GlueX TOF Meeting, June 21, 2016

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GlueX Time-of-Flight Meeting
Tuesday, June 21, 2016
11:00 am EDT
JLab: CEBAF Center, Room F326/327

There is a recording of this meeting on the blueJeans site.


  1. Announcements
  2. Review of minutes from the previous meeting
  3. PMT Gains
    • Example: position of the MPV as a function of run number for various paddles
      Tofgain plane1 paddle5.gif Pad5 Tofgain plane1 paddle15.gif Pad15 Tofgain plane1 paddle19.gif Pad19
      Tofgain plane1 paddle22.gifPad22 Tofgain plane2 paddle22.gif Pad22P2 Tofgain plane2 paddle21.gif Pad21P2
      Tofgain plane2 paddle22 zoom.gif P22P2
    • the overall loss in gain over the running period ranges from 5% for paddle 1 to 8% for paddle 6 to 12% for paddel 12 to 16% to paddle 18 to 22% for paddle 20.
    • in addition to the overall loss in gain there are substantial gain variations from run to run for some of the inner most paddles and can be identified with periods when the measured PMT current of the HV supply increased by 15 mico Amps or more due to the high luminosity.
    • these two behavior indicate that the PMTs were operated at too high gain causing large currents going though the PMT.
    • tof response of paddle 22 and paddle 21 for runs 10780 and 10783
      Tofresponse plane2 paddle22 run10780.gif Tofresponse plane2 paddle21 run10780.gif RUN10780
      Tofresponse plane2 paddle22 run10783.gif Tofresponse plane2 paddle21 run10783.gif RUN10783
    • What is the difference between these two runs? The Radiator!, run 10780 had a 50um radiator, run 10783 had a 20um radiator. The beam currents were in both cases 100nA. the lifetime was 55% for run 10780 and 85% for run 10783. This means the rates were larger in run 10780! To illustrate this the scaler rate of paddle 21 and 22 of plane 1 as well as the beam current and active target a plotted during this period:
      Tofscaler 21 22 c.jpg
      as can be seen during the time with thicker target the rate in paddle 22 increased while in paddle 21 it looks like saturation!
    • Note all the above data is using the integral with pedestal subtracted.
  1. Calibration Status
  2. NIM paper: svn co



Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2016 on the JLab CUE. This directory is accessible from the web at .