[BLAST_ANAWARE] ed elastic

From: zhangchi (zhangchi@general.lns.mit.edu)
Date: Mon Jun 30 2003 - 14:10:31 EDT


Hi, all,

I seem to start seeing signitures of ed elastic events from the recent
data. please see the two figures atatched. they plot coincidence events in
tof left 15 and right 0.

in ed1501.eps, it plots the timing differences. blue is with some very
general cuts: both sector have tracks, chi square<0.1. red applies on top
of that a coplanary cut of +-2 degrees. the first peak is cut off by
coplanarity much more than the second one.

in ed1501_colpain.eps, it plots phi right - phi left -180. blue is with
the same general cuts and red is with requirement that time left - time
right > 30ns. red loosely satisfies phi_r-phi_l-180 within +-2deg.
(ofcourse, since the timing cut is determined by the coplanarity cut
applied to the 1st plot. but at least, things seem to be consistant to
each other)

so far I checked paddle combinations: 15:0, 15:1, 14:1, 14:2, 14:3. all
seem to have the same signiture of two timing peaks, the one at smaller
timing difference is cut off by coplainarity much more significantly than
the other.

10 runs during the last few days were used. found a few dozen events in
left pad 15 passed both timing(left-right>30ns) and coplanarity(+-2deg)
cuts.

Chi







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