HitTripletsIntroduction < CMS

---+++!!Low p<sub>T</sub> tracking

For global reconstruction the defaults are
<verbatim>
GlobalTrackingRegion ( float ptMin = 1., float originRadius = 0.2,
                       float originHalfLength = 15., float originZPos = 0.,
                       bool precise = false );
</verbatim>

---++++Generation of hit pairs

=ORCA/src/TrackerReco/TkHitPairs= %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitPairs/\
src/HitPairGeneratorFromLayerPair.cc?v=snapshot][HitPairGeneratorFromLayerPair.cc]] %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitPairs/\
interface/HitPairGeneratorFromLayerPair.h?v=snapshot][HitPairGeneratorFromLayerPair.h]]

---++++Generation of hit triplets

=ORCA/src/TrackerReco/TkHitTriplets= %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitTriplets/\
src/HitTripletGeneratorFromPairAndLayers.cc?v=snapshot][HitTripletGeneratorFromPairAndLayers.cc]] %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitTriplets/\
src/HitTripletGeneratorFromPairAndLayers.h?v=snapshot][HitTripletGeneratorFromPairAndLayers.h]]

Sensitive parameters for the extrapolation of the third hit are %BR%
=float dphi = 0.03;= %BR%
=if (fabs(dist) > 0.025) continue;=

*Rough prediction*

=ORCA/src/TrackerReco/TkHitTriplets= %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitTriplets/\
src/ThirdHitRZPrediction.cc?v=snapshot][ThirdHitRZPrediction.cc]] %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitTriplets/\
interface/ThirdHitRZPrediction.h?v=snapshot][ThirdHitRZPrediction.h]]

Important parameters are %BR%
=theTolerance = Margin(0.03,0.03);= %BR%
=theTolerance = Margin(0.02,0.02);=

*More accurate prediction*

Fast circle fit with the conformal mapping method ([[http://dx.doi.org/10.1016/0168-9002(88)90722-X][article]]) %BR%
=ORCA/src/TrackerReco/TkHitTriplets= %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitTriplets/\
src/ThirdHitPredictionFromInvParabola.cc?v=snapshot][ThirdHitPredictionFromInvParabola.cc]] %BR%
[[http://cmsdoc.cern.ch/swdev/lxr/ORCA/source/ORCA/src/TrackerReco/TkHitTriplets/\
interface/ThirdHitPredictionFromInvParabola.h?v=snapshot][ThirdHitPredictionFromInvParabola.h]]

-- Main.FerencSikler - 14 Mar 2006

This topic: CMS > TrackerSoftware > HitTripletsIntroduction
Topic revision: r3 - 2006-03-15 - FerencSikler

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