PixelFitterByHelixProjections Class Reference

#include <PixelFitterByHelixProjections.h>

Inheritance diagram for PixelFitterByHelixProjections:

Public Member Functions
	PixelFitterByHelixProjections (const TrackerTopology *ttopo, const MagneticField *field, bool scaleErrorsForBPix1, float scaleFactor)
std::unique_ptr< reco::Track >	run (const std::vector< const TrackingRecHit * > &hits, const TrackingRegion &region) const override
	~PixelFitterByHelixProjections () override
Public Member Functions inherited from PixelFitterBase
virtual	~PixelFitterBase ()

Private Attributes
const MagneticField *	theField
const bool	thescaleErrorsForBPix1
const float	thescaleFactor
const TrackerTopology *	theTopo

Detailed Description

Definition at line 14 of file PixelFitterByHelixProjections.h.

Constructor & Destructor Documentation

PixelFitterByHelixProjections::PixelFitterByHelixProjections ( const TrackerTopology *  ttopo, const MagneticField *  field, bool  scaleErrorsForBPix1, float  scaleFactor  )

explicit

Definition at line 90 of file PixelFitterByHelixProjections.cc.

    : theTopo(ttopo), theField(field), thescaleErrorsForBPix1(scaleErrorsForBPix1), thescaleFactor(scaleFactor) {}

PixelFitterByHelixProjections::~PixelFitterByHelixProjections ( )

inlineoverride

Definition at line 20 of file PixelFitterByHelixProjections.h.

{}

Member Function Documentation

std::unique_ptr< reco::Track > PixelFitterByHelixProjections::run ( const std::vector< const TrackingRecHit * > &  hits, const TrackingRegion &  region  ) const

overridevirtual

Implements PixelFitterBase.

Definition at line 96 of file PixelFitterByHelixProjections.cc.

References PV3DBase< T, PVType, FrameType >::barePhi(), PV3DBase< T, PVType, FrameType >::basicVector(), PixelTrackBuilder::build(), CircleFromThreePoints::center(), RecoTauCleanerPlugins::charge, RZLine::chi2(), HLT_FULL_cff::chi2, funct::cos(), PixelRecoUtilities::curvature(), CircleFromThreePoints::curvature(), declareDynArray, alignCSCRings::e, PixelTrackErrorParam::errCot(), PixelTrackErrorParam::errPhi(), PixelTrackErrorParam::errPt(), PixelTrackErrorParam::errTip(), PixelTrackErrorParam::errZip(), validate-o2o-wbm::f, mps_fire::i, MagneticField::inverseBzAtOriginInGeV(), PixelRecoUtilities::inversePt(), PixelPluginsPhase0_cfi::isBarrel, LIKELY, Basic2DVector< T >::mag(), nhits, TrackingRegion::origin(), phi, PixelSubdetector::PixelBarrel, DiDispStaMuonMonitor_cfi::pt, TrackerTopology::pxbLayer(), runTheMatrix::ret, funct::sin(), theField, thescaleErrorsForBPix1, thescaleFactor, theTopo, HLT_FULL_cff::tip, Basic2DVector< T >::x(), Basic2DVector< T >::y(), and ComparisonHelper::zip().

                                                                                                    {
  std::unique_ptr<reco::Track> ret;

  int nhits = hits.size();
  if (nhits < 2)
    return ret;

  declareDynArray(GlobalPoint, nhits, points);
  declareDynArray(GlobalError, nhits, errors);
  declareDynArray(bool, nhits, isBarrel);

  for (int i = 0; i != nhits; ++i) {
    auto const& recHit = hits[i];
    points[i] = GlobalPoint(recHit->globalPosition().basicVector() - region.origin().basicVector());
    errors[i] = recHit->globalPositionError();
    isBarrel[i] = recHit->detUnit()->type().isBarrel();
  }

  CircleFromThreePoints circle = (nhits == 2) ? CircleFromThreePoints(GlobalPoint(0., 0., 0.), points[0], points[1])
                                              : CircleFromThreePoints(points[0], points[1], points[2]);

  float valPhi, valTip, valPt;

  int iCharge = charge(points);
  float curvature = circle.curvature();

  if ((curvature > 1.e-4) && (LIKELY(theField->inverseBzAtOriginInGeV()) > 0.01)) {
    float invPt = PixelRecoUtilities::inversePt(circle.curvature(), *theField);
    valPt = (invPt > 1.e-4f) ? 1.f / invPt : 1.e4f;
    CircleFromThreePoints::Vector2D center = circle.center();
    valTip = iCharge * (center.mag() - 1.f / curvature);
    valPhi = phi(center.x(), center.y(), iCharge);
  } else {
    valPt = 1.e4f;
    GlobalVector direction(points[1] - points[0]);
    valPhi = direction.barePhi();
    valTip = -points[0].x() * sin(valPhi) + points[0].y() * cos(valPhi);
  }

  float valCotTheta = cotTheta(points[0], points[1]);
  float valEta = std::asinh(valCotTheta);
  float valZip = zip(valTip, valPhi, curvature, points[0], points[1]);

  // Rescale down the error to take into accont the fact that the
  // inner pixel barrel layer for PhaseI is closer to the interaction
  // point. The effective scale factor has been derived by checking
  // that the pulls of the pixelVertices derived from the pixelTracks
  // have the correct mean and sigma.
  float errFactor = 1.;
  if (thescaleErrorsForBPix1 && (hits[0]->geographicalId().subdetId() == PixelSubdetector::PixelBarrel) &&
      (theTopo->pxbLayer(hits[0]->geographicalId()) == 1))
    errFactor = thescaleFactor;

  PixelTrackErrorParam param(valEta, valPt);
  float errValPt = errFactor * param.errPt();
  float errValCot = errFactor * param.errCot();
  float errValTip = errFactor * param.errTip();
  float errValPhi = errFactor * param.errPhi();
  float errValZip = errFactor * param.errZip();

  float chi2 = 0;
  if (nhits > 2) {
    RZLine rzLine(points, errors, isBarrel);
    chi2 = rzLine.chi2();
  }

  PixelTrackBuilder builder;
  Measurement1D pt(valPt, errValPt);
  Measurement1D phi(valPhi, errValPhi);
  Measurement1D cotTheta(valCotTheta, errValCot);
  Measurement1D tip(valTip, errValTip);
  Measurement1D zip(valZip, errValZip);

  ret.reset(builder.build(pt, phi, cotTheta, tip, zip, chi2, iCharge, hits, theField, region.origin()));
  return ret;
}

Member Data Documentation

const MagneticField* PixelFitterByHelixProjections::theField

private

Definition at line 26 of file PixelFitterByHelixProjections.h.

Referenced by run().

const bool PixelFitterByHelixProjections::thescaleErrorsForBPix1

private

Definition at line 27 of file PixelFitterByHelixProjections.h.

Referenced by run().

const float PixelFitterByHelixProjections::thescaleFactor

private

Definition at line 28 of file PixelFitterByHelixProjections.h.

Referenced by run().

const TrackerTopology* PixelFitterByHelixProjections::theTopo

private

Definition at line 25 of file PixelFitterByHelixProjections.h.

Referenced by run().