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 ( ) –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

Impact on trigger rates

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) Patt. Coverage (4-comb.) (  / a 4 )[ [1-(1-a 5 ) 5 ]+5(1-  )a 5 ]

D 0 yield x 1.7±0.1 (L3 tracks) (Roberto) 4/4 4/5 379 nb nb -1

D 0 yield x1.46±0.01 (full reco) (Stefano) = 1.55

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