G4EqEMFieldWithSpin Class Reference

#include <G4EqEMFieldWithSpin.hh>

Inheritance diagram for G4EqEMFieldWithSpin:

Collaboration diagram for G4EqEMFieldWithSpin:

Public Member Functions
	G4EqEMFieldWithSpin (G4ElectroMagneticField *emField)
	~G4EqEMFieldWithSpin ()
void	SetChargeMomentumMass (G4ChargeState particleCharge, G4double MomentumXc, G4double mass)
void	EvaluateRhsGivenB (const G4double y[], const G4double Field[], G4double dydx[]) const
void	SetAnomaly (G4double a)
G4double	GetAnomaly () const
Public Member Functions inherited from G4EquationOfMotion
	G4EquationOfMotion (G4Field *Field)
virtual	~G4EquationOfMotion ()
virtual void	EvaluateRhsGivenB (const G4double y[], const G4double B[3], G4double dydx[]) const =0
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)

Private Attributes
G4double	charge
G4double	mass
G4double	magMoment
G4double	spin
G4double	fElectroMagCof
G4double	fMassCof
G4double	omegac
G4double	anomaly
G4double	beta
G4double	gamma

Detailed Description

Definition at line 49 of file G4EqEMFieldWithSpin.hh.

Constructor & Destructor Documentation

G4EqEMFieldWithSpin()

G4EqEMFieldWithSpin::G4EqEMFieldWithSpin

(

G4ElectroMagneticField *

emField

)

Definition at line 45 of file G4EqEMFieldWithSpin.cc.

  : G4EquationOfMotion( emField ), charge(0.), mass(0.), magMoment(0.),
    spin(0.), fElectroMagCof(0.), fMassCof(0.), omegac(0.), 
    anomaly(0.0011659208), beta(0.), gamma(0.)
{
}

~G4EqEMFieldWithSpin()

G4EqEMFieldWithSpin::~G4EqEMFieldWithSpin

(

)

Definition at line 52 of file G4EqEMFieldWithSpin.cc.

{
} 

Member Function Documentation

EvaluateRhsGivenB()

void G4EqEMFieldWithSpin::EvaluateRhsGivenB	(	const G4double	y[],
		const G4double	Field[],
		G4double	dydx[]
	)		const

Definition at line 85 of file G4EqEMFieldWithSpin.cc.

{

   // Components of y:
   //    0-2 dr/ds,
   //    3-5 dp/ds - momentum derivatives
   //    9-11 dSpin/ds = (1/beta) dSpin/dt - spin derivatives

   // The BMT equation, following J.D.Jackson, Classical
   // Electrodynamics, Second Edition,
   // dS/dt = (e/mc) S \cross
   //              [ (g/2-1 +1/\gamma) B
   //               -(g/2-1)\gamma/(\gamma+1) (\beta \cdot B)\beta
   //               -(g/2-\gamma/(\gamma+1) \beta \cross E ]
   // where
   // S = \vec{s}, where S^2 = 1
   // B = \vec{B}
   // \beta = \vec{\beta} = \beta \vec{u} with u^2 = 1
   // E = \vec{E}

   G4double pSquared = y[3]*y[3] + y[4]*y[4] + y[5]*y[5] ;

   G4double Energy   = std::sqrt( pSquared + fMassCof );
   G4double cof2     = Energy/c_light ;

   G4double pModuleInverse  = 1.0/std::sqrt(pSquared) ;

   G4double inverse_velocity = Energy * pModuleInverse / c_light;

   G4double cof1     = fElectroMagCof*pModuleInverse ;

   dydx[0] = y[3]*pModuleInverse ;                         
   dydx[1] = y[4]*pModuleInverse ;                         
   dydx[2] = y[5]*pModuleInverse ;                        

   dydx[3] = cof1*(cof2*Field[3] + (y[4]*Field[2] - y[5]*Field[1])) ;
   
   dydx[4] = cof1*(cof2*Field[4] + (y[5]*Field[0] - y[3]*Field[2])) ; 
 
   dydx[5] = cof1*(cof2*Field[5] + (y[3]*Field[1] - y[4]*Field[0])) ;  
   
   dydx[6] = dydx[8] = 0.;//not used

   // Lab Time of flight
   dydx[7] = inverse_velocity;
   
   G4ThreeVector BField(Field[0],Field[1],Field[2]);
   G4ThreeVector EField(Field[3],Field[4],Field[5]);

   EField /= c_light;

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

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

   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))
                           // from Jackson
                           // -uce*Spin.cross(u.cross(EField)) );
                           // but this form has one less operation
                     - uce*(u*(Spin*EField) - EField*(Spin*u)) );
   }

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

   return ;
}

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GetAnomaly()

G4double G4EqEMFieldWithSpin::GetAnomaly ( ) const

inline

Definition at line 68 of file G4EqEMFieldWithSpin.hh.

{ return anomaly; }

SetAnomaly()

void G4EqEMFieldWithSpin::SetAnomaly ( G4double  a )

inline

Definition at line 67 of file G4EqEMFieldWithSpin.hh.

{ anomaly = a; }

SetChargeMomentumMass()

void G4EqEMFieldWithSpin::SetChargeMomentumMass ( G4ChargeState  particleCharge, G4double  MomentumXc, G4double  mass  )

virtual

Implements G4EquationOfMotion.

Definition at line 57 of file G4EqEMFieldWithSpin.cc.

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

   fElectroMagCof =  eplus*charge*c_light ;
   fMassCof = mass*mass;

   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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Member Data Documentation

anomaly

G4double G4EqEMFieldWithSpin::anomaly

private

Definition at line 78 of file G4EqEMFieldWithSpin.hh.

beta

G4double G4EqEMFieldWithSpin::beta

private

Definition at line 79 of file G4EqEMFieldWithSpin.hh.

charge

G4double G4EqEMFieldWithSpin::charge

private

Definition at line 73 of file G4EqEMFieldWithSpin.hh.

fElectroMagCof

G4double G4EqEMFieldWithSpin::fElectroMagCof

private

Definition at line 75 of file G4EqEMFieldWithSpin.hh.

fMassCof

G4double G4EqEMFieldWithSpin::fMassCof

private

Definition at line 76 of file G4EqEMFieldWithSpin.hh.

gamma

G4double G4EqEMFieldWithSpin::gamma

private

Definition at line 79 of file G4EqEMFieldWithSpin.hh.

magMoment

G4double G4EqEMFieldWithSpin::magMoment

private

Definition at line 73 of file G4EqEMFieldWithSpin.hh.

mass

G4double G4EqEMFieldWithSpin::mass

private

Definition at line 73 of file G4EqEMFieldWithSpin.hh.

omegac

G4double G4EqEMFieldWithSpin::omegac

private

Definition at line 78 of file G4EqEMFieldWithSpin.hh.

spin

G4double G4EqEMFieldWithSpin::spin

private

Definition at line 73 of file G4EqEMFieldWithSpin.hh.

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

• G4EqEMFieldWithSpin.hh
• G4EqEMFieldWithSpin.cc