[Halld-pid] Minutes of the July 9 GlueX PID meeting

[Mark M. Ito]

Find the minutes posted at 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_PID_Meeting%2C_July_9%2C_2010 
and reproduced below:

GlueX PID Meeting, July 9, 2010
Minutes

    FSU: Sasha Ostrovidov JLab: Eugene Chudakov, Mark Ito (chair), Yi
    Qiang, Sascha Somov, Elton Smith, Tim Whitlatch, Elliott Wolin, Beni
    Zihlmann

Review of minutes from last meeting

    We went over the [24]minutes from June 11 meeting.

PMT purchase for TOF prototypes

    The PO went out. Paul Eugenio is waiting on delivery.

Refrigerator for the target

      * Tim still needs to do the cryo review. A cost estimated is needed
        as well.
      * Chris Keith is confident about the ^4He capability of the proposed
        refrigerator, but this needs verification. Chris was planning to
        talk to the vendor about this.


Time-of-flight prototype

    Sasha O. reported that the LED pulser system up and running, but has
    not yet been tried with the prototype counters.

Need for a laser calibration system for the time-of-flight

    Elton reported on the use of a nitrogen laser in CLAS for calibration
    of their time-of-flight system. It was only used for for time-walk
    corrections and was useful but a lot of effort was necessary to build,
    install, and maintain the system. Time-walk corrections could have been
    measured with the data, but would have been difficult since the data
    does not have a explicity external start time. He pointed out the need
    to choose a frequency so that the scintillator itself is excited.

    Elton was recently down at the University of South Carolina. Ralf Gothe
    there is doing similar things for the CLAS12 forward TOF. They have
    decided against a laser system; they will do everything with the data.
    With their cosmic ray set up they have obtained time-walk correction
    constants.

    Elton pointed out that we will have two planes, and that will help
    doing the calibration with the data. A large dynamic range in energies
    needed. There was a lot of discussion about possible data-based
    calibration schemes. Clearly a study of a particular scheme or schemes
    is needed. If a workable scheme can be proposed, then we may not need a
    calibration system as elaborate as that used by CLAS.

Other TOF issues

      * Sasha mentioned that tests with a flash ADC would be desirable at
        some time.
      * The trapezoidal light guides are not large enough to cover PMT.
        That frustrated the first attempt to measure the response of the
        edges of the PMT's.
      * The new data acquisition system using the TI is written; it has not
        been tested yet.


Time-of-flight prototype progress

    Sasha O. has been working on cosmic ray measurements using different
    wrapping material for the prototype counters. He showed [31]plots of
    the ADC spectra for materials tried so far. Future plans include
    aluminized Mylar and ESR DF2000.

    Elton mentioned that at USC, Ralf is using aluminized Mylar. That
    worked well for Ralf on a previous experiment. Elton also mentioned
    that CLAS uses aluminum foil to wrap their counters.
      __________________________________________________________________

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References

   24. 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_PID_Meeting%2C_June_11%2C_2010#Minutes
   31. 
https://halldweb1.jlab.org/talks/2010-07/ADC%20spectra%20with%20different%20wrappings.html