Apr 12, 2011 Calorimetry

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Teleconference Time: 11:00 a.m. EST

  • ESNET (Number is 8542553) and EVO session (GlueX Calorimetry meeting room)
  • JLab Phone: in CC F326 is 757-269-6337
  • Regina Phone: in LB228 is 306-585-4204
  • Athens Phone: in Christina's office is 011-30-210-727-6947
  • Phone connection only upon request.
    • +1-866-740-1260 : US+Canada
    • +1-303-248-0285 : International
    • then enter participant code: 3421244# (remember the "#").
    • or www.readytalk.com (and code without the #)

Items for followup from previous meeting(s)

  1. Monitoring
    • Fcal: check cross talk of calibration inputs across modules.
  2. Simulation
    • Need to study the reconstruction efficiency.
    • Investigate timing resolution as it impacts delta_theta. Start with understanding of resolution at 90 deg.
  3. SiPMs
    • Re-measure original SiPM sample to verify rates are in fact lower for new arrays

Tentative Agenda

  1. Announcements
  2. Review of Action Items
  3. Calibration
  4. FCAL
    1. Construction Status: mechanical, bases
  5. BCAL
    1. Construction Status: builds, fibre QA
    2. First article testing (Yi)
  6. Simulations


Attending:Yi, Tim, David, Eugene, Elton (JLab); Matt, Ryan, Mihajlo (IU); Andrei (UofR); Will (USM).

  1. Announcements
  2. Review of Action Items
  3. Monitoring
    • Elton reported that the Athens system with one controller supplying signals to 4 strings with 10 LED boards each could be used for the Fcal. The separate strings would be used to pulse different color LEDs in the case of the Fcal. For the Bcal each string would fire a column (tower) of light guides in one wedge.
    • Eugene asked why the Fcal LEDs will have different colors. Matt: To provide an additional handle on radiation damage as a function of wavelength.
  4. FCAL
    1. Construction Status: mechanical, bases
      • Getting ready to process shipment to JLab. Expected arrival date is April 18, but will confirm
      • Started fabrication of light guides
      • Testing bases: 400 under power and no failures
      • Mechanical prototype: hardware in hand, shop is machining parts
      • Tim: Company Amuneal (supplying mu-metal shields) might be contacting Matt or John for bidding on their shields
  5. BCAL
    1. Construction Status: builds, fibre QA
      • Module 35 and 36 are built up midway
      • Shipped modules 25-28 (arrived yesterday)
      • Machining 29-32. Will ship shortly
      • Fiber shipment steady and on track
      • Extra module: It has been determined that there is sufficient fiber and likely sufficient lead to build an extra module at minimal additional cost. After checking some details, the project will likely decide to plan to build one more.
    2. Elton: We would like to finalize decisions on light guides in order to be able to place a PR. This involves deciding on final dimensions and also on features that may be needed for mounting the monitoring system. Regina is considering various options.
      • Andrei asked about accessibility: Elton said that access will be limited but possible, so there should be an emphasis on reliability.
    3. First article testing (Yi)
      • Completed testing of 80 samples
      • Two outliers: one has a relatively "hot" cell (but still meets specs); the second has low PDE, but will be remeasured
      • Preparing for radiation test and effect of magnetic field
      • Remeasure an old sample to check that the new setup reproduces the old dark rates.
      • Eugene: Sasha and Vitaly Baturin (Hall B) have been testing 1x1, 3x3 and one array for timing and rate response. The 1x1 and 3x3 units indicate a strong output dependence on rate, suggesting multi microsecond deadtime of single pixels. The arrays are less sensitive but rate dependence is still observable at 3 MHz. Data are being analyzed.
  6. Simulations
    1. BCAL Segmentation (David)
    2. Showed plots with photons uniformly populating 0-4 GeV. No cuts on primary conversion.
    3. Generally reproduces results shown by Andrei at the last meeting, but questions still remain. The theta resolution plots for the coarse segmentation show very large tails.
    4. Efficiency plots, defined as reconstructed shower within 20% of generated shower, shows large inefficiencies below about 2 GeV. Andrei reported even higher inefficiencies (60% at 2 GeV)
    5. On the surface it does not seem like the theta resolution would be consistent with timing resolution from the beam test, and the inefficiencies are different than early studies by Mihajlo (see for example Gamma Efficiency. My recollection is that the efficiency was computed for 1 GeV photons, although it only goes out to 30 degrees. [Reference added by Mihajlo] Here is efficiency from GlueX-doc-1081 for 3x3 vs 6x4 inner segmentation. Other previous configurations were studied in GlueX-doc-951 and GlueX-doc-852.
    6. Andrei suggested the use of the energy measurements to supplement z-position measurements.
    7. Matt: rewritten reconstruction code and checked in. Still not optimized but could be tested.