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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,_February_21,_2017">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_February_21,_2017</a>
.</p>
<p> -- Mark</p>
<p>_______________</p>
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<h2 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="Minutes">Minutes</span></h2>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Present:</p>
<ul style="list-style-type: square;">
<li><b>FSU</b>: Paul Eugenio</li>
<li><b>JLab</b>: Thomas Britton, Mark Ito (chair), Sasha
Ostrovidov, Simon Taylor, Beni Zihlmann</li>
</ul>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">There is a<span
class="Apple-converted-space"> </span><a rel="nofollow"
class="external text"
href="https://bluejeans.com/s/eD_ST/" style="color:
inherit !important; background: transparent; padding:
0px !important; text-decoration: inherit !important;">recording
of this meeting</a><span class="Apple-converted-space"> </span>on
the BlueJeans site. Use your JLab credentials.</p>
<h3 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="Announcements">Announcements</span></h3>
<ul style="list-style-type: square;">
<li><b>Lucite Shield Simulation</b>. Thomas has had a
possible issue with his environment. He is rerunning the
simulation now.</li>
</ul>
<h3 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline"
id="Review_of_minutes_from_the_previous_meeting">Review
of minutes from the previous meeting</span></h3>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">We went over the<span
class="Apple-converted-space"> </span><a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_February_7,_2017#Minutes"
title="GlueX TOF Meeting, February 7, 2017"
style="color: rgb(85, 34, 0); background: transparent;
padding: 0px !important; text-decoration: underline;">minutes
from February 7</a>. There were no significant comments.</p>
<h3 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="Run_Status">Run Status</span></h3>
<ul style="list-style-type: square;">
<li>Sasha is the run coordinator until tomorrow.</li>
<li>He reported the the occupancy plots look good, one set
of scalars [ADCs?] for the TOF is missing in EPICS.</li>
<li>Even with the Lucite shield, the upstream plane shows
a higher scalar rate than the downstream, by 50%. It
will be interesting what the Monte Carlo has to say
about this.</li>
</ul>
<h3 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="Calibration">Calibration</span></h3>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Beni reported that the timing
calibrations are being re-run now for all runs.</p>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Also we need to get started on
comparisons of efficiency and resolution between data and
Monte Carlo. Simon has been working on improving the
matching between charged tracks and the TOF.</p>
<h3 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="New_PMT_bases">New PMT bases</span></h3>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Beni presented results from<span
class="Apple-converted-space"> </span><a
href="https://halldweb.jlab.org/wiki/index.php/PMT_rate_tests"
title="PMT rate tests" style="color: rgb(85, 34, 0);
background: transparent; padding: 0px !important;
text-decoration: underline;">tests with the new base</a><span
class="Apple-converted-space"> </span>with on-board
amplifier from Vladimir Popov. (See his wiki page for
details and plots.)</p>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">He did the tests with a standard PMT
and one with a modified base. He reproduced the collapse
of pulse height for the standard base at 1300 V and a rate
of 10 MHz from the laser. The amplitude was adjusted to be
that of a minimum ionizing TOF hit. The modified base went
to 10 MHz with signal collapse but only after the voltage
on the tube was reduced to 1000 V. Under those conditions
a 18 mV DC offset appears on the baseline. We need to ask
Vladimir about the inductive coupling scheme he proposed
at one point.</p>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Vladimir suggested a test in the
Hall. We discussed options. Beni suggested shipping a
half-width counter from the mini-TOF from FSU to JLab and
mounting it in the Hall, location to be determined. In
front of the TOF? Behind the FCAL? Paul thought that we
could get it here with a week's notice so doing it this
run seemed not impossible. We will have to talk to Tim
Whitlatch and Tom Carstens about the feasibility of
mounting and possible locations.</p>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">We would also like to know if the PMT
gains have remained stable during the current run with the
new reduced voltages.</p>
<h3 style="break-after: avoid; font-weight: bold;"><span
class="mw-headline" id="PMT_Replacement">PMT Replacement</span></h3>
<p style="widows: 3; orphans: 3; margin: 1em 0px;
line-height: 1.2em;">Several comments were made and
questions asked.</p>
<ul style="list-style-type: square;">
<li>Can amplifiers be added to the bases in situ, i. e.,
without dismounting the planes from the FCAL carriage?</li>
<li>Can the gain loss suffered by the inner PMTs be
compensated by running them at higher voltage?</li>
<li>Has the performance of the PMTs deteriorated during
the current run now that they are being run at lower
voltage?</li>
<li>Which PMTs do we want to replace?</li>
<li>Do we need to build more gluing fixtures to facilitate
PMT replacement?</li>
<li>What are the schedule constraints for producing the
amplifier electronics?</li>
</ul>
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