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Folks,<br>
<br>
Find the meeting minutes reproduced below and at<br>
<br>
<a class="moz-txt-link-freetext" href="http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2767">http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2767</a>
.<br>
<br>
-- Mark<br>
___________________________________<br>
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<span dir="auto">GlueX TOF Meeting, July 14, 2015</span><span
class="mw-headline" id="Minutes">, Minutes</span><br>
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lang="en">
<br>
Present:
<br>
<ul>
<li> <b>FSU</b>: Paul Eugenio, Sasha Ostrovidov,
Aristeidis Tsaris</li>
<li> <b>JLab</b>: Mark Ito (chair), Simon Taylor, Beni
Zihlmann</li>
<li> <b>NU</b>: Sean Dobbs</li>
</ul>
<br>
<span class="mw-headline" id="Announcements">Announcements</span><br>
<ul>
<li> DAQ crates for the TOF have not been turned on in
the Hall yet.</li>
</ul>
<br>
<span class="mw-headline" id="Calibration_GlueX_Note">Calibration
GlueX Note</span><br>
<br>
We took a brief look at <a rel="nofollow" class="external
text"
href="http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2767">Beni's
note</a>. In addition to producing the document Beni add
comments to the code and rationalized some variable names.
He also found an off-by-one bug in the paddle numbering
and fixed it.
<br>
The last page shows a histogram of the time difference of
mean times between the front and back planes, summed over
all channels. The fit gives an RMS of 136 ps corresponding
to 96 ps resolution in mean time per plane. This compares
well to the TDR design goal of 90 to 95 ps.
<br>
ADC information is not covered in this note.
<br>
With the release of this note, Mark thought that it would
be much easier to involve a student in the calibration
process with the note serving as a road map. This would
help us get a running start on new data from future runs.
Paul will look into possible candidates.
<br>
Paul asked about the location of the code. It is in Beni's
private area (home/zihlmann) of the Subversion repository.
This started a discussion of a standard home for
calibration programs. Such a convention would also need to
accommodate scripts, ROOT macros, etc. Sean mentioned that
we will discuss this issue at tomorrow's Calibration
Meeting.
<br>
<br>
<span class="mw-headline" id="Calibration.2C_FSU">Calibration,
FSU</span><br>
<br>
Sasha reported on an alternate method for using cable
reflections to extract time-walk corrections. In mode 8,
the waveform data can be used to measure timing between
the two pulses. He has identified a problem: the
reflection is only clearly visible for large pulses and so
is sitting on the tail of the main pulse. This shifts the
effective threshold in the TDC in a way independent of
time-walk. He is working on way to overcome this
difficulty.
<br>
<br>
<span class="mw-headline" id="Areas_for_Future_Work">Areas
for Future Work</span><br>
<br>
Sean asked about the next steps now that we have an
initial timing calibration. Beni told us that there was no
more low hanging fruit in the time calibration. There are
things like better functional forms for the timing fits
that could be improved but are not likely to yield
significantly better resolution.
<br>
The ADC calibration is still in progress; it remains on
the list of things to do. For example, there are
mysterious shifts in the position of the minimum ionizing
peak as a function of position along the paddle after
accounting for attenuation. Beni plans to return to it at
some point.
<br>
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<h3><span class="mw-headline" id="CAEN_TDC_Calibration">CAEN
TDC Calibration</span></h3>
<p>Sasha asked about the status of the calibration needed
to equalize the size of the bins in the CAEN TDCs. Beni
summarized:
</p>
<ul>
<li> Bryan Moffit has produced a library so that these
constants can be downloaded.</li>
<li> Currently there are no constants (zeros) in the
CAEN.</li>
<li> To start with we will write the values recommended
by CAEN.</li>
<li> We need to ask Bryan if the code has a capability
for read-back of constants.</li>
</ul>
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