[Halld-pid] Minutes of the GlueX PID meeting, May 28, '10

[Mark M. Ito]

Find the minutes posted at 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_PID_Meeting%2C_May_28%2C_2010#Minutes 
and as text below.

    ========

GlueX PID Meeting, May 28, 2010
Minutes

      * FSU: Paul Eugenio, Sasha Ostrovidov
      * JLab: Eugene Chudakov, Mark Ito (chair), Sascha Somov, Tim
        Whitlatch, Elliott Wolin, Beni Zihlmann
      * UMass: Rory Miskimen


Announcements

      * Eugene announced that the recent change request approved has been
        approved and we can go ahead and buy some PMT's for the TOF
        prototype.
      * This generated some discussion:
           + Paul reported that Hamamatsu has offered to put a dynode
             output on the base for same price as for the standard
             configuration. He reminded us that the original plan was to
             use an XP2020 with both anode and dynode outputs.
           + Paul discussed using a passive splitter with Fernando Barbosa
             at the last collaboration meeting. We should discuss all
             options further.
           + Paul will send Mark a new quote for use in writing up the PR.


Reviewing minutes from the last meeting

    We went over them.

    Tim mentioned a recent meeting where there was a lab-wide review of
    helium demand in the future. At the meeting he mentioned the idea of
    getting a pulse tube refrigerator for target and our needs for the
    solenoid. Others at the meeting raised the possibility of supporting
    various other types of targets, include a FROST target. We agreed that
    for now our planning should only include hydrogen, deuterium and helium
    4; other possibilities would have to be raised and developed before
    impacting current plans. The change request to support a purchase has
    been approved.

Time-of-Flight

    We went over several items.

calibration

    Paul reminded us that in Hall B, time-walk studies are done with a
    laser pulsing system. To explore doing similar studies ourselves, he
    has received LED's from [27]Nichia, both UV and blue. A circuit has
    been constructed to drive the LED's. The UV LED will be used to excite
    the scintillator. He is working with a scope right now. He can get down
    to 8 ns width and 5 V pulse height with the pulser he has.

    We had originally discussed using the system being developed for the
    calorimeter to pulse the TOF. There was some concern about whether that
    system could vary output amplitude precisely enough to calibrate the
    time-walk.

change of thickness of counters

    Paul proposed that we increase the thickness of the TOF counters to
    better match the size of the photocathode of the PMT, from 1 in. to
    1-1/3 in. He has talked to Matt, who thought that there would be little
    effect on calorimeter. The width would remain the same at 6 cm.

    There was some discussion about how much might really be gained. We
    probably should try to understand the limits to light collection in
    either plan.

wrapping material

    Paul discussed choices of wrapping material:
      * He is now using Tyvek, some aluminized mylar, and aluminum foil
      * The material formerly known as VM2000 is now called ESR DF2000MA.
        It was originally sold as roll. Yuri Sharabian got some, PrimEx
        used it, the new start counter for CLAS used it, and they are
        planning on using it for the CLAS12 TOF.
      * It is not sold in rolls anymore; LCD screens is the current big
        market.
      * Paul has obtained a sample, 20 ft. long, 1.5 ft wide; he will fool
        around with it. He will also test other materials.
      * Cost: $1000 for a 150 ft. roll. The thickness is 2.6 mils.
      * It is non-conductive, non-magnetic, reflectivity north of 99%.
      * The current plan is to use black Tedlar for wrapping. Although
        DuPont says there is a shortage, they will send Paul a sample, 6
        ft. by 150 ft., which ought to hold him for a while.


other items

      * prototype work: The scintillator has been machined down to the
        nominal 6 cm wide.
      * MOU: Paul has recent put effort on the MOU on hold pending
        completing of his DOE proposal. He will send Mark a final draft
        next week.


Target

    Rory has sent a recently revised version of the UMass MOU to JLab.

New Action Items

     1. Arrange a meeting to discuss signal splitting schemes for the TOF
        PMT signals.
     2. Think about light collection studies for the TOF.

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References

   27. http://www.nichia.co.jp/en/about_nichia/index.html