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folks,<br>
<br>
Please find the minutes below and at
<a class="moz-txt-link-freetext" href="https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_5,_2015#Minutes">https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_5,_2015#Minutes</a>
.<br>
<br>
-- Mark<br>
__________________________________<br>
<br>
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<h1 id="firstHeading" class="firstHeading" style="font-weight:
bold;" lang="en"><span dir="auto">GlueX Start Counter Meeting,
November 5, 2015</span>, Minutes</h1>
<div id="bodyContent" class="mw-body-content"><span
class="mw-headline" id="Minutes"></span>
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lang="en">
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Present:</p>
<ul style="list-style-type: square;">
<li><b>FIU</b>: Werner Boeglin, Mahmoud Kamel</li>
<li><b>JLab</b>: Mark Ito (chair), Simon Taylor, Beni
Zihlmann</li>
</ul>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">There is a recording of this meeting
available at<span class="Apple-converted-space"> </span><a
rel="nofollow" class="external free"
href="https://bluejeans.com/s/8MLS/" style="color:
inherit !important; padding: 0px !important;
text-decoration: inherit !important; background:
transparent;"><a class="moz-txt-link-freetext" href="https://bluejeans.com/s/8MLS/">https://bluejeans.com/s/8MLS/</a></a><span
class="Apple-converted-space"> </span>.</p>
<h3 style="page-break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="Announcements">Announcements</span></h3>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">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.</p>
<h3 style="page-break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="Calibration">Calibration</span></h3>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Mahmoud gave us an on recent progress
in calibration.</p>
<ul style="list-style-type: square;">
<li><b>Time-Walk Corrections</b>. 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.</li>
<li><b>Inefficiency at the tip of the nose</b>. 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.</li>
<li><b>Azimuthal orientation of the start counter</b>.
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.</li>
</ul>
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