[Halld-pid] Minutes, June 11 PID Meeting

[Mark M. Ito]

Find the minutes of the June 11, 2010 PID meeting at 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_PID_Meeting%2C_June_11%2C_2010#Minutes 
and as text below.

GlueX PID Meeting, June 11, 2010
Minutes

    FSU: Paul Eugenio, Sasha Ostrovidov Jlab: Tom Carstens, Eugene
    Chudakov, Mark Ito (chair), Chris Keith, Sascha Somov, Simon Taylor,
    Tim Whitlatch, Beni Zihlmann

Review of minutes from the last meeting

    We went over [27]the minutes.

PMT purchase for TOF prototypes

    Paul sent the quote, Mark submitted the purchase requisition, and now
    the purchase order is all set to go out, we just need a shipping
    address at FSU to attach to the PO.

Refrigerator for the target

    We started from the entry in the minutes about the lab-wide review of
    helium demand.
      * Chris commented that if we do get a pulse tube refrigerator for
        cryotargets, that it actually might be able to service a frozen
        spin target. We did note, again, that such a target is not part of
        any current plan for Hall D.
      * Tim is in the middle of a cryogenic requirements review for the
        Hall and a decision on purchase of the recommended refrigerator is
        pending on completion of his work.


Time-of-Flight

    We spent a lot of time updating issues discussed at the last meeting.

Calibration

      * Bein told us the LED system planned for the calorimeters cannot
        easily change the intensity of the light output, as would be
        convenient for time-walk calibration.
      * We need to talk to Elton Smith or Dan Carman about experience with
        the CLAS TOF nitorgen laser calibration system.
      * Right now, Paul is working on a LED pulser system aimed at
        developing experience with the prototype counters.
      * Stability of pmts is an issue, but not as critical as for the
        calorimeters.
      * Paul informed us that the time-walk calibration was repeated on a
        time scale of order a year.
      * Eugene told of us of a laser system that was being used in Hall A
        that may be available.
      * Tom reminded us that the CLAS electromagnetic calorimeter also has
        a nitrogen laser calibration scheme. Kevin Giovanetti developed
        that system.


Change of Thickness of Counters

      * Paul is exploring where the effective edge of the photocathode are
        with the Hamamatsu tubes.
           + PMT spec. states that the minimum cathode diameter is 46 mm
           + cutting an ERT disk to that diameter to obscure photocathode
           + plans is to look for residual signal
      * We talked about the light guide to PMT coupling scheme.
           + current plan: silicon cookies
           + initially glued used (still being used on one of the current
             counters)
           + Tim has done lay-outs that incorporate compression of the
             cookie
           + Eugene mentioned RTV glue as a possibility; joint can easily
             be broken with a razor blade


Wrapping

      * large sample of ESR DF2000 MA in hand at FSU
      * studies about to start
      * final light tight overwrapping: still waiting for delivery


Other TOF issues


Changing the Data Acquisition

      * Sasha has received TI board
      * Will be running with LED system to explore time-walk; naturally
        will result in trigger rate increase over cosmics; the TI will help
        here to correctly correlate ADC and TDC hits
      * Note: using a VME64 bridge (not using a CODA ROC)


New Counters

    FSU is changing change the trigger to use a longer counter; this will
    improve the rate for cosmic triggers.

MOU

    Progress will resume now that DOE grant work is done.

New Action Items

     1. Ask Elton about experience with the CLAS TOF laser calibration
        system.

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References

   27. 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_PID_Meeting%2C_May_28%2C_2010#Minutes