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<p>Folks,</p>
<p>Please find the minutes <a moz-do-not-send="true" href="https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_9,_2021#Minutes">here</a>
and below.</p>
<p> -- Mark</p>
<p> ______________________________</p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span dir="auto">GlueX Start Counter Meeting, December 9, 2021,
</span><span class="mw-headline" id="Minutes">Minutes</span></h2>
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<p>Present: Eugene Chudakov, Mark Ito, Igal Jaegle, Simon
Taylor, Beni Zihlmann
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<p>There is <a rel="nofollow" class="external text" href="https://bluejeans.com/s/3xt7NebOwNA">a recording
of this meeting</a> on the BlueJeans site. Use your
JLab credentials to gain access.
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<h3><span class="mw-headline" id="Review_of_minutes_from_the_last_meeting">Review of
minutes from the last meeting</span></h3>
<p>We went over the <a href="https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_October_14,_2021#Minutes" title="GlueX Start Counter Meeting, October 14, 2021">minutes
from the meeting on October 14th</a> without
significant comment.
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<h3><span class="mw-headline" id="Run_report">Run report</span></h3>
<p>Beni showed evidence of increased dark noise in the
SiPMs. He looks at a statistic that is sensitive to a
high-side tail of the pedestal distribution taken from
beam-off data in raw mode. The higher the dark noise,
the lower the statistic. This measure was explained at a
<a href="https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_21,_2019#SiPM_dark_rate_measurement" title="GlueX Start Counter Meeting, March 21, 2019">previous
start counter meeting</a>. There is a clear trend,
year-to-year, of increased dark noise.
</p>
<p><a href="https://halldweb.jlab.org/wiki/index.php/File:Paddle_response_p1.gif" class="image"><img alt="Paddle response p1.gif" src="https://halldweb.jlab.org/wiki/images/7/7e/Paddle_response_p1.gif" class="thumbborder" width="698" height="474"></a><br>
Pedestal distributions showing high-side tails.<br>
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<a href="https://halldweb.jlab.org/wiki/index.php/File:Sc_darkratetest.gif" class="image"><img alt="Sc darkratetest.gif" src="https://halldweb.jlab.org/wiki/images/d/da/Sc_darkratetest.gif" class="thumbborder" width="698" height="474"></a><br>
Statistic as a function of run number<br>
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<p>We discussed possible ameliorations, including
replacing the SiPMs. We are nowhere near deciding on
that course of action; more study is needed.
</p>
<h3><span class="mw-headline" id="Calibration">Calibration</span></h3>
<p>Mark will try to round up some volunteers to calibrate
the start counter for the PrimEx and SRC runs.
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