<div dir="ltr">Just expand on MK's message: you should *always* recalculate the vertex using the MVRT algorithm for every event and for every final-state-topology in your analysis. This is especially crucial for g12 as there is a significant chance of an out-of-time track making the MVRT bank in pass1 data unreliable - though you can measure this effect and correct for it if you wish - or exclude events that have time-based tracks not in your final-state topology.</div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature">-- <a href="https://sites.google.com/site/theodoregoetz/" target="_blank">Johann</a></div></div>
<br><div class="gmail_quote">On Fri, Apr 10, 2015 at 4:08 PM, Michael C. Kunkel <span dir="ltr"><<a href="mailto:mkunkel@jlab.org" target="_blank">mkunkel@jlab.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Greetings Carlos,<br>
<br>
Yes this has been seen and discussed previously in G12. What this is
is the intersection of the x-y plane with a projection on the z.
This value should be used in a DOCA analysis, but if you want to
have the proper vertex, use MVRT which is the projection of rays and
points within all particles in the event.<br>
<br>
The only downfall to using MVRT is if a stray particle with DC
tracking (i.e. "semi-out of time") events.<br>
I usually redo MVRT after I do topology selection.<br>
<br>
<pre 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 href="http://www.fz-juelich.de/ikp" target="_blank">www.fz-juelich.de/ikp</a></pre><div><div class="h5">
<div>On 4/10/15 12:02 PM, Carlos Salgado
wrote:<br>
</div>
</div></div><blockquote type="cite"><div><div class="h5">
<pre>Hello g12s
A question: Attached is (what is called in his tree): the proton vertex-x versus vertex-y from Andres' Ppippim skim.
Have you ever seen a similar distribution? What is going on? we get a beautiful picture of CLAS sectors!
-Carlos</pre>
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