[G12] vertex distribution

[Michael Paolone]

If this is true, tightening the missing mass = 0 and effective mass = pi0
cuts should reduce the x-y vertex spread, right?

-Michael


> 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
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