GlueX TOF Meeting, January 19, 2012

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Thursday, January 19, 2012
10:00 am EST
JLab: CEBAF Center, Room F326


  1. Announcements
  2. Minutes from the last meeting
  3. Mechanical design: Tim, Chuck
  4. Prototype status: Paul, Sasha
  5. Contract Status: Mark



  1. ESNet: 8542553
  2. EVO: EVO site


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2012-1Q on the JLab CUE. This directory is accessible from the web at .

Chairman's Cell Phone




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

Phototube Purchase

Beni reviewed the proposal he floated last month along with the subsequent discussion on the email list (see the items in the "PMT choice for TOF" thread). We agreed that, all things considered, we should go ahead an adopt his proposal and initiate the purchase of the ten-stage tubes for the entire array. Some things we need to bear in mind:

  • Eugene suggested that we have amplifier ready if needed (see "subsequent discussion").
  • We still want to test eight-stage tubes. FSU has a couple of these and will pursue these tests.
  • We want to have a mechanical design that allows replacement of tubes in the high-rate area with reasonable effort during a shutdown period.

Mark will initiate writing of the PR.

Mechanical Design

This morning there was a phone conference to discuss issues with the light guides for the half-width counters. Present were Paul Eugenio, Kurt Koetz, Randall Smith, and Ian Winger at FSU and Chuck Hutton at JLab. They agreed on:

  • adding 1 cm flat sections, as we have for the full-width guides
  • reducing the over-all length by 4 cm to avoid interference with the carriage

Another meeting is scheduled for Tuesday, January 24 at 9:00 am to discuss progress.


  • Paul has starting on construction documentation.
  • Mark has not heard anything from Procurement on the RFP. He will check on progress.

Prototype Status

  • Sasha replaced a trigger PMT and using a new propagation speed calibration, he gets 98 ps resolution, 90 ps if he restricts triggers to a narrow region at the center of the counter. The calibration was obtained by taking data with an americium source at various positions along the counter.


  • Paul showed us the first light guide with the latest design.
  • Ian is working on structure for gluing together three modules at a time. The system will allow rotation by 180 degrees.

Action Items

  • Initiate procurement of the 10-stage tubes.
  • Test the 8-stage tubes.
  • Check on the status of the Construction Contract.