TSCPBuilderNoMaterial.cc

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#include "TrackingTools/PatternTools/interface/TSCPBuilderNoMaterial.h"
#include "DataFormats/GeometrySurface/interface/Surface.h"
#include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h"
#include "TrackingTools/AnalyticalJacobians/interface/AnalyticalCurvilinearJacobian.h"
#include "DataFormats/GeometrySurface/interface/BoundPlane.h"
#include "TrackingTools/GeomPropagators/interface/HelixBarrelPlaneCrossingByCircle.h"
#include "TrackingTools/TrajectoryParametrization/interface/TrajectoryStateExceptions.h"
#include "MagneticField/Engine/interface/MagneticField.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
 
TrajectoryStateClosestToPoint TSCPBuilderNoMaterial::operator()(const FTS& originalFTS,
                                                                const GlobalPoint& referencePoint) const {
  if (positionEqual(referencePoint, originalFTS.position()))
    return constructTSCP(originalFTS, referencePoint);
 
  // Now do the propagation or whatever...
 
  PairBoolFTS newStatePair = createFTSatTransverseImpactPoint(originalFTS, referencePoint);
  if (newStatePair.first) {
    return constructTSCP(newStatePair.second, referencePoint);
  } else {
    return TrajectoryStateClosestToPoint();
  }
}
 
TrajectoryStateClosestToPoint TSCPBuilderNoMaterial::operator()(const TSOS& originalTSOS,
                                                                const GlobalPoint& referencePoint) const {
  if (positionEqual(referencePoint, originalTSOS.globalPosition()))
    return constructTSCP(*originalTSOS.freeState(), referencePoint);
 
  // Now do the propagation
 
  PairBoolFTS newStatePair = createFTSatTransverseImpactPoint(*originalTSOS.freeState(), referencePoint);
  if (newStatePair.first) {
    return constructTSCP(newStatePair.second, referencePoint);
  } else {
    return TrajectoryStateClosestToPoint();
  }
}
 
TSCPBuilderNoMaterial::PairBoolFTS TSCPBuilderNoMaterial::createFTSatTransverseImpactPoint(
    const FTS& originalFTS, const GlobalPoint& referencePoint) const {
  //
  // Straight line approximation? |rho|<1.e-10 equivalent to ~ 1um
  // difference in transversal position at 10m.
  //
  if (fabs(originalFTS.transverseCurvature()) < 1.e-10) {
    return createFTSatTransverseImpactPointNeutral(originalFTS, referencePoint);
  } else {
    return createFTSatTransverseImpactPointCharged(originalFTS, referencePoint);
  }
}
 
TSCPBuilderNoMaterial::PairBoolFTS TSCPBuilderNoMaterial::createFTSatTransverseImpactPointCharged(
    const FTS& originalFTS, const GlobalPoint& referencePoint) const {
  GlobalVector pvecOrig = originalFTS.momentum();
  GlobalPoint xvecOrig = originalFTS.position();
  double kappa = originalFTS.transverseCurvature();
  double pxOrig = pvecOrig.x();
  double pyOrig = pvecOrig.y();
  double pzOrig = pvecOrig.z();
  double xOrig = xvecOrig.x();
  double yOrig = xvecOrig.y();
  double zOrig = xvecOrig.z();
 
  //  double fac = 1./originalFTS.charge()/MagneticField::inInverseGeV(referencePoint).z();
  double fac = 1. / originalFTS.charge() / (originalFTS.parameters().magneticField().inInverseGeV(referencePoint).z());
  GlobalVectorDouble xOrig2Centre = GlobalVectorDouble(fac * pyOrig, -fac * pxOrig, 0.);
  GlobalVectorDouble xOrigProj = GlobalVectorDouble(xOrig, yOrig, 0.);
  GlobalVectorDouble xRefProj = GlobalVectorDouble(referencePoint.x(), referencePoint.y(), 0.);
  GlobalVectorDouble deltax = xRefProj - xOrigProj - xOrig2Centre;
  GlobalVectorDouble ndeltax = deltax.unit();
 
  PropagationDirection direction = anyDirection;
  Surface::PositionType pos(referencePoint);
  // Need to define plane with orientation as the
  // ImpactPointSurface
  GlobalVector X(ndeltax.x(), ndeltax.y(), ndeltax.z());
  GlobalVector Y(0., 0., 1.);
  Surface::RotationType rot(X, Y);
  BoundPlane* plane = new BoundPlane(pos, rot);
  // Using Teddy's HelixBarrelPlaneCrossingByCircle for general barrel planes.
  // A large variety of other,
  // direct solutions turned out to be not so stable numerically.
  HelixBarrelPlaneCrossingByCircle planeCrossing(HelixPlaneCrossing::PositionType(xOrig, yOrig, zOrig),
                                                 HelixPlaneCrossing::DirectionType(pxOrig, pyOrig, pzOrig),
                                                 kappa,
                                                 direction);
  std::pair<bool, double> propResult = planeCrossing.pathLength(*plane);
  if (!propResult.first) {
    edm::LogWarning("TSCPBuilderNoMaterial") << "Propagation to perigee plane failed!";
    return PairBoolFTS(false, FreeTrajectoryState());
  }
  double s = propResult.second;
  HelixPlaneCrossing::PositionType xGen = planeCrossing.position(s);
  GlobalPoint xPerigee = GlobalPoint(xGen.x(), xGen.y(), xGen.z());
  // direction (reconverted to GlobalVector, renormalised)
  HelixPlaneCrossing::DirectionType pGen = planeCrossing.direction(s);
  pGen *= pvecOrig.mag() / pGen.mag();
  GlobalVector pPerigee = GlobalVector(pGen.x(), pGen.y(), pGen.z());
  delete plane;
 
  if (originalFTS.hasError()) {
    const AlgebraicSymMatrix55& errorMatrix = originalFTS.curvilinearError().matrix();
    AnalyticalCurvilinearJacobian curvilinJacobian(originalFTS.parameters(), xPerigee, pPerigee, s);
    const AlgebraicMatrix55& jacobian = curvilinJacobian.jacobian();
    CurvilinearTrajectoryError cte(ROOT::Math::Similarity(jacobian, errorMatrix));
 
    return PairBoolFTS(
        true,
        FreeTrajectoryState(GlobalTrajectoryParameters(
                                xPerigee, pPerigee, originalFTS.charge(), &(originalFTS.parameters().magneticField())),
                            cte));
  } else {
    return PairBoolFTS(true,
                       FreeTrajectoryState(GlobalTrajectoryParameters(
                           xPerigee, pPerigee, originalFTS.charge(), &(originalFTS.parameters().magneticField()))));
  }
}
 
TSCPBuilderNoMaterial::PairBoolFTS TSCPBuilderNoMaterial::createFTSatTransverseImpactPointNeutral(
    const FTS& originalFTS, const GlobalPoint& referencePoint) const {
  GlobalPoint xvecOrig = originalFTS.position();
  double phi = originalFTS.momentum().phi();
  double theta = originalFTS.momentum().theta();
  double xOrig = xvecOrig.x();
  double yOrig = xvecOrig.y();
  double zOrig = xvecOrig.z();
  double xR = referencePoint.x();
  double yR = referencePoint.y();
 
  double s2D = (xR - xOrig) * cos(phi) + (yR - yOrig) * sin(phi);
  double s = s2D / sin(theta);
  double xGen = xOrig + s2D * cos(phi);
  double yGen = yOrig + s2D * sin(phi);
  double zGen = zOrig + s2D / tan(theta);
  GlobalPoint xPerigee = GlobalPoint(xGen, yGen, zGen);
 
  GlobalVector pPerigee = originalFTS.momentum();
 
  if (originalFTS.hasError()) {
    const AlgebraicSymMatrix55& errorMatrix = originalFTS.curvilinearError().matrix();
    AnalyticalCurvilinearJacobian curvilinJacobian(originalFTS.parameters(), xPerigee, pPerigee, s);
    const AlgebraicMatrix55& jacobian = curvilinJacobian.jacobian();
    CurvilinearTrajectoryError cte(ROOT::Math::Similarity(jacobian, errorMatrix));
 
    return PairBoolFTS(
        true,
        FreeTrajectoryState(GlobalTrajectoryParameters(
                                xPerigee, pPerigee, originalFTS.charge(), &(originalFTS.parameters().magneticField())),
                            cte));
  } else {
    return PairBoolFTS(true,
                       FreeTrajectoryState(GlobalTrajectoryParameters(
                           xPerigee, pPerigee, originalFTS.charge(), &(originalFTS.parameters().magneticField()))));
  }
}