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Folks,<br>
<br>
Please find the minutes below and at <br>
<br>
<a class="moz-txt-link-freetext" href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_19,_2015">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_19,_2015</a><br>
<br>
-- Mark<br>
___________________________________<br>
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<span dir="auto">GlueX TOF Meeting, May 19, 2015</span><br>
<div id="bodyContent" class="mw-body-content"><span
class="mw-headline" id="Minutes">Minutes</span><br>
<div id="mw-content-text" dir="ltr" class="mw-content-ltr"
lang="en">
<br>
Present:
<br>
<ul>
<li> <b>FSU</b>: Hussein Al Ghoul, Brad Cannon, Paul
Eugenio, Sasha Ostrovidov, Aristeidis Tsaris</li>
<li> <b>JLab</b>: Mark Ito (chair), Simon Taylor, Beni
Zihlmann</li>
</ul>
<br>
<span class="mw-headline" id="Announcements">Announcements</span><br>
<ul>
<li> Mark spoke to Sergey Boyarinov of Hall B. Turns out
they did not do the bin-equalizing calibration on
their CAEN TDCs. Beni reminded us that Bryan Moffit
has released the library functions we need to do the
calibration. We decided that it is worth doing for
Hall D and the group will form a plan for doing it
before the next run. Beni suggested that we talk to
Sergey Furletov and see if we can get him to help
since the code will have to be maintained by the
online group in any case. As a first step Beni
suggested downloading the values recommended by CAEN.</li>
</ul>
<br>
<span class="mw-headline"
id="Review_of_minutes_from_May_5">Review of minutes from
May 5</span><br>
<br>
We went over <a
href="https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_5,_2015#Minutes"
title="GlueX TOF Meeting, May 5, 2015">the minutes</a>.
<br>
<br>
Mike Staib is on board with the re-arrangement of the
meaning of the timing calibration constants that we
discussed last time. This clears the way for using our
constants for the channel-to-channel time offsets.
<br>
<br>
<span class="mw-headline" id="Calibration_Status_FSU">Calibration
Status FSU</span><br>
<br>
Sasha has been looking at recent data with multiple hits
per channel in both the FADCs and the TDCs. The second hit
is often a cable reflection. For these events, he is
exploring doing a time-walk correction by comparing the
time difference measured by the ADCs and comparing it to
the TDCs. When the second pulse is small reflection, the
effect of time walk should be much greater for the second
TDC hit.
<br>
<br>
<span class="mw-headline" id="Calibration_Status_JLab">Calibration
Status JLab</span><br>
<br>
Beni led us through recent work documented on <a
href="https://halldweb.jlab.org/wiki/index.php/ADC_data#ADC_data"
title="ADC data">his wiki page</a>. See the page for
details.
<br>
<ul>
<li> He sees the expected correlation between positions
determined by end-to-end time difference in the TDCs
and positions determined by the ratio of ADC
amplitudes from the two ends of a counter.</li>
<li> After at time difference cut to select hits near
the center of a counter, he sees clear Landau
distributions in the energy deposition.</li>
<li> Added in press: he is also able to extract
attenuation lengths from each counter. These show a
long-range and short-range component in the relation
of amplitude vs. distance from the PMT.</li>
</ul>
<br>
All of the these observation can serve as a basis for gain
calibration and for future gain adjustments via
high-voltage changes.
<br>
<br>
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