ch3-01-triggering.tex

\section{Triggering and Data Acquisition}

The basic building block of nearly all physics analyses in the 200 GeV pp
program is the minimum-bias (MB) trigger defined by coincident signals in the
East and West BBCs, yielding a sensitivity of 26.1$\pm$2.0 mb (87\%) of the
NSD cross section as deduced from a Vernier scan performed in 2003. On top of
the MB trigger STAR layers a variety of requirements based on signals in the
electromagnetic calorimeters that bias the event sample towards rare events
with large transverse energy depositions.

The dominant trigger algorithm in this analysis is the BEMC jet patch (JP)
trigger, which sums transverse energy depositions over fixed groups of 400
towers covering an area of $\Delta \eta \times \Delta \phi$ = 1.0 $\times$
1.0. The JP trigger is designed for efficient, minimally-biased selection of
high-energy jets. The threshold for the primary JP trigger in the 2005 (2006)
run was 6.4 (8.3) GeV, and the trigger sampled an integrated luminosity during
longitudinal running of 3.3 (6.8) $pb^{-1}$.

% The 8.3 number excludes transverse running.  Including that the 06 number would be 1.95 (1st long) + 3.20 (trans) + 6.30 (2nd long) = 11.45
% also assumes a MB cross section of 25 mb, not 26.1 as stated here
% http://www.star.bnl.gov/protected/common/common2006/trigger2006/lum_pertriggerid_pp2006.txt

% 2006 DSM prescales
% mysql --host=dbbak.starp.bnl.gov --port=3405 Conditions_rts
% SELECT run.idx_rn, dict.value FROM dict,run WHERE dict.hash=run.dicthash AND dict.label='mb-prescale' AND run.idx_rn<7160000 AND dict.value>0;

% Regular prescales, event counts (port 3404 for 05, port 3405 for 06)
% mysql --host=dbbak.starp.bnl.gov --port=3405 RunLog
% SELECT run, offlineTriggerID, prescale, numberOfEvents FROM l0TriggerSet;

% my thresholds assume final calibrations, I think

% Jamie's integrated lumi numbers are somewhat smaller than mine, presumably because of some basic quality cuts.  My numbers for 06 BJP1 are

% 117221 2.4
% 127221 3.6
% 137221 0.1
% 137222 6.8

% for a total sampled lumi from longitudinal running of 9.3, rather than 8.3