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<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,_November_3,_2021#Minutes">here</a>
and below.</p>
<p> -- Mark</p>
<p> _________________________________</p>
<p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span dir="auto">GlueX TOF Meeting, November 3, 2021, </span><span class="mw-headline" id="Minutes">Minutes</span></h2>
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<p>Present: Edmundo Barriga, Eugene Chudakov, Mark Ito
(chair), Sasha Ostrovidov, Simon Taylor, Beni Zihlmann
</p>
<p>There is a <a rel="nofollow" class="external text" href="https://bluejeans.com/s/jWw4CuOUZxl/">recording
of this meeting</a>. Log into the <a rel="nofollow" class="external text" href="https://jlab.bluejeans.com">BlueJeans site</a>
first to gain access (use your JLab credentials).
</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 went over the <a href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_October_6,_2021#Minutes" title="GlueX TOF Meeting, October 6, 2021">minutes
from the meeting on October 6th</a>.
</p>
<h4><span class="mw-headline" id="Occupancy_Plots">Occupancy
Plots</span></h4>
<p>Beni remarked on the changes in the monitoring plots
for the current run after the magnetic field was turned
on.
</p>
<p><b>Before: run 81347</b>
</p>
<p><a href="https://halldweb.jlab.org/wiki/index.php/File:TOF_occupancy_before.png" class="image"><img alt="TOF occupancy before.png" src="https://halldweb.jlab.org/wiki/images/0/05/TOF_occupancy_before.png" width="696" height="472"></a>
</p>
<p><b>After: run 81696</b>
</p>
<p><a href="https://halldweb.jlab.org/wiki/index.php/File:TOF_occupancy_after.png" class="image"><img alt="TOF occupancy after.png" src="https://halldweb.jlab.org/wiki/images/1/17/TOF_occupancy_after.png" width="696" height="472"></a>
</p>
<p>The "before" plots are much more symmetric, left-right,
up-down, and front-layer-back-layer. Beni remember that
this effect is also seen in the distribution of charged
tracks around the beam line.
</p>
<p>We could not recall exactly when the acrylic shield for
the inner TOF was removed; that may have had an effect.
Eugene mentioned that high TOF rate near the beamline
may have an effect on the current η reconstruction
efficiency since the TOF is used as a veto for photons.
Here the acrylic shield may help. Beni also noted that
there is a big rate difference in the TOF depending on
whether the target is full or empty.
</p>
<p>Beni is planning a study of the observed asymmetries
using scalar records from the EPICS Archiver.
</p>
<h4><span class="mw-headline" id="Calibration">Calibration</span></h4>
<p>Beni reported that the TOF gains have dropped a bit
during the course of the current run.
</p>
<p>He is going to get back in touch with Jackson Pybus.
The TOF calibration has been streamlined to make it
easier to hand off.
</p>
<h3><span class="mw-headline" id="TOF_II_Trigger">TOF II
Trigger</span></h3>
<p>Mark and Beni reported on the discussion at the CPP
Meeting earlier today. Ilya has a plan for the test, but
we have run out of time to execute it during the PrimEx
run. The CPP group will try to get a short period of
time for a test during SRC. Beni pointed out that since
there is a lot of set-up to do, trigger-wise, for SRC,
that the new TOF firmware might be made part of the
plan, at least for very high-level tests (basic
operation, i.e., no crashes).
</p>
<h3><span class="mw-headline" id="Beam_Angle_Measurement_during_SRC">Beam Angle
Measurement during SRC</span></h3>
<p>Beni suggested that during the period where SRC is
running with a series of thin carbon targets (8 of them,
2 mm thick each, equally spaced in z, spanning 21 cm in
z) we might be able to reconstruct vertices and measure
the beam angle, using a series of x-y measurements at
several z-positions.
</p>
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