GlueX TOF Meeting, October 23, 2019

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GlueX Time-of-Flight Meeting
Wednesday, October 23, 2019
10:00 am EDT
JLab: CEBAF Center, Room F226
BlueJeans: 350 531 998


  1. Announcements
  2. Review of minutes from the last meeting
  3. Upgrade Status
    1. Halo Shield []
    2. PMT Mounter [ ]
  4. Software Issues
  5. TOF NIM papers
  6. Action Item Recap


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2019 on the JLab CUE. This directory is accessible from the web at .



  • FSU: Jason Barlow, Edmundo Barriga, Sean Dobbs, Paul Eugenio
  • JLab: Mark Ito (chair), Tim Whitlatch, Beni Zihlmann

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


Tim announced that the Hall will close for the upcoming run in 4.5 weeks.

Review of minutes from the last meeting

We reviewed the minutes from the meeting on October 9.

  • Yesterday Sean showed some plots at the HDGeant4 meeting showing an anomaly in the monitoring histograms. He reported that he has found the cause and corrected it. The wrong propagation speed was being used for Monte Carlo. Now bggen simulations for HDG3 and HDG4 look consistent.
  • Mark issued an erratum on his statement from last time that the cable numbering goes increases going from positive x to negative x. The numbers do indeed increase from negative x to positive x as Beni asserted.

Upgrade Status

  • Tim reported that the TOF is installed and surveyed. It sits a bit high, 4 or 5 mm higher than the previous survey.
    Img 20191015 154012.jpg
  • Beni went into the Hall and measured the TOF with a tape measure. From counter #3 to counter #25 on the upstream layer he sees only an additional 3 mm from the ideal sum of the widths of unwrapped scintillator, a testament to how well the modules were packed into the frame. Using tracking with TOF I, he saw a bigger effect, perhaps due to the tracking itself. Kelly Tremblay is going to give Beni some stickers that can be placed on the array itself as targets for another survey. Unfortunately, this can only be done with the upstream (horizontal) layer of the TOF.
  • Beni told us that as of last night half of the TOF is cabled up.
  • PMT Mounter. Paul showed pictures of the fixture, designed by Ian Winger, that can be used to glue PMTs to light guides in situ on the mounted TOF. Paul wants to do a test fit in the Hall and then make 4 or 6 of these so than multiple PMT replacement operations can be done at the same time.
  • Paul asked Mark to check on the order of more new PMTs.
  • Beni would like to look at changing the resister values on the voltage divider to get more voltage drop between the photocathode and first dynode in order to reduce the current load on the anode without compromising timing resolution. There are some spare PMTs in the Hall that he can use for tests.
  • Halo Shield. Paul showed a slide with a sketch of his idea for a new halo shield in front of the TOF. He proposes a Lucite square, 30×30 cm. After some discussion in the meeting, he may increase this to 34.5×34.5 cm. There is an inner wall, inside the beam hole support, to shield the inner edges of the inner counters. The shield needs to be installed by November 19, the date when the carriage will be pushed up against the DIRC.

Software Issues

  • Mark spoke with Hovanes Egiyan about the labeling for the Slow Control channels, both high voltage and discriminator scalers. Hovanes will follow the old scheme of using the cable labels to label channels in the GUI, but arrange them in the true geometric relation when appropriate.
  • Mark needs to talk to David Lawrence about the translation tables for TOF II.
  • Beni reported that the calibration software is ready for the upgraded TOF. All changes needed for the geometry have been made and the code can now handle TOF I and TOF II as appropriate.

TOF NIM paper

Sasha Ostrovidov is working a draft of the testing section of the paper in consultation with Paul.

Action Item Recap

  1. Build a halo shield (Paul)
  2. Check on PMT order (Mark)
  3. Write the testing section for the NIM paper (Sasha)
  4. Do a new build of the offline software when all pull requests from Sean have been merged (Mark)
  5. Figure out a backup scheme for the TOF NIM paper (Beni, Mark)