GlueX TOF Meeting, February 2, 2012

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Thursday, February 2, 2012
10:00 am EST
JLab: ARC, Room 428


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



  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: Chuck Hutton, Mark Ito (chair), Tim Whitlatch, Beni Zihlmann

Minutes from the last meeting

We reviewed the minutes from the January 19th meeting. Some items received continuing discussion in this meeting. See below.


Procurement at JLab and the Office of Sponsored Research at FSU are in touch and are exchanging information about the construction contract.

Mechanical Design

There have been a couple of conference calls with the design teams on the design of the light guides for the half-width (or split) paddles. We have agreement on a final design in hand.

Chuck showed the latest drawings, demonstrating the assembly steps we might follow on the floor of the Hall.

We talked a little about how the thickness of the scintillator wrapping material affects the design. Paul agreed to send us numbers on the thickness.

Paul showed a jig, produced by his machine shop, for gluing PMT's to the light guides. The light guide is housed in an aluminum frame and there is a clamp for holding the PMT while the glue dries.

Prototype Status

Sasha showed results from on-going tests of the eight-stage phototubes from Hamamatsu. The gains are a several times lower than for the ten-stage, as expected, but still show good separation from pedestal. Efficiency was reduced to about 80% when using a 30 mV discriminator threshold, for triggers in the middle of the counter (no amplification). Time resolution measurements are in the works.

TDC Choice

Paul was wondering if there is any data-acquisition-based reason for not using the CAEN VX1290 TDC's. They see better performance with this unit than with the F1 TDC at FSU, both with a pulser and with detector pulses. They are purchasing the unit they have; up until now it has been on loan from CAEN. Paul is willing to loan it out if that helps answer any questions.

Mark promised to ask the DAQ folks if there is any fundamental reason we cannot use it.

Action Items

  1. Paul agreed to send us numbers on the thickness of the scintillator wrapping.
  2. Mark will ask about compatibility of the CAEN VX1290 TDC with the GlueX DAQ.