[Halld-pid] Minutes, Time-of-Flight Meeting, March 1, 2012

[Mark M. Ito]

Find the minutes at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_March_1,_2012#Minutes 
and below.
   _____

GlueX TOF Meeting, March 1, 2012

Minutes

    Present:
      * FSU: Paul Eugenio, Kurt Koetz, Sasha Ostrovidov, Ian Winger
      * JLab: Chuck Hutton, Mark Ito (chair), Tim Whitlatch

Mechanical Design

    Note: Chuck brought his PC into the meeting room so we were able to
    look at the 3-D I-DEAS drawings.
      * The TOF detector modules are clamped between two U-channels that
        run along the entire edge of the array.
      * Tim proposed lengthening the long scintillators by 1 cm, so that
        the edges protrude another 0.5 cm. This is to make the clamp share
        load equally between scintillator and light guide.
           + [Added in press] Elton Smith pointed out that it is not a good
             idea to put any pressure on the scintillator surface. That
             practice promotes crazing. So it looks like in fact we want to
             make the counters shorter.
      * Tim proposed building a 1/4-scale model of the entire frame,
        including some of the detector modules, to see if there are any
        assembly issues with the current design.
      * Paul proposed building a full-scale model of one corner of the
        frame, to test whether mechanical tolerances in the assembled array
        are sufficient.
      * Kurt expressed some skepticism that the clamping U-channels could
        be made with enough precision to both hold the scintillator and
        provide a suitable mounting surface for the outer steel magnetic
        shields. In fact the current design does not have a provision for
        adjusting the angle of the long axis of the shields so that they
        miss the PMT's and their bases. That would have to be added.
      * Kurt advocated a different approach, where the support for each end
        of each module is a separate mechanical assembly, each assembly
        supported on a common backbone. These assemblies would allow
        adjustment of more of the degrees of freedom and would have greater
        precision in doing so. Ian had drawn up a [20]concept some months
        ago.

    We decided that a lot of issues had been raised that require some study
    and further discussion. We agreed to meet again, in a week, Thursday,
    March 8, at 10 am (in ARC 428, so Chuck can bring his PC again).

Prototype Status

    There was not much to report since the collaboration meeting. The next
    step is to measure next measure light transmission through the light
    guides.

TDC Choice

    Paul repeated his preference for using the CAEN TDC's.

Contract Status

    Paul is working on documents to respond the the RFP. Elton sent him
    examples from the Indiana contract; Paul has found them helpful.

    Retrieved from
    
"https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_March_1,_2012"

References

   20. 
https://halldweb1.jlab.org/wiki/images/8/83/LightGuideMountConcept.pdf

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