JEF meeting Aug 31, 2015

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Meeting time and location= 13:30 EST (JLab time) CC F326-327

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Attendees: J. Feng, L. Gan., B. Karki, D. Mack, A. Somov, S. Taylor, J. Stevens

  • Dave gave a report about his toy monte-carlo studies of proton/kaon/pion separation using time-of-flight with the GlueX detector
    • Using a nominal 100 ps timing resolution and 3% momentum resolution for forward-tracks, expect e-/π separation below ~1 GeV/c, π/K separation below ~3 GeV/c, K/proton separation below ~6 GeV/c
    • Looked at mass distributions computed using p and beta -- maybe not ideal for using in a confidence-level analysis because of non-Gaussian tails
    • Some understanding of ghost bands seen in PID plots from real data = wrong beam bucket
      • Biggest impact is for kaon id
  • We discussed what the next step in the survey of neutral final states started by Bishnu and Justin (looking at final states with 2 photons)
    • Expand survey to include 2π0, 3π0, etc.?
    • Focus on channels that might lead to the first papers from the commissioning data?
      • Exclusive π0 production, looking at Σ beam asymmetry?
      • η production cross section?
    • Consensus was to continue the 2γ work started by Bishnu and Justin, focussing on asymmetries/angular distributions while we work out the details of normalization.
  • Sascha reported that pieces are starting to come together for magnetic shielding studies (Hall probe, a Helmholtz coil is available, perhaps a permanent magnet?). Jing and Sascha will start working on setting up for measurements next week.

In particular we need to determine how many layers of mu-metal will be needed and whether we need a soft-iron outer layer as well.

  • Sascha lead a discussion regarding PMTs for the insert crystals
    • Peak anode current needs to be considered carefully -- non-linearity? Need to do some work on divider design.
    • Hamamatsu have another PMT (other than the round-face model we have been considering) with a square face (2.3x2.3 cm^2) that can handle higher peak current
    • Hammatsu have cheaper (but with worse performance) round-face PMTs than the ones we've been considering.