[d2n-analysis-talk] E/p Correction & Effects on Pion Rejection Efficiencies

[David Flay]

Hi all,

I've made corrections to the E/p vs. p plot I showed on 11/17/09 so that
E/p lies along a straight line now (see first plot).  Yesterday I've also
made a plot of sigma/p vs. p, where sigma is obtained from a Gaussian fit
to the E/p distribution (see second plot).  This fit is consistent with
Patricia's work, however I am not too comfortable with the leading
parameter being negative -- I'm currently looking into this.

Now, as for the effects on the efficiencies -- if you recall from 12/1/09,
I showed the pion rejection efficiencies in both the GC and the PR.  They
both tended to have a momentum dependence.  In particular, the E/p cut
used in the PR in conjunction with a cut in the GC had a very pronounced
effect.  This is the cut combination I investigated first.  My corrections
to the E/p drift as a function of p seem, at the moment, to have little to
no effect.  I'm not too sure as to why this is (see third plot).

Finally, I revisited the Gas Cerenkov pion rejection efficiency as a
function of cut position in the Cerenkov.  This as well seems to not
change by much now that E/p has been corrected (to make sure I was testing
the correction, I now select particles in the E/p (corrected)
distribution, as opposed to the L.prl1.e vs. L.prl2.e plot).  However, I
calculated the percent differences for these three data sets here, and on
average the percent difference of p = 0.6 to p = 1.20 is ~0.25%, while the
percent difference for p = 0.6 to p = 1.70 is ~0.68%.  These percent
differences seem reasonable, but the effect looks more pronounced on the
plot (see last plot).

Dave

-------------------------------------------------
David Flay
Physics Department
Temple University
Philadelphia, PA 19122

office: Barton Hall, BA319
phone: (215) 204-1331

e-mail: flay at jlab.org
              david.flay at temple.edu

website: http://www.jlab.org/~flay
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