<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 <a moz-do-not-send="true"
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_8,_2019#Minutes">here</a>
and below.</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">Minutes, GlueX TOF Meeting, May 8, 2019</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> FSU: </b> Paul Eugenio, Sasha Ostrovidov</li>
<li> <b> JLab: </b> Thomas Britton, Ashley Ernst, Mark
Ito (chair), Simon Taylor, Tim Whitlatch, Beni
Zihlmann</li>
</ul>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/K8rxT/">recording of
this meeting</a> on the BlueJeans site. Use your JLab
credentials to access it.
</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 looked at <a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_April_24,_2019#Minutes"
title="GlueX TOF Meeting, April 24, 2019">the minutes
from the meeting on April 24</a>. Mark did end up
buying the mill bit and the scintillator modules as per
Paul's specs.
</p>
<h3><span class="mw-headline" id="Upgrade_Reports">Upgrade
Reports</span></h3>
<ul>
<li> Paul reported that the scintillator order was
received by Eljen. Delivery to FSU is expected May 31.</li>
<li> More light guide material will be needed. There is
another run planned at the factory this month. Paul is
reluctant to try a different manufacturer since the
material from this one has been problem-free.</li>
<li> Beni has had a second look at the electronics
situation. We seem to be OK. Fernando Barbosa is aware
of what we will need.</li>
<li> Tim reported that the technical staff is all ready
to go on the job of unmounting the TOF and laying it
horizontal in the Hall. Work can start as soon as the
current tasks on the DIRC have been completed.</li>
<li> Paul will send photos of the arrays during the
initial installation. He would like it if the
orientation could be the same as it was last time.</li>
</ul>
<h3><span class="mw-headline" id="Air_Light_Guides">Air
Light Guides</span></h3>
<p>Sasha has been testing joining the half-length counters
optically across the beam hole region with an air
channel; essentially extending the ESR/Tedlar wrapping
across the gap. He has been using the half-length
counters from the mini-TOF at FSU. Looking at scaled
coincidence rates of cosmics using an end-to-end
coincidence of a full-length counter as trigger, he sees
the following probabilities of seeing a signal in one
half-length counter when the other one fires:
</p>
<table border="border">
<tbody>
<tr>
<th> HV (V) </th>
<th> Hit Probability (%)
</th>
</tr>
<tr>
<td> 1200 </td>
<td> 3
</td>
</tr>
<tr>
<td> 1300 </td>
<td> 18
</td>
</tr>
<tr>
<td> 1400 </td>
<td> 60
</td>
</tr>
</tbody>
</table>
<p>However if an additional scintillator is added to the
coincidence to insure a cosmic hit near the air light
guide (within 6 cm), the other-counter-hit-probability
increases to 90% at 1400 V.
</p>
<p>Sasha is repeating the study with a full data
acquisition system.
</p>
<p>Beni suggested some stiffening material for the walls
of the light guide (low mass, e. g., cardboard).
</p>
<p>There was some discussion of support for the ends of
the counters around the beam hole. This would be
complicated by the presence of air light guides.
</p>
<h3><span class="mw-headline" id="Geometry">Geometry</span></h3>
<p>Ashley pointed out that we will need to modify the
geometry of the TOF for the upgraded configuration. She
will look into how much work is involved in that.
</p>
<h3><span class="mw-headline" id="Collaboration_Meeting">Collaboration
Meeting</span></h3>
<p>Paul will give a report at next week's collaboration
meeting on the status of the upgrade.
</p>
<h3><span class="mw-headline" id="Calibration">Calibration</span></h3>
<p>Beni has started calibrating the Spring 2019 data.
Results are hard to check because of the absence of
tracking. Simon pointed out that the FDC was on for a
few runs; perhaps those runs can be examined.
</p>
</div>
<div class="printfooter">
Retrieved from "<a dir="ltr"
href="https://halldweb.jlab.org/wiki/index.php?title=GlueX_TOF_Meeting,_May_8,_2019&oldid=92559">https://halldweb.jlab.org/wiki/index.php?title=GlueX_TOF_Meeting,_May_8,_2019&oldid=92559</a>"</div>
</div>
</div>
</div>
<div id="footer" role="contentinfo">
<ul id="f-list">
<li id="lastmod"> This page was last modified on 8 May 2019,
at 13:47.</li>
</ul>
</div>
</div>
</body>
</html>