<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<p>People,</p>
<p>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,_December_1,_2016">https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_1,_2016</a>
. Mahmoud have a very nice presentation on start counter
efficiency.<br>
</p>
<p> -- Mark<br>
</p>
___________________________<br>
<br>
<div id="globalWrapper">
<div id="column-content">
<div id="content" class="mw-body" role="main">
<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">GlueX Start Counter Meeting, December 1, 2016,
</span><span class="mw-headline" id="Minutes">Minutes</span></h2>
<div id="bodyContent" class="mw-body-content">
<div id="mw-content-text" dir="ltr" class="mw-content-ltr"
lang="en">
<p>Present:
</p>
<ul>
<li> <b>FIU</b>: Werner Boeglin, Mahmoud Kamel</li>
<li> <b>JLab</b>: Thomas Britton, Eugene Chudakov, Mark
Ito (chair), Simon Taylor</li>
</ul>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/ppuDa/">recording of
this meeting</a> on the BlueJeans site.
</p>
<h3><span class="mw-headline" id="Efficiency_Study">Efficiency
Study</span></h3>
<p>Mahmoud presented <a rel="nofollow" class="external
text"
href="https://halldweb.jlab.org/talks/2016/SC_meeting_Dec1st_2016.pdf">an
updated efficiency study</a>. He started from raw data
for these results. Please see his slides for the
details. Cuts are described and counter-by-counter
efficiencies are shown. He tried various timing cuts and
also considered two cases: one where a single sector,
identified by a charged track, was interrogated for a
start counter hit and another where both nearest
neighbors were also considered. He also compared results
with Monte Carlo, using the sim1.1 sample.
</p>
<p>Two general conclusions:
</p>
<ol>
<li> Start counter efficiency is generally above 95% in
all regions of the counters.</li>
<li> Efficiency is the same, within 1%, in Monte Carlo
data.</li>
</ol>
<p>Some items from the discussion:
</p>
<ul>
<li> Not clear why the time distribution of time
difference between the start counter and track time[?]
is so wide, ten ns or so full width.</li>
<li> Werner wondered if we could generate simulated data
with various perturbations to the geometry to see if
we can reproduce some of the non-uniformities in
efficiency from counter to counter.</li>
<li> Another interesting study would be to require a
start counter hit in a particular counter and look at
the charged particle azimuthal distribution at the
start counter, repeated for all counters and at
various z-positions. This should give a survey of the
counter edges and help us refine knowledge of the
as-found geometry.</li>
</ul>
</div>
</div>
</div>
</div>
</div>
</body>
</html>