JEF meeting Jul 27, 2015

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

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Attendees: M. Kamel, B. Karki, D. Mack, A. Somov, S. Taylor, J. Stevens

  • A. Somov: the 2π0 background to the η→π0γγ channel needs to be understood better. Sascha fears that this is being underestimated in our PYTHIA background simulation. A theory colleague (S. Gevorkyan) is working on a 2π0 generator (σ(600) production or π+π-→π0π0 charge exchange).
  • S. Taylor started looking at reconstructing two-photon events from the Spring run data. He showed evidence of late-time hit contamination of FCAL showers. These bad hits can be eliminated in the clusterization by applying a +-15 ns time cut. The logbook entries are here: [1],[2].
  • D. Mack: should try to understand how statistics from Spring run scale up to expected luminosity during regular production JEF/GlueX running. Unfortunately the Spring run was not at the right electron beam energy...
  • We discussed the need for magnetic field studies for determining the appropriate shielding for the PMTs for the insert crystals. A. Gasparian has tubes and dividers. Alternatively could purchase new tubes from Hamamatsu; current cost=$375/tube (A.S.). T. Horn (Hall-C) has ordered 2x2 cm^2 lead tungstate crystals we may be able to use for a test. These dimensions are a little smaller than we anticipate we will need to accommodate the appropriate shielding. We will also need light guides because the mu-metal shielding should stick out beyond the face of the tube to be truly functional.