GlueX TOF Meeting, February 13, 2014

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GlueX Time-of-Flight Meeting
Thursday, February 13, 2014
10:00 am EST
JLab: CEBAF Center, F326/7


  1. Announcements
  2. Review of meeting on January 30
  3. Collaboration Meeting
  4. Installation Update
  5. Calibration
  6. Testing Results



  1. ESNet: 8542554 non-standard number

Desktop Sharing

  1. Go to
  2. In the "join a meeting" box enter the code: 1833622
  3. Fill in the participant registration form.


To connect by telephone:

  1. dial:
  2. enter access code followed by the # sign: 1833622#


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2014-1Q on the JLab CUE. This directory is accessible from the web at .



  • FSU: Paul Eugenio, Sasha Ostrovidov, Aristeidis Tsaris
  • JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair), Tim Whitlatch, Beni Zihlmann

Review of meeting on January 30

We looked over the minutes.

  • Beni is finishing the changes to the TOF geometry to incorporate the half-width counters. In addition, he has consolidated hard-coded constants into a single place in the code.
  • Mark mentioned that he had inadvertently omitted from the minutes the discussion of a TOF fast-shutdown mechanism that we had last time. We had concluded that the built-in safeguards of the CAEN high-voltage supplies are sufficient protection for the TOF.

Collaboration Meeting

Sasha will give the TOF update at the Collaboration Meeting.

Installation Update

Paul gave the report.

  • The studs were all brought back to FSU and the machining of middle sections is complete. They are all packaged up and ready for the return trip to JLab.
  • Paul will bring up a holding frame for repairing the two counters whose glue joints (between the light guide and scintillator) broke during the installation dry-runs. The frame was made from parts from the gluing fixture used during module construction. The plan is to hang the frame and modules from the forward platform. Eljen EJ-500 two-component epoxy is used.
  • Paul was planning to come up just before the collaboration meeting and do the repairs over the the weekend, but Tim told us there is a power outage planned for the entire Hall on that Saturday and Sunday, so that plan will have to be adjusted.
  • Tim reported that the clamps to compress the entire array have come in.
  • Tim also reported a plan to add foam pieces in the spaces where the aluminum cheese pieces were to have gone originally, as a mechanical backstop in case there is any slippage in the clamping channels. There was some discussion about the need for foam in this area. When Paul gets to the Lab he and Tim will review the plan.


Sasha is enhancing capabilities of his stand-alone Monte Carlo. He is generating pπππ events and matching x and y planes using the TOF alone. For two-tracks in the TOF, he gets the matching wrong 15% of the time; for three tracks, 40% of the events have matching mistakes. He is working on improvements. Mark suggested that at some point Sasha might consider doing studies with HDGeant where charge particle tracking would help.

Testing Modules in the Hall

  • Hussein has found a few light leaks in the first layer. He is simply looking at rates on the scope with a single PMT.
  • Paul was planning on bringing another HV supply channel to enable triggering on one end and looking at the other, but Beni told us he has a four channel supply that they can use. Beni will get together with Hussein on this.