TransverseImpactPointExtrapolator Class Reference

#include <TransverseImpactPointExtrapolator.h>

List of all members.

Public Member Functions
TrajectoryStateOnSurface	extrapolate (const FreeTrajectoryState &fts, const GlobalPoint &vtx) const
	extrapolation with default (=geometrical) propagator
TrajectoryStateOnSurface	extrapolate (const TrajectoryStateOnSurface tsos, const GlobalPoint &vtx, const Propagator &u) const
	as above, but from TrajectoryStateOnSurface
TrajectoryStateOnSurface	extrapolate (const TrajectoryStateOnSurface tsos, const GlobalPoint &vtx) const
	as above, but from TrajectoryStateOnSurface
TrajectoryStateOnSurface	extrapolate (const FreeTrajectoryState &fts, const GlobalPoint &vtx, const Propagator &u) const
	extrapolation with user-supplied propagator
	TransverseImpactPointExtrapolator (const MagneticField *field)
	constructor with default geometrical propagator
	TransverseImpactPointExtrapolator ()
	constructor with default geometrical propagator
	TransverseImpactPointExtrapolator (const Propagator &u)
	constructor with user-supplied propagator
Private Member Functions
TrajectoryStateOnSurface	doExtrapolation (const TrajectoryStateOnSurface tsos, const GlobalPoint &vtx, const Propagator &u) const
	extrapolation of (multi) TSOS with (internal or user-supplied) propagator
TrajectoryStateOnSurface	doExtrapolation (const FreeTrajectoryState &fts, const GlobalPoint &vtx, const Propagator &u) const
	extrapolation of (single) FTS with (internal or user-supplied) propagator
ReferenceCountingPointer < BoundPlane >	tipSurface (const GlobalPoint &position, const GlobalVector &momentum, const double &signedTransverseRadius, const GlobalPoint &vtx) const
	computation of the TIP surface
Private Attributes
DeepCopyPointerByClone < Propagator >	thePropagator

---

Detailed Description

Extrapolate to impact point with respect to vtx, i.e. point of closest approach to vtx in 2D. The surface of the returned TrajectoryStateOnSurface is chosen centred on vtx; the axes of the local coordinate system (x_loc, y_loc, z_loc) are z_loc // trajectory direction in transverse plane at impact point; x_loc normal to trajectory and along impact vector (impact point - vtx); y_loc forms a right-handed system with the other axes.

Definition at line 26 of file TransverseImpactPointExtrapolator.h.

---

Constructor & Destructor Documentation

TransverseImpactPointExtrapolator::TransverseImpactPointExtrapolator

(

)

constructor with default geometrical propagator

Definition at line 15 of file TransverseImpactPointExtrapolator.cc.

                                                                      :
  thePropagator(0) {}

TransverseImpactPointExtrapolator::TransverseImpactPointExtrapolator

(

const MagneticField *

field

)

constructor with default geometrical propagator

Definition at line 19 of file TransverseImpactPointExtrapolator.cc.

                                                                                                :
  thePropagator(new AnalyticalPropagator(field, anyDirection)) {}

TransverseImpactPointExtrapolator::TransverseImpactPointExtrapolator

(

const Propagator &

u

)

constructor with user-supplied propagator

Definition at line 22 of file TransverseImpactPointExtrapolator.cc.

References anyDirection, and thePropagator.

                                                                                         :
  thePropagator(u.clone()) 
{
  thePropagator->setPropagationDirection(anyDirection);
}

---

Member Function Documentation

TrajectoryStateOnSurface TransverseImpactPointExtrapolator::doExtrapolation	(	const TrajectoryStateOnSurface	tsos,
		const GlobalPoint &	vtx,
		const Propagator &	u
	)		const [private]

extrapolation of (multi) TSOS with (internal or user-supplied) propagator

Definition at line 69 of file TransverseImpactPointExtrapolator.cc.

References Vector3DBase< T, FrameTag >::cross(), TrajectoryStateOnSurface::freeState(), TrajectoryStateOnSurface::globalMomentum(), TrajectoryStateOnSurface::globalPosition(), LogDebug, PlaneBuilder::plane(), Propagator::propagate(), idealTransformation::rotation, tipSurface(), FreeTrajectoryState::transverseCurvature(), TrajectoryStateOnSurface::transverseCurvature(), csvLumiCalc::unit, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

Referenced by extrapolate().

{
  //
  // Compute tip surface
  //
  if (fabs(tsos.freeState()->transverseCurvature())<1.E-6){
    LogDebug("TransverseImpactPointExtrapolator")<< "negligeable curvature: using a trick to extrapolate:\n"<<tsos;

    //0T field probably
    //x is perpendicular to the momentum
    GlobalVector xLocal = GlobalVector(-tsos.globalMomentum().y(),tsos.globalMomentum().x(),0).unit();
    //y along global Z
    GlobalVector yLocal(0.,0.,1.);
    //z accordingly
    GlobalVector zLocal(xLocal.cross(yLocal));

    Surface::PositionType origin(vtx);
    Surface::RotationType rotation(xLocal,yLocal,zLocal);
    ReferenceCountingPointer<BoundPlane> surface =  PlaneBuilder().plane(origin,rotation);
    
    return p.propagate(*tsos.freeState(),*surface);
  }else{
  ReferenceCountingPointer<BoundPlane> surface = 
    tipSurface(tsos.globalPosition(),tsos.globalMomentum(),
               1./tsos.transverseCurvature(),vtx);
  //
  // propagate
  //
  return p.propagate(tsos,*surface);
  }
}

TrajectoryStateOnSurface TransverseImpactPointExtrapolator::doExtrapolation	(	const FreeTrajectoryState &	fts,
		const GlobalPoint &	vtx,
		const Propagator &	u
	)		const [private]

extrapolation of (single) FTS with (internal or user-supplied) propagator

Definition at line 104 of file TransverseImpactPointExtrapolator.cc.

References Vector3DBase< T, FrameTag >::cross(), LogDebug, FreeTrajectoryState::momentum(), PlaneBuilder::plane(), FreeTrajectoryState::position(), Propagator::propagate(), idealTransformation::rotation, tipSurface(), FreeTrajectoryState::transverseCurvature(), csvLumiCalc::unit, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

{
  //
  // Compute tip surface
  //
  if (fabs(fts.transverseCurvature())<1.E-6){
    LogDebug("TransverseImpactPointExtrapolator")<< "negligeable curvature: using a trick to extrapolate:\n"<<fts;

    //0T field probably
    //x is perpendicular to the momentum
    GlobalVector xLocal = GlobalVector(-fts.momentum().y(),fts.momentum().x(),0).unit();
    //y along global Z
    GlobalVector yLocal(0.,0.,1.);
    //z accordingly
    GlobalVector zLocal(xLocal.cross(yLocal));

    Surface::PositionType origin(vtx);
    Surface::RotationType rotation(xLocal,yLocal,zLocal);
    ReferenceCountingPointer<BoundPlane> surface =  PlaneBuilder().plane(origin,rotation);
    
    return p.propagate(fts,*surface);
  }else{
  ReferenceCountingPointer<BoundPlane> surface = 
    tipSurface(fts.position(),fts.momentum(),
               1./fts.transverseCurvature(),vtx);
  //
  // propagate
  //
  return p.propagate(fts,*surface);
  }
}

TrajectoryStateOnSurface TransverseImpactPointExtrapolator::extrapolate	(	const FreeTrajectoryState &	fts,
		const GlobalPoint &	vtx
	)		const

extrapolation with default (=geometrical) propagator

Definition at line 29 of file TransverseImpactPointExtrapolator.cc.

References doExtrapolation(), and thePropagator.

Referenced by GroupedCkfTrajectoryBuilder::advanceOneLayer(), reco::TrackTransientTrack::calculateTSOSAtVertex(), reco::TransientTrackFromFTS::calculateTSOSAtVertex(), reco::GsfTransientTrack::calculateTSOSAtVertex(), MuonCkfTrajectoryBuilder::collectMeasurement(), MultiRefittedTS::computeFreeTrajectoryState(), GsfConstraintAtVertex::constrainAtPoint(), SimpleNavigableLayer::crossingState(), MultiTrajectoryStateTransform::extrapolatedState(), GsfTrackProducerBase::fillMode(), CkfTrajectoryBuilder::findCompatibleMeasurements(), KFBasedPixelFitter::run(), reco::TrackTransientTrack::stateOnSurface(), reco::GsfTransientTrack::stateOnSurface(), reco::TransientTrackFromFTS::stateOnSurface(), and IPTools::transverseExtrapolate().

{
  return doExtrapolation(fts, vtx, *thePropagator);
}

TrajectoryStateOnSurface TransverseImpactPointExtrapolator::extrapolate	(	const TrajectoryStateOnSurface	tsos,
		const GlobalPoint &	vtx
	)		const

as above, but from TrajectoryStateOnSurface

Definition at line 36 of file TransverseImpactPointExtrapolator.cc.

References doExtrapolation(), TrajectoryStateOnSurface::isValid(), and thePropagator.

{
  if ( !tsos.isValid() )  return tsos;
  return doExtrapolation(tsos, vtx, *thePropagator);
}

TrajectoryStateOnSurface TransverseImpactPointExtrapolator::extrapolate	(	const TrajectoryStateOnSurface	tsos,
		const GlobalPoint &	vtx,
		const Propagator &	u
	)		const

as above, but from TrajectoryStateOnSurface

Definition at line 56 of file TransverseImpactPointExtrapolator.cc.

References anyDirection, doExtrapolation(), and TrajectoryStateOnSurface::isValid().

{
  if ( !tsos.isValid() )  return tsos;
  //
  // set propagator for bidirectional propagation
  //
  SetPropagationDirection setter(p,anyDirection);
  return doExtrapolation(tsos,vtx,p);
} 

TrajectoryStateOnSurface TransverseImpactPointExtrapolator::extrapolate	(	const FreeTrajectoryState &	fts,
		const GlobalPoint &	vtx,
		const Propagator &	u
	)		const

extrapolation with user-supplied propagator

Definition at line 44 of file TransverseImpactPointExtrapolator.cc.

References anyDirection, and doExtrapolation().

{
  //
  // set propagator for bidirectional propagation
  //
  SetPropagationDirection setter(p,anyDirection);
  return doExtrapolation(fts,vtx,p);
} 

ReferenceCountingPointer< BoundPlane > TransverseImpactPointExtrapolator::tipSurface	(	const GlobalPoint &	position,
		const GlobalVector &	momentum,
		const double &	signedTransverseRadius,
		const GlobalPoint &	vtx
	)		const [private]

computation of the TIP surface

Definition at line 139 of file TransverseImpactPointExtrapolator.cc.

References Vector3DBase< T, FrameTag >::cross(), LogDebug, PV2DBase< T, PVType, FrameType >::mag(), PlaneBuilder::plane(), idealTransformation::rotation, PV3DBase< T, PVType, FrameType >::x(), and PV3DBase< T, PVType, FrameType >::y().

Referenced by doExtrapolation().

{

  LogDebug("TransverseImpactPointExtrapolator")<< position<<"\n"
                                                    <<momentum<<"\n"
                                                    <<"signedTransverseRadius : "<<signedTransverseRadius<<"\n"
                                                    <<vertex;

  typedef Point2DBase<double,GlobalTag> PositionType2D;
  typedef Vector2DBase<double,GlobalTag> DirectionType2D;
  
  PositionType2D x0(position.x(),position.y());
  DirectionType2D t0(-momentum.y(),momentum.x());
  t0 = t0/t0.mag();

  PositionType2D xc(x0+signedTransverseRadius*t0);

  DirectionType2D vtxDirection(xc.x()-vertex.x(),xc.y()-vertex.y());
  double vtxDistance = vtxDirection.mag();

  Surface::PositionType origin(vertex);
  GlobalVector xLocal(vtxDirection.x()/vtxDistance,
                      vtxDirection.y()/vtxDistance,
                      0.);
  if ( vtxDistance<fabs(signedTransverseRadius) ) {
    LogDebug("TransverseImpactPointExtrapolator")<<"Inverting the x axis.";
    xLocal = -xLocal;
  }
  GlobalVector yLocal(0.,0.,1.);
  GlobalVector zLocal(xLocal.cross(yLocal));
  if ( zLocal.dot(momentum)<0. ) {
    LogDebug("TransverseImpactPointExtrapolator")<<"Inverting the y,z frame.";
    yLocal = -yLocal;
    zLocal = -zLocal;
  }
  Surface::RotationType rotation(xLocal,yLocal,zLocal);
  
  LogDebug("TransverseImpactPointExtrapolator")<<"plane center: "<<origin<<"\n"
                                               <<"plane rotation axis:\n"
                                               <<xLocal<<"\n"
                                               <<yLocal<<"\n"
                                               <<zLocal<<"\n"
                                               <<"x0: "<<x0<<"\n"
                                               <<"t0: "<<t0<<"\n"
                                               <<"xc: "<<xc<<"\n"
                                               <<"vtxDirection: "<<vtxDirection;

  return PlaneBuilder().plane(origin,rotation);
}

---

Member Data Documentation

DeepCopyPointerByClone<Propagator> TransverseImpactPointExtrapolator::thePropagator [private]

Definition at line 70 of file TransverseImpactPointExtrapolator.h.

Referenced by extrapolate(), and TransverseImpactPointExtrapolator().