SVT 4/5 operation CDF meeting 1/16/2003

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SVT 4/5 operationCDF meeting 1/16/2003

• G. Punzi for the SVT group

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• 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...)

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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

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Impact on trigger rates
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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)
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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)55(1-?)a5
Patt. Coverage (4-comb.)
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D0 yield x1.70.1 (L3 tracks) (Roberto)
4/4
379 nb-1
4/5
471 nb-1
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D0 yield x1.460.01 (full reco)(Stefano)
1.55
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Plans

• Analyze SVT calibration run taken last week
  (being produced)
• Studyoptimize 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