December 14, 2007 Calorimetry

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  • The meeting will be held at 11:00 EST (10:00 CST)
  • ESNET No.: 8242553 (If ESNET is not an option for you, please let Zisis know in advance, so that we can patch in the telephone line below)
  • Phone:
    • +1-800-377-8846 : US
    • +1-888-276-7715 : Canada
    • +1-302-709-8424 : International
    • then enter participant code: 39527048# (remember the "#")


  1. Previous minutes: November 29, 2007 Calorimetry
  2. Calorimetry Document Preparation
  3. FCAL Hardware/Software
    • Flash ADC Timing: see Email List Server
    • Light guides: ongoing, update
    • Low energy threshold: cosmics/Cherenkov: ongoing, update
    • Hadronic backgrounds: ongoing, update
  4. BCAL Hardware/Software
  5. FCAL-BCAL Hole: preliminary photon conversion plots with new geometry (Richard)
  6. Any other business


Attendees: (IU) Alex, Mihajlo (UofR) George, Andrei (Athens) Christine (JLab) Elton, Tim, Carl.
Zisis was not online. Elton took minutes.
We agreed that we would meet again next Friday Dec 21 at 10 am EST (9 am Canada).

  1. Previous minutes: November 29, 2007 Calorimetry
    • No comments.
  2. Calorimetry Document Preparation
  3. FCAL Hardware/Software
    • Mihajlo has been generating gp->b_1pi0 and f_1pi0 (all neutral) final states for reconstruction studies. The learning curve on high multiplicity events is taking more time than anticipated. Hopes to have results to show soon.
    • Alex mentioned that a comparison of Mihajlo's reconstruction with his parametric simulation has been conducted and agrees well. The input of photon detection for the parametric MC was parameterized from Mihajlo's output. For a_0 and a_2 production the realistic acceptance is about 30-35% and agrees between the two analysis. This reconstruction has been updated since the collaboration meeting where a 40% reconstruction efficiency was reported.
    • The reconstructed masses of pi0 is about 10-11 MeV, eta is 35 MeV. The widths agree between full reconstruction and MC. For photons that hit the Fcal only, the pi0 width is about 7 MeV and photons that hit the Bcal only the width is about 11 MeV.
  4. BCAL Hardware/Software
    • George reported on the SiPM work. Two new results will be posted to the portal shortly. Conclusions from the Phase I tests are
      • Quality of SiPMs fell below expectations, at least for these early units
      • Factor of 2 variation in gain which is not acceptable
      • The sensor tiles showed extreme sensitivity of electronics to external parameters, such as the power supply and noise. Large pedestal widths are due mainly to the electronics.
      • Tested tiled arrays provide a proof-in-principle of use of detection over a large area, but characteristics are below specifications.
      • Carl asked for the voltage used for the reported tests: The breakdown voltate was 27.3 V, operation was about 28.8 V or about 1.5 V above breakdown.
      • SensL initially did not believe the large gain variations measured, but UofR measurements are reproducible and seem to stand up.
      • SensL has asked UofR to make further tests, specifically to check the connectivity from cell-to-cell, with they will do.
      • New detectors (advertized on the SensL web-site) are expected both at UofR and Jlab and will be re-tested. The Jlab detector group is also ordered an array that allows readout of each of the cells separately.
    • Fibers: Carl has received batch of fibers from St. Gobain (half to be shipped to UofR) early next week. Fibers from Kurary were ordered a week ago.
  5. FCAL-BCAL Hole: preliminary photon conversion plots with new geometry (Richard)
    • Richard was not available at the phone conference.