[Halld-pid] Start Counter Meeting Minutes, December 13, 2012

[Mark M. Ito]

Find the minutes below and at
 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_13,_2012#Minutes
___

GlueX Start Counter Meeting, December 13, 2012
Minutes

    Present:
      * FIU: Eric Pooser
      * JLab: Eugene Chudakov, Mark Ito (chair), Puneet Khetarpal, Chuck
        Hutton, Beni Zihlmann

Review minutes from previous meeting

    We went over the [25]minutes from the November 29th meeting.
      * The ST-2 board should be coming back to FIU soon.
      * There are discriminators at JLab that could be lent to FIU. Mark
        has an email in to Fernando.
      * The CODA set-up at FIU
           + A trigger supervisor is running accepting triggers from a
             pulse generator.
           + There is no read-out of DAQ boards yet, read-out lists have
             not been downloaded yet. David Abbott will advise on which to
             use from list of model numbers already sent to him. Beni
             mentioned that the code might be found on /site/coda/3.0 at
             JLab.

Construction

    Eric gave a report.

Bending scintillator at Eljen

    Yesterday Eric had a conversation with Chuck Hurlbut, chief engineer at
    Eljen. They reviewed the start counter geometry and discussed types of
    heating methods. Chuck thought localized infra-red heating should be
    tried. He proposed using aluminum foid to cover areas that need not
    heated and to support the scintillator in its bent form on a polichs
    aluminum surface. He recommended trying for the minum heat necessary to
    bend the scintillator. He thought that it would relatively simple for
    Eljen to bend the scintillator before it is sent to McNeal for
    machining. If Eljen does the bending there would be no need for
    diamond-polished edges.

    In the previous batch, McNeal removed the protectective tape to heat
    the counters for bending and so when machining was done there was no
    protection in that region with a resulting degradation in surface
    quality. Eljen would re-apply the protective tape over the entire
    surface before shipping to McNeal.

    Eugene asked if can we leave the tape on the counters permanently.
    There was some concern that the tape might defeat internal reflection,
    but Eric will give it a try and test a counter with the tape on.

CLAS start counter experience

    Eric has gone through the paper describing the CLAS start counter. He
    found a lot of interesting ideas in there and is now in contact with
    Youri Sharabian. They have already had some useful discussions.

Tests with wrapping materials

    The current plan calls for 2-micron aluminum coated mylar. Eric will
    also try aluminum foil. In the past it is possible results were less
    than optimal due to wrapping the counters too tightly with Mylar.

    Eric will also look at making each counter light tight. Beni will give
    some black Tedlar to bring back to FIU.

Questions on the drawings

    Eric noticed, looking at finalized geometry, that the width of the
    counters has changed from a previous version. Chuck reported that he
    had discussed these same changes with Werner previously; they were
    necessary to accommodate the SiPM read-out boards in the space between
    the CDC and the target.

    Eric asked Chuck to send him the drawing of the foam cone assembly in
    VXF or DWG format, not STP.

SiPM Read-out status

    Eugene reminded us that we need to measure the amplitude of pulses from
    the counter in the SiPM to finalize the gain in the design. Eric is
    planning on doing that measurement as soon as he gets ST-2 back from
    JLab.

    We will need amplitude information for time-walk corrections since we
    are using leading edge discriminators.

Contract

    Mark is answering some final questions from Jarrod Fitzpatrick of
    Procurement so that the Request for Proposals can be issued to FIU.

    Retrieved from
 
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_13,_2012"

References

   25. 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_29,_2012#Minutes

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