User name R. Michaels
Log entry time 10:46:47 on March 4,2006
Entry number 165128
keyword=helicity check, run 2620Some people asked me to look at helicity in run 2620. It looks
great (see fig 1). The time spent in helicity=0 is about 1.6% and
the GenHelicity class reports ZERO errors. Notes about this:
1. helicity can be -1, 0, +1. A "0" means "unknown", e.g. the
transition between helicities (1.6% of time) or a failure.
2. Must avoid trigger T9 when filling this histogram. T9 are timed
at the helicity transitions (for good reason, to help ensure
reliable reconstruction).
3. Analyzer should not skip events for the purpose of GenHelicity.
In principle some deadtime is tolerated but it makes reconstruction
less reliable.
4. It takes 26 quads to load the helicity prediction. This corr-
esponds to 3.12 sec which at 1 kHz is 3120 events. Here I cut on
500 events (I didn't check too carefully, I think the rate was
about 100 Hz). This means we lose 3.12 sec at the start of each run.
FIGURE 1
