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SVT 4/5 operation CDF meeting 1/16/2003. G. Punzi for the SVT group. SVT had a test run after Christmas with 4/5 operation and standard physics table (155818+) Uses all 5 SVXII layers allowing 1 miss Standard mode (4/4): require 4 hits on a fixed set of 4 layers
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SVT 4/5 operationCDF meeting 1/16/2003 G. Punzi for the SVT group
SVT had a test run after Christmas with 4/5 operation and standard physics table (155818+) • Uses all 5 SVXII layers allowing 1 miss • Standard mode (4/4): require 4 hits on a fixed set of 4 layers • Separate test of 3/3 (recover 3-layer wedges) (155918) • Expect efficiency improvement and less need for SVT config changes with changing SVX conditions. • 4/5 mode is part of the SVT design, yet took lots of hard software work to implement: patterns, simulation, download code…(Roberto, Bill, Jahred...)
Impact on trigger timing • SVT execution time increase 7µs • due to increased number of candidate track fits (compatible with expectations) • limited impact on overall L2: ~40µs ~47µs (+17%) • No significant effect with the current L1 rate limitation • but we are looking at ways to control this anyway • Optimize patterns • Cut on strip noise
Resolution • Resolution uniform between combinations - slightly worse when L0 is missing • 3-layers: larger I.P. tails: 28% vs 17% (small number of wedges) (µm)
Efficiency • Expect track efficiency improvement ~1.4 for the 2/3 of wedges with 5 active layers ~1.25 overall • Measurements of track eff. and S/B underway Eff. Gain (for tracks with 4 good hits) (/a4)[[1-(1-a5)5]+5(1-)a5] Patt. Coverage (4-comb.)
D0 yield x1.7±0.1 (L3 tracks) (Roberto) 4/4 379 nb-1 4/5 471 nb-1
Plans • Analyze “SVT calibration” run taken last week (being produced) • Study&optimize: 4/5 has even more free parameters than 4/4 - try to get maximum benefit with minimal side effects. • Further L3 rate reduction by Si tracking will be important (Marco,Rolf : ~x2 reduction) • Look forward to starting up with a new improved hadronic trigger after the shutdown