Jun 14, 2011 Readout

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Teleconference Time: 11:00 a.m. EST

  • ESNET 8542553 and EVO session
  • JLab Phone: in CC F326 is 757-269-6337 (usual room)
  • JLab Phone in CC L207 is 757-269-7084
  • Phone in the Regina Videoconference Suite is 306-585-4204
  • Athens Phone: in Christina's office is 011-30-210-727-6947
  • Phone:
    • +1-866-740-1260 : US and Canada
    • +1-303-248-0285 : International
    • then use participant code: 3421244# (the # is needed when using the phone)
    • OR from www.readytalk.com type access code 3421244 into "join a meeting" without the # (you need java plugin)

Items for followup from previous meeting

  1. Ship out 10 SiPM arrays each to UofR and USM (Elton). Shipped out last week with tracking numbers.

Documents to Review

Tentative Agenda

  1. Announcements
  2. Review of Action Items
  3. Simulated light collection from the Plexiglas board (Christine)
  4. USM Update
  5. SiPM update
  6. Electrical/cooling (Elton)
  7. Geometry and light guides
  8. Simulations for production guides / Draft (Elton)
  9. Simulations


Attending:Beni, John, Tim, Yi, Elton, Eugene (Jlab); Christine, Pavlos, George, Stratos (Athens); Andrei (UofR); Serguei, Will (USM)

  1. Announcements
    • Athens construction MOU has been signed by all parties.
  2. Review of Action Items
  3. Simulated light collection from the Plexiglas board (Christine)
    • Two of the posted documents discussed measurements of the Fcal monitoring system, so they will be presented next week at the cal working group meeting.
    • The "Test LED Board" file was discussed by George
    • The slope of LED output vs driver voltage is very steep and a circuit is proposed to lower the slope that allows better control over the LED
    • Circuit tested works well and continues to be linear but the output is 50% lower at the same drive voltage.
    • After discussion it was agreed that the required dynamic range must be specified more clearly using upcoming LED mounting options. If the new design can satisfy the required dynamic range it may be substituted for the nominal design and provide increased control.
  4. USM update
    1. Light guides
      • Christina inquired about the status of light guides, which could be used for testing various LED mounting options.
      • Will: Current status is that about 30 light guides have been produced, but only one test piece polished
      • No schedule yet for completing the project
      • Decision: Polish and ship 2 light guides to Athens as soon as possible. George suggested using standard US mail
      • Will commented that problems were encountered in separating the pair of fabricated light guides. This problem has been addressed by building two jigs and developing a clean procedure for cutting the two guides apart.
      • Existing polishing facility at the university is now being utilized by the physics group and a local source for polishing powder has been found. Additionally diamond bits have been purchased and may produced desired finishes on light guides, but they have not been tried yet.
    2. Contract with Hamamatsu
      • JLab contract to USM has been placed and discussions are ongoing with Hamamatsu to complete negotiations for the USM-Hamamatsu contract.
    3. Electronics Board
      • Currently improving an automatic calibration system for the preamp and multiplexor "big" board. Results will be shown at the next meeting
  5. SiPM update
    • Working on temp compensation system. The temp control circuit is working well
    • Temp control setup is under construction and should be tested soon.
    • Ivan left Jlab sooner than expected due to visa complications. Yi will continue the work he started.
  6. Electrical/cooling (Elton)
    • Mechanical parts were received a week ago and should be assembled this week
  7. Geometry and light guides
  8. Simulations for production guides / Draft (Elton)
    • Elton presented some results of simulation of the new phi-symmetric geometry
    • The new design produces very uniform outputs
    • Guide #6 was studied in more detail, including some variations considered for mounting the LEDs. Nominal acceptance is about 64%
    • One mounting scheme included cutting a step into the light guide, which could be used to secure the board, The step reduced the acceptance to about 60%, but the acceptance as a function of vertical position was very non-uniform (step was on the top of the guide). Interestingly, the acceptance at the bottom was improved, because the flat surface of the step transmitted light more efficiently than the nominal slanted slope. However, this option is disfavored due to the highly non-uniform acceptance.
    • A second variation for mounting assumes an area of 0.94 cm2 completely obscured due to mounting of the LED. This had an acceptance of 62% and no visible non-uniformity.
    • A GlueX-doc will be completed shortly
  9. Simulations
    • Ongoing work by David and Andrei continues, and will be reported once results are digested.