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Minutes of Tracking Meeting, June 20, 2007
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taken by U. Husemann


Pat Lukens: Tools for Hyperon Reconstruction
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- 2 new tools (see ~ptl/ana/v6.1.4/VertexAlg)
  1) better pointing constraint for charged objects (CVTMFT)
  2) add silicon hits to Xi- and daughter track

1) CVTMFT
- Motivation for charged Xi pointing constraint: cannot assume straight line
- Treat Xi- as track to fit into framework
- Current pointing constraint L_xy cross P = 0:
  wrong for charged particle track -> upgrade L_xy to L_xy'
- Extend CVTMFT (FORTRAN):
  o change to COMMON block: add variable to indicate if charged
  o computation: choose L_xy or L_xy'
  o no changes to the interface
- Test on MC Xi_B -> Xi and data: track based method works well

2) Silicon in Xi- reconstruction
- Establish topology using only COT information 
- Adding silicon hits to long-lived particles (with decay lengths 
  comparable to ISL outer radius, e.g. Lambda, K0S) gives wrong answers
- Don't add hits close to the track intersections
- Wanted: function to add hits track by track within a given radius range
- Hacked CharmMods K0S finder
- Tested adding silicon hits: check impact parameter uncertainty
  o not very many tracks have silicon hits (large group: 1 ISL hit)
  o one hit helps, two hits help a lot
  o Lambda from Xi- decay: not worth the effort (except maybe ISL)
  o pi form Xi- decay: reduction of impact parameter uncertainty marginal
  o road definition for Xi- track: silicon (ISL) hit on pi helps
- Add silicon hits to Xi- track itself:
  o at least 70% have at least one hit
  o "short fliers" are lost: good part of the missing 30%
  o reduction of combinatorial background

Discussion:
- New feature works only on pointing constraints
- Add a switch to activate the new features
- What has to be changed downstream of the package
  (e.g. private COMMON block conversions will break)
- Duplicated CVTMFT code anywhere else?
- Validation of SECVTX: should see zero change (convener Chris Neu present)
- Librarian for VertexAlg: 
  o Original author of CVTMFT: John Marriner 
  o Later maintained by Peter Berge
  o Early Run II: Craig Blocker
- How far do we have to spread the word? 
  o B-group already knows
  o Pat (and Dmitry) "only users"
- Integrate into development or some frozen release?


All: First Pre-Gen7-Release
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- Aseet will add changes to axial segment linking today
- Plan to build release starting tomorrow (may be delayed by integration of ROOT5)
- Antonio: will reprocess high-pt electron/muon triggers (2 weeks)
  o start on 0d and 0h datasets
  o could save production output to tape to create standard ntuples
- Oliver/Ulrich: further validation
  o Koji's validation plots
  o 10k tests with Pasha Murat
  o discuss further validation effort with Doug