StateOnTrackerBound.cc

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#include "TrackingTools/GeomPropagators/interface/StateOnTrackerBound.h"
#include "TrackingTools/GeomPropagators/interface/Propagator.h"
#include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "TrackingTools/GeomPropagators/interface/TrackerBounds.h"
#include "DataFormats/GeometrySurface/interface/BoundDisk.h"
#include "DataFormats/GeometrySurface/interface/BoundCylinder.h"

//Ported from ORCA

StateOnTrackerBound::StateOnTrackerBound(const Propagator* prop) : thePropagator(prop->clone()) {}

StateOnTrackerBound::~StateOnTrackerBound() { delete thePropagator; }

TrajectoryStateOnSurface StateOnTrackerBound::operator()(const TrajectoryStateOnSurface& tsos) const {
  return operator()(*tsos.freeState());
}

TrajectoryStateOnSurface StateOnTrackerBound::operator()(const FreeTrajectoryState& fts) const {
  // try to guess if propagation should be first to cylinder or first to disk
  float tanTheta = (fts.position().perp() > 70) ? fts.position().perp() / fts.position().z()
                                                : fts.momentum().perp() / fts.momentum().z();
  float corner = TrackerBounds::radius() / TrackerBounds::halfLength();

  TrajectoryStateOnSurface firstTry;
  if (tanTheta < 0 && fabs(tanTheta) < corner) {
    firstTry = thePropagator->propagate(fts, TrackerBounds::negativeEndcapDisk());

    if (!firstTry.isValid()) {
      return thePropagator->propagate(fts, TrackerBounds::barrelBound());
    }
    if (firstTry.globalPosition().perp() > TrackerBounds::radius()) {
      // the propagation should have gone to the cylinder
      return thePropagator->propagate(fts, TrackerBounds::barrelBound());
    } else
      return firstTry;
  } else if (tanTheta > 0 && fabs(tanTheta) < corner) {
    firstTry = thePropagator->propagate(fts, TrackerBounds::positiveEndcapDisk());
    if (!firstTry.isValid()) {
      return thePropagator->propagate(fts, TrackerBounds::barrelBound());
    }
    if (firstTry.globalPosition().perp() > TrackerBounds::radius()) {
      return thePropagator->propagate(fts, TrackerBounds::barrelBound());
    } else
      return firstTry;
  } else {
    // barrel
    firstTry = thePropagator->propagate(fts, TrackerBounds::barrelBound());
    if (!firstTry.isValid()) {
      if (tanTheta < 0)
        return thePropagator->propagate(fts, TrackerBounds::negativeEndcapDisk());
      if (tanTheta >= 0)
        return thePropagator->propagate(fts, TrackerBounds::positiveEndcapDisk());
      return firstTry;
    }
    if (firstTry.globalPosition().z() < -TrackerBounds::halfLength()) {
      // the propagation should have gone to the negative disk
      return thePropagator->propagate(fts, TrackerBounds::negativeEndcapDisk());
    } else if (firstTry.globalPosition().z() > TrackerBounds::halfLength()) {
      // the propagation should have gone to the positive disk
      return thePropagator->propagate(fts, TrackerBounds::positiveEndcapDisk());
    } else
      return firstTry;
  }
  return firstTry;
}