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Start Counters,<br>
<br>
Please find the minutes reproduced below and posted at
<a class="moz-txt-link-freetext" href="http://tinyurl.com/qajlvk2">http://tinyurl.com/qajlvk2</a> .<br>
<br>
-- Mark<br>
_________________________________________________<br>
<br>
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<h3 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">GlueX Start Counter Meeting, August 3, 2015 </span><span
class="mw-headline" id="Minutes">Minutes</span></h3>
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<p>Present:
</p>
<ul>
<li> <b>FIU</b>: Werner Boeglin, Mahmoud Kamel</li>
<li> <b>JLab</b>: Mark Ito (chair), Eric Pooser, Simon
Taylor, Beni Zihlmann</li>
<li> <b>NU</b>: Sean Dobbs</li>
</ul>
<h3><span class="mw-headline"
id="Plans_for_Automating_Calibrations">Plans for
Automating Calibrations</span></h3>
<p>Eric noted that the next step was to write a GlueX Note
describing the current calibration procedures. He will
also discuss plans with Mahmoud. We will discuss the
issue again next time.
</p>
<h3><span class="mw-headline"
id="Start_Counter_Efficiency">Start Counter Efficiency</span></h3>
<p>Mahmoud has refined the efficiency measuring procedure.
He changed the plug-in to use only one candidate from
each charged track, the one with the highest
figure-of-merit. The efficiency improves from about 84%
to about 97%.
</p>
<p>Mahmoud will give us a presentation on this topic at
the next meeting.
</p>
<h3><span class="mw-headline" id="Calibration">Calibration</span></h3>
<p>Eric gave a detailed presentation of all aspects of the
calibration procedure he has settled on. See <a
rel="nofollow" class="external text"
href="http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2787">his
slides</a> for details.
</p>
<p>He covered three main areas:
</p>
<ol>
<li> Time-Walk Corrections</li>
<li> Attenuation Corrections</li>
<li> Propagation Time Corrections</li>
</ol>
<p>The secretary will not attempt to summarize all 60-some
slides in this space. The talk itself serves as a
document of what was tried and what has worked.
</p>
<p>There was discussion throughout the presentation and we
did come to some conclusions about further work:
</p>
<ul>
<li> <b>Time-Walk Corrections</b>. These look to be in
good shape. No further work is anticipated as far as
developing procedures is concerned.</li>
<li> <b>Attenuation Corrections</b>. We need to control
for particle ID, momentum, and angle of incidence
before looking at the energy response of the detector.</li>
<li> <b>Propagation Time Corrections</b>. The
application of an effective propagation velocity also
requires a different time offset for each region
(straight, bend, nose).</li>
</ul>
<p>Eric will be working with Simon to incorporate the best
constants, as currently calculated, into the CCDB and
the reconstruction.
</p>
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