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<p>Folks,</p>
<p>Please find the minutes below and at
<a class="moz-txt-link-freetext" href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_December_13,_2016#Minutes">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_December_13,_2016#Minutes</a>
.<br>
</p>
-- Mark<br>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">GlueX TOF Meeting, December 13, 2016, </span><span
class="mw-headline" id="Minutes">Minutes</span></h2>
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lang="en">
<p>Present:
</p>
<ul>
<li> <b>FSU</b>: Sasha Ostrovidov</li>
<li> <b>JLab</b>: Thomas Britton, Brad Cannon, Paul
Eugenio, Mark Ito (chair), Simon Taylor</li>
</ul>
<h3><span class="mw-headline" id="Announcement">Announcement</span></h3>
<p>Beam is due in the Hall this afternoon. Shifts start
today at 16:00.
</p>
<h3><span class="mw-headline" id="Lucite_Shield">Lucite
Shield</span></h3>
<p>Paul has updated the <a rel="nofollow" class="external
text" href="https://logbooks.jlab.org/entry/3437900">run
plan</a> in the logbook. We will need to talk to
Alexandre Deur to incorporate it into the larger
schedule.
</p>
<h3><span class="mw-headline" id="PMT_Testing">PMT Testing</span></h3>
<p>Paul showed <a rel="nofollow" class="external text"
href="http://hadron.physics.fsu.edu/wiki/index.php/Photomultiplier_tubes">a
page listing the steps used at FSU</a> to qualify the
original order for PMTs for the Time-of-Flight. They
are:
</p>
<ul>
<li> Preliminary assessment of the signal shape with a
scope</li>
<li> Single photo-electron gain measurement</li>
<li> Americium source anode sensitivity measurement</li>
<li> NaI crystal quantum efficiency assessment</li>
</ul>
<p>The plan is for Paul to drive back to Tallahassee with
the new PMTs for testing. Mark will have to prepare the
paperwork for this.
</p>
<h3><span class="mw-headline"
id="PMT_bases_with_Amplifiers">PMT bases with
Amplifiers</span></h3>
<p>Mark reported on progress Beni has been making.
</p>
<ul>
<li> He has given specs to Vladimir Popov.</li>
<li> He measured time resolution of the new tubes with a
laser as the light source and a scope using its
built-in data acquisition functions. He sees a
significant degradation in timing resolution when the
tube is run at a lowered voltage, from about 50 ps RMS
at 1550 V to a few hundred ps at 1250 V.</li>
<li> If an external amplifier is used the resolution
recovers to about 50 ps, RMS.</li>
<li> He is preparing to do tests with different
proportions of voltage drops from the voltage divider.</li>
</ul>
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