Soft physics

LatexModePLugin

Data

• http://cmsdbs.cern.ch/DBS2_discovery/
  • /CSA07Minbias_GEN_SIM/CMSSW_1_6_0-PreCSA07-A1/GEN-SIM-DIGI-RAW, contains 1958006 events, 193 files, 1.3TB.

Software

• Modifications for A-A tracking
  • RecoLocalTracker/SiStripRecHitConverter/src/SiStripRecHitMatcher.cc
  • RecoLocalTracker/SiStripRecHitConverter/src/StripCPEfromTrackAngle.cc
  • RecoTracker/MeasurementDet/src/TkStripMeasurementDet.cc

Definitions

Applied to primary tracks

• A simTrack is reconstructible if it has at least 3 hits in different pixel layers.
• A recTrack is associated to a simTrack if more than 50% of its recHits, but at least 3, are shared with the simTrack. (A recTrack can be associated to zero or one simTrack.)
• A simTrack is reconstructed n times if there are n recTracks which are associated to it.
• A recTrack is a fake if it has no associated simTrack.
• Acceptance: fraction of simTracks which are reconstructible.
• Efficiency: fraction of reconstructible simTracks which are at least once reconstructed.
• Multiple counting: fraction of reconstructible simTracks which are more than once reconstructed.
• Reconstruction rate: average number of reconstruction <n> for reconstructible simTracks.
• Fake rate: fraction of recTracks which are fake.

  	Depends on
  	kinematics	particle	multiplicity
  Acceptance
  Efficiency
  Multiple counting			?
  Fake rate

Applied to V0s

• A V0 is reconstructible if its daughters have at least 3 pixel hits separately
• Acceptance: fraction of V0s which are reconstructible
• Efficiency: fraction of reconstructible V0s which are reconstructed

Corrections

• Event related
• Track related
  For a given η bin
  dN_rec(p_T) = momTrans(p_T, p_T') * recRate(p_T') * acc(p_T') * dN_sim(p_T') + fakeRate(p_T, N_sim) * dN_sim(p_T)
  dN_sim(p_T') = acc^-1(p_T') * recRate^-1(p_T') * momTrans^-1(p_T', p_T) * [dN_rec(p_T)/(1 - fakeRate(p_T, N_rec))]

Track cleaning and merging

• Pixel tracks (RecoPixelVertexing/PixelLowPtUtilities/.../LowPtPixelTrackCleanerBySharedHits)
  Two tracks are considered if they have more than min(foundHits1,foundHits2)/2 recHits shared and their separate recHits do not share a detUnit.
  • If their impact parameter d0 is closer than 0.1 cm, then they are merged: separate hits of the second are given to the first one, the second track is removed.
  • Otherwise remove the track with higher impact.
• Global tracks (TrackingTools/TrajectoryCleaning/.../TrajectoryCleanerMerger.cc)
  Two trajectories are considered if they have more than min(foundHits1,foundHits2)/2 shared.
  • If their seed is the same, then they are merged: separate hits of the second are given to the first one, the second track is removed.
  • Otherwise both tracks are kept.

V0 reconstruction

• Impact: distance of the straight propagation line of the mother particle from the found primary vertex. If there are multiple vertices found, choose the smallest distance. If there are no vertices found, it is the distance of the straight propagation line from the beam line.

Batch jobs

CERN

• http://plus.web.cern.ch/plus/SLC4.html
• http://batch.web.cern.ch/batch/doc/quick-intro.html

LCG (LHC Computing Grid)

• http://www.lcg.kfki.hu/users.html
• http://pki.kfki.hu/index.hu.html

Links

• WorkBookTrackReco

-- FerencSikler - 26 Jul 2007