[d2n-analysis-talk] Trigger Plots for Coin. and LHRS runs (& evtypebits description)

[David Flay]

Hey Brad,

I had a question regarding:

"In principle, if trigger X is what forms the level 1 accept (L1A) that
 actually triggers the TDCs and ADCs, then those events should form a
 self-timing spike in the DL.bitX histogram (the stop is the same signal
 as the start, only with some fixed hardware delay between them).  The
 cut in step (2) would ideally cut around that self-timing spike.  (In
 practice this can get a little complicated, particularly on coincidence
 runs where the TDC may be triggered off a retimed signal.)

 By histogramming the DL.bitX variables you can identify the self-timing
 spike that tells you trigger X actually formed the trigger for the event
 you are looking at."

I'm thinking that the hierarchy is L1A->TDC histograms & ADCs.  If that's
the case, wouldn't I see 8 peaks in the L1A (one for each trigger)? So
that, I could cut on evtypebits and pick out each of the peaks,
corresponding to each trigger? I've tried this, but some triggers pick out
one peak, and others pick out a few, and they tend to overlap.

However, I'm not sure I trust this variable I'm using -- it's 'DL.L_l1a',
as opposed to 'DL.l1a' (this is a coin. run I'm looking at, run 1229, so
the variables that I'm working with are DL.tX, and not DL.LTX, for
instance).  The 'DL.l1a' is not working at the moment, I'll take a closer
look at this..

Also -- I've histogrammed the 'DL.bitX' variable, and, for instance using
X = 3, I was thinking if the code is doing things right, if I cut on
(DL.evtypebits&(1<<3))==(1<<3) shouldn't I see a peak within the range 200
- 1500 (plot attached -- that cut does work)?  I would expect if things
were not being done right, that cut would kill the histogram?  Also, a cut
on T1 is implemented (in the hope that this cut would also kill the histo
on the bit3 histo, assuming that bit3->T3, etc.)

-------------------------------------------------
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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