prune

Fraction of events at low hsbeta (04/24/05)

The HMS had approximately 5% of the events with reduced or zero beta due to hadronic interactions of the pion. This analyisis was shown previously (here). Running the same analysis side by side with the old:

low hsbeta fraction, pass1 vs. the prune method
	pass1	pass1a_(prune)
Events in loose cut	2309	2359
Events in tight cut	2195	2303
Low hsbeta fraction	0.951	0.976

It can be seen that not only has the fraction of events with low hsbeta been improved, but the raw number of events in the loose cut cut increased by 2%. The entire ntuple was replayed in both cases.

This is likely to result in an increased HMS fid efficiency, however, the HMS fid efficiency increased from 96.6% to 97.4%, which is a relative increase of less than 1%. The fid effic used hcer_npe>2, and so it selected pions.

Pass1, e-pi events in a loose hsbeta cut and a tight hsbeta cut

Pass1a (prune), e-pi events in a loose hsbeta cut and a tight hsbeta cut