General Meeting Summary 8/26/21

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PARTICIPANTS: Aaron Brown, Arshak Asaturyan, Bogdan Wojtsekhowski, Brad Sawatzky, Carlos Munoz-Camacho, Carlos Yero, Charles Hyde, Rolf Ent, Hakob Voskanyan, Hamlet Mkrtchyan, Marie Boer, Paulo Medeiros, Petr Stepanov, Steven Lassiter, Tristan Anderson, Vardan Tadevosyan, Vladimir Berdnikov, Tanja Horn, Julie Roche,

HV DIVIDERS (Vladimir)

  • Tests have been completed and moving on to next stage
  • Julie sent all dividers to JLab - arrived
  • Nonlinearity measured is ~1-2%


  • Concept: additional connectors to extend PCB (2cm longer), flat cable to get voltage to dividers; 32 channels per column
  • Questions:
  • How many channels can be chained - Fernando's calculation suggests 8 limited by power supply margin to keep low for minimum power dissipation
  • Mechanical integration - options for thin connectors identified
  • Stabilizer in amplifier?


  • Updates on action items from last time:
  • CAEN HV Interlock - to prevent interlock switch from being flipped into the wrong position, implemented administrative control
  • Chiller remote power controller: specifications indicate that should be not damaged by radiation; will also procure spares
  • Hardware interlock monitoring program: limits input and monitoring
  • crystal
  • electronics
  • chiller
  • Thermal analysis
  • Applied 0.5 Watt longitudinally to surface of crystal (based on HV divider dissipation from back - simulation had ~500 W and divided by ~1000 blocks)
  • Max temperature ~13 degrees in center at back face of detector
  • Action items:
  • implement alternative to "do not touch" sign, e.g., markers indicating correct alignment of the switch
  • take into account air flow
  • temperature map across the crystal

MECHANICAL (Paulo, Steven L.)

  • Cable trays/supports and roof block
  • model exists but no final model yet; concept for cable trays/supports needs further development
  • plan to get roof block to procurement - longer lead item
  • Cable dolleys concept exists - tied to design of cable trays/support item
  • Overall much progress and not many remaining items


  • Overall in good shape
  • Many pre-assembly tasks can continue/start while international travel remains uncertain
  • Actions:
  • Mark items that need more attention/follow-up in next 4-6 months
  • Follow up on pre-shaping activity


  • Please send replies to the following question to Tristan (
  • Using GEANT4 I am currently simulating Marie's DDVCS initiative of placing muon hodoscopes behind the NPS detector. Shielding is required in-front of these hodoscopes, to suppress the overwhelming pion background produced during a run. Within about 10 centimeters, how much room is there behind NPS (in the detector hut) to position both shielding and auxiliary hodoscopes? An answer to this question will improve this GEANT4 model, and would be greatly appreciated.