two higher than in PrimEx. So, for ~1200 dividers (blocks) heat energy deposition would be 500-600 W.
  • Discussion about possible measurements with 3x3 prototype to test temperature control system
  • chiller selection ongoing - idea is to have one that can also be used for the full NPS later


  • No significant impact of long cables on the signal
  • tested 10ft vs. 65 ft cables, signal on order several 100 mV, see 5-10% attenuation as expected
  • Checked rate dependence of output signal with actual fADC
  • previously had observed on scope that HV divider is linear up to ~2 MHz
  • present test is carried out in Hall D
  • Action item: before final production still need to generate a complete design drawing
  • Future testing: effects correlated with range of HV divider
  • optimization of gain of PMT, LY~10-15 pe/MeV, calo at ~1 GeV then ~10k photons
  • optimization of fADC range


  • Discussion of the recent 28 March meeting
  • Discussion of Pavel's recent background simulation results
  • Jixie and Bogdan also have new results and will present at the upcoming meeting on 20 April
  • Discussion of a few slides on source and a new physics idea from Bogdan