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Greetings,<br>
<br>
My map uses a | tpho + tprop - scVertexTime|<1ns<br>
Where scVertexTime uses an input of mass to calculate betta<br>
double beta = p/sqrt(p*p + mass * mass);<br>
scVertexTime = tbidptr()->sc_time -
scPathLen()/(LIGHTSPEED*beta);<br>
<br>
I do not use ST to do timing cuts.<br>
<br>
<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 27/07/15 19:28, Lei Guo wrote:<br>
</div>
<blockquote cite="mid:682E3F99-34D3-490E-B7D7-7FD0CD542460@jlab.org"
type="cite">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<div class="">The TOF paddles are knocked out manually, so you
need the paddle IDs…. In fact, rafael just produced another list
of additional new bad paddles. MK is rederiving his track
efficiency correction map.</div>
<div class=""><br class="">
</div>
To check if the drift chamber wire efficiency map has been applied
correctly, you need to compare the lab theta, and phi
distributions by sectors.
<div class="">Do you account for the number of good events you
throw away with the kinematic fitting CL cut? That percentage
that we throw away with CL cut is not entirely consistent with
the simulation, and you have to correct for that as well. Or
maybe you have already done that?</div>
<div class="">Another thing one might have overlooked is that if
one uses start counter timing. I don’t know if MK’s map is
derived after applying the |Stvtime-RFvtime|<1ns cut. SO, it
may or may not affect you. The 1ns cut will throw away good
events (ST resolution is not ~400ps), and since the ST
resolution is not simulated, you have to account for that.
However, it really depends on whether the map was derived with
the ST timing cut or not.</div>
<div class=""><br class="">
</div>
<div class="">Lei</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>
<blockquote type="cite" class="">
<div class="">On Jul 27, 2015, at 9:53 AM, 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="">Hey Volker,<br class="">
<br class="">
The behavior is odd indeed. I have some thoughts, but
before I jump into<br class="">
them, let me know what your channel is exactly and how you
indentify it. <br class="">
Is it pi+, pi- and p detected, with a missing pi0 you cut
on? Is it a<br class="">
kinematic fit to the missing pi0?<br class="">
<br class="">
An overall thought: Have you looked at the distribution of
each detected<br class="">
particle in the DC (in x,y) at that specific energy to see
if you can<br class="">
"see" any strange holes or behavior? Then you could see
how it compares<br class="">
to simulation.<br class="">
<br class="">
-Michael<br class="">
<br class="">
<br class="">
<blockquote type="cite" class="">Hi Everybody,<br class="">
<br class="">
I know that we are all working on finalizing various g12
analyses.<br class="">
However, we found a serious issue with our γp â pÏ
cross section that<br class="">
currently prevents us from moving on. We are somewhat
stuck and it may<br class="">
affect the whole run group.<br class="">
<br class="">
The attached pictures show the 3Ï invariant mass for
the energy range<br class="">
1650 - 1700 MeV and for forward angles of the 3Ï
system. A nice Ï peak<br class="">
is visible and a massive hole on the right side of the
peak. This hole is<br class="">
not supposed to be there (unless somebody has a good
physics argument).<br class="">
The energy range is probably very low for most of the
g12 analyses.<br class="">
However, the hole will slowly move to higher masses with
increasing photon<br class="">
energy but it will not disappear. The other two pictures
show the same<br class="">
distribution if one (1) uses events where only sectors
1, 3, 5 triggered<br class="">
or alternatively, (2) only sectors 2, 4, 6 triggered.<br
class="">
<br class="">
We assume the effect is based on track inefficiencies,
perhaps dead<br class="">
regions in the drift chamber. In principle, Michael
Kunkelâs "trigger<br class="">
map" should account for this since his approach is based
on comparing two-<br class="">
and three-track events, i.e. it combines trigger and
track inefficiencies;<br class="">
the idea is good. In our analysis however, this trigger
map leads to an<br class="">
overall disagreement with the g11 Ï cross section,
whereas Zulkaida's<br class="">
current cross section is in fair agreement with g11 but
exhibits certain<br class="">
problematic regions, e.g. the forward direction. These
holes in the mass<br class="">
distributions are not accounted for by the Monte Carlo
simulations and we<br class="">
assume the effect is not in the MC.<br class="">
<br class="">
We have a few questions we would like some help with
(and need to find an<br class="">
answer for).<br class="">
<br class="">
1) Since it is still possible that the problem is at our
end, would<br class="">
anybody be able to reproduce this problem for us? The
effect is so big<br class="">
that even a quick and dirty look at it, will probably
work.<br class="">
<br class="">
2) We tried to knock out dead TOF paddles as suggested
in the analysis<br class="">
note. The paddle numbers are available in the data.
However in the Monte<br class="">
Carlo, the numbers appear to be available only for the
proton and not for<br class="">
the pions. Has anybody else noticed this issue? How do
others knock out<br class="">
the paddles in the MC? Or is this done automatically? It
is difficult to<br class="">
do this based on measured angles since two particles
with the same polar<br class="">
and azimuthal angles, one produced at the beginning of
the target and one<br class="">
at the end, may hit different TOF paddles. The g12
target was very long.<br class="">
<br class="">
3) The Monte Carlo âgpp" options given in the analysis
note do not<br class="">
reproduce the holes in the mass distributions. For this
reason, we do not<br class="">
know if dead wires are actually simulated and to what
extent. Can anybody<br class="">
comment on this?<br class="">
<br class="">
This problem shows up in the γp â pÏ channel but we
are concerned that<br class="">
it may also affect the two-pion channel we are
analyzing, perhaps not as<br class="">
holes in mass distributions but as general track
inefficiencies in certain<br class="">
regions of the drift chamber. In the latter case, it
would extremely<br class="">
difficult to notice. If so, it can potentially affect
any reaction that<br class="">
uses Monte Carlo for the acceptance correction. My
understanding is that<br class="">
we partially use the pÏ and the KÎ cross sections to
make sure that the<br class="">
g12 MC, trigger, etc. is working correctly.<br class="">
<br class="">
Best wishes,<br class="">
<br class="">
<span class="Apple-tab-span" style="white-space:pre"> </span>Volker<br
class="">
<br class="">
<br class="">
<br class="">
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</blockquote>
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