JEF meeting, March 25, 2022

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Meeting time and location

  • 9:30 am EST (JLab time) remote only
  • Zoom meeting ID: 161 050 9142 Passcode: 004965


  • Preparation for mass production of FCAL2 modules -- Sasha
    • PMT selection
      • Olga checked PMT diameter of 360 newly received PMTs. Many PMTs from the last shipment (210 pcs) are tight (about 40%)
      • These PMTs were exchanged with NPS. 40 more PMTs were selected with Vlad and are ready for exchange when purchase spares.
      • Total number of PMTs: ordered and received: 1510, 140 installed on CCAL.
        • Need to order about 100 (?) spare modules.
        • These PMTs are also used in different test setups
    • Production of Silicon cookies
    • DSG group: continue preshaping ESR reflectors (18 a day), and wrapping crystals (about 6 a day)
    • Chris A. is brazing brass straps, Bobby is honing PMT housings.
    • Igal is cutting Tedlar and ESR foils
  • Module fabrication -- Sasha
  • Light Monitoring System March 25 LMS update -- Arshak
  • COMCAL tests, TAC running, etc. -- Sasha
    • Discussion at the CPP engineering meeting regarding using assembled modules (an array of 3x3) as a TAC) during the CPP run
  • Data analysis
  • Simulations


Attendees: Bill, Zisis, Arshak, Tegan, Igal, Jon, Liping, Olga, Phil, Jane, Sasha, S.T.

  • Arshak gave an update on the LMS
    • Illuminated a small plexiglas plate with light from 2 blue LEDs from 10 fibers injected on one side and looked at the light uniformity across the plate
    • Saw noticeable gradient in the measured light the further the probe was from the fibers, as expected, but relatively uniform in a column near the center, and an increase in the column furthest from the source due to reflection
    • Plan to illuminate the plate with additional fibers on the opposite side of the current set of fibers
    • Plan to build a larger scale prototype
  • Sasha reported plan to purchase 100 PMT spares -- plan to ask Hamamatsu to pre-select for diameter given the relatively large fraction of tubes from a recent batch that were too wide
    • Trades with NPS to get their smaller diameter PMTs
    • Also plan to order 200 new sockets
  • Fabrication of modules continues -- now up to 209
  • Plan to build 28(?) new PMT dividers by summer, all dividers for FCAL-II ordered by fall?
  • We had some discussion about the state of the single-block TAC and the possibility of building a 3x3 array using lead tungstate crystals
    • Test setup downstream of FCAL?
  • Lab has switched to MedCon-3: Sasha will check what this means for students in the summer (Phil potentially has students he could send but needs to know soon)
  • Sasha to meet with Tim regarding cables/patch panels for FCAL-II