[d2n-analysis-talk] Gas Cerenkov Cut Efficiencies (Background Corrected)

[David Flay]

Hi all,

I've attached the gas Cerenkov cut efficiencies as they stood before
corrections for the first two plots.  I've fit the pion background from my
selected electron sample (see 2/18/10 talk:
http://www.jlab.org/~flay/analysis_2010.html) an subtracted it off. The
last two plots show the corrected gas Cerenkov efficiencies.

The correction brings all efficiencies to better than 95% across most of
the cut range up to ~500 channels (2.5 photoelectrons).

All the values are much more consistent with each other, but across the
full kinematic range, the variation is about 1-2%.

The correction at the low end of the kinematic range corrects the
efficiency by up to ~15-20%, and at the highest momenta, the correction is
on the order of 1-2%.  Most of the (statistical) error bars are ~1-2% -- I
have not added more runs to my previous studies (in other words, I have
chosen runs that have one particular target configuration --
transverse-270, as an example -- I did not mix target configurations.)

The high momenta data have the largest error bars (in particular p = 1.70
GeV) as we have a very short list of runs to use (I am currently using all
of them).  Also, the background is very very difficult to fit at the
highest momenta (p = 1.51,1.60,1.70 GeV).  This is the region where the
contamination is on the order of ~2%.  There is barely any structure to
the background distribution, and I don't know if it's terribly useful to
even fit this distribution -- any suggestions?

While I do think these results look better, I think it can be improved. 
However, I am not sure how much of it has to do with my fit -- which I
think is doing a good job, but I am concerned about the corrections to the
highest momenta.

Any comments are welcome!

Thanks,

Dave


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

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

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

website: http://www.jlab.org/~flay
              http://quarks.temple.edu
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