JEF meeting, June 14, 2019

From GlueXWiki
Jump to: navigation, search

Meeting time and location= 1:00 pm EST (JLab time) F228

Connection instructions

We are using BlueJeans Video/Audio conferencing. Our meeting ID number is 370588741. Click "Expand" for more details.

  • Make sure you have created a BlueJeans account via your JLab CUE account using this link:
  • If connecting via Web Browser: click this link (no passcode is needed):
  • If connecting via Phone: Dial one of the following numbers and then enter the meeting ID above and hit "#" or "##"
  • If connecting via Polycom unit:
    • Dial or
    • Enter meeting ID above


Magnetic shielding studies


Attendees: Josh, Wolfgang, Liping, Sasha, Simon

  • Liping is working on finishing up an eta/eta-prime review article
  • No news on NSF MRI proposal
  • Progress on magnetic field shielding studies
    • Poisson calculations indicate that the longitudinal field varies between 90 Gauss and 50 Gauss over the length of the FCAL
    • Would need to place the insert crystals somewhere in the middle of the FCAL z-range -- offset face of crystal 10 cm downstream of face of FCAL?
    • Sasha suggests pushing whole FCAL-II assembly downstream by 35 cm -- this puts the PMTs for the insert in a better magnetic field region but changes the acceptance of FCAL-II as a whole.
      • Could in principle stack the lead glass crystals removed from the inner region at the outer radius of FCAL-II
    • 3x3 prototype of soft-iron (1020 steel) tubes + mu-metal inserts
      • 1020 could be annealed for ~20% improvement
      • Length of housing still needs to be optimized
      • mu-metal shielding thickness still needs to be optimized but promising results obtained with 350 micron mu-metal, could in principle increase another ~50 microns or so (50 micron material due at lab this week).
      • Sasha and Josh looked at PMT response with and without sheilding
        • At 4 Gauss longitudinal, saw 10% drop in amplitude without shielding
        • With shielding, response flat up to 40 Gauss external field, 2-3% drop at 50 Gauss
        • Still need to check transverse field impact
  • Next step: address stacking and assembly of FCAL-II (frame design, distribution of stress
  • Need to keep working on divider design.