<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
</head>
<body bgcolor="#FFFFFF" text="#000000">
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_5,_2015">https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_5,_2015</a><br>
<br>
-- Mark<br>
___________________________________________________________<br>
<br>
<div id="globalWrapper">
<div id="column-content">
<div id="content" class="mw-body" role="main"> <br>
<span dir="auto">GlueX TOF Meeting, May 5, 2015</span><span
class="mw-headline" id="Minutes">, Minutes</span><br>
<div id="bodyContent" class="mw-body-content">
<div id="mw-content-text" dir="ltr" class="mw-content-ltr"
lang="en">
<br>
Present:
<br>
<ul>
<li> <b>FSU</b>: Hussein Al Ghoul, 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>
<br>
The run is over, but all detector systems are turned on in
the Hall. Beni reports that last night cosmic data was
taken. Further data taking is not anticipated, but a
decision to turn everything off has not been made either.
<br>
<br>
<span class="mw-headline" id="Calibration">Calibration</span><br>
<br>
<span class="mw-headline" id="Structure_of_Constants">Structure
of Constants</span><br>
<br>
Simon gave an overview of the current calibration scheme.
Mike Staib has put channel-by-channel constants into the
TOF/timing_offsets table. These equalize the times between
TDCs and ADCs for each channel. We would like to put
TDC-derived constants into this table. The TDC-ADC time
offsets will appear in the TOF/adc_timing_offsets table.
Mike scheme will calculate a global offset between the TOF
and the rest of the detectors. This scheme should be
independent of whether we use the JLab-style constants or
the FSU-style constants for timing_offsets.
<br>
<br>
The next step for implementation is to talk to Mike and
get his buy-in on the plan. Simon will do that.
<br>
<br>
<span class="mw-headline" id="FSU_Status">FSU Status</span><br>
<br>
Sasha continues work on the timing constants for the
Spring 15 data. Recall that the fitting scheme suffered
from a large level of background hits. He is now trying to
isolate good hits by requiring a match with a charged
track. The background situation improves, but does not go
away. He is also experimenting with timing cuts to purify
his sample.
<br>
<br>
<span class="mw-headline" id="JLab_Status">JLab Status</span><br>
<br>
Beni has started looking at timing calibrations constants
for the single-ended counters. He uses events that have
coincidences between the counter of interest and the
common reference counter in the other plane.
<br>
He has also started looking a the energy calibration. He
is selecting events where the hit is near the center of
the counter judging from end-to-end timing (he is using
±0.5 ns for now). He plans to do this for several
regions of each counter, not just the center. <br>
Mark mentioned a scheme where the geometric mean of the
energy is used for each counter. That yields a quantity
that is roughly independent of position for each counter
and may give higher statistics by allowing inclusion of
all double-ended hits.
<br>
<br>
<span class="mw-headline" id="Time_Bin_Calibration">Time
Bin Calibration</span><br>
<br>
We discussed the idea of doing a time bin calibration on
the CAEN TDCs. The goal is to equalize the size of the
time bins associated with the four TDC devices used in
each read-out channel of the device. Bryan Moffit has
recently given us new driver software that will allow us
to make the adjustment. Sasha did the calibration for the
TDC at FSU. Beni has already looked at the variation in
bin width for a few channels, he sees variation of 5 to
10%, consistent with what Sasha has seen at FSU. We did
not make a detailed plan, but agreed to discuss the issue
at future meetings.
<br>
<br>
</div>
<div class="printfooter">
Retrieved from "<a dir="ltr"
href="https://halldweb.jlab.org/wiki/index.php?title=GlueX_TOF_Meeting,_May_5,_2015&oldid=66724">https://halldweb.jlab.org/wiki/index.php?title=GlueX_TOF_Meeting,_May_5,_2015&oldid=66724</a>"</div>
</div>
</div>
</div>
</div>
<br>
</body>
</html>