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Archived Messages for CLAS_OFFLINE@cebaf.gov: Re: Bug in aao_gen

Re: Bug in aao_gen

Volker Burkert (burkert@jlab.org)
Tue, 26 May 1998 02:48:33 -0400 (EDT)

Hi, I am little surprised to read that secondaries are turned off in
GSIM. Shouldn't we turn them ON since otherwise we will not know how a
muon from pion decay is treated by the reconstruction code. I am sure
there are a lot of decaying pions at backward angles.

Volker

On Mon, 25 May 1998, Lee Cole Smith wrote:

> >>I don't think we should do anything to the data since we are not using
> >>the pi+ data to make them look like the data but to do the acceptance
> >>corrections, which should be little affected by this bug.
>
> I agree, I just didn't want anyone to draw any unwarranted conclusions
> about the physics in AO. I think it is also worthwhile to try to make
> some absolute comparison to the data. It was in doing so that the bug
> was discovered.
>
> My point was that the pi+ channel has special problems the p channel
> doesn't since you have a lot of low momentum pions filling up the
> acceptance. Even with the bug fix we are seeing discrepancies between
> sim and data in the pi+ channel that to my eye look like pion decay
> effects. In GSIM we have secondaries turned off so pions
> which decay before leaving the DCs simply disappear, whereas in the real
> data the decay muon may result in the track being reconstructed with
> a different momentum or possibly even different sign.
>
> Cole
> cole@apollo.phys.virginia.edu
>
>