Nov 12, 2009 Calorimetry

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Teleconference Time: 11:00 a.m. EST

  • ESNET and EVO session
  • Phone only if requested:
    • +1-800-377-8846 : US
    • +1-888-276-7715 : Canada
    • +1-302-709-8424 : International
    • then enter participant code: 77438230# (remember the "#"). Phone line by request only.

Items for followup from previous meeting(s)

  1. Fcal
    • Specify the number of Rad Hard blocks to writeup a change request to the project.
  2. Bcal
    • Run MC to investigate changes in resolution due to different fiber attenuation length and light output.
  3. Bcal readout
    • JLab will investigate purchasing some prototypes from Plastic Craft.
    • USM will investigate options for producing prototypes in Chile.

Documents to Review

Tentative Agenda

  1. Announcements
  2. Review of Action Items
  3. Calibration/Monitoring
  4. Fcal
    • CR for rad hard glass
    • PMT procurement
  5. Bcal
    • Construction Status
  6. BCAL Readout
  7. Simulations
  8. Other business


Attendees: Elton, Fernando, Eugene, Carl, Sasha (JLab); Zisis, George, Andrei (UofR); Matt (IU); Will, Alam, Pedro, Edward, Hayk (USM)

  1. Announcements
    1. USM has received their grant dollars promised in June and can begin purchasing materials for the lab. Serguei is also back in Chile and will be directing the operation. They are investigating options for obtaining acrylic material for light guides, checking contacts with the chemistry department and local businesses. If those options fail, material can be obtained from CERN, but will likely be more expensive.
  2. Review of Action Items
  3. Fcal - rad hard blocks, work is ongoing, but no conclusion yet (see below)
  4. Bcal - Run MC to investigate changes in resolution due to different fiber attenuation length and light output. Work in progress. Andrei has found how to incorporate several attenuation lengths into FLUKA and investigating the optimum way for getting answers to the question of dependence of resolution vs. fiber properties.
  5. Bcal readout
    • JLab has obtained quotes from Plastic-craft for two prototype light guides and will proceed with order. The present estimate for completion is 6-8 weeks ARO.
    • USM will investigate options for producing prototypes in Chile - continues.
  6. Calibration/Monitoring
    1. No report.
  7. Fcal
    1. CR for rad hard glass
      • Received rad hard glass, which looks "beautiful", except the ends are not polished, an error by the manufacturer. Round trip shipping and customs is prohibitive in cost and schedule. The manufacturer promises to deduct any machining costs from future purchases. IU is investigating contacts in optometry (Zisis suggests astronomy) for possible polishing options.
      • Brian and Ryan have incorporated a model for glass degradation into MC to estimate time period for curing, but it is a work in progress. Measured doses to irradiated glass are still unnormalized.
    2. PMT procurement
      • No definite plan yet. Eugene mentioned JLab priorities: 1) obtain new FEU-84-3 tubes 2) obtain (unused) old FEU-84-3 tubes 3) accommodate a new tube into the FCAL, eg. FEU-115. Denisov has not yet had a chance to respond to us. We should pursue other avenues as quickly as possible.
    3. Prototype
      • Jake is working on GEANT4 model for cosmic-ray interaction in prototype to understand measured energy with MC.
    4. FADC
      • Waiting on response from Chris/Hai to specify how to turn on digitization. Fernando promised to check up on this.
    5. Bases
      • Paul Smith is preparing to build 10 prototypes at the beginning of the year to check the design and make sure that they are ready for purchasing 500 by late spring according to the contract.
      • Fernando requested that Matt send him the latest base schematics.
  8. Bcal
    1. Construction Status
      • Handful of fibers from shipment 6 tested
      • 21 layers for module 1 laid and are "super-straight"
      • "Runner" HD polyethylene used to check straightness of sheets, but still being improved to avoid parallax
      • Adding more epoxy to matrix to allow easily removing lead sheet if necessary.
      • Close attention paid to make sure that Pb goes down smoothly.
      • Machined a "groomer" matching all lead grooves to run through Pb sheet to clear out any irregularities
      • Mike Martin suggested more consistent testing. Have developed a pair of "grooved" brass pieces that will allow daily checking of lead thickness.
  9. BCAL Readout
    1. SiPM testing 1st look at Hamamatsu MPPC
      • Checked uniformity of Hamamatsu arrays using source that is about 16 photons/mm2 (corresponds to 1% pixels firing at PDE=25%)
      • Adjusted Hamamatsu suggested operating voltages from 25deg to 27-28deg (lab temperature), using about 56 mV/degC.
      • Checked average response of SiPM relative to average of 9 units, all within about 4%
      • Checked variation of 4 "sectors" relative to SiPM average. All within about 4%, except for #8 that has a 20% deviation. This is consistent with Hamamatsu supplied data.
      • Vop of all sectors is within 0.1 V of average for SiPM
      • Vop of nine units varies from 70.2 - 70.8 V.
      • Data sheets give 4-5 MHz/cell x 16 ~ 80 MHz /array.
      • Next will measure PDE, and robustness of response.
    2. Light guide prototypes.
      • GEANT4 simulation of light guides implemented
      • Imported Pedro's initial geometry into GEANT4 using an import facility CAD->G4TessellatedSolid.
      • Problem found with this geometry rays did not obey total internal reflection. However, simple geometries entered by hand are fine.
      • This problem has been reported to the GEANT4 development team and they have promised to fix the bug.
      • Elton: suggestion to make light guides with simple geometries so that these can be generated by hand. This will make it easier to specify and check against specifications.
    3. Baby CAL
      • Was shipped about 2 weeks ago, but not received. Zisis will check on shipping status of baby Bcal.
  10. Simulations
  11. Other business