Jun 21, 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; JLab Phone in CC L207 is 757-269-7084
  • Athens Phone: in Christina's office is 011-30-210-727-6947
  • Regina Phone: in LB228 is 306-585-4204
  • 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: Review if cross talk experience from other detectors is relevant to this geometry and, if needed, suggest test/simulations to investigate.

Tentative Agenda

  1. Announcements
  2. Review of Action Items
  3. Monitoring
  4. FCAL
    1. Construction Status: mechanical, bases
  5. BCAL
    1. Construction Status: builds, fibre QA
  6. Simulations
  7. Any other business


Attending: Matt (IU); Andrei (UofR); Christine (Athens); Elton, Beni, Tim, David, John

  1. Notes:
    • The meeting started in a bit of confusion as the usual JLab room had been booked for the CLAS collaboration meeting. We finally found a smaller room that accommodated the participants and connected via EVO. Christine was connected to EVO and could hear us, but we could not hear her. She did transmit some messages via the chat program.
  2. Review of Action Items
  3. Monitoring
    1. Simulated light collection from the Plexiglas board (Athens)
      • We went over the slides that were collected on the portal
    2. light_through_cal.pdf. Two options a) well (assume a drilled hole), b) channel slot across light guide. Both features implemented on opposite sides of the same Winston cone light guide.
      • These results were very interesting as it might be a feature which could be implemented in the light guides.
      • The ratio of far/near was about 3
      • The channel also collected 3x more light than the well (we assume they were essentially normalized)
      • Question: Were both LEDs simply laid into the channel or well? Was there any grease or other couplings?
    3. Latest from Lucite Illumination.pdf
      • Results of measurements of light generated by two types of LEDs (dome and flat) at a single location. Simulations used to estimate the light uniformity for LEDs placed along two sides of a plexiglass pane.
      • Dome LED had a broader distribution than the flat LEDs. Range of signals for dome was 8:1 and for the flat was 16:1.
      • Effect of reflections visible in spectrum, and their effect could be determined from comparison between fits with one and two exponentials. The effect of reflections is only noticeable for light collection at the far side of the pane.
      • Simulations show that the distributions for the dome and flat with several LEDs is not too different. Dynamic range is about 5:1.
      • Matt: The corner with the highest light output would be located opposite the round edge of the calorimeter, so the high points would not be seen by the calorimeter. This by itself could reduce the range of monitoring light to be relatively uniform. The light distribution should be optimized by looking at the region of the calorimeter that would be active (eliminate the corners with no blocks).
      • Athens should also repeat some of these tests using the lead glass block and pmt, which may affect light collection and geometry.
  4. FCAL
    1. Construction Status: mechanical, bases
      • Final base production procurement is underway. Deliveries expected by October, recovering previous schedule delays.
      • Mechanical drawings are at JLab under review, before starting fabrication
      • Tim: the drawings will be checked before John returns from vacation in the beginning of July
      • mu-metal shields are at JLab waiting final confirmation before order is placed. Tim will check with magnet measurement
  5. BCAL
    1. Construction Status: builds, fibre QA
      • module 40 will be completed tomorrow. Modules 39-40 will be transferred to Ross for machining
      • module 41 is up to layer 20
    2. Lead concerns
      • New batch of lead from Vulcan has some issues to be resolved
      • Sample sent to JLab for testing
      • The lead seems to have oils on it, so cleaning may be a problem.
      • We all agree that this lead should NOT be used in any new modules, at least until further evaluation.
      • It had been proposed to use some samples of the new lead in the ongoing production. However, the oil is a concern and we do not want to compromise the production. At the moment we should assume that the new lead will be used only for the extra module.
      • In parallel, we will a) test the new lead, b) investigate if we can return the lead and replace it with a clean batch.
      • Andrei indicated that the new lead could all be used in the extra module if the old "spaghetti" technique is used.
  6. Simulations (Andrei)
    • Checked calibration with parameterized fit functions works for both coarse and fine segmentation
    • Calibrations works very well, with small exceptions (~3%) found below 100 MeV
    • Andrei will continue to play with scripts to make them more robust before committing them
    • Irina and Andrei have archives of Fluka files generated with 2 GeV and 60 MeV hitting the upstream and downstream edges that were used for dynamic range studies. These can be used for calibrations.
    • Waiting for Elton to give feedback on calibration methodology
    • David: Working on energy weighted time distribution at the end of the Bcal for use in calibrations and especially for position resolution studies.
  7. Any other business