TrackFitter Class Reference

#include <TrackFitter.h>

Inheritance diagram for TrackFitter:

Public Member Functions
std::unique_ptr< reco::Track >	run (const std::vector< const TrackingRecHit * > &hits, const TrackingRegion &region) const override
	TrackFitter (const TrackerGeometry *tracker, const MagneticField *field, const TransientTrackingRecHitBuilder *ttrhBuilder)
	~TrackFitter () override
Public Member Functions inherited from PixelFitterBase
virtual	~PixelFitterBase ()

Private Member Functions
float	getCotThetaAndUpdateZip (const GlobalPoint &inner, const GlobalPoint &outer, float radius, float phi, float d0, float &zip) const
void	getErrTipAndErrZip (float pt, float eta, float &errZip, float &errTip) const
float	getPhi (float xC, float yC, int charge) const
float	getZip (float d0, float curv, const GlobalPoint &inner, const GlobalPoint &outer) const

Private Attributes
const MagneticField *	theField
const TrackerGeometry *	theTracker
const TransientTrackingRecHitBuilder *	theTTRecHitBuilder

Detailed Description

Definition at line 16 of file TrackFitter.h.

Constructor & Destructor Documentation

TrackFitter::TrackFitter ( const TrackerGeometry *  tracker, const MagneticField *  field, const TransientTrackingRecHitBuilder *  ttrhBuilder  )

inline

Definition at line 18 of file TrackFitter.h.

      : theTracker(tracker), theField(field), theTTRecHitBuilder(ttrhBuilder) {}

TrackFitter::~TrackFitter ( )

inlineoverride

Definition at line 22 of file TrackFitter.h.

{}

Member Function Documentation

float TrackFitter::getCotThetaAndUpdateZip ( const GlobalPoint &  inner, const GlobalPoint &  outer, float  radius, float  phi, float  d0, float &  zip  ) const

private

Definition at line 110 of file TrackFitter.cc.

References funct::cos(), runTauDisplay::dr, PVValHelper::dz, listHistos::IP, M_PI_2, perp(), funct::sin(), and PV3DBase< T, PVType, FrameType >::z().

                                                                                                             {
  float chi = phi - M_PI_2;
  GlobalPoint IP(d0 * cos(chi), d0 * sin(chi), zip);

  float phi1 = 2 * asin(0.5 * (inner - IP).perp() / radius);
  float phi2 = 2 * asin(0.5 * (outer - IP).perp() / radius);

  float dr = radius * (phi2 - phi1);
  float dz = outer.z() - inner.z();

  // Recalculate ZIP
  zip = (inner.z() * phi2 - outer.z() * phi1) / (phi2 - phi1);

  return (fabs(dr) > 1.e-3) ? dz / dr : 0;
}

void TrackFitter::getErrTipAndErrZip ( float  pt, float  eta, float &  errZip, float &  errTip  ) const

private

Definition at line 157 of file TrackFitter.cc.

References DiDispStaMuonMonitor_cfi::pt, and mathSSE::sqrt().

                                                                                            {
  float coshEta = cosh(eta);

  {                       // transverse
    float c_ms = 0.0115;  //0.0115;
    float s_le = 0.0095;  //0.0123;
    float s_ms2 = c_ms * c_ms / (pt * pt) * coshEta;

    errTip = sqrt(s_le * s_le + s_ms2);
  }

  {  // z
    float c_ms = 0.0070;
    float s_le = 0.0135;

    errZip = sqrt((s_le * s_le + c_ms * c_ms / (pt * pt)) * coshEta * coshEta * coshEta);
  }
}

float TrackFitter::getPhi ( float  xC, float  yC, int  charge  ) const

private

Definition at line 128 of file TrackFitter.cc.

                                                              {
  float phiC;

  if (charge > 0)
    phiC = atan2(xC, -yC);
  else
    phiC = atan2(-xC, yC);

  return phiC;
}

float TrackFitter::getZip ( float  d0, float  curv, const GlobalPoint &  inner, const GlobalPoint &  outer  ) const

private

Definition at line 140 of file TrackFitter.cc.

References PV3DBase< T, PVType, FrameType >::perp(), PV3DBase< T, PVType, FrameType >::perp2(), diffTwoXMLs::r1, diffTwoXMLs::r2, and PV3DBase< T, PVType, FrameType >::z().

                                                                                                        {
  // phi = asin(r*rho/2) with asin(x) ~= x+x**3/(2*3)
  float rho3 = curv * curv * curv;

  float r1 = inner.perp();
  double phi1 = r1 * curv / 2 + inner.perp2() * r1 * rho3 / 48.;

  float r2 = outer.perp();
  double phi2 = r2 * curv / 2 + outer.perp2() * r2 * rho3 / 48.;

  double z1 = inner.z();
  double z2 = outer.z();

  return z1 - phi1 / (phi1 - phi2) * (z1 - z2);
}

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

overridevirtual

Implements PixelFitterBase.

Definition at line 41 of file TrackFitter.cc.

References PixelTrackBuilder::build(), CircleFromThreePoints::center(), RecoTauCleanerPlugins::charge, RZLine::chi2(), HLT_FULL_cff::chi2, PixelRecoUtilities::curvature(), CircleFromThreePoints::curvature(), declareDynArray, DeDxTools::getCharge(), mps_fire::i, PixelRecoUtilities::inversePt(), PixelPluginsPhase0_cfi::isBarrel, Basic2DVector< T >::mag(), nhits, DiDispStaMuonMonitor_cfi::pt, runTheMatrix::ret, 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);

  unsigned int i = 0;
  for (auto const& ih : hits) {
    auto recHit = theTTRecHitBuilder->build(ih);

    points[i] = recHit->globalPosition();
    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]);

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

  // pt
  float invPt = PixelRecoUtilities::inversePt(curvature, *theField);
  float valPt = (invPt > 1.e-4) ? 1. / invPt : 1.e4;
  float errPt = 0.055 * valPt + 0.017 * valPt * valPt;

  CircleFromThreePoints::Vector2D center = circle.center();

  // tip
  float valTip = charge * (center.mag() - 1 / curvature);
  // zip
  float valZip = getZip(valTip, curvature, points[0], points[1]);
  // phi
  float valPhi = getPhi(center.x(), center.y(), charge);
  // cot(theta), update zip
  float valCotTheta = getCotThetaAndUpdateZip(points[0], points[1], 1 / curvature, valPhi, valTip, valZip);

  // errors
  float errTip, errZip;
  getErrTipAndErrZip(valPt, points.back().eta(), errTip, errZip);
  float errPhi = 0.002;
  float errCotTheta = 0.002;

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

  // build pixel track
  PixelTrackBuilder builder;

  Measurement1D pt(valPt, errPt);
  Measurement1D phi(valPhi, errPhi);
  Measurement1D cotTheta(valCotTheta, errCotTheta);
  Measurement1D tip(valTip, errTip);
  Measurement1D zip(valZip, errZip);

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

Member Data Documentation

const MagneticField* TrackFitter::theField

private

Definition at line 35 of file TrackFitter.h.

const TrackerGeometry* TrackFitter::theTracker

private

Definition at line 34 of file TrackFitter.h.

const TransientTrackingRecHitBuilder* TrackFitter::theTTRecHitBuilder

private

Definition at line 36 of file TrackFitter.h.