Wednesday, November 20, 2019, 11:00 EST

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ack to Main Compton Page >> Compton Meetings

1. Dial Toll-Free Number: 1-888-240-2560 (U.S. & Canada)
2. International participants dial:
Toll Number: 1-408-740-7256
3. Enter meeting ID:140287970

Desktop sharing: 


Meeting room = Cebaf Center F226


  • Experiment will start December 2 - may be some beam in Hall before that (Spin Dance)
  • Dave G. will be out of town next Wednesday-Sunday. Mark Dalton is laser LSS while I'm gone.

Electron detector

  • Detector status
  • QWAD adapter boards
  • Counting DAQ


  • Mirrors replaced
  • Entrance scans
  • Cavity birefringence scans

Photon Detector

  • PREX checks
  • CREX preparations


  • Too busy for analysis!


  1. Electron detector
    1. Detector
      1. Can see rates on VTROC using Ben's stand alone software.
      2. kHz level at 33 mV threshold. Would like to decrease to ~17 mV so a lot of noise to overcome.
    2. QWAD adaptor boards
      1. These have arrived at UM. Will test one with a detector and then have a technician put the right resistors on all.
    3. QWADs
      1. Another QWAD found. We have 3 now but 1 is location unknown right now.
      2. 48 channels per board. 192 strips per plane on the detector but we only plan to read out half of the detector. Once good operation is demonstrated will begin to figure out which other boards to use.
    4. Counting DAQ
      1. New computer ordered for the DAQ system.
      2. New cables needs to get laser, BPM, BCM and photon detector output signals to the new crate.
  2. Laser
    1. Birefringence in the cavity seems a lot smaller now. YAY! The optimum at the entrance and at the exit are very close.
    2. Cavity will be pumped down soon. Alignment will need to be checked and the cavity locked.
  3. Photon detector
    1. PREX tube, PREX base, PREX settings
      1. 3 settings to cover the full span of loads during PREX. This doesn't have much effect.
      2. Final opportunity to take data before we lock up the hall for CREX.
      3. Need to formalize how we include pileup, nonlinearity and changing "load" and gain for analyzing power during PREX.
    2. CREX
      1. Will use jaws instead of smaller collimator for CREX.
  4. Analysis
    1. Dither data needs to be studied and possibly removed.