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#include "PhysicsTools/LeptonIsolation/interface/PropagateToCal.h"
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PropagateToCal::PropagateToCal(const edm::ParameterSet & cfg)
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{
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theIgnoreMaterial_ = cfg.getParameter<bool>( "IgnoreMaterial" );
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radius_ = cfg.getParameter<double>("CalRadius");
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maxZ_ = cfg.getParameter<double>("CalMaxZ");
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minZ_ = cfg.getParameter<double>("CalMinZ");
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if (maxZ_ < minZ_) {
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throw cms::Exception("BadConfig") << "PropagateToCal: CalMaxZ (" << maxZ_
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<< ") smaller than CalMinZ (" << minZ_ << ").";
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}
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}
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PropagateToCal::~PropagateToCal()
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{
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}
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bool PropagateToCal::propagate(const GlobalPoint& vertex,
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GlobalVector& Cand, int charge, const edm::EventSetup &setup) const
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{
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///the code is inspired by Gero's CosmicGenFilterHelix class:
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bool result = true;
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const MagneticField * field = getMagneticField(setup);
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typedef std::pair<TrajectoryStateOnSurface, double> TsosPath;
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SteppingHelixPropagator propagator(field); // should we somehow take it from ESetup???
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propagator.setMaterialMode(theIgnoreMaterial_); // no material effects if set to true
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propagator.setNoErrorPropagation(true);
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const FreeTrajectoryState fts(GlobalTrajectoryParameters(vertex, Cand, charge, field));
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const Surface::RotationType dummyRot;
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/// target cylinder, around z-axis
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Cylinder::ConstCylinderPointer theTargetCylinder =
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Cylinder::build(Surface::PositionType(0.,0.,0.), dummyRot, radius_);
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/// plane closing cylinder at 'negative' side
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Plane::ConstPlanePointer theTargetPlaneMin =
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Plane::build(Surface::PositionType(0.,0.,minZ_), dummyRot);
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/// plane closing cylinder at 'positive' side
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Plane::ConstPlanePointer theTargetPlaneMax =
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Plane::build(Surface::PositionType(0.,0.,maxZ_), dummyRot);
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TsosPath aTsosPath(propagator.propagateWithPath(fts, *theTargetCylinder));
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if (!aTsosPath.first.isValid()) {
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result = false;
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} else if (aTsosPath.first.globalPosition().z() < theTargetPlaneMin->position().z()) {
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// If on cylinder, but outside minimum z, try minimum z-plane:
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// (Would it be possible to miss rdius on plane, but reach cylinder afterwards in z-range?
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// No, at least not in B-field parallel to z-axis which is cylinder axis.)
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aTsosPath = propagator.propagateWithPath(fts, *theTargetPlaneMin);
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if (!aTsosPath.first.isValid()
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|| aTsosPath.first.globalPosition().perp() > theTargetCylinder->radius()) {
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result = false;
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}
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} else if (aTsosPath.first.globalPosition().z() > theTargetPlaneMax->position().z()) {
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// Analog for outside maximum z:
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aTsosPath = propagator.propagateWithPath(fts, *theTargetPlaneMax);
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if (!aTsosPath.first.isValid()
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|| aTsosPath.first.globalPosition().perp() > theTargetCylinder->radius()) {
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result = false;
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}
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}
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///The result is the vector connecting the extrapolation endPoint on the Calorimeter surface and
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///the origin of the coordinate system, point (0,0,0).
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if (result) {
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Cand = GlobalVector(aTsosPath.first.globalPosition().x(),
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aTsosPath.first.globalPosition().y(),
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aTsosPath.first.globalPosition().z() );
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}
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return result;///Successfully propagated to the calorimeter or not
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}
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const MagneticField* PropagateToCal::getMagneticField(const edm::EventSetup &setup) const
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{
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edm::ESHandle<MagneticField> fieldHandle;
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setup.get<IdealMagneticFieldRecord>().get(fieldHandle);
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return fieldHandle.product();
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}
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