JEF meeting, December 13, 2017

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Meeting time and location= 10:00 am EST (JLab time) CC-B101

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  • Magnetic shielding options (S. Glamazdin)

File:FCal shield.pdf


Attendees: J. Crafts, L. Gan, S. Glamazdin, Z. Papandreou, S. Somov, S. Taylor,

  • S. Glamazdin studied 2 designs for shielding the PMTs in the insert using TOSCA:
    • A longitudinal field of 60 Oersted was assumed
    • Design 1: individual pipes of 1010 steel + 1 layer of mu-metal (360 microns) for each PMT
      • Reduction down to ~<0.5 Gauss is possible but with a rapid rise toward the face of the steel in z
      • Studies suggest need for a ~3cm long light guide
    • Design 2: steel box with 4 mm thick walls housing entire insert
      • Shielding improved when an additional 1 cm thick plate was placed at the back of the insert
      • Shielding also improved when the steel tube for the beam hole was included
      • Looks possible to reduce field down to the level where mu-metal should be sufficient to further reduce the field down to where the PMTs will see low enough field.
      • Sasha will study what happens if the wall thickness of the box is reduced and if the hole for the beam is reduced.
  • S. Somov reported that an assembly of iron tubes will be assembled and studied with field in Hall D.
  • Zisis reported on less expensive SiPM options from SensL (compared to $408 16x16 mm^2 arrays he mentioned previously): 14x14 mm^2 arrays -> $170-$200/unit
    • Additional cost for amplifier/LV/HV/etc could make this option cost >$900/channel
  • S. Somov reported that Hall-B (HPS) went with APDs instead of SiPMs due to concerns about radiation.