Compton Meeting, May 23, 2011

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Previous Meeting Compton Meeting, April 11, 2011

Following Meeting Compton Meeting, June 2, 2011


Doodle poll reminder


  1. Update on plans for laser work (Mark)
    1. Kent's Transfer function measurement note
    2. Designing mount for transfer function
    3. Summer intern (Brandon Cavness) arrives tomorrow

Photon detector

  • Replay (wdc):
    • On ifarml, aim for middle of June
    • All resulting ROOT files will be stored on work disk
    • Replay will include all macros as well
    • Prereq: full BCM/BPM analysis
  • Photon detector analyzer status:
    • Scaler BCM/BPM read-out status (jc)
    • What else? (excl. electron det)
  • PbWO4:
    • Summary meeting with Hamlet last Wednesday (kent/mark/dave/wdc)
    • Dual pulser linearity test system (pulser logic) (jc?)
  • DAQ summer plans:
    • Increase data transfer speed to allow for more snapshots/longer sample windows
    • Coincidence mode: What specs? Are we happy with what we have (Mark's accumulator mode response function)?

Electron detector


Mark, Amrendra, Wouter, JC, Kent, DD, Don, Vladas



  1. Discussed the need for the new mount: the ability to align the optical axis of the GL and the rotation axis of the rotation mount.
  2. Discussed the cavity power measurement. Electron detector group will do some analysis to see their sensitivity to this. We may want to revise how the power is measured.

Photon detector


  1. JC - working on BCM and BPM analyser code for replay. BPM - waiting for commit from Paul - something will be out within the next week. Will allow absolute positions and position differences. Talked about the benefits of having the BPMs calibrated - a rough calibration should be sufficient.
  2. Dithering - we only have the flag since beginning of April but this should be enough to show that we aren't sensitive to the modulation.
  3. Pedestals for replay, we will have long periods of constant pedestal for each detector-ADC combination. Mark to make plots of pedestal over time. Use 'beam off' pedestals.
  4. Agreement that 'burst-mode' analysis not necessary for photon detector, will revisit later for electron detector.

Detector development

  1. Summary of the separate meeting: PMT in middle of 4 PbWO4 crystals, Hamlet found ice-box (Don to check if it fits in beamline), will mount 1 mm plastic fibers from back to reflect of mylar on the front (JC to talk to Vardan about this.)
  2. JC has Megan's paper on LED pulser linearity system and is beginning to work on it.


  1. Increase speed by going to DMA.
  2. There is a benefit to coincidence mode to find unexpected 'stuff' in both detectors but it's not a high priority.

Electron detector

  1. Busy organizing analysis into more systematic effort, DD says they plan to implement the suggestions here More in the next meeting.