JEF meeting, March 17, 2023

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Meeting time and location:

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

Agenda

  • Preparation of parts for FCAL2 modules -- Sasha
    • Available crystals:
      1450 (modules)
      32 (ready for fabrication)
      40 (installed on CCAL) available on March 20
      (some CCAL crystals from the inner part will not be used for the FCAL2)
      95 expect to receive from CRYTUR in May [1]
      Total 1617
    • Olga brought about 200 Silicon cookies from GW. The quality is good.
    • George (DSG group) finished with disassembling CCAL modules and removing LMS caps. Will work on preshaping ESR reflectors for CRYTUR. The oven will be ready in a week.
    • Mindy (DSG group) solder wires to sockets (while waiting for crystals). More crystals will come from the CCAL during next week. The CCAL was moved to the ESB, but it was activated.
  • Module fabrication -- Sasha
    • Fabricated modules: Total 1470 (15 modules fabricated since last week)
      Currently available for fabrication: 12
  • Testing of PMT dividers -- Sasha / Arshak
    • FCAL2 modules with dividers installed on the CCAL [2]
  • Installation of the FCAL2 detector & integration to GlueX -- Sasha / Arshak
  • Light Monitoring System -- Arshak
  • Simulations/Analysis

Minutes

Attendees: Liping, Arshak, Bill, Zisis, Susan, Jane, Jon, Sasha, Igal, Olga, Eugene, S.T.

  • CCAL will be disassembled -> 40 more modules to convert to FCAL-2 modules after checking for discoloration
  • Grand total fabricated FCAL-2 modules=1470, 12 more crystals available for fabrication
  • Chris C. has updated PCB for PMT electronics w/ larger size to accommodate new connectors
    • Need to do final checks before ordering full set (soon)
  • Unstacking and restacking of FCAL to start in May
    • Need to know height of lead glass stack up to level that includes lead tungstate crystals -> survey several points
    • Shimming needed: need to take into account slightly different sizes of Crytur and SICCAS crystals along with accounting for the fact the LG blocks are not exactly 2x the size of PWO crystals
    • Will put Crytur crystals near beam hole (slightly more rad-hard than SICCAS crystals)
  • Hovanes to start working on slow controls+scalers for FCAL-2, decoupled from lead glass
  • Sasha has been working on translation tables, went over cable distribution
    • Crystals labeled with bar codes -> database
    • Readout arranged in triangles to handle high occupancy near the beam hole
    • HV/LV in 4 quadrants
  • Arshak gave a presentation comparing results for plexiglas solution for LMS compared to individual fibers
    • Going with individual fibers to each crystal increases price of LMS, but would still be okay for the budget this year
    • Plexiglas design would have two pieces of plexiglas each with 1mm fibers attached on the periphery for light input
      • One fiber at interface between two crystals, 50-55 fibers/plexiglas plate
      • Edges cutes with reflective paint to improve uniformity near the edges
      • Good uniformity at the 20% level, with a slight drop near the center
      • Checked cross talk on bench with 3x3 prototype: <1% cross talk w/ low amplitude, but not zero cross talk
      • Beam tests with PS setup also showed low but non-zero cross talk
    • Individual fiber tests
      • 250 micron fibers had low light output but okay uniformity
      • 500 micron fibers: higher light output, better(?) uniformity
      • Using donuts helps with uniformity (due to easier polishing?)
    • Impact of different amount of material in front of crystals for 2 solutions on position reconstruction came up
    • Consensus generally favored individual fiber solution, decision next meeting
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