NuclearInteractionFinder.cc

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#include "RecoTracker/NuclearSeedGenerator/interface/NuclearInteractionFinder.h"
#include "TrackingTools/TrackFitters/interface/TrajectoryStateWithArbitraryError.h"
#include "TrackingTools/PatternTools/interface/TrajMeasLessEstim.h"

#include "Geometry/TrackerGeometryBuilder/interface/TrackerGeometry.h"

#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "TrackingTools/KalmanUpdators/interface/Chi2MeasurementEstimatorBase.h"
#include "DataFormats/TrajectorySeed/interface/PropagationDirection.h"

NuclearInteractionFinder::NuclearInteractionFinder(const Config& iConfig,
                                                   const TrackerGeometry* iTrackerGeom,
                                                   const Propagator* iPropagator,
                                                   const MeasurementEstimator* iEstimator,
                                                   const MeasurementTracker* iMeasurementTracker,
                                                   const GeometricSearchTracker* iGeomSearchTracker,
                                                   const NavigationSchool* iNavigationSchool)
    : maxHits(iConfig.maxHits),
      rescaleErrorFactor(iConfig.rescaleErrorFactor),
      checkCompletedTrack(iConfig.checkCompletedTrack) {
  thePropagator = iPropagator;
  theEstimator = iEstimator;
  theMeasurementTracker = iMeasurementTracker;
  theGeomSearchTracker = iGeomSearchTracker;
  theNavigationSchool = iNavigationSchool;

  LogDebug("NuclearSeedGenerator") << "New NuclearInteractionFinder instance with parameters : \n"
                                   << "maxHits : " << maxHits << "\n"
                                   << "rescaleErrorFactor : " << rescaleErrorFactor << "\n"
                                   << "checkCompletedTrack : " << checkCompletedTrack << "\n";

  nuclTester = std::make_unique<NuclearTester>(maxHits, theEstimator, iTrackerGeom);

  currentSeed = std::make_unique<SeedFromNuclearInteraction>(thePropagator, iTrackerGeom, iConfig.ptMin);

  thePrimaryHelix = std::make_unique<TangentHelix>();
}

//----------------------------------------------------------------------
bool NuclearInteractionFinder::run(const Trajectory& traj, const MeasurementTrackerEvent& event) {
  if (traj.empty() || !traj.isValid())
    return false;

  LogDebug("NuclearSeedGenerator") << "Analyzis of a new trajectory with a number of valid hits = " << traj.foundHits();

  std::vector<TrajectoryMeasurement> measurements = traj.measurements();

  // initialization
  nuclTester->reset(measurements.size());
  allSeeds.clear();

  LayerMeasurements layerMeasurements(*theMeasurementTracker, event);

  if (traj.direction() == alongMomentum) {
    std::reverse(measurements.begin(), measurements.end());
  }

  std::vector<TrajectoryMeasurement>::const_iterator it_meas = measurements.begin();

  std::vector<double> ncompatibleHits;
  bool NIfound = false;

  // Loop on all the RecHits.
  while (!NIfound) {
    if (it_meas == measurements.end())
      break;

    // check only the maxHits outermost hits of the primary track
    if (nuclTester->nHitsChecked() > maxHits)
      break;

    nuclTester->push_back(*it_meas, findCompatibleMeasurements(*it_meas, rescaleErrorFactor, layerMeasurements));

    LogDebug("NuclearSeedGenerator") << "Number of compatible meas:" << (nuclTester->back()).size() << "\n"
                                     << "Mean distance between hits :" << nuclTester->meanHitDistance() << "\n"
                                     << "Forward estimate :" << nuclTester->fwdEstimate() << "\n";

    // don't check tracks which reach the end of the tracker if checkCompletedTrack==false
    if (checkCompletedTrack == false && (nuclTester->compatibleHits()).front() == 0)
      break;

    if (nuclTester->isNuclearInteraction())
      NIfound = true;

    ++it_meas;
  }

  if (NIfound) {
    LogDebug("NuclearSeedGenerator") << "NUCLEAR INTERACTION FOUND at index : " << nuclTester->nuclearIndex() << "\n";

    // Get correct parametrization of the helix of the primary track at the interaction point (to be used by improveCurrentSeed)
    definePrimaryHelix(measurements.begin() + nuclTester->nuclearIndex() - 1);

    this->fillSeeds(nuclTester->goodTMPair());

    return true;
  }

  return false;
}
//----------------------------------------------------------------------
void NuclearInteractionFinder::definePrimaryHelix(std::vector<TrajectoryMeasurement>::const_iterator it_meas) {
  // This method uses the 3 last TM after the interaction point to calculate the helix parameters

  GlobalPoint pt[3];
  for (int i = 0; i < 3; i++) {
    pt[i] = (it_meas->updatedState()).globalParameters().position();
    it_meas++;
  }
  thePrimaryHelix = std::make_unique<TangentHelix>(pt[0], pt[1], pt[2]);
}
//----------------------------------------------------------------------
std::vector<TrajectoryMeasurement> NuclearInteractionFinder::findCompatibleMeasurements(
    const TM& lastMeas, double rescale, const LayerMeasurements& layerMeasurements) const {
  const TSOS& currentState = lastMeas.updatedState();
  LogDebug("NuclearSeedGenerator") << "currentState :" << currentState << "\n";

  TSOS newState = rescaleError(rescale, currentState);
  return findMeasurementsFromTSOS(newState, lastMeas.recHit()->geographicalId(), layerMeasurements);
}
//----------------------------------------------------------------------
std::vector<TrajectoryMeasurement> NuclearInteractionFinder::findMeasurementsFromTSOS(
    const TSOS& currentState, DetId detid, const LayerMeasurements& layerMeasurements) const {
  using namespace std;
  int invalidHits = 0;
  vector<TM> result;
  const DetLayer* lastLayer = theGeomSearchTracker->detLayer(detid);
  vector<const DetLayer*> nl;

  if (lastLayer) {
    nl = theNavigationSchool->nextLayers(*lastLayer, *currentState.freeState(), alongMomentum);
  } else {
    edm::LogError("NuclearInteractionFinder") << "In findCompatibleMeasurements : lastLayer not accessible";
    return result;
  }

  if (nl.empty()) {
    LogDebug("NuclearSeedGenerator") << "In findCompatibleMeasurements :  no compatible layer found";
    return result;
  }

  for (vector<const DetLayer*>::iterator il = nl.begin(); il != nl.end(); il++) {
    vector<TM> tmp = layerMeasurements.measurements((**il), currentState, *thePropagator, *theEstimator);
    if (!tmp.empty()) {
      if (result.empty())
        result = tmp;
      else {
        // keep one dummy TM at the end, skip the others
        result.insert(result.end() - invalidHits, tmp.begin(), tmp.end());
      }
      invalidHits++;
    }
  }

  // sort the final result, keep dummy measurements at the end
  if (result.size() > 1) {
    sort(result.begin(), result.end() - invalidHits, TrajMeasLessEstim());
  }
  return result;
}

//----------------------------------------------------------------------
void NuclearInteractionFinder::fillSeeds(
    const std::pair<TrajectoryMeasurement, std::vector<TrajectoryMeasurement> >& tmPairs) {
  // This method returns the seeds calculated by the class SeedsFromNuclearInteraction

  const TM& innerTM = tmPairs.first;
  const std::vector<TM>& outerTMs = tmPairs.second;

  // Loop on all outer TM
  for (std::vector<TM>::const_iterator outtm = outerTMs.begin(); outtm != outerTMs.end(); outtm++) {
    if ((innerTM.recHit())->isValid() && (outtm->recHit())->isValid()) {
      currentSeed->setMeasurements(innerTM.updatedState(), innerTM.recHit(), outtm->recHit());
      allSeeds.push_back(*currentSeed);
    } else
      LogDebug("NuclearSeedGenerator") << "The initial hits for seeding are invalid"
                                       << "\n";
  }
  return;
}
//----------------------------------------------------------------------
std::unique_ptr<TrajectorySeedCollection> NuclearInteractionFinder::getPersistentSeeds() {
  auto output = std::make_unique<TrajectorySeedCollection>();
  for (std::vector<SeedFromNuclearInteraction>::const_iterator it_seed = allSeeds.begin(); it_seed != allSeeds.end();
       it_seed++) {
    if (it_seed->isValid()) {
      output->push_back(it_seed->TrajSeed());
    } else
      LogDebug("NuclearSeedGenerator") << "The seed is invalid"
                                       << "\n";
  }
  return output;
}
//----------------------------------------------------------------------
void NuclearInteractionFinder::improveSeeds(const MeasurementTrackerEvent& event) {
  std::vector<SeedFromNuclearInteraction> newSeedCollection;

  LayerMeasurements layerMeasurements(*theMeasurementTracker, event);

  // loop on all actual seeds
  for (std::vector<SeedFromNuclearInteraction>::const_iterator it_seed = allSeeds.begin(); it_seed != allSeeds.end();
       it_seed++) {
    if (!it_seed->isValid())
      continue;

    // find compatible TM in an outer layer
    std::vector<TM> thirdTMs =
        findMeasurementsFromTSOS(it_seed->updatedTSOS(), it_seed->outerHitDetId(), layerMeasurements);

    // loop on those new TMs
    for (std::vector<TM>::const_iterator tm = thirdTMs.begin(); tm != thirdTMs.end(); tm++) {
      if (!tm->recHit()->isValid())
        continue;

      // create new seeds collection using the circle equation
      currentSeed->setMeasurements(*thePrimaryHelix, it_seed->initialTSOS(), it_seed->outerHit(), tm->recHit());
      newSeedCollection.push_back(*currentSeed);
    }
  }
  allSeeds.clear();
  allSeeds = newSeedCollection;
}
//----------------------------------------------------------------------
TrajectoryStateOnSurface NuclearInteractionFinder::rescaleError(float rescale, const TSOS& state) const {
  AlgebraicSymMatrix55 m(state.localError().matrix());
  AlgebraicSymMatrix55 mr;
  LocalTrajectoryParameters ltp = state.localParameters();

  // we assume that the error on q/p is equal to 20% of q/p * rescale
  mr(0, 0) = (ltp.signedInverseMomentum() * 0.2 * rescale) * (ltp.signedInverseMomentum() * 0.2 * rescale);

  // the error on dx/z and dy/dz is fixed to 10% (* rescale)
  mr(1, 1) = 1E-2 * rescale * rescale;
  mr(2, 2) = 1E-2 * rescale * rescale;

  // the error on the local x and y positions are not modified.
  mr(3, 3) = m(3, 3);
  mr(4, 4) = m(4, 4);

  return TSOS(ltp, mr, state.surface(), &(state.globalParameters().magneticField()), state.surfaceSide());
}