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Atlfast::TrackTrajectory Class Reference

Represents the trajectory of a track. More...

#include <TrackTrajectory.h>

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Public Methods

 TrackTrajectory ()
 Default Constructor.

 TrackTrajectory (TrackParameters,::HepPoint3D, double)
 Explicit Constructor.

 TrackTrajectory (const Hep3Vector &p, const Hep3Vector &vertex, double charge, double bField)
 Constructor from a 3-momentum, vertex, charge and magnetic field.

 TrackTrajectory (const TrackTrajectory &src)
 Copy Constructor.

 ~TrackTrajectory ()
 Destructor.

TrackTrajectory & operator= (const TrackTrajectory &src)
 Assignment.

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

Detailed Description

Represents the trajectory of a track.

Definition at line 36 of file TrackTrajectory.h.

Constructor & Destructor Documentation

Atlfast::TrackTrajectory::TrackTrajectory (    )  [inline]
 

Default Constructor.

Definition at line 48 of file TrackTrajectory.h. 

00048 {}

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

Explicit Constructor.

Definition at line 92 of file TrackTrajectory.cxx. 

00095                                       : 
00096     m_parameters(p), m_startPoint(startPoint), m_curvature(curvature)
00097   {  }

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.

References m_curvature, m_parameters, m_startPoint, and radius(). 

00122   {
00123     double pt = momentum.perp();
00124     double q  = charge;
00125     q /= abs(q); //  q = |1|
00126     
00127     // calculate helix radius of curvature and centre
00128     
00129     double radius = pt/(2*0.00149898*bField);
00130     double x0  = vertex.x() + q*radius*sin(momentum.phi());
00131     double y0  = vertex.y() - q*radius*cos(momentum.phi());
00132     Hep3Vector hCentre(x0,y0);
00133     
00134     // calculate parameters     
00135     // Tidier version of Fortran code zvhepa.F - Tarta
00136     
00137     double impactParameter = -q*(hCentre.perp() - radius);
00138     double theta = momentum.theta();
00139     double cotTheta = 1/tan(theta);
00140     double eta = momentum.pseudoRapidity();
00141     double zPerigee;
00142     double phi;
00143     
00144     //  Calculate Phi
00145     
00146     if (abs(vertex.x()) < 1e-4 && abs(vertex.y()) < 1e-4)
00147       {phi = momentum.phi();} else 
00148         {if ( (vertex.phi() - hCentre.phi()) > 0 )
00149           { phi =  hCentre.phi() + M_PI/2; } else   
00150             { phi = hCentre.phi() - M_PI/2;} }
00151     
00152     double x1 =  sin(phi)*q*hCentre.perp()/(radius*radius);
00153     double y1 = -cos(phi)*q*hCentre.perp()/(radius*radius);
00154     if (x1*x0 < 0 || y1*y0 < 0) {phi += M_PI;}
00155     if (phi < 0) {phi += 2.*M_PI;} else 
00156       { if(phi > 2.*M_PI) {phi -= 2.*M_PI;} }
00157     
00158     // z of perigee
00159     
00160     double dot = vertex.x()*momentum.x() + vertex.y()*momentum.y();
00161     double dotsign = dot/abs(dot) ;
00162     double dV = (vertex.perp()*vertex.perp()) - 
00163       (impactParameter*impactParameter);
00164     double denom = hCentre.perp()/radius;
00165     
00166     // NAN protection
00167     if (dV < 0) {dV = 0;}    
00168     if (abs(dotsign)!=1) dotsign=0;
00169     
00170     zPerigee = vertex.z() - (2*q*radius)*dotsign*cotTheta*
00171       asin((sqrt(dV/(denom)))*q/(2*radius) );
00172     
00173     // set parameters
00174     m_parameters = TrackParameters
00175       (eta, phi, pt, impactParameter, zPerigee, cotTheta, q/pt );
00176     m_startPoint = HepPoint3D(vertex);
00177     m_curvature = radius;  
00178   }

Atlfast::TrackTrajectory::TrackTrajectory (  const TrackTrajectory &    src ) 
 

Copy Constructor.

Definition at line 100 of file TrackTrajectory.cxx. 

00101   {
00102     (*this) = other;
00103   }

Atlfast::TrackTrajectory::~TrackTrajectory (    ) 
 

Destructor.

Definition at line 113 of file TrackTrajectory.cxx. 

00113 {}

Member Function Documentation

double Atlfast::TrackTrajectory::curvature (    )  const
 

Definition at line 189 of file TrackTrajectory.cxx.

References m_curvature.

Referenced by Atlfast::operator<<(). 

00190   { return m_curvature ; }

TrackTrajectory & Atlfast::TrackTrajectory::operator= (  const TrackTrajectory &    src ) 
 

Assignment.

Definition at line 105 of file TrackTrajectory.cxx.

References m_curvature, m_parameters, and m_startPoint. 

00105                                                                             {
00106     m_parameters      = other.m_parameters ;
00107     m_startPoint      = other.m_startPoint;
00108     m_curvature       = other.m_curvature;
00109     return *this ;
00110   }

TrackParameters Atlfast::TrackTrajectory::parameters (    )  const
 

Definition at line 181 of file TrackTrajectory.cxx.

References m_parameters.

Referenced by Atlfast::operator<<(). 

00181                                                     {
00182     return m_parameters;
00183   }

double Atlfast::TrackTrajectory::radius (    )  const
 

Definition at line 186 of file TrackTrajectory.cxx.

References m_startPoint.

Referenced by Atlfast::operator<<(), and TrackTrajectory(). 

00187   { return m_startPoint.perp() ; }

int Atlfast::TrackTrajectory::signOfCharge (    )  const
 

Definition at line 192 of file TrackTrajectory.cxx.

References Atlfast::TrackParameters::invPtCharge(), and m_parameters. 

00193   { return int( abs(m_parameters.invPtCharge() )/m_parameters.invPtCharge() ) ;  }

HepPoint3D Atlfast::TrackTrajectory::startPoint (    )  const
 

Definition at line 184 of file TrackTrajectory.cxx.

References m_startPoint. 

00185   { return m_startPoint ; }

Member Data Documentation

double Atlfast::TrackTrajectory::m_curvature [private]
 

Definition at line 43 of file TrackTrajectory.h.

Referenced by curvature(), operator=(), and TrackTrajectory().

TrackParameters Atlfast::TrackTrajectory::m_parameters [private]
 

Definition at line 41 of file TrackTrajectory.h.

Referenced by operator=(), parameters(), signOfCharge(), and TrackTrajectory().

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

Definition at line 42 of file TrackTrajectory.h.

Referenced by operator=(), radius(), startPoint(), and TrackTrajectory().

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