[Halld-pid] Start Counter Meeting Minutes, May 31, 2012

[Mark M. Ito]

Folks,

These minutes are for this week's meeting. Find them below and at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_May_31,_2012#Minutes 
.

   -- Mark
_____

GlueX Start Counter Meeting, May 31, 2012
Minutes

    Present:
      * FIU: Werner Boeglin
      * JLab: Chuck Hutton, Mark Ito (chair), Tim Whitlatch, Beni Zihlmann

Simulation

    Puneet Khetarpal has started work on rate studies with the new start
    counter geometry.

Prototype Tests

    Werner reported test results on the new counter from McNeal. They are
    getting about 200 ps resolution from the upstream end and 400 ps from
    the downstream. The average is about 350 ps. This is very near the
    design goal. SiPM's were used for the read-out with no wrapping on the
    scintillator. It seems that McNeal did a good job polishing the edges
    of the scintillator. There were some scratches on the flat sections but
    they appear not to effect performance.

    Puneet would like to confirm in simulation that good edge quality
    results in good resolution but it is not obvious how to make a volume
    in Geant4 that has different surface quality on one face versus
    another.

    Werner is looking forward to trying out the new SiPM read-out system
    when it becomes available.

Mechanical Design

    Chuck showed about a dozen [19]pictures of the latest mechanical
    design. A compromise was reached with the target design guys that
    resolved the space problem with the cable connector. The design has
    progressed a lot; we now have a model that will work in principle.

    Werner pointed out that the first step is to machine the inner foam
    support mandrill and glue it to the metal support tube upstream of the
    counters. Then the scintillators can be placed on the mandrill, with
    reflective material between the counters, and the whole thing secured
    on the outside with some sort of banding or wrapping.

    For now we are assuming that we do not need any foam on the outside of
    the counters, even though that foam was present in the CLAS design.
    This will reduce the amount of material seen by particles. Chuck and
    Mark will check with Youri Sharabian to see if there was a compelling
    reason to have the foam on the outside. In the nose section, we will
    see how much of the inner foam can be removed at the far downstream
    end, again to reduce the amount of material, while maintaining
    mechanical stability.

    We discussed the division of labor for manufacturing, assembly, and
    test. Although FIU does have a machine shop, we formed a consensus
    around having the foam mandrill and support tube machined and glued at
    JLab, shipping the assembly to Florida, and having FIU assemble the
    scintillators, plug in the electronics, and test the system. FIU would
    also be responsible for designing and building any jigs or tooling
    necessary to perform the assembly and test.

    Werner would perhaps like to build a three-counter prototype to
    practice assembly and gain experience with a fully-loaded SiPM read-out
    board (three channels per board). He will be in contact with McNeal to
    give them feedback on the counters delivered and to order more for the
    prototype. This order will also allow us to see if McNeal can reproduce
    the good quality of the one non-crazed counter they delivered.

Contract

    No action yet. Things are getting late. Werner will be at JLab next
    week and he and Mark will get the ball rolling.

    Retrieved from
    
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_May_31,_2012"

References

   19. https://halldweb1.jlab.org/talks/2012-2Q/sc_5_31_12.pptx

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