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<p>Seconded. The most recent physics workshop was in 2016, before
many of us working on GlueX data started. There's been a few
subtle changes in software and procedures, and some of those who
developed these tools and processes are no longer around to
explain them. It'd at least make things easier for future newbies
to get things moving...</p>
<p>Cheers,</p>
<p>Stuart<br>
</p>
<br>
<div class="moz-cite-prefix">On 20/03/18 18:29, Curtis Meyer wrote:<br>
</div>
<blockquote type="cite"
cite="mid:6686C425-4E1A-4ECC-8274-08E1EB957216@cmu.edu">
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Hi Richard -
<div class=""><br class="">
</div>
<div class=""> that sounds like a good suggestion. We take a lot
of things for granted that may not be so obvious after all. More
important would be the worked out examples…</div>
<div class=""><br class="">
</div>
<div class="">Curtis<br class="">
<div class="">
<div style="word-wrap: break-word; -webkit-nbsp-mode: space;
-webkit-line-break: after-white-space;" class="">
<div style="color: rgb(0, 0, 0); font-family: Helvetica;
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---------</div>
<div style="color: rgb(0, 0, 0); font-family: Helvetica;
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text-align: start; text-indent: 0px; text-transform: none;
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-webkit-text-stroke-width: 0px;" class="">
Curtis A. Meyer<span class="Apple-tab-span" style="white-space: pre;"> </span>MCS
Associate Dean for Research<br class="">
Phone: (412) 268-2745<span class="Apple-tab-span" style="white-space: pre;"> </span>
Professor of Physics<br class="">
Cell: (412) 260-6290<span class="Apple-tab-span" style="white-space: pre;">
</span>Carnegie Mellon University<br class="">
Fax: (412) 681-0648<span class="Apple-tab-span" style="white-space: pre;">
</span>Pittsburgh, PA 15213<br class="">
<a href="mailto:cmeyer@cmu.edu" class=""
moz-do-not-send="true">cmeyer@cmu.edu</a><span class="Apple-tab-span" style="white-space: pre;">
</span><a class="moz-txt-link-freetext" href="http://www.curtismeyer.com/">http://www.curtismeyer.com/</a></div>
</div>
</div>
<div><br class="">
<blockquote type="cite" class="">
<div class="">On Mar 20, 2018, at 2:15 PM, Richard Jones
<<a href="mailto:richard.t.jones@uconn.edu" class=""
moz-do-not-send="true">richard.t.jones@uconn.edu</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div dir="ltr" class="">Justin,
<div class=""><br class="">
</div>
<div class="">I wonder if it might make sense to devote
10 minutes at the beginning of each physics meeting to
a "How-To" presentation on basics of our data
analysis. Accidentals subtraction is something that
seems to keep coming up over and over. An alternative
to a "basics of physics analysis" series, we could
also commission a series of short Tech Notes. Maybe
the first one could be, "How photon tagging works",
just a couple of pages with a worked-out example would
do.</div>
<div class=""><br class="">
</div>
<div class="">-Richard J.</div>
</div>
<div class="gmail_extra"><br class="">
<div class="gmail_quote">On Tue, Mar 20, 2018 at 1:18
PM, Peter Pauli <span dir="ltr" class="">
<<a href="mailto:ppauli@jlab.org" target="_blank"
class="" moz-do-not-send="true">ppauli@jlab.org</a>></span>
wrote:<br class="">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Hello everybody,<br class="">
<br class="">
I apologise in advance for this lengthy email.<br
class="">
I am trying to understand how to properly do the
random subtraction while avoiding double counting.
After talking to a couple of people at the
collaboration meeting and during shifts I found that
this seems to be non trivial and it seemed that some
people where not to sure about it either.<br
class="">
<br class="">
According to Paul's talk that he gave at the 2016
software workshop the rule is to always include all
the variables into your uniqueness tracking that are
used to calculate the histogrammed quantity.<br
class="">
Let's say I look at gp->p pip pim. I want to
histogram the pip pim invariant mass and do the
random subtraction. Although I only use the pip and
pim tracks to calculate the invariant mass I have to
include the beam photon in my uniqueness tracking
because I also use that quantity (timing) in the
following step to get the random subtracted
histogram. But as far as I understand in the voting
on the best RF bunch each track gets a vote. So do I
need to include the proton in the uniqueness
tracking as well?<br class="">
<br class="">
What happens if I use the track vectors coming out
of the kin fit? The standard 4-mom fit that is
usually used will include information from all
tracks in the combo. Does that mean as soon as I
plot e.g. the invariant mass using kin fitted tracks
I need to include everything in the uniqueness
tracking?<br class="">
<br class="">
What about binned quantities. Many results are shown
in bins of momentum transfer squared. In my analysis
I look at gp->kp Lambda(->km proton) and
calculate the momentum transfer as t^2 =
(g_P4-kp_P4)^2. If I now want to bin the proton
Kminus inv mass in t-bins does that mean I need to
include the beam particle and Kplus in my uniqueness
tracking? Aren't bins in principle like a 2D plot?
Binning means effectively histogramming a 2D plot I
would say, therefore I need to include them. But
what is if now make my bins really large (e.g. 0 to
-inf)? This would effectively be unbinned and I
would just track the beam particle, proton and km.
Does that mean I need uniqueness tracking of beam,
km, proton for each of my bins individually but not
include kp in the tracking?<br class="">
<br class="">
If there is a document somewhere that clarifies
those issues I would be happy if you could point me
to it. I didn't find anything but maybe I missed it.<br
class="">
<br class="">
These are only a couple of questions I have about
this but I think it is enough for one email. I
thought about this stuff for quite some time now and
feel like I start to confuse myself about some of
the issues. Therefore I thought I just send it to
the physics mailing list. Maybe there are straight
forward answers and I just don't see them or maybe
this is worth a discussion at an analysis meeting.
Either way I am sure this is interesting for more
people than just me.<br class="">
<br class="">
Cheers,<br class="">
Peter<br class="">
<br class="">
-- <br class="">
==============================<wbr class="">==<br
class="">
Peter Pauli<br class="">
<br class="">
Dept. of Physics & Astronomy<br class="">
University of Glasgow,<br class="">
Glasgow G12 8QQ.<br class="">
Scotland. UK.<br class="">
<br class="">
Tel: <a href="tel:%2B44%20%280%29141%20330%206398"
value="+441413306398" target="_blank" class=""
moz-do-not-send="true">
+44 (0)141 330 6398</a><br class="">
==============================<wbr class="">==<br
class="">
<br class="">
______________________________<wbr class="">_________________<br
class="">
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class="">
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<pre class="moz-signature" cols="72">--
Dr Stuart Fegan
Postdoctoral Researcher
George Washington University/Hall-D
F351, CEBAF Center
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:sfegan@jlab.org">sfegan@jlab.org</a>
Telephone: (757)-269-7473</pre>
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