Present: Ito, McNulty, Teymurazyan, Payne, Wood, Clinton
On Phone: Dale, Miskimen
Secretary: Clinton
Secretary for next week: Teymurazyan
Previous week meeting minutes approved.
1.) Eric showed his analysis for reconstructing live1 and live 2. Showed
two methods. One was the 'predictive method' based on knowledge of live2
with the constant deadtime of the trigger supervisor. (live1 =
live2(1-deadtime*# of events)) The other method corrected live1 using
knowledge of live2 with the constant deadtime of the trigger supervisor.
his slides are at www.jlab.org/~eclinton/13May2005/index.html. Methods
agreed to within 0.02% except for a few points.
2.)Aram presented his correction method. Compared to predictive method,
his is within 0.02% as well. Aram's method assumes the first few hundred
events in a file are good, then adds or subtracts 2^16 or 2^24 to fix
bits 16 and 24. For bit 8, 2^8 is subtracted until live2>live1 and
live1(new) > live1(old).
A few people where not convinced that the TS had a constant dead time as
it built events. Requested that Dave L be consulted and plots showing
that DT does not change with beam current, LMS runs, or pedestals.
Aram suggested that these methods of correction could be a rough check on
beam trip status.
3.) Dustin's presentation regarding hycal cluster calibration and
reconstruction versus tagger timing. Separate studies where done on
entire lead data and entire carbon data
the slideas are here.
http://www.jlab.org/primex/weekly_meetings/slides_2005_05_13/lead_timing_summary.pshttp://www.jlab.org/primex/weekly_meetings/slides_2005_05_13/carbon_timing_summary.ps
Two highlighted points
A. Plots of the tagged photon (tagm) timing distribution versus t_counter
id showed fairly nice calibration (centered ~tightly around zero) for
lead and not as nice for carbon (at least 2 pronounced peaks, maybe
more). Remember the lead dataset contains fewer runs (86 instead of 218
for carbon) and spans a tighter region in calender time. Maybe tagger
timing could be a bit better (especially for carbon).
B. Plots of the cluster time versus anything showed a double peak
structure (larger peak around 0ns and a smaller peak around -20ns. The
conclusion was that this double peak structure is not understood and is
not desirable. Further investigation is needed.
4.) Tagger problems brought up by Aram. A single TAGT event and two
TAGE events give rise to two photons, and their timing is two close to
separate them in downstream events. Also, dual, distinct TAGT hits and
two identical TAGE hits give rise to two photons of the same energy.
These events constitute ~5% of events in TAC runs--too high. Eric is
still looking into them.
eric r.i. clinton
madpiper@physics.umass.edu
eclinton@jlab.org