Wednesday, January 8, 2020, 1:00 pm EST

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Back 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 F227


  • New meeting time: 1pm Wednesdays
  • BPM offsets for laser table BPMs not yet loaded into epics

Electron detector

  • Detector status
  • QWAD adapter boards
  • Counting DAQ


  • Cavity/laser status

Photon Detector

  • Detector, DAQ status


  • Too busy for analysis!


Attend: Mark, Adam, Amali, Alex, Jinlong, Iris, Juan Carlos, Cip, Brian

  1. General
    1. New meeting time
    2. Want to tune through the chicane ASAP before changing out the PPLN crystal.
  2. Electron Detector
    1. Detector Status
      1. Ready for beam
      2. Webcam looking at dark current is working
    2. QWAD adaptor boards
      1. We have the adaptor boards, enough for all channels
      2. We have 1 and will wait to see how well it works before scavenging from Hall C. Alex believes the he has
    3. DAQ
      1. Scaler DAQ, can read with standalone code but scaler data is not recorded in the CODA file.
      2. Helicity DAQ, helicity signal connected to TI. Trigger banks not being opened in CODA file. Working with Brian.
  3. Laser
    1. Before the break change the PPLN temp, seed power, green power, in order to lock--didn't work. Increasing the voltage on the EOM got a good lock.
    2. After beam returned ability to lock was lost. Cycled the temperature but temp controller was stuck in a bad state. Power cycling didn't work. Swapped out temp controller. Optimum temp was lower and power out was lower. It attempted to lock but didn't succeed until the fibre amp power was lowered.
    3. It's now locking unreliably with 2.5 kW in the cavity. Good enough to commission with.
  4. Photon Detector
    1. Scaler crate had a fault to scaler values were bad. DAQ was NOT running so issue was not noticed. Script to write values to epics also failed. This was all fixed with a reboot of roc6.
    2. The concern is the we blasted the table with radiation without realizing it because the diagnostics were not working.
    3. Detector
      1. Backgrounds due to neutrons will not be a problem for the tube. A large laser power might require going down in gain.
      2. Bremsstrahlung will have to be evaluated when we thread the chicane.
  5. Analysis
    1. Will produce plots of table background asymmetries online in CREX.
    2. Do we need to cut dithering data from the Compton analysis? If so, how much data would we loose?