SeedForPhotonConversion1Leg.cc

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#include "SeedForPhotonConversion1Leg.h"

#include "TrackingTools/KalmanUpdators/interface/KFUpdator.h"
#include "RecoTracker/TkSeedGenerator/interface/FastHelix.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "TrackingTools/MaterialEffects/interface/PropagatorWithMaterial.h"
#include "TrackingTools/GeomPropagators/interface/PropagationExceptions.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateTransform.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"

//#define mydebug_seed
namespace {
  template <class T>
  T sqr(T t) {
    return t * t;
  }
}  // namespace

const TrajectorySeed* SeedForPhotonConversion1Leg::trajectorySeed(TrajectorySeedCollection& seedCollection,
                                                                  const SeedingHitSet& hits,
                                                                  const GlobalPoint& vertex,
                                                                  const GlobalVector& vertexBounds,
                                                                  float ptmin,
                                                                  const edm::EventSetup& es,
                                                                  float cotTheta,
                                                                  std::stringstream& ss) {
  pss = &ss;
  if (hits.size() < 2)
    return nullptr;

  GlobalTrajectoryParameters kine = initialKinematic(hits, vertex, es, cotTheta);
  float sinTheta = sin(kine.momentum().theta());

  CurvilinearTrajectoryError error = initialError(vertexBounds, ptmin, sinTheta);
  FreeTrajectoryState fts(kine, error);

  return buildSeed(seedCollection, hits, fts, es);
}

GlobalTrajectoryParameters SeedForPhotonConversion1Leg::initialKinematic(const SeedingHitSet& hits,
                                                                         const GlobalPoint& vertexPos,
                                                                         const edm::EventSetup& es,
                                                                         const float cotTheta) const {
  GlobalTrajectoryParameters kine;

  SeedingHitSet::ConstRecHitPointer tth1 = hits[0];
  SeedingHitSet::ConstRecHitPointer tth2 = hits[1];

  // FIXME optimize: move outside loop
  const auto& bfield = es.getData(theBfieldToken);
  float nomField = bfield.nominalValue();

  FastHelix helix(tth2->globalPosition(), tth1->globalPosition(), vertexPos, nomField, &bfield, vertexPos);
  kine = helix.stateAtVertex();

  //force the pz/pt equal to the measured one
  if (fabs(cotTheta) < cotTheta_Max)
    kine = GlobalTrajectoryParameters(
        kine.position(),
        GlobalVector(kine.momentum().x(), kine.momentum().y(), kine.momentum().perp() * cotTheta),
        kine.charge(),
        &kine.magneticField());
  else
    kine = GlobalTrajectoryParameters(
        kine.position(),
        GlobalVector(kine.momentum().x(), kine.momentum().y(), kine.momentum().perp() * cotTheta_Max),
        kine.charge(),
        &kine.magneticField());

#ifdef mydebug_seed
  uint32_t detid;
  (*pss) << "[SeedForPhotonConversion1Leg] initialKinematic tth1 ";
  detid = tth1->geographicalId().rawId();
  po.print(*pss, detid);
  (*pss) << " \t " << detid << " " << tth1->localPosition() << " " << tth1->globalPosition();
  detid = tth2->geographicalId().rawId();
  (*pss) << " \n\t tth2 ";
  po.print(*pss, detid);
  (*pss) << " \t " << detid << " " << tth2->localPosition() << " " << tth2->globalPosition() << "\nhelix momentum "
         << kine.momentum() << " pt " << kine.momentum().perp() << " radius " << 1 / kine.transverseCurvature();
#endif

  bool isBOFF = (0 == nomField);
  ;
  if (isBOFF && (theBOFFMomentum > 0)) {
    kine =
        GlobalTrajectoryParameters(kine.position(), kine.momentum().unit() * theBOFFMomentum, kine.charge(), &bfield);
  }
  return kine;
}

CurvilinearTrajectoryError SeedForPhotonConversion1Leg::initialError(const GlobalVector& vertexBounds,
                                                                     float ptMin,
                                                                     float sinTheta) const {
  // Set initial uncertainty on track parameters, using only P.V. constraint and no hit
  // information.
  GlobalError vertexErr(sqr(vertexBounds.x()), 0, sqr(vertexBounds.y()), 0, 0, sqr(vertexBounds.z()));

  AlgebraicSymMatrix55 C = ROOT::Math::SMatrixIdentity();

  // FIXME: minC00. Prevent apriori uncertainty in 1/P from being too small,
  // to avoid instabilities.
  // N.B. This parameter needs optimising ...
  float sin2th = sqr(sinTheta);
  float minC00 = 1.0;
  C[0][0] = std::max(sin2th / sqr(ptMin), minC00);
  float zErr = vertexErr.czz();
  float transverseErr = vertexErr.cxx();  // assume equal cxx cyy
  C[3][3] = transverseErr;
  C[4][4] = zErr * sin2th + transverseErr * (1 - sin2th);

  return CurvilinearTrajectoryError(C);
}

const TrajectorySeed* SeedForPhotonConversion1Leg::buildSeed(TrajectorySeedCollection& seedCollection,
                                                             const SeedingHitSet& hits,
                                                             const FreeTrajectoryState& fts,
                                                             const edm::EventSetup& es) const {
  // FIXME all this stuff shoould go in an initialized...

  // get tracker
  const auto* tracker = &es.getData(theTrackerToken);

  // get propagator
  const Propagator* propagator = &es.getData(thePropagatorToken);

  auto builder = static_cast<TkTransientTrackingRecHitBuilder const*>(&es.getData(theTTRHBuilderToken));
  auto cloner = (*builder).cloner();

  // get updator
  KFUpdator updator;

  // Now update initial state track using information from seed hits.

  TrajectoryStateOnSurface updatedState;
  edm::OwnVector<TrackingRecHit> seedHits;

  const TrackingRecHit* hit = nullptr;
  for (unsigned int iHit = 0; iHit < hits.size() && iHit < 1; iHit++) {
    hit = hits[iHit];
    TrajectoryStateOnSurface state =
        (iHit == 0) ? propagator->propagate(fts, tracker->idToDet(hit->geographicalId())->surface())
                    : propagator->propagate(updatedState, tracker->idToDet(hit->geographicalId())->surface());
    if (!state.isValid())
      return nullptr;

    SeedingHitSet::ConstRecHitPointer tth = hits[iHit];

    std::unique_ptr<BaseTrackerRecHit> newtth(refitHit(tth, state, cloner));

    if (!checkHit(state, &*newtth, es))
      return nullptr;

    updatedState = updator.update(state, *newtth);
    if (!updatedState.isValid())
      return nullptr;

    seedHits.push_back(newtth.release());
#ifdef mydebug_seed
    uint32_t detid = hit->geographicalId().rawId();
    (*pss) << "\n[SeedForPhotonConversion1Leg] hit " << iHit;
    po.print(*pss, detid);
    (*pss) << " " << detid << "\t lp " << hit->localPosition() << " tth " << tth->localPosition() << " newtth "
           << newtth->localPosition() << " state " << state.globalMomentum().perp();
#endif
  }

  if (!hit)
    return nullptr;

  PTrajectoryStateOnDet const& PTraj =
      trajectoryStateTransform::persistentState(updatedState, hit->geographicalId().rawId());

  seedCollection.push_back(TrajectorySeed(PTraj, seedHits, alongMomentum));
  return &seedCollection.back();
}

SeedingHitSet::RecHitPointer SeedForPhotonConversion1Leg::refitHit(SeedingHitSet::ConstRecHitPointer hit,
                                                                   const TrajectoryStateOnSurface& state,
                                                                   const TkClonerImpl& cloner) const {
  //const TransientTrackingRecHit* a= hit.get();
  //return const_cast<TransientTrackingRecHit*> (a);
  //This was modified otherwise the rechit will have just the local x component and local y=0
  // To understand how to modify for pixels

  //const TSiStripRecHit2DLocalPos* b = dynamic_cast<const TSiStripRecHit2DLocalPos*>(a);
  //return const_cast<TSiStripRecHit2DLocalPos*>(b);
  return (SeedingHitSet::RecHitPointer)(cloner(*hit, state));
}