genfit::WireMeasurement Class Reference

Class for measurements in wire detectors (Straw tubes and drift chambers) which do not measure the coordinate along the wire. More...

#include <WireMeasurement.h>

Inheritance diagram for genfit::WireMeasurement:

Collaboration diagram for genfit::WireMeasurement:

Public Member Functions
	WireMeasurement (int nDim=7)
	WireMeasurement (const TVectorD &rawHitCoords, const TMatrixDSym &rawHitCov, int detId, int hitId, TrackPoint *trackPoint)
virtual	~WireMeasurement ()
virtual AbsMeasurement *	clone () const
	Deep copy ctor for polymorphic class.
virtual SharedPlanePtr	constructPlane (const StateOnPlane &state) const
virtual std::vector< MeasurementOnPlane * >	constructMeasurementsOnPlane (const StateOnPlane &state) const
virtual const AbsHMatrix *	constructHMatrix (const AbsTrackRep *) const
void	setMaxDistance (double d)
void	setLeftRightResolution (int lr)
double	getMaxDistance ()
int	getLeftRightResolution () const
Public Member Functions inherited from genfit::AbsMeasurement
	AbsMeasurement ()
	AbsMeasurement (int nDims)
	AbsMeasurement (const TVectorD &rawHitCoords, const TMatrixDSym &rawHitCov, int detId, int hitId, TrackPoint *trackPoint)
virtual	~AbsMeasurement ()
TrackPoint *	getTrackPoint () const
void	setTrackPoint (TrackPoint *tp)
const TVectorD &	getRawHitCoords () const
const TMatrixDSym &	getRawHitCov () const
int	getDetId () const
int	getHitId () const
unsigned int	getDim () const
void	setDetId (int detId)
void	setHitId (int hitId)
virtual void	Print (const Option_t *="") const

Protected Attributes
double	maxDistance_
double	leftRight_
Protected Attributes inherited from genfit::AbsMeasurement
TVectorD	rawHitCoords_
TMatrixDSym	rawHitCov_
int	detId_
int	hitId_
TrackPoint *	trackPoint_
	Pointer to TrackPoint where the measurement belongs to.

Additional Inherited Members
Protected Member Functions inherited from genfit::AbsMeasurement
	AbsMeasurement (const AbsMeasurement &)
	protect from calling copy c'tor from outside the class. Use clone() if you want a copy!

Detailed Description

Class for measurements in wire detectors (Straw tubes and drift chambers) which do not measure the coordinate along the wire.

Author

Christian Höppner (Technische Universität München, original author)

Lia Lavezzi (INFN Pavia, original author)

Sebastian Neubert (Technische Universität München, original author)

Johannes Rauch (Technische Universität München, original author)

This hit class is not valid for any kind of plane orientation choice: to use it you MUST choose a plane described by u and v axes with v coincident with the wire (and u orthogonal to it, obviously). The hit will be described by 7 coordinates: w_x1, w_y1, w_z1, w_x2, w_y2, w_z2, rdrift where w_ji (with j = x, y, z and i = 1, 2) are the wire extremities coordinates; rdrift = distance from the wire (u coordinate in the plane)

Definition at line 52 of file WireMeasurement.h.

Constructor & Destructor Documentation

WireMeasurement() [1/2]

genfit::WireMeasurement::WireMeasurement

(

int

nDim = 7

)

Definition at line 38 of file WireMeasurement.cc.

  : AbsMeasurement(nDim), maxDistance_(2), leftRight_(0)
{
  assert(nDim >= 7);
}

WireMeasurement() [2/2]

genfit::WireMeasurement::WireMeasurement	(	const TVectorD &	rawHitCoords,
		const TMatrixDSym &	rawHitCov,
		int	detId,
		int	hitId,
		TrackPoint *	trackPoint
	)

Definition at line 44 of file WireMeasurement.cc.

  : AbsMeasurement(rawHitCoords, rawHitCov, detId, hitId, trackPoint), maxDistance_(2), leftRight_(0)
{
  assert(rawHitCoords_.GetNrows() >= 7);
}

~WireMeasurement()

virtual genfit::WireMeasurement::~WireMeasurement ( )

inlinevirtual

Definition at line 58 of file WireMeasurement.h.

{;}

Member Function Documentation

clone()

virtual AbsMeasurement * genfit::WireMeasurement::clone ( ) const

inlinevirtual

Deep copy ctor for polymorphic class.

Implements genfit::AbsMeasurement.

Reimplemented in genfit::WirePointMeasurement.

Definition at line 60 of file WireMeasurement.h.

{return new WireMeasurement(*this);}

constructHMatrix()

const AbsHMatrix * genfit::WireMeasurement::constructHMatrix ( const AbsTrackRep *  ) const

virtual

Returns a new AbsHMatrix object. Caller must take ownership.

Implements genfit::AbsMeasurement.

Reimplemented in genfit::WirePointMeasurement.

Definition at line 124 of file WireMeasurement.cc.

                                                                                {
  if (dynamic_cast<const RKTrackRep*>(rep) == NULL) {
    Exception exc("WireMeasurement default implementation can only handle state vectors of type RKTrackRep!", __LINE__,__FILE__);
    throw exc;
  }
 
  return new HMatrixU();
}

constructMeasurementsOnPlane()

std::vector< MeasurementOnPlane * > genfit::WireMeasurement::constructMeasurementsOnPlane ( const StateOnPlane &  state ) const

virtual

Hits with a small drift distance get a higher weight, whereas hits with big drift distances become weighted down. When these initial weights are used by the DAF, the smoothed track will be closer to the real trajectory than if both sides are weighted with 0.5 regardless of the drift distance. This helps a lot when resolving l/r ambiguities with the DAF. The idea is that for the first iteration of the DAF, the wire positions are taken. For small drift radii, the wire position does not bend the fit away from the trajectory, whereas the wire position for hits with large drift radii is further away from the trajectory and will therefore bias the fit if not weighted down.

Implements genfit::AbsMeasurement.

Reimplemented in genfit::WirePointMeasurement.

Definition at line 89 of file WireMeasurement.cc.

{
  double mR = rawHitCoords_(6);
  double mL = -mR;
  double V = rawHitCov_(6,6);
 
  MeasurementOnPlane* mopL = new MeasurementOnPlane(TVectorD(1, &mL),
             TMatrixDSym(1, &V),
             state.getPlane(), state.getRep(), constructHMatrix(state.getRep()));
 
  MeasurementOnPlane* mopR = new MeasurementOnPlane(TVectorD(1, &mR),
       TMatrixDSym(1, &V),
       state.getPlane(), state.getRep(), constructHMatrix(state.getRep()));
 
  // set left/right weights
  if (leftRight_ < 0) {
    mopL->setWeight(1);
    mopR->setWeight(0);
  }
  else if (leftRight_ > 0) {
    mopL->setWeight(0);
    mopR->setWeight(1);
  }
  else {
    double val = 0.5 * pow(std::max(0., 1 - mR/maxDistance_), 2.);
    mopL->setWeight(val);
    mopR->setWeight(val);
  }
 
  std::vector<MeasurementOnPlane*> retVal;
  retVal.push_back(mopL);
  retVal.push_back(mopR);
  return retVal;
}

constructPlane()

SharedPlanePtr genfit::WireMeasurement::constructPlane ( const StateOnPlane &  state ) const

virtual

Construct (virtual) detector plane (use state's AbsTrackRep). It's possible to make corrections to the plane here. The state should be defined somewhere near the measurement. For virtual planes, the state will be extrapolated to the POCA to point (SpacepointMeasurement) or line (WireMeasurement), and from this info the plane will be constructed.

Implements genfit::AbsMeasurement.

Reimplemented in genfit::WirePointMeasurement.

Definition at line 50 of file WireMeasurement.cc.

                                                                              {
 
  // copy state. Neglect covariance.
  StateOnPlane st(state);
 
  TVector3 wire1(rawHitCoords_(0), rawHitCoords_(1), rawHitCoords_(2));
  TVector3 wire2(rawHitCoords_(3), rawHitCoords_(4), rawHitCoords_(5));
 
  //std::cout << " wire1(" << rawHitCoords_(0) << ", " << rawHitCoords_(1) << ", " << rawHitCoords_(2) << ")" << std::endl;
  //std::cout << " wire2(" << rawHitCoords_(3) << ", " << rawHitCoords_(4) << ", " << rawHitCoords_(5) << ")" << std::endl;
 
  // unit vector along the wire (V)
  TVector3 wireDirection = wire2 - wire1;
  wireDirection.SetMag(1.);
 
  //std::cout << " wireDirection(" << wireDirection.X() << ", " << wireDirection.Y() << ", " << wireDirection.Z() << ")" << std::endl;
 
  // point of closest approach
  const AbsTrackRep* rep = state.getRep();
  rep->extrapolateToLine(st, wire1, wireDirection);
  const TVector3& poca = rep->getPos(st);
  TVector3 dirInPoca = rep->getMom(st);
  dirInPoca.SetMag(1.);
  const TVector3& pocaOnWire = wire1 + wireDirection.Dot(poca - wire1)*wireDirection;
 
  // check if direction is parallel to wire
  if (fabs(wireDirection.Angle(dirInPoca)) < 0.01){
    Exception exc("WireMeasurement::detPlane(): Cannot construct detector plane, direction is parallel to wire", __LINE__,__FILE__);
    throw exc;
  }
 
  // construct orthogonal vector
  TVector3 U = dirInPoca.Cross(wireDirection);
  // U.SetMag(1.); automatically assured
 
  return SharedPlanePtr(new DetPlane(pocaOnWire, U, wireDirection));
}

getLeftRightResolution()

int genfit::WireMeasurement::getLeftRightResolution ( ) const

inline

Definition at line 91 of file WireMeasurement.h.

{return leftRight_;}

getMaxDistance()

double genfit::WireMeasurement::getMaxDistance ( )

inline

Definition at line 90 of file WireMeasurement.h.

{return maxDistance_;}

setLeftRightResolution()

void genfit::WireMeasurement::setLeftRightResolution

(

int

lr

)

select how to resolve the left/right ambiguity: -1: negative (left) side on vector (track direction) x (wire direction) 0: auto select (take side with smallest distance to track) 1: positive (right) side on vector (track direction) x (wire direction)

Definition at line 133 of file WireMeasurement.cc.

                                                  {
  if (lr==0) leftRight_ = 0;
  else if (lr<0) leftRight_ = -1;
  else leftRight_ = 1;
}

setMaxDistance()

void genfit::WireMeasurement::setMaxDistance ( double  d )

inline

Set maximum drift distance. This is used to calculate the start weights of the two measurementsOnPlane.

Definition at line 81 of file WireMeasurement.h.

{maxDistance_ = d;}

Member Data Documentation

leftRight_

double genfit::WireMeasurement::leftRight_

protected

Definition at line 96 of file WireMeasurement.h.

maxDistance_

double genfit::WireMeasurement::maxDistance_

protected

Definition at line 95 of file WireMeasurement.h.

---

The documentation for this class was generated from the following files:

• genfit/measurements/include/WireMeasurement.h
• genfit/measurements/src/WireMeasurement.cc