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<h1 class="firstHeading">Minutes of Aug 13 2009</h1>
<h3 id="siteSub">From EG3Wiki</h3>
<p>Present: Hovanes, Kijun </p>
<p>On the phone: Ralph, Zhiwen, Lewis, Haiyun </p>
<p>Notes by Hovanes.
</p>
<p><br>
</p>
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<a></a>
<h2> Normalization studies </h2>
<dl>
<dd> Lewis started the meeting by a report on the status of the
normalization studies.
<ul>
<li> He showed us the y-projections of the plots for the
normlaized
yields versus the run number for trigger bit 5 and trigger bit 6
separately. </li>
<li> Hovanes suggested that these plots show that there is
trigger inefficiency for trigger bit 6 even even for when the start
counter is not put in coincidence with MOR since the average rates
before Christmas for trigger bit 6 are lower. In Hovanes' plots this
was not present, probably because Hovanes was looking at non-exclusive
events. </li>
<li> Kijun pointed out that there are points present in the
y-projection plots, which are clearly absent from the run-dependent
histograms. Lewis said that he still needs to take these points out
from the y-projection histograms, they were not generated directly from
the 2D histograms shown on the same page.
</li>
</ul>
</dd>
</dl>
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<h2> Tagger timing studies </h2>
<dl>
<dd> Haiyun showed his findings on the timing of the tagger
T-counters.
</dd>
</dl>
<dl>
<dd>
<ul>
<li> The plots of the photon times in the tagger T-counters
#9 and #11 have peaks at negative times. Haiyun suspects that this may
be the cause of the double peaking he saw previously, and might be a
source of inefficiency.
</li>
<li> The counter number there is the number of the physical
counter, not the logical number in the software. Haiyun interpreted the
two sequential numbers in TAGR->T_id as left and right PMTs of the
same physical counter. Hovanes suggested that it is very unlikely to be
correct. Instead, the two sequential numbers are just two different
geometrical parts of the same physical counter.
</li>
<li> Hovanes also pointed out that the negative times in the
quantity plotted, which is the time of the photon at the center of the
target with respect to the time the event trigger happened, does not
necessarily mean that there will be double peaking in the time
difference between the tagger time and start time determined from the
TOF. The TAGR-TOF time difference is the quantity the cuts in physics
analysis are applied to select desired events. But it was unclear to
the participants why there would be a "trigger time" jitter depending
on which part of the tagger T-counter the hit occurred and which other
T-counter there was an overlap with. </li>
<li> Haiyun will continue to investigate this issue.
</li>
</ul>
</dd>
</dl>
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