[Halld-pid] Time-of-Flight Meeting Minutes, October 10, 2013

[Mark M. Ito]

Folks,

Find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_October_10,_2013#Minutes

   -- Mark
__________________________________________________________________

GlueX TOF Meeting, October 10, 2013
Minutes

    Present:
      * 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 [31]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 [32]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.

    Retrieved from
"https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_October_10,_2013"

References

   31. http://hadron.physics.fsu.edu/wiki/index.php/TOF_Installation_Plans
   32. https://mailman.jlab.org/pipermail/halld-pid/2013-October/000517.html