[Halld-pid] Start Counter Meeting Minutes, June 27, 2013

[Mark M. Ito]

Folks,

Find the minutes below and at:

https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_June_27,_2013#Minutes

   -- Mark
_____________________________

GlueX Start Counter Meeting, June 27, 2013
Minutes

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

Construction

    Eric described the five new counters from Eljen/McNeal. He has tested
    all five. Each measurement took about a day. See [20]his slides for
    details. Some of his points:
      * The shipping container that the counters arrived in is much more
        robust than the one used by McNeal in the past. The container came
        originally from Eljen.
      * On balance the new counters look much better than any of the
        samples we have received before.
      * Some of the counters has some light buffing scratches on some
        surfaces.
      * The counters arrived with different protective light-tack plastic
        film than those applied at Eljen. The reason for switching the film
        is not known.
      * The bars had some visible inhomogeneities or ripples not seen in
        straight bars ass Eljen.
      * Comparing the laser scattering images from batch 3 (new ones)
        versus batch 2, there is much less light escaping the counter,
        especially in the bend region.
      * Time resolution for each bar was measured. The resolution is much
        better than those seen in previous batches, in the range from about
        270 to 370 ps, with the worst resolution coming from the bend
        region. The improvement at the nose is from about 370 ps with
        previous counters to about 300 ps.
      * Attenuation lengths were measured, the average of the counters is
        39.6 cm.
      * Properties of the counters are being kept in a SQLite database.
      * Measurements will be repeated every month going forward. Recall
        that one of the previous batches showed large deterioration in
        performance after about three months. One point on one bar went
        from 400 ps resolution to 650 ps due to visible surface crazing.
      * Three of the paddles were handled with the wrong type of glove.
        These gloves had aloe vera on the surface. They were cleaned with
        isopropyl alcohol after this was realized.

Next Steps

    We would like to have the readiness review at a point in time near
    being ready to assemble finished counters on the support structure.
    This will likely be in the early Fall.

    We have to pick up the pace on the support structure, the test fixture,
    and the assembly fixture. One good thing is that the final drawings of
    the detector itself have all been done.

    Retrieved from
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_June_27,_2013"

References

   20. 
https://halldweb1.jlab.org/talks/2013-2Q/McNeal_Batch%20_3_ST_Meeting.pdf


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