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<p>Please find the minutes below and at</p>
<p>
<a class="moz-txt-link-freetext" href="https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_August_24,_2017#Minutes">https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_August_24,_2017#Minutes</a></p>
<p>________________</p>
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<h2><span class="mw-headline" id="Minutes">August 24, 2017,
Minutes</span></h2>
<p>Present:
</p>
<ul>
<li> <b>FIU</b>: Werner Boeglin, Mahmoud Kamel</li>
<li> <b>JLab</b>: Mark Ito (chair), Thomas Britton</li>
</ul>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/W23BR/">recording of this
meeting</a> on the <a rel="nofollow" class="external text"
href="https://jlab.bluejeans.com/">BlueJeans site</a>. Use
your JLab credentials to authenticate.
</p>
<h3><span class="mw-headline" id="Announcements">Announcements</span></h3>
<p>Thomas reported that the start counter hits are in HDvis. Hit
counters are shown in orange; un-hit counters in faint white.
The target has not been added yet. To see the current version, <a
rel="nofollow" class="external text"
href="https://halldweb.jlab.org/talks/2017/HDvis2/js/event.html">click
here</a>.
</p>
<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,_July_27,_2017#Minutes"
title="GlueX Start Counter Meeting, July 27, 2017">minutes
from July 27</a>.
</p>
<ul>
<li> Mahmoud overcame the problem he reported last time with
modifying the PID library.</li>
<li> After putting the new attenuation constants into the CCDB,
Mahmoud did not see a significant improvement in the dE/dx
measurement. He is repeating the calibration with the new,
self-consistent version of the software to see if that makes
any difference.</li>
</ul>
<h3><span class="mw-headline"
id="Start_Counter_Performance_Studies">Start Counter
Performance Studies</span></h3>
<p>Mahmoud presented his latest results. For all of the details
and his plots, see <a rel="nofollow" class="external text"
href="https://halldweb.jlab.org/talks/2017/SC_Meeting_8_24_2017.pdf">his
slides</a>
</p>
<ul>
<li> <b>Propagation Time Corrections</b>. Using charged tracks
he measures the light propagation time in the counters and
fits that time vs. light propagation path length in the
counters to a straight line, separately for each counter and
separately for the three regions of the counters, straight,
bend, and nose.</li>
<li> <b>Time Resolution</b>. In a similar procedure he measures
the time difference between the start counter hit and the
prediction from the charged track taking account of the
propagation time as determined in the previous study. If he
restricts the fit to a single Gaussian to a region of
&plusm; one sigma, he gets an average time resolution of
214 ps. This tight restriction may give a slightly optimistic
results. We discussed various ways of getting a more fair
characteristic resolution number. We also noted that there is
a contribution to the resolution from the charged track
timing.</li>
</ul>
<h3><span class="mw-headline" id="NIM_Paper">NIM Paper</span></h3>
<p>Mark reported status as told to him by Eric Pooser prior to the
meeting.
</p>
<ul>
<li> Many plots had to be redone to get publication quality
versions. There was some significant computer file archaeology
involved, but this work is done. Eric should be done with his
parts of the paper by this week.</li>
<li> Machmoud is working on the plots on the attenuation
measurements with real data and the attendant text. Those
should be ready by the end of next week.</li>
<li> All members of the start counter working group should have
a look at the paper. It is in Eric's Github repo at <a
rel="nofollow" class="external free"
href="https://github.com/pooser/st-nim-article">https://github.com/pooser/st-nim-article</a>.
<ul>
<li> At some point we should move it to the gluex-documents
repository.</li>
</ul>
</li>
<li> We agreed to circulate a draft among collaborations members
for comments and author list corrections.</li>
</ul>
</div>
<pre class="moz-signature" cols="72">--
Mark Ito, <a class="moz-txt-link-abbreviated" href="mailto:marki@jlab.org">marki@jlab.org</a>, (757)269-5295
</pre>
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