[G12] proton vertex?

[Johann Goetz]

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.

-- Johann <https://sites.google.com/site/theodoregoetz/>

On Fri, Apr 10, 2015 at 4:08 PM, Michael C. Kunkel <mkunkel at jlab.org> wrote:

>  Greetings Carlos,
>
> 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.
>
> The only downfall to using MVRT is if a stray particle with DC tracking
> (i.e. "semi-out of time") events.
> I usually redo MVRT after I do topology selection.
>
> BR
> MK
> ----------------------------------------
> Michael C. Kunkel, PhD
> Forschungszentrum Jülich
> Nuclear Physics Institute and Juelich Center for Hadron Physics
> Experimental Hadron Structure (IKP-1)www.fz-juelich.de/ikp
>
> On 4/10/15 12:02 PM, Carlos Salgado wrote:
>
> 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
>
>
>
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