[d2n-analysis-talk] Pion Rejector Electron Detection Efficiencies and Cut Efficiencies

[David Flay]

Hi all,

[Forgot the last plot.  Please delete previous email.]

I've been doing some work concerning electron detection efficiencies as of
late and wanted to share what I've got so far.

I'm investigating the pion rejector first.  The procedure is as follows.
I select an electron sample in the Cerenkov using TDC cuts and selecting:

(L.cer.asum_c>700)&&(L.cer.asum_c<2200).

(standard cuts used to choose good events are also applied to all
histograms.)

Then, I apply all of these cuts to the E/p histogram, and integrate over
the whole distribution.  The ratio of the number found in the PR to that
selected in the GC is my electron detection efficiency.

I've attached a table showing my results over all kinematics.  The error
bars suggest all the values are consistent with each other.

For the cut efficiencies, I follow the same procedure; however, I also
include a cut on E/p when I look at the E/p distribution. Attached are two
plots -- 4-pass data and 5-pass data respectively.  I plotted a low, mid,
and high range momentum bin so we may see the trend.

We see as p increases, again we see a drop in the efficiency.  I believe
this is due to just how 'bad' the PR is at detecting electrons, given its
poor resolution.  (JP mentioned this at the Hall A Collaboration Meeting).
 Also, if we just look at the p = 0.60 GeV data, we see there's a larger
effect on the efficiency as we change the E/p cut -- I think this is
largely due to the fact that we have a larger sigma on this E/p
distribution, while at higher p, we have a smaller sigma (and much more
Gaussian behavior) in the plot.

Overall, while these efficiencies aren't necessarily bad, they're also not
that great either -- in comparison to the > 99% pion rejection
efficiencies we have.  This is still a concern of mine...

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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