GlueX TOF Meeting, August 28, 2019

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GlueX Time-of-Flight Meeting
Wednesday, August 28, 2019
10:00 am
JLab: CEBAF Center, Room F226
BlueJeans: 350 531 998


  1. Announcements
  2. Review of minutes from the last meeting
  3. Upgrade Status
  4. Software Issues
    • New branch for testing: sdobbs_tof_hirecon_update
    • Corresponding CCDB Sqlite file: /work/halld/home/sdobbs/tof_upgrade_test/ccdb.sqlite
  5. TOF NIM Paper (Beni)
  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: Sean Dobbs, Ashley Ernst, Paul Eugenio, Sasha Ostrovidov
  • JLab: Mark Ito (chair), Simon Taylor, Beni Zihlmann

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

Review of minutes from the last meeting

We reviewed the minutes of the meeting on August 14 without significant comment.

Upgrade Status

Paul gave the report.

  • Paul exchanged email with Tim Whitlatch. Tim reports that all work on the frame in the Hall is done. Paul is assuming that the bottom layer has been re-assembled to be in the same state as when he left to go back to FSU on the last trip (Mark will confirm this state of things with Tim). Work was done to drill and tap new holes in the frame and install the nylon bolts that will act as stops against vertical sliding of the modules.
  • All modules have been fabricated.
  • An extra bar or two have been made to act as spares. Those still require testing.
  • The modules have been packed in their boxes and are ready for transport.
  • The new beam box is being fabricated. The original design from Tim and Stephanie Worthington has been modified to be able to accommodate air light guides in the future should we attempt such a modification. There are two layers to the inner surface one of which can be removed to provide access to the scintillator. The new box is made of G10 and should be sturdier than the one we used in the past.
  • Ian Winger is working a new tool for gluing PMTs to light guides in situ. It will not be used for the upcoming installation but may be used if we have to replace PMTs on the modules as mounted on the forward carriage should the need arise.
  • The Lucite shield has not been fabricated yet. We will wait until the TOF is installed in the Hall with all of the cables and electronics checked out. As with the previous version, this can be added later.
  • Paul sees a time line for transport and installation as follows:
    • Arrive at JLab on a Wednesday
    • Install Wed., Thu., Fri. Spill into the weekend if need be.
    • Be back as FSU on Tue. to teach his class.
  • The installation should take a day if everything goes well, thus contingency is built into this schedule.
  • The only remaining question is which Wednesday. It will be either September 4th or 11th (maybe the 18th).

Software Issues

Sean described the changes he has made on the reconstruction software and related plug-ins. The new code is designed to accommodate either the old TOF or the new TOF geometry. It is on a new branch of halld_recon: sdobbs_tof_hirecon_update. diffs with the master can be found here.

  • The DTOFGeometry class was refurbished to reflect all relevant parameters from the HDDS XML input. The XML will depend on the run number, thus the TOF parameters can be used to determine which version of the TOF is to be used in the code.
    • The parsing was updated
    • Values previously hard-coded are now served by DTOFGeometry.
  • Simple tests have been done and things look good.
  • Ashley is having some difficulties with the new code in her tests having to do with obtaining calibration constants from the CCDB.
  • Overall amount of work to create the "dual purpose" code was not too bad.
  • Sean does not have a strong feeling about whether the calibration code needs to be done in the dual-purpose style or with a brand new set of code, developed independently of the old calibration code.
  • The calibration constants are in tables which have different dimensions for TOF I vs. TOF II and thus must be retrieved from a different set of tables. The constants being used for development now can be found in the following file:
  • Mark argued for having the new constants in a new directory say TOF2, at the same level as the old TOF directory in the CCDB. The current scheme has them in a v2 sub-directory of TOF.


Beni pointed out that we need to do a new integral non-linearity calibration of the CAEN TDCs. The new channels of the TDCs, those put into play with the upgrade, probably do not have even have a calibration.


We reviewed the email from Beni announcing a draft/outline version of the TOF NIM paper on Overleaf. We agreed this was a good way to jump-start the effort and will feed into the recently re-started effort by Elton Smith on a GlueX detector NIM paper. Beni has declared a deadline of December 1st for a complete first draft.