G4Mag_SpinEqRhs Class Reference

#include <G4Mag_SpinEqRhs.hh>

Inheritance diagram for G4Mag_SpinEqRhs:

Collaboration diagram for G4Mag_SpinEqRhs:

Public Member Functions
	G4Mag_SpinEqRhs (G4MagneticField *MagField)
	~G4Mag_SpinEqRhs ()
void	SetChargeMomentumMass (G4ChargeState particleCharge, G4double MomentumXc, G4double mass)
void	EvaluateRhsGivenB (const G4double y[], const G4double B[3], G4double dydx[]) const
void	SetAnomaly (G4double a)
G4double	GetAnomaly () const
Public Member Functions inherited from G4Mag_EqRhs
	G4Mag_EqRhs (G4MagneticField *magField)
virtual	~G4Mag_EqRhs ()
G4double	FCof () const
Public Member Functions inherited from G4EquationOfMotion
	G4EquationOfMotion (G4Field *Field)
virtual	~G4EquationOfMotion ()
void	RightHandSide (const G4double y[], G4double dydx[]) const
void	EvaluateRhsReturnB (const G4double y[], G4double dydx[], G4double Field[]) const
void	GetFieldValue (const G4double Point[4], G4double Field[]) const
const G4Field *	GetFieldObj () const
void	SetFieldObj (G4Field *pField)

Detailed Description

Definition at line 51 of file G4Mag_SpinEqRhs.hh.

Constructor & Destructor Documentation

G4Mag_SpinEqRhs::G4Mag_SpinEqRhs

(

G4MagneticField *

MagField

)

Definition at line 45 of file G4Mag_SpinEqRhs.cc.

  : G4Mag_EqRhs( MagField ), charge(0.), mass(0.), magMoment(0.),
    spin(0.), omegac(0.), anomaly(0.0011659208), beta(0.), gamma(0.)
{
}

G4Mag_SpinEqRhs::~G4Mag_SpinEqRhs

(

)

Definition at line 51 of file G4Mag_SpinEqRhs.cc.

{
}

Member Function Documentation

void G4Mag_SpinEqRhs::EvaluateRhsGivenB ( const G4double  y[], const G4double  B[3], G4double  dydx[]  ) const

virtual

Implements G4Mag_EqRhs.

Definition at line 83 of file G4Mag_SpinEqRhs.cc.

{
   G4double momentum_mag_square = sqr(y[3]) + sqr(y[4]) + sqr(y[5]);
   G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
   G4double cof = FCof()*inv_momentum_magnitude;

   dydx[0] = y[3] * inv_momentum_magnitude;       //  (d/ds)x = Vx/V
   dydx[1] = y[4] * inv_momentum_magnitude;       //  (d/ds)y = Vy/V
   dydx[2] = y[5] * inv_momentum_magnitude;       //  (d/ds)z = Vz/V

   if (charge == 0.) {
      dydx[3] = 0.;
      dydx[4] = 0.;
      dydx[5] = 0.;
   } else {
      dydx[3] = cof*(y[4]*B[2] - y[5]*B[1]) ;   // Ax = a*(Vy*Bz - Vz*By)
      dydx[4] = cof*(y[5]*B[0] - y[3]*B[2]) ;   // Ay = a*(Vz*Bx - Vx*Bz)
      dydx[5] = cof*(y[3]*B[1] - y[4]*B[0]) ;   // Az = a*(Vx*By - Vy*Bx)
   }

   G4ThreeVector u(y[3], y[4], y[5]);
   u *= inv_momentum_magnitude; 

   G4ThreeVector BField(B[0],B[1],B[2]);

   G4double udb = anomaly*beta*gamma/(1.+gamma) * (BField * u); 
   G4double ucb = (anomaly+1./gamma)/beta;

   // Initialise the values of dydx that we do not update.
   dydx[6] = dydx[7] = dydx[8] = 0.0;

   G4ThreeVector Spin(y[9],y[10],y[11]);

   G4double pcharge;
   if (charge == 0.) pcharge = 1.;
   else pcharge = charge;

   G4ThreeVector dSpin(0.,0.,0.);
   if (Spin.mag2() != 0.) {
      dSpin = pcharge*omegac*(ucb*(Spin.cross(BField))-udb*(Spin.cross(u)));
   }

   dydx[ 9] = dSpin.x();
   dydx[10] = dSpin.y();
   dydx[11] = dSpin.z();

   return ;
}

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G4double G4Mag_SpinEqRhs::GetAnomaly ( ) const

inline

Definition at line 70 of file G4Mag_SpinEqRhs.hh.

{ return anomaly; }

void G4Mag_SpinEqRhs::SetAnomaly ( G4double  a )

inline

Definition at line 69 of file G4Mag_SpinEqRhs.hh.

{ anomaly = a; }

void G4Mag_SpinEqRhs::SetChargeMomentumMass ( G4ChargeState  particleCharge, G4double  MomentumXc, G4double  mass  )

virtual

Reimplemented from G4Mag_EqRhs.

Definition at line 56 of file G4Mag_SpinEqRhs.cc.

{
   G4Mag_EqRhs::SetChargeMomentumMass( particleCharge, MomentumXc, mass);

   charge = particleCharge.GetCharge();
   mass      = particleMass;
   magMoment = particleCharge.GetMagneticDipoleMoment();
   spin      = particleCharge.GetSpin();

   omegac = (eplus/mass)*c_light;

   G4double muB = 0.5*eplus*hbar_Planck/(mass/c_squared);

   G4double g_BMT;
   if ( spin != 0. ) g_BMT = (std::abs(magMoment)/muB)/spin;
   else g_BMT = 2.;

   anomaly = (g_BMT - 2.)/2.;

   G4double E = std::sqrt(sqr(MomentumXc)+sqr(mass));
   beta  = MomentumXc/E;
   gamma = E/mass;
}

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

• geant4.10.03.p01/source/geometry/magneticfield/include/G4Mag_SpinEqRhs.hh
• geant4.10.03.p01/source/geometry/magneticfield/src/G4Mag_SpinEqRhs.cc