[d2n-analysis-talk] Cerenkov Cut Efficiency (revisited)

[David Flay]

Hi all,

I revisited the Cerenkov cut efficiency and elaborated a bit more on
cutting lower in the Cerenkov spectrum.  I've attached some plots.  The
runs used here were the elastic 3He runs 1229, 1230.

The first plot is the Cerenkov cut efficiency as a function of cut
position in the GC.  The second is the GC sum subject to the graphical cut
in the shower (shown in last plot) and various GC cuts (for cut
efficiency).

For a complete description of my (detector) efficiency calculation, please
see:

http://www.jlab.org/~flay/LHRS_9_15_09.pdf

Note:  Changes to this method are:

1. Trigger type cut is now using evtypebits
2. No cut on beta
3. Additional cuts to theta and phi (attached) (of the form:
(abs(L.tr.tg_th)<0.05)&&(abs(L.tr.tg_ph)<0.03))
4. No cut on z-react
5. No cut on tracking variables in PR detector plane

Once again, I believe that the quick drop off in efficiency at ~2.5
photoelectrons is due to a threshold effect when cutting on the Cerenkov,
as we have only ~6 photoelectrons on average in the GC.

I'm going to start looking at pion rejection factors for production runs.

-------------------------------------------------
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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