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Minutes of the Tracking Meeting, December 5, 2007
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taken by U. Husemann


Ji-Eun Jung: Beamlines
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- Relative shift between SVX and COT beam lines: before/after shutdown
  -> larger now, about 20 micron


Aart Heijboer: Beam Lines
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- Before shutdown: 
  o Performed 40 micron correction a while ago
  o Observe jump, possible at start of Period 13 (East ISL/L00 off)
- Larger offsets after shutdown: 23 microns in x, 30 microns in y
- No indications for slope changes over time: no rotations
- Decided to move mean y offset to -15 microns: new table created
- Working with Andreas Schmidt on Period 14 SVX alignment:
  o SVX unchanged
  o Small L00 correction
- Question: what is the effect of the global silicon alignment shift on ISL


Juan Pablo Fernandez: Update on Gen7 ISL Alignment
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(presented by Ulrich)

- Studied details of Gen7 ISL alignment:
  o residuals as function of z position on sensor
  o see differences between different tracking algorithm
  o z residuals: one bulkhead seems shifted in z, one seems rotated
- Questions to Juan Pablo:
  o How is refit done (same algorithm)
  o How small a residual is "good enough" for tracking algorithms?


Discussion on Gen7
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- 3% loss in J/psi yield in 7.0.0pre2 tracked down to muon linking
  o COT finds all tracks
  o SiSA track attached to stub instead of OI track
- Discussion: can muon linker be improved?
  o Simple solution: reject tracks with e.g. fewer than 10 COT hits
  o More sophisticated: ordering by tracking algorithm
  o Changes to FWD tracking: problem should be much smaller in 7.0.0pre3
  o Unclear: time for change and validation vs. physics gain