General Meeting Summary 1/16/20

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COLLABORATION MEETING - 3 FEBRUARY AT JLAB

  • Need substitute for talks from ANLS as speakers cannot be at JLab and large time zone difference


MAGNET (Charles)

  • Full magnet mapping measurements in test lab have been completed - thanks to T. Hartlove and M. Kerver
  • Note that these tests included the central magnet only
  • Ready to move magnet to the hall
  • Polarity of magnet - horizontal field so from NPS point of view the polarization doesn't matter
  • Action items:
  • Is it possible to compare measurements with calculation?
  • Schedule availability for test in Hall C in 2020?


PMT MAGNETIZATION (Carlos, Bogdan)

  • Frame modifications:
  • back of carbon frame replaced by my metal mesh - now have 30mm in front of photocathode PMT and 27.5mm at back of PMT
  • outer soft iron layer is 1.5mm
  • Amount of mu metal depends on length of dynode chain - most important is the distance from photocathode to the first dynode
  • Estimate for R4125 (8-10cm long tube, 1" diameter, 10 stages): distance relatively large
  • Measurement from Hall D: 4.6cm is the distance to the first dynode
  • Action items:
  • Find out length of dynode chain for R4125
  • Mu metal test to determine impact of shielding on PMTs
  • mu metal plus mesh and use external field order ~50 Gauss (no PMT needed)


CRYSTALS (Vladimir, Alex, Tanja)

  • Recent interactions with SICCAS about 500 crystal delivery
  • Phone meeting on 5 January with SICCAS - Alex, Vlad, Tanja, Liping, and Jane - discussion about quality control and delivery of first crystals
  • On-site inspection of first 250 crystals at SICCAS shows 10% of produced crystals have to be rejected due to discoloration and/or low transmittance, light yield measurements currently not possible (system broken), no capability for radiation hardness tests
  • Also found problems with chamfer tolerance due to imperfection in grinding procedure - being addressed
  • No new crystals from Crytur yet
  • Discussion about impact of magnetic field on EM shower distribution in crystal
  • for NPS fields are low - angular distributions are very wide, energy electron is 0.5 MeV
  • more likely to damage PMT before impact crystals


TCS BACKGROUND SIMULATION UPDATE (Vardan)

  • Problems displaying slides during meeting - please see the posted slides in the 1/16 agenda and send comments


NEXT MEETING: NPS COLLABORATION MEETING - MONDAY 3 FEBRUARY AT JLAB