G4MollerBhabhaModel Class Reference

#include <G4MollerBhabhaModel.hh>

Inheritance diagram for G4MollerBhabhaModel:

Public Member Functions
	G4MollerBhabhaModel (const G4ParticleDefinition *p=0, const G4String &nam="MollerBhabha")
virtual	~G4MollerBhabhaModel ()
virtual void	Initialise (const G4ParticleDefinition *, const G4DataVector &)
virtual G4double	ComputeCrossSectionPerElectron (const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy, G4double maxEnergy)
virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kineticEnergy, G4double Z, G4double A, G4double cutEnergy, G4double maxEnergy)
virtual G4double	CrossSectionPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy, G4double maxEnergy)
virtual G4double	ComputeDEDXPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy)
virtual void	SampleSecondaries (std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin, G4double maxEnergy)
Public Member Functions inherited from G4VEmModel
	G4VEmModel (const G4String &nam)
virtual	~G4VEmModel ()
virtual void	Initialise (const G4ParticleDefinition *, const G4DataVector &)=0
virtual void	SampleSecondaries (std::vector< G4DynamicParticle * > *, const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double tmin=0.0, G4double tmax=DBL_MAX)=0
virtual G4double	ComputeDEDXPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=DBL_MAX)
virtual G4double	CrossSectionPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A=0., G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
virtual G4double	ChargeSquareRatio (const G4Track &)
virtual G4double	GetChargeSquareRatio (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual G4double	GetParticleCharge (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual void	StartTracking (G4Track *)
virtual void	CorrectionsAlongStep (const G4MaterialCutsCouple *, const G4DynamicParticle *, G4double &eloss, G4double &niel, G4double length)
virtual G4double	Value (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy)
virtual G4double	MinPrimaryEnergy (const G4Material *, const G4ParticleDefinition *)
virtual void	SetupForMaterial (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual void	DefineForRegion (const G4Region *)
void	InitialiseElementSelectors (const G4ParticleDefinition *, const G4DataVector &)
G4double	ComputeDEDX (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=DBL_MAX)
G4double	CrossSection (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
G4double	ComputeMeanFreePath (const G4ParticleDefinition *, G4double kineticEnergy, const G4Material *, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, const G4Element *, G4double kinEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
G4int	SelectIsotopeNumber (const G4Element *)
const G4Element *	SelectRandomAtom (const G4MaterialCutsCouple *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
const G4Element *	SelectRandomAtom (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=0.0, G4double maxEnergy=DBL_MAX)
void	SetParticleChange (G4VParticleChange *, G4VEmFluctuationModel *f=0)
void	SetCrossSectionTable (G4PhysicsTable *)
G4PhysicsTable *	GetCrossSectionTable ()
G4VEmFluctuationModel *	GetModelOfFluctuations ()
G4VEmAngularDistribution *	GetAngularDistribution ()
void	SetAngularDistribution (G4VEmAngularDistribution *)
G4double	HighEnergyLimit () const
G4double	LowEnergyLimit () const
G4double	HighEnergyActivationLimit () const
G4double	LowEnergyActivationLimit () const
G4double	PolarAngleLimit () const
G4double	SecondaryThreshold () const
G4bool	LPMFlag () const
G4bool	DeexcitationFlag () const
G4bool	ForceBuildTableFlag () const
void	SetHighEnergyLimit (G4double)
void	SetLowEnergyLimit (G4double)
void	SetActivationHighEnergyLimit (G4double)
void	SetActivationLowEnergyLimit (G4double)
G4bool	IsActive (G4double kinEnergy)
void	SetPolarAngleLimit (G4double)
void	SetSecondaryThreshold (G4double)
void	SetLPMFlag (G4bool val)
void	SetDeexcitationFlag (G4bool val)
void	ForceBuildTable (G4bool val)
G4double	MaxSecondaryKinEnergy (const G4DynamicParticle *dynParticle)
const G4String &	GetName () const
void	SetCurrentCouple (const G4MaterialCutsCouple *)
const G4Element *	GetCurrentElement () const

Protected Member Functions
virtual G4double	MaxSecondaryEnergy (const G4ParticleDefinition *, G4double kinEnergy)
void	SetParticle (const G4ParticleDefinition *p)
Protected Member Functions inherited from G4VEmModel
G4ParticleChangeForLoss *	GetParticleChangeForLoss ()
G4ParticleChangeForGamma *	GetParticleChangeForGamma ()
virtual G4double	MaxSecondaryEnergy (const G4ParticleDefinition *, G4double kineticEnergy)
const G4MaterialCutsCouple *	CurrentCouple () const
void	SetCurrentElement (const G4Element *)

Protected Attributes
const G4ParticleDefinition *	particle
G4ParticleDefinition *	theElectron
G4ParticleChangeForLoss *	fParticleChange
G4bool	isElectron
G4double	twoln10
G4double	lowLimit
Protected Attributes inherited from G4VEmModel
G4VParticleChange *	pParticleChange
G4PhysicsTable *	xSectionTable
const std::vector< G4double > *	theDensityFactor
const std::vector< G4int > *	theDensityIdx

Detailed Description

Definition at line 63 of file G4MollerBhabhaModel.hh.

Constructor & Destructor Documentation

G4MollerBhabhaModel()

G4MollerBhabhaModel::G4MollerBhabhaModel	(	const G4ParticleDefinition *	p = 0,
		const G4String &	nam = "MollerBhabha"
	)

Definition at line 74 of file G4MollerBhabhaModel.cc.

  : G4VEmModel(nam),
    particle(0),
    isElectron(true),
    twoln10(2.0*log(10.0)),
    lowLimit(0.02*keV),
    isInitialised(false)
{
  theElectron = G4Electron::Electron();
  if(p) { SetParticle(p); }
  fParticleChange = 0;
}

~G4MollerBhabhaModel()

G4MollerBhabhaModel::~G4MollerBhabhaModel ( )

virtual

Definition at line 90 of file G4MollerBhabhaModel.cc.

{}

Member Function Documentation

ComputeCrossSectionPerAtom()

G4double G4MollerBhabhaModel::ComputeCrossSectionPerAtom ( const G4ParticleDefinition *  p, G4double  kineticEnergy, G4double  Z, G4double  A, G4double  cutEnergy, G4double  maxEnergy  )

virtual

Reimplemented from G4VEmModel.

Definition at line 172 of file G4MollerBhabhaModel.cc.

{
  return Z*ComputeCrossSectionPerElectron(p,kineticEnergy,cutEnergy,maxEnergy);
}

ComputeCrossSectionPerElectron()

G4double G4MollerBhabhaModel::ComputeCrossSectionPerElectron ( const G4ParticleDefinition *  p, G4double  kineticEnergy, G4double  cutEnergy, G4double  maxEnergy  )

virtual

Reimplemented in G4PolarizedMollerBhabhaModel.

Definition at line 119 of file G4MollerBhabhaModel.cc.

{
  if(!particle) { SetParticle(p); }
 
  G4double cross = 0.0;
  G4double tmax = MaxSecondaryEnergy(p, kineticEnergy);
  tmax = std::min(maxEnergy, tmax);
 
  if(cutEnergy < tmax) {
 
    G4double xmin  = cutEnergy/kineticEnergy;
    G4double xmax  = tmax/kineticEnergy;
    G4double tau   = kineticEnergy/electron_mass_c2;
    G4double gam   = tau + 1.0;
    G4double gamma2= gam*gam;
    G4double beta2 = tau*(tau + 2)/gamma2;
 
    //Moller (e-e-) scattering
    if (isElectron) {
 
      G4double gg = (2.0*gam - 1.0)/gamma2;
      cross = ((xmax - xmin)*(1.0 - gg + 1.0/(xmin*xmax)
                  + 1.0/((1.0-xmin)*(1.0 - xmax)))
            - gg*log( xmax*(1.0 - xmin)/(xmin*(1.0 - xmax)) ) ) / beta2;
 
    //Bhabha (e+e-) scattering
    } else {
 
      G4double y   = 1.0/(1.0 + gam);
      G4double y2  = y*y;
      G4double y12 = 1.0 - 2.0*y;
      G4double b1  = 2.0 - y2;
      G4double b2  = y12*(3.0 + y2);
      G4double y122= y12*y12;
      G4double b4  = y122*y12;
      G4double b3  = b4 + y122;
 
      cross = (xmax - xmin)*(1.0/(beta2*xmin*xmax) + b2
            - 0.5*b3*(xmin + xmax)
        + b4*(xmin*xmin + xmin*xmax + xmax*xmax)/3.0)
            - b1*log(xmax/xmin);
    }
 
    cross *= twopi_mc2_rcl2/kineticEnergy;
  }
  return cross;
}

Referenced by ComputeCrossSectionPerAtom(), G4PolarizedMollerBhabhaModel::ComputeCrossSectionPerElectron(), and CrossSectionPerVolume().

ComputeDEDXPerVolume()

G4double G4MollerBhabhaModel::ComputeDEDXPerVolume ( const G4Material *  material, const G4ParticleDefinition *  p, G4double  kineticEnergy, G4double  cutEnergy  )

virtual

Reimplemented from G4VEmModel.

Definition at line 210 of file G4MollerBhabhaModel.cc.

{
  if(!particle) { SetParticle(p); }
  // calculate the dE/dx due to the ionization by Seltzer-Berger formula
  // checl low-energy limit
  G4double electronDensity = material->GetElectronDensity();
  
  G4double Zeff  = electronDensity/material->GetTotNbOfAtomsPerVolume();
  G4double th    = 0.25*sqrt(Zeff)*keV;
  //  G4double cut;  
  // if(isElectron) { cut  = std::max(th*0.5, cutEnergy); }
  // else           { cut  = std::max(th, cutEnergy); }
  G4double tkin  = kineticEnergy;
  if (kineticEnergy < th) { tkin = th; }
 
  G4double tau   = tkin/electron_mass_c2;
  G4double gam   = tau + 1.0;
  G4double gamma2= gam*gam;
  G4double bg2   = tau*(tau + 2);
  G4double beta2 = bg2/gamma2;
 
  G4double eexc  = material->GetIonisation()->GetMeanExcitationEnergy();
  eexc          /= electron_mass_c2;
  G4double eexc2 = eexc*eexc; 
 
  G4double d = std::min(cut, MaxSecondaryEnergy(p, tkin))/electron_mass_c2;
  G4double dedx;
 
  // electron
  if (isElectron) {
 
    dedx = log(2.0*(tau + 2.0)/eexc2) - 1.0 - beta2
         + log((tau-d)*d) + tau/(tau-d)
         + (0.5*d*d + (2.0*tau + 1.)*log(1. - d/tau))/gamma2;
   
  //positron
  } else {
 
    G4double d2 = d*d*0.5;
    G4double d3 = d2*d/1.5;
    G4double d4 = d3*d*0.75;
    G4double y  = 1.0/(1.0 + gam);
    dedx = log(2.0*(tau + 2.0)/eexc2) + log(tau*d)
         - beta2*(tau + 2.0*d - y*(3.0*d2 
         + y*(d - d3 + y*(d2 - tau*d3 + d4))))/tau;
  } 
 
  //density correction 
  G4double x = log(bg2)/twoln10;
  dedx -= material->GetIonisation()->DensityCorrection(x); 
 
  // now you can compute the total ionization loss
  dedx *= twopi_mc2_rcl2*electronDensity/beta2;
  if (dedx < 0.0) { dedx = 0.0; }
 
  // lowenergy extrapolation
 
  if (kineticEnergy < th) {
    x = kineticEnergy/th;
    if(x > 0.25) { dedx /= sqrt(x); }
    else { dedx *= 1.4*sqrt(x)/(0.1 + x); }
  }
  return dedx;
}

CrossSectionPerVolume()

G4double G4MollerBhabhaModel::CrossSectionPerVolume ( const G4Material *  material, const G4ParticleDefinition *  p, G4double  kineticEnergy, G4double  cutEnergy, G4double  maxEnergy  )

virtual

Reimplemented from G4VEmModel.

Definition at line 184 of file G4MollerBhabhaModel.cc.

{
  G4double eDensity = material->GetElectronDensity();
  return eDensity*ComputeCrossSectionPerElectron(p,kinEnergy,cutEnergy,maxEnergy);
  /*
  G4double Zeff     = eDensity/material->GetTotNbOfAtomsPerVolume();
  G4double th       = 0.25*sqrt(Zeff)*keV;
  G4double cut;  
  if(isElectron) { cut  = std::max(th*0.5, cutEnergy); }
  else           { cut  = std::max(th, cutEnergy); }
  G4double res = 0.0;
  // below this threshold no bremsstrahlung
  if (kinEnergy > th) { 
    res = eDensity*ComputeCrossSectionPerElectron(p,kinEnergy,cut,maxEnergy);
  }
  return res; 
  */
}

Initialise()

void G4MollerBhabhaModel::Initialise ( const G4ParticleDefinition *  p, const G4DataVector &    )

virtual

Implements G4VEmModel.

Definition at line 105 of file G4MollerBhabhaModel.cc.

{
  if(!particle) { SetParticle(p); }
 
  if(isInitialised) { return; }
 
  isInitialised = true;
  fParticleChange = GetParticleChangeForLoss();
}

MaxSecondaryEnergy()

G4double G4MollerBhabhaModel::MaxSecondaryEnergy ( const G4ParticleDefinition *  , G4double  kinEnergy  )

protectedvirtual

Reimplemented from G4VEmModel.

Definition at line 95 of file G4MollerBhabhaModel.cc.

{
  G4double tmax = kinEnergy;
  if(isElectron) { tmax *= 0.5; }
  return tmax;
}

Referenced by G4PolarizedMollerBhabhaModel::ComputeCrossSectionPerElectron(), ComputeCrossSectionPerElectron(), and ComputeDEDXPerVolume().

SampleSecondaries()

void G4MollerBhabhaModel::SampleSecondaries ( std::vector< G4DynamicParticle * > *  vdp, const G4MaterialCutsCouple *  , const G4DynamicParticle *  dp, G4double  tmin, G4double  maxEnergy  )

virtual

Implements G4VEmModel.

Reimplemented in G4PolarizedMollerBhabhaModel.

Definition at line 281 of file G4MollerBhabhaModel.cc.

{
  G4double kineticEnergy = dp->GetKineticEnergy();
  //const G4Material* mat = couple->GetMaterial();
  //G4double Zeff = mat->GetElectronDensity()/mat->GetTotNbOfAtomsPerVolume();
  // G4double th   = 0.25*sqrt(Zeff)*keV;
  G4double tmax;
  G4double tmin = cutEnergy;  
  if(isElectron) { 
    tmax = 0.5*kineticEnergy; 
  } else {
    tmax = kineticEnergy; 
  }
  if(maxEnergy < tmax) { tmax = maxEnergy; }
  if(tmin >= tmax) { return; }
 
  G4double energy = kineticEnergy + electron_mass_c2;
  G4double totalMomentum = sqrt(kineticEnergy*(energy + electron_mass_c2));
  G4double xmin   = tmin/kineticEnergy;
  G4double xmax   = tmax/kineticEnergy;
  G4double gam    = energy/electron_mass_c2;
  G4double gamma2 = gam*gam;
  G4double beta2  = 1.0 - 1.0/gamma2;
  G4double x, z, q, grej;
 
  G4ThreeVector direction = dp->GetMomentumDirection();
 
  //Moller (e-e-) scattering
  if (isElectron) {
 
    G4double gg = (2.0*gam - 1.0)/gamma2;
    G4double y = 1.0 - xmax;
    grej = 1.0 - gg*xmax + xmax*xmax*(1.0 - gg + (1.0 - gg*y)/(y*y));
 
    do {
      q = G4UniformRand();
      x = xmin*xmax/(xmin*(1.0 - q) + xmax*q);
      y = 1.0 - x;
      z = 1.0 - gg*x + x*x*(1.0 - gg + (1.0 - gg*y)/(y*y));
      /*
      if(z > grej) {
        G4cout << "G4MollerBhabhaModel::SampleSecondary Warning! "
               << "Majorant " << grej << " < "
               << z << " for x= " << x
               << " e-e- scattering"
               << G4endl;
      }
      */
    } while(grej * G4UniformRand() > z);
 
  //Bhabha (e+e-) scattering
  } else {
 
    G4double y   = 1.0/(1.0 + gam);
    G4double y2  = y*y;
    G4double y12 = 1.0 - 2.0*y;
    G4double b1  = 2.0 - y2;
    G4double b2  = y12*(3.0 + y2);
    G4double y122= y12*y12;
    G4double b4  = y122*y12;
    G4double b3  = b4 + y122;
 
    y    = xmax*xmax;
    grej = 1.0 + (y*y*b4 - xmin*xmin*xmin*b3 + y*b2 - xmin*b1)*beta2; 
    do {
      q = G4UniformRand();
      x = xmin*xmax/(xmin*(1.0 - q) + xmax*q);
      y = x*x;
      z = 1.0 + (y*y*b4 - x*y*b3 + y*b2 - x*b1)*beta2; 
      /*
      if(z > grej) {
        G4cout << "G4MollerBhabhaModel::SampleSecondary Warning! "
               << "Majorant " << grej << " < "
               << z << " for x= " << x
               << " e+e- scattering"
               << G4endl;
      }
      */
    } while(grej * G4UniformRand() > z);
  }
 
  G4double deltaKinEnergy = x * kineticEnergy;
 
  G4double deltaMomentum =
           sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2));
  G4double cost = deltaKinEnergy * (energy + electron_mass_c2) /
                                   (deltaMomentum * totalMomentum);
  G4double sint = (1.0 - cost)*(1. + cost);
  if(sint > 0.0) { sint = sqrt(sint); }
  else { sint = 0.0; }
 
  G4double phi = twopi * G4UniformRand() ;
 
  G4ThreeVector deltaDirection(sint*cos(phi),sint*sin(phi), cost) ;
  deltaDirection.rotateUz(direction);
 
  // primary change
  kineticEnergy -= deltaKinEnergy;
  fParticleChange->SetProposedKineticEnergy(kineticEnergy);
 
  G4ThreeVector dir = totalMomentum*direction - deltaMomentum*deltaDirection;
  direction = dir.unit();
  fParticleChange->SetProposedMomentumDirection(direction);
 
  // create G4DynamicParticle object for delta ray
  G4DynamicParticle* delta = new G4DynamicParticle(theElectron,
                           deltaDirection,deltaKinEnergy);
  vdp->push_back(delta);
}

SetParticle()

void G4MollerBhabhaModel::SetParticle ( const G4ParticleDefinition *  p )

inlineprotected

Definition at line 132 of file G4MollerBhabhaModel.hh.

{
  particle = p;
  if(p != theElectron) { isElectron = false; }
}

Referenced by ComputeCrossSectionPerElectron(), ComputeDEDXPerVolume(), G4MollerBhabhaModel(), and Initialise().

Member Data Documentation

fParticleChange

G4ParticleChangeForLoss* G4MollerBhabhaModel::fParticleChange

protected

Definition at line 114 of file G4MollerBhabhaModel.hh.

Referenced by G4MollerBhabhaModel(), Initialise(), G4PolarizedMollerBhabhaModel::SampleSecondaries(), and SampleSecondaries().

isElectron

G4bool G4MollerBhabhaModel::isElectron

protected

Definition at line 116 of file G4MollerBhabhaModel.hh.

Referenced by ComputeCrossSectionPerElectron(), ComputeDEDXPerVolume(), G4PolarizedMollerBhabhaModel::G4PolarizedMollerBhabhaModel(), MaxSecondaryEnergy(), G4PolarizedMollerBhabhaModel::SampleSecondaries(), SampleSecondaries(), and SetParticle().

lowLimit

G4double G4MollerBhabhaModel::lowLimit

protected

Definition at line 118 of file G4MollerBhabhaModel.hh.

particle

const G4ParticleDefinition* G4MollerBhabhaModel::particle

protected

Definition at line 112 of file G4MollerBhabhaModel.hh.

Referenced by ComputeCrossSectionPerElectron(), ComputeDEDXPerVolume(), Initialise(), and SetParticle().

theElectron

G4ParticleDefinition* G4MollerBhabhaModel::theElectron

protected

Definition at line 113 of file G4MollerBhabhaModel.hh.

Referenced by G4MollerBhabhaModel(), G4PolarizedMollerBhabhaModel::G4PolarizedMollerBhabhaModel(), G4PolarizedMollerBhabhaModel::SampleSecondaries(), SampleSecondaries(), and SetParticle().

twoln10

G4double G4MollerBhabhaModel::twoln10

protected

Definition at line 117 of file G4MollerBhabhaModel.hh.

Referenced by ComputeDEDXPerVolume().

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

• G4MollerBhabhaModel.hh
• G4MollerBhabhaModel.cc