<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""></div><div class=""><br class=""></div><br class=""><div><blockquote type="cite" class=""><div class="">On Apr 1, 2015, at 7:57 AM, Michael C. Kunkel <<a href="mailto:mkunkel@jlab.org" class="">mkunkel@jlab.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
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Greetings,<br class="">
<br class="">
I to was curious to know why FSU and myself did not agree, so I
looked at the entire run range in which had the lepton trigger set,
also the MorB configuration was the same.<br class="">
<br class="">
<a class="moz-txt-link-freetext" href="https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#April_1">https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#April_1</a><br class="">
<br class="">
I noticed an overall difference of 3% from when I used earlier runs.
So I decided to look run by run and I noticed there was a dependence
on run.<br class="">
<br class="">
For instance compare run 56726 to run 57195 using this<br class="">
<a class="moz-txt-link-freetext" href="https://www.jlab.org/Hall-B/secure/g12/mkunkel/MULTIPLE_PHOTONS/Plot_1.pdf">https://www.jlab.org/Hall-B/secure/g12/mkunkel/MULTIPLE_PHOTONS/Plot_1.pdf</a><br class="">
<br class="">
<pre class="moz-signature" cols="72">BR
MK
----------------------------------------
Michael C. Kunkel, PhD
Forschungszentrum Jülich
Nuclear Physics Institute and Juelich Center for Hadron Physics
Experimental Hadron Structure (IKP-1)
<a class="moz-txt-link-abbreviated" href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a></pre>
<div class="moz-cite-prefix">On 31/03/15 20:51, Lei Guo wrote:<br class="">
</div>
<blockquote cite="mid:1FC24CF3-6456-4B68-88D6-AC43EF7CDBF3@jlab.org" type="cite" class="">
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charset=windows-1252" class="">
Hi, MK and Michael,
<div class=""><br class="">
</div>
<div class="">In general I agree with Michael what you are showing
is reasonable. The 1-photon-only probability plot shows
basically the percentage (for Egamma > 3.6GeV) is about
86.6%+-1% (eyeballing). What Will showed from his ppbar channel
is about 87%+-1% (also eyeballing, and he starts from 3.9GeV).
There is no difference here. The two plots (you and will) looks
dramatically different because of the energy range (x-axis), and
because of will shows on the Y-axis from 0 to 100%, and you
zoomed in from 80% to 90%. It tells exactly the same story.</div>
<div class=""><br class="">
</div>
<div class="">For the low energy part (Egamma <3.6 GeV), I
think Michael’s explanation is probably right — although I won’t
call it trigger efficiency or inefficiency. It’s only
inefficient when a event that should have triggered and been
recorded did not get registered.</div>
<div class="">But even if you compare these two ranges, it’s
really a only 1.5% difference. Do you think our systematic
uncertainty on the normalization is less than 1.5%? I think in
the big picture, we are fine.</div>
<div class=""><br class="">
</div>
<div class="">But I do agree with MK that his picture is different
from FSU, particularly in the low energy part, since it showed
opposite trend. </div>
<div class=""><br class="">
</div>
<div class="">How does Rafael’s results compare with you,
particularly for the low energy part?</div>
<div class=""><br class="">
</div>
<div class="">Is it possible that again this is due to you and FSU
are not showing the data from exactly the same set of runs?</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
<div apple-content-edited="true" class="">
<div class="">
<div class="">
<div class="">Lei Guo</div>
<div class="">Assistant Professor</div>
<div class="">Physics Department</div>
<div class="">Florida International University</div>
<div class="">Miami, FL</div>
</div>
<div class=""><br class="">
</div>
<div class="">email: <a moz-do-not-send="true" href="mailto:leguo@fiu.edu" class="">leguo@fiu.edu</a> or
<a moz-do-not-send="true" href="mailto:lguo@jlab.org" class="">lguo@jlab.org</a></div>
<div class="">Office:305-348-0234</div>
</div>
</div>
<br class="">
<div class="">
<blockquote type="cite" class="">
<div class="">On Mar 31, 2015, at 2:31 PM, Michael Paolone
<<a moz-do-not-send="true" href="mailto:mpaolone@jlab.org" class="">mpaolone@jlab.org</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">Hi MK, All,<br class="">
<br class="">
This looks reasonable, and I think I can explain the
energy dependence. <br class="">
The key is that all events have to fire a trigger whose
efficiency is<br class="">
dependent on the momentum and angle of the tracks created
from the<br class="">
reaction which itself IS photon energy dependent.<br class="">
<br class="">
Look at the 1 photon probability plot and ask how likely
is it that that<br class="">
photon is the one that created the trigger. For very low
energy photons<br class="">
the overall trigger efficiency drops, and since we see an
event at all, it<br class="">
becomes more likely that another higher energy photon in
the same beam<br class="">
bucket generated the reaction that triggered the event.<br class="">
<br class="">
The sharp jump at 3.6 GeV shows that the event is now more
likely to<br class="">
trigger with just that photon (since that's where the
primary trigger<br class="">
starts).<br class="">
<br class="">
The downward slope after 3.6 GeV might again be a trigger
efficiency<br class="">
effect, where it becomes more likely that we lose small
angle tracks down<br class="">
the beam hole which could have fired the trigger.<br class="">
<br class="">
-Michael<br class="">
<br class="">
<blockquote type="cite" class="">Greetings,<br class="">
<br class="">
I did not want to show this last night because I thought
there was a bug<br class="">
in my code. But I do not think I have a bug in my code,
so I want to<br class="">
show you what I concluded.<br class="">
<br class="">
First of all, my result does not agree with the values
found by FSU or<br class="">
FIU. I actually see a strange dependence on energy. What
I am depicting<br class="">
are plots of the probability of multiple photons within
the same bucket<br class="">
as clasEvent choose ±1.002 ns, meaning the photon
energy on the X-axis<br class="">
of the plots are of clasEvent chosen, which was the best
timed beam<br class="">
photon compared to the average _of_ start times.<br class="">
<br class="">
The data used for this is only the 566* runs, which is
approximately 7%<br class="">
of the data.<br class="">
Please see:<br class="">
<a moz-do-not-send="true" href="https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#March_31" class="">https://clasweb.jlab.org/rungroups/g12/wiki/index.php/TAGR_code#March_31</a><br class="">
<br class="">
--<br class="">
BR<br class="">
MK<br class="">
----------------------------------------<br class="">
Michael C. Kunkel, PhD<br class="">
Forschungszentrum Jülich<br class="">
Nuclear Physics Institute and Juelich Center for Hadron
Physics<br class="">
Experimental Hadron Structure (IKP-1)<br class="">
<a class="moz-txt-link-abbreviated" href="http://www.fz-juelich.de/ikp">www.fz-juelich.de/ikp</a><br class="">
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