[Halld-pid] Start Counter Meeting Minutes, November 5, 2015

[Mark Ito]

folks,

Please find the minutes below and at 
https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_5,_2015#Minutes 
.

   -- Mark
__________________________________


  GlueX Start Counter Meeting, November 5, 2015, Minutes

Present:

  * *FIU*: Werner Boeglin, Mahmoud Kamel
  * *JLab*: Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting available 
athttps://bluejeans.com/s/8MLS/.


      Announcements

The current plan is to start running December 4, though there is the 
usual considerable uncertainty. We will aim to have hot check-out done 
the Wednesday before Thanksgiving, November 25.


      Calibration

Mahmoud gave us an on recent progress in calibration.

  * *Time-Walk Corrections*. He is using the "standard" ROOT fitter. It
    seems to be doing about as well as the custom fitter. He was
    concerned about not being able to do a check of the correction with
    a plugin that does not output a ROOT Tree in the context of the
    Calibration Challenge. Only histograms will be allowed. Checks will
    have to be done during subsequent passes.
  * *Inefficiency at the tip of the nose*. The efficiency has been seen
    to drop as one moves to the far downstream "nose" of the star
    counter. The worst offender is paddle 7. Mahmoud showed plots
    measuring the difference in sector number between start counter hits
    and the prediction from charged particles. For sector 7 the correct
    sector is predicted correctly less than half the time. At the nose
    the spatial size of the counters in the azimuthal direction shrinks;
    prediction is more difficult. This demonstrates that the geometry
    could use some fine adjustment.
  * *Azimuthal orientation of the start counter*. There was an apparent
    rotation of the start counter with respect to its expected rotation
    of 11.25 degrees from nominal. This is likely an artifact of how the
    center of each sector, in azimuth, is calculated. Mahmoud will make
    further checks.

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  * This page was last modified on 9 November 2015, at 12:25.


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