Atlfast::TrackTrajectory Class Reference

#include <TrackTrajectory.h>

Collaboration diagram for Atlfast::TrackTrajectory:

[legend]List of all members.

Public Member Functions
	TrackTrajectory ()
	TrackTrajectory (TrackParameters,::HepPoint3D, double)
	TrackTrajectory (const Hep3Vector &p, const Hep3Vector &vertex, double charge, double bField)
	TrackTrajectory (const TrackTrajectory &src)
	~TrackTrajectory ()
TrackTrajectory &	operator= (const TrackTrajectory &src)
TrackParameters	parameters () const
int	signOfCharge () const
HepPoint3D	startPoint () const
double	radius () const
double	curvature () const
Private Attributes
TrackParameters	m_parameters
::HepPoint3D	m_startPoint
double	m_curvature

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Detailed Description

Represents the trajectory of a track

Definition at line 36 of file TrackTrajectory.h.

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Constructor & Destructor Documentation

Atlfast::TrackTrajectory::TrackTrajectory

(

)

[inline]

Default Constructor

Definition at line 48 of file TrackTrajectory.h.

{}

Atlfast::TrackTrajectory::TrackTrajectory	(	TrackParameters	,
		::HepPoint3D	,
		double
	)

Explicit Constructor

Definition at line 92 of file TrackTrajectory.cxx.

                                      : 
    m_parameters(p), m_startPoint(startPoint), m_curvature(curvature)
  {  }

Atlfast::TrackTrajectory::TrackTrajectory	(	const Hep3Vector &	p,
		const Hep3Vector &	vertex,
		double	charge,
		double	bField
	)

Constructor from a 3-momentum, vertex, charge and magnetic field

Definition at line 116 of file TrackTrajectory.cxx.

  {
    double pt = momentum.perp();
    double q  = charge;
    q /= abs(q); //  q = |1|
    
    // Calculate helix radius of curvature and centre

    // Working in GeV and cm 
    //double radius = pt/(2*0.00149898*bField);

    // Working in MeV and mm 
    double radius = pt/(2*0.149898*bField);
    double x0  = vertex.x() + q*radius*sin(momentum.phi());
    double y0  = vertex.y() - q*radius*cos(momentum.phi());
    Hep3Vector hCentre(x0,y0);
    
    // calculate parameters     
    // Tidier version of Fortran code zvhepa.F - Tarta
    
    double impactParameter = -q*(hCentre.perp() - radius);
    double theta = momentum.theta();
    double cotTheta = 1/tan(theta);
    double eta = momentum.pseudoRapidity();
    double zPerigee;
    double phi;
    
    //  Calculate Phi
    
    if (abs(vertex.x()) < 1e-4 && abs(vertex.y()) < 1e-4)
      {phi = momentum.phi();} else 
        {if ( (vertex.phi() - hCentre.phi()) > 0 )
          { phi =  hCentre.phi() + M_PI/2; } else   
            { phi = hCentre.phi() - M_PI/2;} }
    
    double x1 =  sin(phi)*q*hCentre.perp()/(radius*radius);
    double y1 = -cos(phi)*q*hCentre.perp()/(radius*radius);
    if (x1*x0 < 0 || y1*y0 < 0) {phi += M_PI;}
    if (phi < 0) {phi += 2.*M_PI;} else 
      { if(phi > 2.*M_PI) {phi -= 2.*M_PI;} }
    
    // z of perigee
    
    double dot = vertex.x()*momentum.x() + vertex.y()*momentum.y();
    double dotsign = dot/abs(dot) ;
    double dV = (vertex.perp()*vertex.perp()) - 
      (impactParameter*impactParameter);
    double denom = hCentre.perp()/radius;
    
    // NAN protection
    if (dV < 0) {dV = 0;}    
    if (abs(dotsign)!=1) dotsign=0;
    
    zPerigee = vertex.z() - (2*q*radius)*dotsign*cotTheta*
      asin((sqrt(dV/(denom)))*q/(2*radius) );
    
    // set parameters
    m_parameters = TrackParameters
      (eta, phi, pt, impactParameter, zPerigee, cotTheta, q/pt );
    m_startPoint = HepPoint3D(vertex);
    m_curvature = radius;  
  }

Atlfast::TrackTrajectory::TrackTrajectory

(

const TrackTrajectory &

src

)

Copy Constructor

Definition at line 100 of file TrackTrajectory.cxx.

  {
    (*this) = other;
  }

Atlfast::TrackTrajectory::~TrackTrajectory

(

)

Destructor

Definition at line 113 of file TrackTrajectory.cxx.

{}   

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Member Function Documentation

TrackTrajectory & Atlfast::TrackTrajectory::operator=

(

const TrackTrajectory &

src

)

Assignment

Definition at line 105 of file TrackTrajectory.cxx.

                                                                            {
    m_parameters      = other.m_parameters ;
    m_startPoint      = other.m_startPoint;
    m_curvature       = other.m_curvature;
    return *this ;
  } 

TrackParameters Atlfast::TrackTrajectory::parameters

(

)

const

Definition at line 185 of file TrackTrajectory.cxx.

                                                    {
    return m_parameters;
  }

int Atlfast::TrackTrajectory::signOfCharge

(

)

const

Definition at line 196 of file TrackTrajectory.cxx.

  { return int( abs(m_parameters.invPtCharge() )/m_parameters.invPtCharge() ) ;  }

HepPoint3D Atlfast::TrackTrajectory::startPoint

(

)

const

Definition at line 188 of file TrackTrajectory.cxx.

  { return m_startPoint ; }

double Atlfast::TrackTrajectory::radius

(

)

const

Definition at line 190 of file TrackTrajectory.cxx.

  { return m_startPoint.perp() ; }

double Atlfast::TrackTrajectory::curvature

(

)

const

Definition at line 193 of file TrackTrajectory.cxx.

  { return m_curvature ; }

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Member Data Documentation

TrackParameters Atlfast::TrackTrajectory::m_parameters [private]

Definition at line 41 of file TrackTrajectory.h.

::HepPoint3D Atlfast::TrackTrajectory::m_startPoint [private]

Definition at line 42 of file TrackTrajectory.h.

double Atlfast::TrackTrajectory::m_curvature [private]

Definition at line 43 of file TrackTrajectory.h.

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

• /afs/cern.ch/user/s/sdean/project_builds/AtlasOffline-rel_1/Simulation/Atlfast/AtlfastEvent/AtlfastEvent/TrackTrajectory.h
• /afs/cern.ch/user/s/sdean/project_builds/AtlasOffline-rel_1/Simulation/Atlfast/AtlfastEvent/src/TrackTrajectory.cxx

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