<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>Folks,</p>
<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_TOF_Meeting,_January_31,_2018#Minutes">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_January_31,_2018#Minutes</a></p>
<p> -- Mark</p>
<p>__________________________________________</p>
<p>
</p>
<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 TOF Meeting, January 31, 2018, </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>JLab</b>: Mark Ito (chair), Simon Taylor, Beni
Zihlmann</li>
</ul>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/ITFps/">recording of
this meeting</a> on the BlueJeans site. Use your JLab
credentials.
</p>
<h3><span class="mw-headline"
id="Review_of_minutes_from_the_previous_meeting">Review
of minutes from the previous meeting</span></h3>
<p>We went over the <a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_January_3,_2018#Minutes"
title="GlueX TOF Meeting, January 3, 2018">minutes
from the meeting on January 3</a> without significant
comment.
</p>
<h3><span class="mw-headline" id="Calibration_Status">Calibration
Status</span></h3>
<ul>
<li> Beni performed a step-by-step calibration of recent
data using run 40460, interactively on the ifarm.
Comparison with previous constants show only small
differences. Only a few channels show significant
differences (50 to 100 ps). He characterized the
agreement as "amazing". The database has not yet been
updated with these constants.</li>
<li> Beni took the Spring 2017 constants for ADC vs. TDC
time difference (channel-by-channel) and used them as
the constants for recent running in the CCDB. Sean
reported significant improvement in timing results.
The relevant monitoring plots look good now.</li>
<li> Beni spoke to Ashley Ernst about her taking
responsibility for the TOF calibration.</li>
</ul>
<h3><span class="mw-headline"
id="Low_Efficiency_in_High-Rate_Counters">Low
Efficiency in High-Rate Counters</span></h3>
<p>Beni first did the analysis that showed this problem.
There were no updates at this meeting.
</p>
<h3><span class="mw-headline"
id="Amplified_Base_Prototype">Amplified Base Prototype</span></h3>
<p>Beni has started to look at data taken recently with
the test counter in the Hall. One end has a standard
PMT, the other has a PMT with an amplifier in the base,
designed and built by Vladimir Popov.
</p>
<ul>
<li> He looked at TDC times vs. ADC times to get time
walk corrections for these two new channels.</li>
<li> After walk correction, the t<sub>TDC</sub>-t<sub>ADC</sub>
distribution of the amplified end looks better than
that of the un-amplified end, the former with an RMS
of 160 ps vs. 300 ps for the latter. Beni suspects
that the HV is lower than optimal on the un-amplified
end.</li>
<li> He plotted the time difference in the test counter
vs. the time difference of a standard counter in the
TOF (paddle 14, plane 0). These counters are in
orthogonal orientations. There is a clear blob where
coincidences appear. The RMS spread of the blob is
worse for the test counter (220 ps) than for the
standard counter (220 ps).</li>
<li> These results are preliminary. Beni has more to go
on his first set of analysis ideas.</li>
</ul>
<p>Overall the on-base amplifier seems to performing
reasonably well. We await further results.
</p>
<br>
</div>
</div>
</div>
</div>
</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>
</body>
</html>