GlueX TOF Meeting, December 16, 2020

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GlueX Time-of-Flight Meeting
Wednesday, December 16, 2020
10:00 am EST
BlueJeans: 350 531 998


  1. Announcements
  2. Review of minutes from the last meeting
  3. PMT Repair
  4. TOF NIM paper
  5. Action Item Recap


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2020 on the JLab CUE. This directory is accessible from the web at .


Present: Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting. Log into the BlueJeans site first to gain access (use your JLab credentials).

More on the Gain Study

We went over additions Beni made to his study since the last meeting. In particular he plotted amplitude spectra for individual PMTs overlaying the data from the high intensity and low intensity runs. All show clear minimum ionizing peaks. The difference in the mean value in the histograms, reported last time, is indeed due to taking the average over the entire histogram, with the high intensity runs having many more hits a low pulse height, as we speculated last time.

The anomaly in PMT 69 is revealed as a broad peak in the pulse height spectrum around 3500 counts. The rate in this peak seems independent of beam intensity. The minimum ionizing peak is present in both high and low intensity runs and at a typical value of pulse height, so at some level the PMT is working with an unremarkable gain. It is hard to imagine that a broken light guide is causing the strange behavior. This tube remains a candidate for replacement.

Beni also reported that he has looked at the signal from PMT 69 on the scope and could not see anything out of the ordinary.

Action Item Recap

  1. Decide on when to ship PMTs to JLab from FSU (Mark, Paul Eugenio)
  2. Prepare a complete draft of the TOF NIM paper. (all)
  3. Make a plan for TOF repair during the SAD, including Paul in the discussion. (all)