G4EqEMFieldWithEDM Class Reference

G4EqEMFieldWithEDM implements the right-hand side of equation of motion in a combined electric and magnetic field, with spin tracking for both MDM and EDM terms. More...

#include <G4EqEMFieldWithEDM.hh>

Inheritance diagram for G4EqEMFieldWithEDM:

Public Member Functions
	G4EqEMFieldWithEDM (G4ElectroMagneticField *emField)
	~G4EqEMFieldWithEDM () override=default
void	SetChargeMomentumMass (G4ChargeState particleCharge, G4double MomentumXc, G4double mass) override
void	EvaluateRhsGivenB (const G4double y[], const G4double Field[], G4double dydx[]) const override
void	SetAnomaly (G4double a)
G4double	GetAnomaly () const
void	SetEta (G4double n)
G4double	GetEta () const
G4EquationType	GetEquationType () const override
Public Member Functions inherited from G4EquationOfMotion
	G4EquationOfMotion (G4Field *Field)
virtual	~G4EquationOfMotion ()=default
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
G4Field *	GetFieldObj ()
void	SetFieldObj (G4Field *pField)

Detailed Description

G4EqEMFieldWithEDM implements the right-hand side of equation of motion in a combined electric and magnetic field, with spin tracking for both MDM and EDM terms.

Definition at line 50 of file G4EqEMFieldWithEDM.hh.

Constructor & Destructor Documentation

G4EqEMFieldWithEDM()

G4EqEMFieldWithEDM::G4EqEMFieldWithEDM

(

G4ElectroMagneticField *

emField

)

Constructor for G4EqEMFieldWithEDM.

Parameters

[in]

emField

Pointer to the electromagnetic field.

Definition at line 41 of file G4EqEMFieldWithEDM.cc.

  : G4EquationOfMotion( emField ) 
{
}

~G4EqEMFieldWithEDM()

G4EqEMFieldWithEDM::~G4EqEMFieldWithEDM ( )

overridedefault

Default Destructor.

Member Function Documentation

EvaluateRhsGivenB()

void G4EqEMFieldWithEDM::EvaluateRhsGivenB ( const G4double y[], const G4double Field[], G4double dydx[] ) const

override

Calculates the value of the derivative, given the value of the electromagnetic field.

Parameters

[in]	y	Coefficients array.
[in]	Field	Field value.
[out]	dydx	Derivatives array.

Definition at line 81 of file G4EqEMFieldWithEDM.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, with additions for EDM
   // evolution from 
   // M.Nowakowski, et.al. Eur.J.Phys.26, pp 545-560, (2005)
   // or
   // Silenko, Phys.Rev.ST Accel.Beams 9:034003, (2006)
 
   // dS/dt = (e/m) S \cross 
   // MDM:         [ (g/2-1 +1/\gamma) B
   //               -(g/2-1)\gamma/(\gamma+1) (\beta \cdot B)\beta 
   //               -(g/2-\gamma/(\gamma+1) \beta \cross E 
   //
   // EDM:        eta/2( E - gamma/(gamma+1) \beta (\beta \cdot E)
   //                    + \beta \cross B ) ]
   //
   // 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.);
   G4double ude = beta*gamma/(1.+gamma)*(EField*u);
 
   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))
                         + eta/2.*(Spin.cross(EField) - ude*(Spin.cross(u))
                                 // +Spin.cross(u.cross(Bfield))
                         + (u*(Spin*BField) - BField*(Spin*u)) ) );
   }
      
   dydx[ 9] = dSpin.x();
   dydx[10] = dSpin.y();
   dydx[11] = dSpin.z();
 
   return;
}

GetAnomaly()

G4double G4EqEMFieldWithEDM::GetAnomaly ( ) const

inline

Definition at line 91 of file G4EqEMFieldWithEDM.hh.

{ return anomaly; }

GetEquationType()

G4EquationType G4EqEMFieldWithEDM::GetEquationType ( ) const

inlineoverridevirtual

Returns the equation type-ID, "kEqEMfieldWithEDM".

Reimplemented from G4EquationOfMotion.

Definition at line 102 of file G4EqEMFieldWithEDM.hh.

{ return kEqEMfieldWithEDM; }

GetEta()

G4double G4EqEMFieldWithEDM::GetEta ( ) const

inline

Definition at line 97 of file G4EqEMFieldWithEDM.hh.

{ return eta; }

SetAnomaly()

void G4EqEMFieldWithEDM::SetAnomaly ( G4double a )

inline

Setter and getter for magnetic anomaly.

Definition at line 90 of file G4EqEMFieldWithEDM.hh.

{ anomaly = a; }

SetChargeMomentumMass()

void G4EqEMFieldWithEDM::SetChargeMomentumMass ( G4ChargeState particleCharge, G4double MomentumXc, G4double mass )

overridevirtual

Sets the charge, momentum and mass of the current particle. Used to set the equation's coefficients.

Parameters

[in]	particleCharge	Magnetic charge and moments in e+ units.
[in]	MomentumXc	Particle momentum.
[in]	mass	Particle mass.

Implements G4EquationOfMotion.

Definition at line 47 of file G4EqEMFieldWithEDM.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;
}

SetEta()

void G4EqEMFieldWithEDM::SetEta ( G4double n )

inline

Setter and getter for EDM eta parameter.

Definition at line 96 of file G4EqEMFieldWithEDM.hh.

{ eta = n; }

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

• G4EqEMFieldWithEDM.hh
• G4EqEMFieldWithEDM.cc