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<p>Folks,</p>
<p>Find the minutes below and at
<a class="moz-txt-link-freetext" href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_September_20,_2016">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_September_20,_2016</a></p>
<p> -- Mark<br>
</p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">GlueX TOF Meeting, September 20, 2016, </span><span
class="mw-headline" id="Minutes">Minutes</span></h2>
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<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, Beni Zihlmann</li>
</ul>
<h3><span class="mw-headline" id="Announcement">Announcement</span></h3>
<p>The PMT order for 30 tubes is due in October 27. There
is no immediate plan to replace tubes; these are spares.
</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 looked at the <a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_September_6,_2016#Minutes"
title="GlueX TOF Meeting, September 6, 2016">minutes
from September 6</a>.
</p>
<ul>
<li> <b>TDC time windows</b>. We mentioned last time
that these need to be tightened up. Beni will tune the
parameters once we have beam triggers.</li>
<li> <b>New PMT bases with amplification</b>. Mark paid
a visit to Vladimir Popov to to discuss the
possibility of using his design for the TOF. He was
optimistic that it could be done. One concern of ours
is the AC-coupled output. He says this is an essential
feature of the design, but he thought that it should
not be much of a problem even at our rates and that
there may be other ameliorations to get around it. We
need to meet with him to discuss the idea further.</li>
</ul>
<h3><span class="mw-headline"
id="High_Voltage_Scan_Preparations">High Voltage Scan
Preparations</span></h3>
<p>Beni had been working with Brad. They are transferring
Beni's software and Brad is trying to reproduce the
voltage settings that Beni finds. There are differences
of 20 V with a spread of 20 V (Brad - Beni). He has also
noticed differences in the fit parameters from the fit
to gain vs. voltage. They are working to understand the
differences.
</p>
<p>Beni reminded us that we owe the Run Coordinator a
one-pager describing the program we want to conduct
during the run.
</p>
<h3><span class="mw-headline"
id="Measuring_Difference_Rate_Between_Upstream_and_Downstream_Plane">Measuring
Difference Rate Between Upstream and Downstream Plane</span></h3>
<p>Sasha has been looking for situations where the
upstream plane is hit, but there is no corresponding hit
in the downstream. He wants to look at how much we can
reduce rate by putting up some plastic around the
beamline. He is having a low yield of hits where he gets
a four-fold coincidence: both ends, ADC and TDC. These
are the objects that come out of the hit factory. He is
exploring how to overcome the lack of statistics.
</p>
<h3><span class="mw-headline"
id="Non-Linear_Calibration_for_the_CAEN_TDCs">Non-Linear
Calibration for the CAEN TDCs</span></h3>
<p>Beni has succeeded in measuring the correction curve
for the CAEN TDCs using a self trigger on the TOF. He
can calibrate all channels in a few hours. He has not
seen perfect reproducibility of the constants; there can
be variation of a bin or two.
</p>
<p>There was a discussion of whether we want to download
the corrections to the TDCs or whether to turn off the
on-board correction and do all corrections offline,
using the calibration database. We have decided that an
on-board correction would be much preferable, giving
equivalent, improved resolution without having to keep
track of boards and channels as a function of time. Ed
is exploring whether this can be done; he needs
instructions from the factory.
</p>
<p>The correction cannot be read back to check it. On the
other hand, we can re-do the calibration with the
corrections loaded and check that the resulting spectrum
is linear.
</p>
<p>Paul pointed out that we should make sure Hall B is
aware of this issue.
</p>
<h3><span class="mw-headline" id="NIM_Paper">NIM Paper</span></h3>
<p>Paul is working on it.
</p>
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<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-abbreviated" href="mailto:marki@jlab.org">marki@jlab.org</a>, (757)269-5295
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