Thursday, February 27, 2014 2:30pm EST - Compton

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Previous meeting: Tuesday, December 10, 2013 11am EST - Compton

Tentative Agenda

  1. Updates
    1. laser (Kent)
    2. DAQ (Bob/Alex)
    3. photon detector (Greg/Vahe)
    4. electron detector (Juliette/Dipangkar)
    5. magnetic field mapping (Kent)
    6. beamline status/accelerator schedule (Alex)
  2. consequences of restructuring (Dave/Thia)
  3. Next meeting time


Attending: Juliette, Dustin, Dave, Alex, Brian, Greg, Kent

  1. Updates - Near term and long term goals, mostly near term (DVCS, PREX/CREX)
    1. laser (Kent/Dave)
      1. near term - getting running again (how it was set up before)
      2. few kW green power (easier then IR)
      3. green good for PREX
      4. work in hall (not in laser lab - 2nd floor ARC)
      5. Chuck Long (spectrometer group - Jack Segal running)
      6. single-pass frequency doubling only problem (expertise at the lab)
        1. still trying to locate parts - crystal (several purchased)
        2. thermoelectric chillers to control temp
        3. stage still on table
        4. Abdurahim - thesis - photos, etc.
      7. trying to organize after restructuring
      8. Just photon okay for DVCS (don't want to break anything :))
      9. actuators for optics (after laser is running)
      10. with 12 GeV, green won't fit in beampipe at 12 GeV - redesign e- det can
      11. small slot - French connection? - redesigned?
      12. last real-world experience - power 5kW? - mirrors degrade in tunnel
    2. DAQ (Bob/Alex)
      1. put computer back in counting house
      2. trying to run the flash ADC DAQ on it
      3. High flip rate capability of the DAQ (MOLLER)
        1. old DAQ - ran at 30 Hz
        2. trigger supervisor, event triggered DAQ
        3. PREX won't use e- det - flash ADC with photon det
    3. photon detector (Greg/Brian)
      1. existing GSO brought back to CMU
        1. modified so it will fit
        2. more adjustability - need some safety stops on xy table
        3. eventual plan - two detectors one for higher energy
      2. analyzing power factor of 2 with green laser
      3. with GSO photon energy is not as much of a factor
      4. photon used for DVCS
      5. looking at PbW for 12 GeV
        1. no timeline
        2. Sirish had a source for large crystal - Shanghai?
        3. 2cm square are common - wrap them together... if no choice
        4. 3% would be pretty useful for DVCS
        5. Hall C four crystals will fit (but not the box they're in)
      6. cooling PbW
        1. light output fluctuates near room temp.
        2. more light with cooler - 15 C?
        3. need to calibrate with spectrum in counting, and would be distorted
        4. if energy changes, then effects from that, too
      7. radiation level too high for lead glass? (1 MHz photon rate)
      8. better for lead flouride (3x3cmsq, 18.6 cm long?)
      9. for near term - 4 crystal lead tunsgate in DVCS with and without cooling
    4. electron detector (Juliette/Alex)
      1. MOU completed
      2. Alex preparing contract to loan
        1. single plane w/half not functional
        2. French A/D
        3. QWAD
      3. plan to try to get a postdoc for Compton/PREX
      4. student here to start with borrowed setup, building lab
    5. magnetic field mapping (Kent)
      1. quantitative disagreement with TOSCA
      2. inside the dipole, 30-40 cm 10^-3 differences
      3. nobody ever mapped it - Alex may have it?
      4. Bdl was measured...
    6. beamline status/accelerator schedule (Alex)
      1. upcoming beam test in March
      2. DVCS in the fall
      3. 12 GeV halo bigger
      4. Synchrotron light at 12 GeV running
  2. consequences of restructuring
    1. Halls A/C merged
    2. Dave is tasked with Hall A Compton
    3. plan to make the systems more similar
      1. DAQ more like Hall A
      2. laser more like Hall A (fiber amp., narrow line width IR)
    4. manpower - same amount of work done by less people
      1. user support will be very valuable
      2. photon detector under control
      3. electron detector has challenges, but people are working on it
  3. next meeting time
    1. keep meeting with a large group
    2. once a month for now, more frequent in summer
    3. beginning of April - Doodle poll last week of March

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