[d2n-analysis-talk] Positron Vertex Histogram Question

[Matthew R. Posik]

Hi Gregg,

 here is a plot of the z vertex with the BigBite magnet running in positive
polarity. I applied all of the cut we have been using for the electrons to
this plot, ie projected track to calorimeter positions, cerenkov cuts,
pre-shower ect. The only cut I changed a little was the E/p, the low end of
that cut for electrons was 0.833 and I lowered it to 0.763 for positive
polarity.

-Matt

On Tue, May 3, 2011 at 8:30 PM, Gregg B. Franklin <gbfranklin at cmu.edu>wrote:

> Matt,
>   I've been re-reading some of the info you provided on the positron
> data.  In your talk of 4/21/2011, you have comparisons of distributions
> from standard BigBite running and reverse-polarity running.  The
> distributions are generally very similar.  The z-vertex distribution
> (your slide 12) is particularly interesting since I would expect the
> z-vertex distribution for positrons to be very different from
> elecxtronce since (I think) the tracks should point back to gamma
> conversion points.
>
>   I assume your plot is for all good positive tracks.  Am I right?
> Would it be possible to see what this same distribution would look like
> if all the "good electron" cuts (like Cerenkov, preshower, E/p...) were
> applied also?  I'm thinking that the positrons might come from the
> collimators that shield BigBite from the ends of target.  If this is
> true, the z-vertex distribution for positrons should be greatly enhanced
> at z=+/- 0.2 m.  AND if this is true, we could cut at least some of them
> out.
>
>   Would it be possible to produce the z-vertex plot for positrons only?
>  (If slide 12 already has these cuts, then I'm really confused on why
> it looks just like the normal-polarity running.)
>
> Regards,
> Gregg
>
>
>
> --
> Prof. Gregg B Franklin
> Head, Department of Physics
> Carnegie Mellon University
> phone: (412) 268-2743   fax: (412) 681-0648
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>



-- 
Matthew Posik
Email: posik at temple.edu
Temple University Physics Dept.
Office: BA-319
Office #:  215-204-1331
WebSites:
Temple:
http://quarks.temple.edu/
d2n:
http://hallaweb.jlab.org/experiment/E06-014/
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