[Halld-pid] Minutes, GlueX Start Counter Meeting, December 15, 2011

[Mark M. Ito]

Folks,

Find the minutes at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_15,_2011#Minutes 
and below as text.

   -- Mark
   _____

GlueX Start Counter Meeting, December 15, 2011

Minutes

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

Scintillator shaping and polishing

    Werner was not happy with the scintillator shaped and polished and then
    re-polished by Plastic Craft. Two came back from re-polishing slightly
    better, two came back worse. He started looking for another vendor and
    has identified two candidates so far, [17]McNeal Enterprises and
    [18]E&F Plastics. He sent drawings to both, and both say that they can
    do the job. E&F proposes to mill all thirty counters out of a single
    solid piece of scintillator. (Plastic Craft presses the scintillator.)
    Responses from both companies have been prompt. The quotes come in at
    about $200 per piece. Subsequently, Werner sent a "good" and "bad"
    scintillator to each; the "good" for re-re-polishing, the "bad" any
    destructive studies they care to do.

Re-measurement of Plastic Craft samples

    Eric re-measured the two "good" scintillators after re-polishing by
    Plastic craft. He sees about 500 ps resolution from the far end and
    about 300 ps from the near end, a slight improvement from what was
    measured before re-polishing. These are unwrapped pieces, using SiPM
    read-out.

SiPM read-out geometry

    We looked at [19]drawings from Werner and [20]some from Chuck showing
    concepts for placement and mounting of "custom" arrays of 3×3 mm
    SiPM's. Werner would prefer a configuration where no light guide is
    needed.

    Beni noted that with no light guide, there will be non-linearity when
    hits are near the read-out end due to short-attenuation-length photons
    being detected. He also repeated Eugene Chudakov's point that some
    modularity in the mounting would be convenient if SiPM's ever had to be
    replaced.

    Mark reported that the drawings on the wiki page have been sent to
    Hamamatsu, but no response has been received yet.

    There was a basic question that came up: are the SiPM's individual
    surface-mount components that we place on a circuit board ourselves or
    are they packaged in the 1×5 configuration by Hamamatsu? More homework
    is obviously needed.

Retrieved from
    
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_15,_2011"

References

   17. http://www.mcnealplasticmachining.com/
   18. http://www.enfplastics.com/
   19. https://halldweb1.jlab.org/wiki/images/1/17/Sym_30_front_combined.pdf
   20. https://halldweb1.jlab.org/talks/2011-4Q/SC_12_15_11.pptx