User name R. Michaels
Log entry time 03:01:16 on October29,2005
Entry number 158350
keyword=Left arm background studyWe are doing production (don't worry).
Here is an analysis of run 2912 - a low-current counting mode run.
The issue is: Can we find any indication of backgrounds in
det1 which is DIFFERENT from det2 (these are L-arm dets, same
notation as HAPPEX detector numbering). It's tied to our
worries about det1 ...
Fig 1 shows the Theta-Phi at collimator with large histogram
limits. Bad tracks (whether background or mis-reconstructions)
would miss the collimator. To clean things up a bit, we demand
one track in the event. To isolate det1 versus det2 we make
hard ADC cuts. A "det1 event" requires ADC1>1400 and ADC2<550 for
example (pedestal is around 500). From these plots, the percentage
of tracks missing collimator is 4% and 2.8% for det1 and det2
resp. Not a huge difference.
Fig 2: Two other windows on backgrounds are events with no track
(possible neutrals) and events with more than 1 track (possible
spray from shower). We plot the ADC spectra of detectors.
Similar cuts as above demand that det1 and not det2 got some
energy (and vice versa). The neutral candidates are 0.29 +/- 0.05%
in det1, and 0.59 +/- 0.06% in det2. Not much different (and det2
has "more"). The number of events with more than 1 track is quite
similar for det1 and det2 (ca 9.7%).
So far I don't see any difference between these detectors except
that they sample a different range of angles (see collimator plots).
If anyone wants to play around with the macro, see "bgr1.C" in
the adaq onlana directory.
FIGURE 1
FIGURE 2
