[Halld-pid] Start Counter Meeting Minutes, August 22, 2013

[Mark M. Ito]

Folks,

Find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_August_22,_2013#Minutes

   -- Mark
______________________________

GlueX Start Counter Meeting, August 22, 2013
Minutes

    Present:
      * FIU: Eric Pooser
      * JLab: Mark Ito (chair), Beni Zihlmann

Electronics

    Fernando wrote an email asking about a couple of issues.

Tolerance on SiPM placement

    Fernando asked about the tolerance for placement of the SiPMs on the
    circuit board.
      * We have to remind ourselves how adjustable the position of the PC
        board is.
      * The tolerance is should be in the range of 100 to 300 microns.
      * Mark will discuss this issue with Fernando.

Shipping Electronics and Technical Support

    We had a wide-ranging discussion of when would be a good time to send
    Nick Sandoval down to FIU to help set-up the electronics. Fernando
    proposed September, but the counters will be far from ready for a
    full-system test. Eric mentioned that he has had some email dialogue
    with Fernando on this already. We need have a discussion involving
    Fernando and Werner to resolve this.

Testing Update

Additional Measurements on Prototype Paddles

    Eric updated [25]plots of time resolution and attenuation length from
    last time to include paddles 4 and 5, both initially and from 7 weeks
    after delivery. These two paddles were not handled with the aloe-coated
    gloves. The results look good, consistent with the other initial
    measurements, and no deterioration is seen for paddles 4 and 5.

    Even in the non-aloe regions there are some visible surface
    imperfections. It is hard to tell visually if it is due to the on-set
    of crazing or buffing scratches. Eric is proposing to send one of the
    never-handled-with-wrong-glove counters to McNeal for them to have a
    look and get their reaction to these features.

    Eric also showed a plot from Eljen showing [26]light output spectra
    from three regions of a sample machined by McNeal. There seems to be no
    significant difference in the spectra from the straight region, the
    near-bend region, and the bend region.

Cross-Talks Suppression and Wrapping

    Eric points out that if we add two layers of VM2000 between each
    counter to suppress cross talk, the outer surface of the counters moves
    out by a millimeter or so. This is probably too much. On the other hand
    aluminized Mylar should do the job just as well.

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References

   25. 
https://halldweb1.jlab.org/talks/2013-3Q/Initial_&_7_Week_Measurements.pdf
   26. 
https://halldweb1.jlab.org/talks/2013-3Q/Fla-Intl-U%20heat%20bent%20strips%20LOtest%2014Aug13.pdf