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<font face="Helvetica, Arial, sans-serif">Hi Joerg,<br>
<br>
I wrote my own little plugin:<br>
/w/halld-scshelf2101/halld2/home/zihlmann/HallD/work/scmatch<br>
<br>
yes there are many reasons why we could lose light. Like light
loss due to creasing that developed<br>
on the surfaces. That one could probably be tested by
investigating the reference paddles you still<br>
have at FIU.<br>
<br>
cheers,<br>
Beni<br>
</font><br>
<div class="moz-cite-prefix">On 11/23/22 10:46, Joerg Reinhold
wrote:<br>
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Hi Beni,</div>
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<br>
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Gain could be an issue. I could also think of two other
possibilities:</div>
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<ul>
<li><span>a loss in transmission through the plastic; I would
expect that all other things equal this should be a
gradual process, which could be tested.</span></li>
<li><span>A loss of transmission from the plastic to the SiPM.
I recall that the SiPMs needed to get very accurately
adjusted. There is no direct coupling; i.e., there is an
air gap of about 160 um; if this somehow increases to 300
um or more, a substantial light loss is expected.The
counter has been handled when taken out and put back in
before and after CPP. So, something could have happened.</span></li>
</ul>
<div><br>
</div>
<div>What plugin did you run for this? </div>
<div><br>
</div>
<div>Also, I probably should join the halld-pid group.</div>
<div><br>
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<div>Best,</div>
<div><br>
</div>
<div>Joerg</div>
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<span style="font-size: 10pt;">Department of Physics</span></div>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt"
face="Calibri, sans-serif" color="#000000"><b>From:</b> Beni
Zihlmann <a class="moz-txt-link-rfc2396E" href="mailto:zihlmann@jlab.org"><zihlmann@jlab.org></a><br>
<b>Sent:</b> Wednesday, November 23, 2022 10:24<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:halld-pid@jlab.org">halld-pid@jlab.org</a> <a class="moz-txt-link-rfc2396E" href="mailto:halld-pid@jlab.org"><halld-pid@jlab.org></a>;
Joerg Reinhold <a class="moz-txt-link-rfc2396E" href="mailto:reinhold@fiu.edu"><reinhold@fiu.edu></a><br>
<b>Subject:</b> Start Counter issues</font>
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Note: This message originated from outside the FIU
Faculty/Staff email system.</p>
<br>
<div><font face="Helvetica, Arial, sans-serif">Hi All,<br>
attached you find a note I cobbled together looking at the
start counter data<br>
and made me worry that we are looking at the issue wrong.
This may be not <br>
a problem with the path correction but rather a "gain"
problem.<br>
<br>
I plot the TDC_time minus the RF time VS the signal
amplitude. And I do this<br>
for two runs: 73262 (for reference) and a current run
111145.<br>
These plots are generated at three different positions along
the z axis at<br>
60cm (middle of the strait section) at 80 cm (bend section)
and 92cm<br>
close to the nose (last two plots).<br>
<br>
you can (starting from the last plots) that the issue may be
the "gain".<br>
in run 73262 the minimum ionizing peak is clearly identified
and separated<br>
from the pedestal. This is not so clear for run 111145.
Which leads me<br>
to the conclusion that the earlier plots are indicating we
cut into the <br>
minimum ionizing peak because the gain is too low.<br>
<br>
I will go and look at other runs that are closer to the
current run period<br>
with the start counter on. I will also look at what the
operating voltages are<br>
and if they are truly the same as in the past.<br>
<br>
Happy Thanksgiving,<br>
Beni<br>
<br>
<br>
</font></div>
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