[G12] vertex distribution

[Hicks, Kenneth]

I think Dennis is correct.  This is the likely explanation.....Ken

From: g12-bounces at jlab.org [mailto:g12-bounces at jlab.org] On Behalf Of Dennis Weygand
Sent: Monday, March 18, 2013 4:27 PM
To: Michael C. Kunkel
Cc: g12 at jlab.org
Subject: Re: [G12] vertex distribution

OK, I think I got it:

Your e+ e- gamma sample has a large number of events such that:

1) pi0 --> gamma gamma
2) One of the gamma's converts in material outside of the target

MVRT still has the correct vertex since the e+ e- opening angle is 0.

Dennis




On Mar 18, 2013, at 3:52 PM, Michael C. Kunkel wrote:


Greetings,

I got my hands on PPipPim data to plot the MVRT information.
I have posted the plots of the r of MVRT and x vs. y of MVRT for the following topologies:

Pion; Missing Mass Proton Pi+ Pi- -> 0 (exclusive)
         Effective Mass Pi+ Pi- ->Omega

Lepton: Missing Mass Proton e+ e-  < Pi0
             Missing Mass Proton e+ e- gamma -> 0 (exclusive)
             Effective Mass e+ e- gamma ->Pi0

Plot can be found at
https://clasweb.jlab.org/rungroups/g7/wiki/index.php/Reconstruction_study
for March 18, 2013

Before anyone cries "bug", let me assure everyone that the manner in which the MVRT data is collected for the pions is the same as for leptons, i.e. a clasEvent function.

From what I deduce, it appears that either exclusive Pi0 production can happen outside of the target (cough cough), or for some reason when the particle is a lepton, we have resolution problems. Neither I can understand from looking at what creates the MVRT.

Thoughts and help would be appreciated greatly.

BR
MK

On 3/13/13 3:46 PM, Dennis Weygand wrote:
Does anyone have  plots of vertex distributions (z, x vs y, r from MVRT) for any topology?
Dennis

--
Dennis Weygand
weygand at jlab.org<mailto:weygand at jlab.org>
(757) 269-5926 (office)
(757) 870-4844 (cell)









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--
Dennis Weygand
weygand at jlab.org<mailto:weygand at jlab.org>
(757) 269-5926 (office)
(757) 870-4844 (cell)





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