GlueX TOF Meeting, December 13, 2016

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GlueX Time-of-Flight Meeting
Tuesday, December 13
11:00 am EST
JLab: CEBAF Center, Room F326/327


  1. Announcements
  2. Review of minutes from the previous meeting
  3. PMT Gain Studies (Brad)
  4. Lucite Shield (Paul)
  5. PMT Testing (Paul)
  6. PMT bases with Amplifiers (Beni)
  7. NIM Paper (Paul)
  8. Action Item Recap



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 .



  • FSU: Sasha Ostrovidov
  • JLab: Thomas Britton, Brad Cannon, Paul Eugenio, Mark Ito (chair), Simon Taylor


Beam is due in the Hall this afternoon. Shifts start today at 16:00.

Lucite Shield

Paul has updated the run plan in the logbook. We will need to talk to Alexandre Deur to incorporate it into the larger schedule.

PMT Testing

Paul showed a page listing the steps used at FSU to qualify the original order for PMTs for the Time-of-Flight. They are:

  • Preliminary assessment of the signal shape with a scope
  • Single photo-electron gain measurement
  • Americium source anode sensitivity measurement
  • NaI crystal quantum efficiency assessment

The plan is for Paul to drive back to Tallahassee with the new PMTs for testing. Mark will have to prepare the paperwork for this.

PMT bases with Amplifiers

Mark reported on progress Beni has been making.

  • He has given specs to Vladimir Popov.
  • He measured time resolution of the new tubes with a laser as the light source and a scope using its built-in data acquisition functions. He sees a significant degradation in timing resolution when the tube is run at a lowered voltage, from about 50 ps RMS at 1550 V to a few hundred ps at 1250 V.
  • If an external amplifier is used the resolution recovers to about 50 ps, RMS.
  • He is preparing to do tests with different proportions of voltage drops from the voltage divider.