Sep 2, 2008 Calorimetry

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Revision as of 13:15, 2 September 2008 by Elton (Talk | contribs) (Review of Calibration Issues)

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Items for followup from last meeting

  1. George: report on trip to Edmonton
  2. Estimates of pedestal width (electronic noise, etc.) for FM PMTs. The dark rate should be negligigle in this case.
  3. Resolution studies with up-to-date geometry (Blake) ONGOING
  4. Resolution studies with different segmentation for the outer section. - LOWER PRIORITY
  5. Add F100 rad hard glass to simulation. - Matt will do this
  6. Decision on Bcal sampling fraction needed by Sep. - Work by Stamatis (on vacation) will be summarized upon his return.

Documents to Review

  1. Please place documents here for review in advance of meeting
  2. Calibration-Monitoring
  3. Paul Smith's Fiber Pulser

Tentative Agenda

Note: This meeting will be dedicated to reviewing calibration issues. Other reports will be included as time permits.

  1. Announcements
  2. Review of Calibration Issues
  3. Reports
  4. Updates
  5. Any other business

Minutes

Attending: Athens: Christina, George, Pavlos; UofR: Zisis, George, Kathryn, Blake; JLab: Elton, Beni, Tim, Fernando; IU: Matt, Mijahlo, Claire Tareert; FIU: Werner.

Announcements

  • Claire Tareert is a new research associate at IU. Welcome!

Review of Calibration Issues

  • Athens update report: GlueX-doc-1092
  • Christina went over the posted presentation
  1. First the laser option was presented
    • APD used to monitor the absolute light from the laser, but noise pick up from the laser was a problem. Elton indicated that a full shield was necessary to shield the laser. Method for shielding similar laser can be found on the bottom of page 3 of Hall B CLAS-NOTE 91-002.
  2. The second LED option was presented.
    • 2x1 cm2 boards with the LED and pulsing electronics have been made; 35 boards produced.
    • The idea is to place the boards near each pmt to be calibrated, e.g. on the light guide of the SiPMs. George: could be placed on the tapered length of the guide.
    • Fernando asked about the temperature dependence: it has not yet been measured.
    • Control board (for about 30 LEDs) has been constructed and would be placed about 2-3 m away from the LED.
    • Question about masking individual channels for firing? This would check (optical) cross talk between channels.
  3. The calibration system needs to have its requirements clearly defined. Each subsystem (Fcal, Bcal, Start counter) reviewed its requirements, but further refinement is necessary.
    • Elton prepared the following table to clarify the requirements. We need to complete it to provide adequate feedback to Athens:


Caption
Characteristic Fcal Bcal TOF Start
Light uniformity channel-to-channel
Dynamic range of input (number of photoelectrons)
Requirement on absolute light input none (PRIMEX might have)
Time stability (one channel)
Location of calibration input From front to monitor rad damage
Geometrical constraints Approximately 90% of front 4x4 cm2 area available

Reports