GlueX TOF Meeting, July 1, 2020

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GlueX Time-of-Flight Meeting
Wednesday, July 1, 2020
10:00 am EDT
BlueJeans: 350 531 998


  1. Announcements
  2. Review of minutes from the last meeting
  3. Calibration
  4. New PMTs testing
  5. TOF NIM paper
  6. 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: Edmundo Barriga, Eugene Chudakov, Mark Ito (chair), Sasha Ostrovidov, Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials to gain access.


Next week the turn on of the GlueX detector will start in earnest.

Review of minutes from the last meeting

We went over the minutes from June 17. Sasha reports that the paperwork from Hamamatsu shows that indeed 23 is the correct number of PMTs ordered.

New PMTs testing

Sasha presented results from testing the new PMTs. He described the preliminary tests, and the gain measurements using the single photoelectron peak. Please see his webpage, linked above, for the plots and a nice description and discussion of his results.

TOF NIM paper

Sasha has complete three sections for the paper.

  1. Testing done during the design phase. This has been entered into Overleaf.
  2. Tests done on components before construction.
  3. Tests performed on the completed modules.

He notes that there is some overlap with parts already written by Paul and Beni and asked for advice on how to proceed. We encouraged him to talk to the authors of the sections in question and/or put the sections into the complete paper to facilitate broader discussion of how to resolve any conflicts.

Attenuation lengths in Monte Carlo

Beni brought our attention to two related GitHub issues, one on the halld_sim site, the other on the hdgeant4 site. It appears that the wrong light attenuation scheme is being used in hdgeant4 giving poor agreement between data and simulation for energy deposition, with the simulation giving a value a factor of two too low. hdgeant(3) may also have pathologies. Beni is actively working on straightening out the situation.

Action Item Recap

  1. Decide on when to ship PMTs to JLab from FSU (Mark, Paul Eugenio)
  2. Start looking at the NIM paper as a whole. (all)
  3. Continue work on the attenuation problem in Monte Carlo (Beni)