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<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,_June_6,_2018#Minutes">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_June_6,_2018#Minutes</a></p>
<p> -- Mark</p>
<p>______________</p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">GlueX TOF Meeting, June 6, 2018, </span><span
class="mw-headline" id="Minutes">Minutes</span></h2>
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<div id="mw-content-text" dir="ltr" class="mw-content-ltr"
lang="en">
<p>Present:
</p>
<ul>
<li> <b> FSU: </b> Sasha Ostrovidov</li>
<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/Gar0v/">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_May_23_Meeting">Review
of Minutes from the May 23 Meeting</span></h3>
<p>We reviewed the <a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_23,_2018#Minutes"
title="GlueX TOF Meeting, May 23, 2018">minutes</a>
without comment.
</p>
<h3><span class="mw-headline" id="Calibration_Status">Calibration
Status</span></h3>
<p>Beni gave the report. Calibration is complete. All runs
for which Sean Dobbs produced files are done. The
constants obtained have not been written to the CCDB
yet.
</p>
<h4><span class="mw-headline"
id="Checking_stability_of_the_timing_constants">Checking
stability of the timing constants</span></h4>
<ul>
<li> The downstream plans appears less stable than the
upstream.</li>
<li> For some PMTs, isolated runs show large excursions.
These are likely due to failures in the calibration
program for these channels. These only appear in the
downstream plane and not the upstream, against naive
expectations.</li>
<li> We may have to revisit calibrations for selected
channels.</li>
</ul>
<h4><span class="mw-headline"
id="Variations_in_the_signal_amplitude">Variations in
the signal amplitude</span></h4>
<p>Beni showed plots of signal amplitude versus run number
for two of the PMTs.
</p>
<p><a
href="https://halldweb.jlab.org/wiki/index.php/File:Pmt19_amplitude.gif"
class="image"><img alt="Pmt19 amplitude.gif"
src="https://halldweb.jlab.org/wiki/images/c/c3/Pmt19_amplitude.gif"
width="567" height="387"></a>
</p>
<p>PMT 19 is in near the beam line in the downstream
plane. Note that the gain seems to have dropped 12-15%
over the course of the run.
</p>
<p><a
href="https://halldweb.jlab.org/wiki/index.php/File:Adc_mpv_pmt110_new1.gif"
class="image"><img alt="Adc mpv pmt110 new1.gif"
src="https://halldweb.jlab.org/wiki/images/3/36/Adc_mpv_pmt110_new1.gif"
width="569" height="385"></a>
</p>
<p>PMT 110 is also near the beam line in the upstream
plane. Note the rise in gain around run 41900. Beni sees
extra noise in the HV voltage read-back around this
time, but the cause of the rise is still under
investigation.
</p>
<h3><span class="mw-headline" id="TOF_Upgrade">TOF Upgrade</span></h3>
<p>Sasha reported that Paul Eugenio has the FSU shop
working on a mock up the the central region of a newly
configured TOF. In particular they are trying ideas for
how the light guides for the half-width paddles should
be shaped.
</p>
<p>Also, in July, Paul is planning on coming up to the
Lab. He wants to paint the ends of half-length paddles
black so that there is little contribution from light
reflected from the beam-adjacent face of the counters.</p>
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<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
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