GlueX TOF Meeting, October 10, 2013

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GlueX Time-of-Flight Meeting
Thursday, October 10, 2013
10:00 am EDT
JLab: CEBAF Center, F326/327


  1. Announcements
  2. Review of meeting on September 12
  3. Construction News
  4. Testing Update
  5. Plane and Module Numbering & Packing Lists
  6. Installation plan



  1. ESNet: 8542553

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/2013-3Q on the JLab CUE. This directory is accessible from the web at .


There is a recording of the meeting on ReadyTalk (auto-deleted after a month).


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

Construction News

  • There are four modules remaining to be completed. Module construction should be done this week.
  • All shipping crates have been constructed, including the cutting of the packing foam.
  • Delivery is planned in two batches. The first shipment could be ready to go by the end of the month.
  • Space is reserved in the ESB to accept shipment.
  • Paul showed an installation plan. The nominal plan is to do a quick visual inspection upon arrival, and then do a quick test under HV in the Hall just prior to placing in the support frame. Details have to be worked out.
  • FSU will bring a module repair kit with them for use at JLab. Included will be the PMT removal tool, extra light guides, glue, the module transport cradle, and possibly spare PMTs.
  • We discussed Paul's email about pieces that remain to be machined at FSU.
    • There are still some drawings that need to be signed at JLab. That will happen today. Then Randall can have a look at them and instruct JLab on what to order.
  • Paul asked about a modification to the details of the threaded rods for the support structure to simplify ordering and machining.[?] We thought that that would be OK.
  • Tim and Chuck will look up the material we decided on for the beam-hole support box (probably high-density polyethylene).
  • The iron tubes all all done (and painted gold (goes with garnet)).
  • The aluminum collars are also all done and ready to go, set screws included.
  • The big channels ordered by JLab are in fabrication. They should be delivered by mid-November. Other small hardware components need to be procured. Some of the related tooling has been ordered. Tim will check on status.
  • Paul pointed out that for the horizontal modules in their running configuration there needs to be a support at the bottom to prevent sagging and to hold the modules close together. Tim and Chuck will add such a structure, and also design similar structures for the top and both sides of the vertical modules.

Testing Update

Sasha reported that all standard size modules have been tested, including the re-test of those originally tested when the trigger timing jitter was observed. He described two small issues:

  1. A few modules, when gain balancing was repeated, preferred voltages about 15 V from the original measurement. Most modules returned to 2 or 3 volts from the initial measurement.
  2. 5 or six of the modules show slightly elevated dark rates, 5 to 10 kHz when normal rates are 1 to 2 kHz. These may be to the light tighting scheme right at the PMT. All modules have had extra tape added to this region to prevent any problems. The noisy modules will be looked at again now that this is done.

Sasha is thinking about how to do the time-walk correction for the half-length modules (single-ended read-out only).

The basic plan for arranging the modules is to put those with the best attenuation length and lowest HV requirements near the beamline so that there is room to raise the HV if the tubes show deterioration over time.

Beni asked about the details of the procedure to measure time resolution and position resolution. He wants to confirm between these two measurements. Paul or Sasha will circulate the relevant reference to Giles, et al.