[Halld-pid] Time-of-Flight Meeting Minutes, September 12, 2013

[Mark M. Ito]

Flighters,

Find the minutes below and at the following URL:

https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_September_12,_2013#Minutes

   Regards,

     Mark
__________________________________

GlueX TOF Meeting, September 12, 2013
Minutes

    Present:
      * FSU: Hussein Al Goul, Paul Eugenio, Sasha Ostrovidov, Aristedis
        Tsaris
      * JLab: Chuck Hutton, Mark Ito (chair), Beni Zihlmann

Review of Minutes from the August 29 Meeting

    We reviewed the [23]minutes from last time.

    Chuck updated us on status of pieces for the support structure to be
    machined at FSU.
      * Some of the drawings for have not been reviewed yet, but will be
        soon. The important ones have been signed; this is not holding us
        up.
      * The material for the aluminum collars have been ordered and should
        be on the way to FSU.
      * Randall Smith has contacted Chuck about the length of the aluminum
        "cheese pieces", those that hold the light guides near the PMT. The
        FSU shop cannot make them 40" long as specified. Chuck will review
        the design and try two 20" pieces instead. When he is done he will
        back to Randall to specify the order for raw materials.

Collaboration Meeting

    Sasha will give the talk at the collaboration meeting on TOF
    construction status.

Construction News

    Paul gave an update on the status of construction.
      * Assembly is complete on the bulk of the standard modules.
           + There are four remain standard modules that need PMTs and
             wrapping.
           + There are 12 modules that only lack the final Tedlar wrapping.
           + Four modules need re-working of the joint between the light
             guide and PMT.
                o This issue is solved now. The latest modules have clean
                  looking glue joints.
           + By the end of the month all of standard modules should be
             done.
      * The next major tasks are construction of the eight half-width and
        eight half-length modules.
      * In October, FSU will turn to packing the modules and the details of
        transport to JLab. They will likely drive them up in two batches,
        one layer at a time.
      * Chuck will check with Tim on storage space at JLab.
      * FSU students are polishing the spare light guides that were
        machined, in case they are needed.
      * Next week Maurizio will lead a search for extremely straight lumber
        to be used in the shipping crates.

Module Testing

    Sasha gave the report.
      * Seven batches of modules have been tested. Testing of batch 8 is in
        progress. Recall that each batch consists of six standard modules.
      * He is now using the TDC lent by JLab. The FSU modules has been sent
        back to CAEN for repair.
      * The problem reported last time with trigger jitter has come and
        gone several times during the past two weeks. We have arranged to
        ship another discriminator to FSU from JLab. It will be tried to
        see if that changes behavior. The discriminator will be shipped as
        soon as Chris Stanislav returns from vacation.
      * Sasha showed an updated [24]plot of nominal gain (at standard HV,
        from the Hamamatsu spec sheet) vs. the HV arrived at after the gain
        balancing procedure. All tubes in the first seven batches are
        represented. As expected, tubes with low nominal gain require a
        higher voltage operation point to be in balance with other tubes.
      * He also showed a [25]plot of nominal dark current (again from the
        manufacturer's spec sheet) vs. singles counting rate for each PMT.
        Here he correlation is weak if it exists at all.
      * For the 42 modules test thus far:
           + The speed-of-light measurements are consistent among the
             modules with an average of 15.2 cm/ns.
           + Mean time resolution is also consistent in the low to mid
             90's, measured in picoseconds. The one batch that was measured
             when the trigger time jitter problem was present is in the
             high 90's. The measurements for that batch may have to be
             repeated.
           + Position resolution results have not been tabulated yet.
      * There is still development to do on the test procedure for the
        single-ended counters (half-length).

    Retrieved from
"https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_September_12,_2013"

References

   23. 
https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_August_29,_2013#Minutes
   24. 
http://hadron.physics.fsu.edu/~ostrov/tof/20130912/balanced-hv-vs-gain.png
   25. 
http://hadron.physics.fsu.edu/~ostrov/tof/20130912/noise-vs-dark-current.png

-- 
Mark M. Ito, Jefferson Lab, (757)269-5295, marki at jlab.org