[Halld-pid] Start Counter Meeting Minutes, June 30, 2016

[Mark Ito]

Folks,

Find the minutes below and at https://goo.gl/oSkcUo .

   -- Mark
_____________________


  GlueX Start Counter Meeting, June 30, 2016, Minutes

Present:

  * *FIU*: Mahmoud Kamel
  * *JLab*: Mark Ito (chair), Simon Taylor, Beni Zihlmann
  * *NU*: Sean Dobbs


      Update on Efficiencies

Mahmoud presented slides on the latest results 
<https://halldweb.jlab.org/talks/2016/ST_meeting_June30_2016.pdf> from 
his efficiency studies. He used a ROOT tree produced from the start 
counter efficiency plugin run as part of the production reconstruction 
pass on the Spring 2016 data. A single file was analyzed. See his slides 
for the plots. His slides covered:

  * criteria for selection of charged tracks in the study
  * histograms of some global properties of the tracks and start counter
    hits
  * start counter efficiencies for all tracks: 98%
  * histograms of the same global properties when a phi cut is applied
    to tracks to keep them away from the edges of the counters (delta
    phi cut)
  * efficiencies with the delta phi cut: 99%
  * same efficiencies for the straight section: 99%
  * for the bend section: 99%
  * and for the nose section: 99%
  * the studies were repeated for protons, pi+, pi-, and K+
  * for K+ no start counter misses were found when the delta phi cut was
    applied; the study was repeated without the cut

Efficiencies are everywhere (almost incredibly) high.


      Calibration

We asked Mahmoud to think about documenting the calibration procedure in 
a cookbook-like fashion so that future students will be able to 
reproduce it.


      Dark Rate Monitoring

Beni brought us the issue of monitoring dark rate of the SiPMs. We don't 
have a regular procedure for doing so. This is important given the start 
counter's proximity to the beamline and Yi Qiang's study that 
degradation can occur with exposure to the beam. We will have to develop 
a way to keep track of this.


      Mcsmear Parameters

Sean reminded Mark and Simon that they promised to come up with a 
sensible parametrization for the smearing function.

He also mentioned that there is no run-dependent time resolution 
currently in the CCDB. Mahmoud has seen evidence for small shifts, but 
has not done a detailed time-dependence study. He will have a look, 
hopefully before the end of July.

Retrieved from 
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  * This page was last modified on 30 June 2016, at 13:53.


-- 
marki at jlab.org, (757)269-5295

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