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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,_April_21,_2016">https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_April_21,_2016</a>
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<h1 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">GlueX Start Counter Meeting, April 21, 2016</span>,
Minutes</h1>
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class="mw-headline" id="Minutes"></span>
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<p>Present:
</p>
<ul>
<li> <b>FIU</b>: Werner Boeglin</li>
<li> <b>JLab</b>: Mark Ito (chair), Simon Taylor</li>
<li> <b>NU</b>: Sean Dobbs</li>
</ul>
<h3><span class="mw-headline" id="Calibration_Update">Calibration
Update</span></h3>
<h4><span class="mw-headline"
id="Propagation_Delay_Parametrization">Propagation
Delay Parametrization</span></h4>
<p>Sean <a rel="nofollow" class="external text"
href="https://halldweb.jlab.org/talks/2016/start_counter_prop_time_corr.pdf">Propagation
Time Corrections identified an inconsistency</a> in
how the propagation time delay was parametrized between
data and Monte Carlo. The issue was fixed in <a
rel="nofollow" class="external text"
href="https://github.com/JeffersonLab/sim-recon/pull/338">Pull
Request #338</a>. From the pull request:
</p>
<ul>
<li> Make propagation time corrections be consistently
defined in terms of path length through scintillator</li>
<li> Rewrite plugins to pull expensive calculations
outside of locks</li>
<li> Other minor changes</li>
</ul>
<h4><span class="mw-headline"
id="Charged-Track.2FStart-Counter_Matching">Charged-Track/Start-Counter
Matching</span></h4>
<p>Sean did a study showing the distribution of azimuthal
angle within a single start counter sector versus z
where the azimuthal angle is determined by the
intersection of the track with the start counter and
only track/start-counter matches are considered. <a
rel="nofollow" class="external text"
href="https://halldweb.jlab.org/wiki/images/a/a1/Sc_match.pdf">Plots
were made for each of the 30 sectors</a>.
</p>
<p>There is feature in the nose sections where a bias is
seen in some counters toward higher or lower azimuth,
depending on the counter. The bias direction and
amplitude seems to be a smooth function of sector number
making geometry a likely candidate for the source of the
effect. Without correction we may have to increase the
tolerance for a match in the nose region.
</p>
<h3><span class="mw-headline" id="Pre-Amp_Strain_Relief">Pre-Amp
Strain Relief</span></h3>
<p>Although this work was done at the beginning of the
run, the photos showing the strain relief system were
never shown at this meeting. See the <a rel="nofollow"
class="external text"
href="https://halldweb.jlab.org/talks/2016/start_counter_strain_relief/">photos
and accompanying email from the designer</a> for
details.
</p>
<h3><span class="mw-headline" id="mcsmear_Parameters">mcsmear
Parameters</span></h3>
<p>We reviewed the <a
href="https://halldweb.jlab.org/wiki/index.php/Mcsmear_updates#START_COUNTER"
title="Mcsmear updates">parameters</a> again. See the
<a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_24,_2016#mcsmear_parameters"
title="GlueX Start Counter Meeting, March 24, 2016">discussion
from last time</a>.
</p>
<p>In discussing the energy resolution, we noted that we
not have a good measurement of the number of photons per
MeV and the measured resolution in real data contains
both the intrinsic energy loss fluctuations as well as
the effect of photon statistics. In Monte Carlo, these
effects are put in separately, and so must be
disentangled in the data if data is to be a guide.
</p>
<h3><span class="mw-headline" id="NIM.2FTDR">NIM/TDR</span></h3>
<p>Werner reported that Eric Pooser has started a TDR
contribution for the start counter.
</p>
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<li id="lastmod"> This page was last modified on 21 April
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<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-abbreviated" href="mailto:marki@jlab.org">marki@jlab.org</a>, (757)269-5295
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