G4eeToTwoGammaModel Class Reference

#include <G4eeToTwoGammaModel.hh>

Inheritance diagram for G4eeToTwoGammaModel:

Public Member Functions
	G4eeToTwoGammaModel (const G4ParticleDefinition *p=0, const G4String &nam="eplus2gg")
virtual	~G4eeToTwoGammaModel ()
virtual void	Initialise (const G4ParticleDefinition *, const G4DataVector &)
virtual G4double	ComputeCrossSectionPerElectron (const G4ParticleDefinition *, G4double kinEnergy, G4double cutEnergy=0., G4double maxEnergy=DBL_MAX)
virtual G4double	ComputeCrossSectionPerAtom (const G4ParticleDefinition *, G4double kinEnergy, G4double Z, G4double A=0., G4double cutEnergy=0., G4double maxEnergy=DBL_MAX)
virtual G4double	CrossSectionPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy, G4double maxEnergy)
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	InitialiseLocal (const G4ParticleDefinition *, G4VEmModel *masterModel)
virtual void	InitialiseForMaterial (const G4ParticleDefinition *, const G4Material *)
virtual void	InitialiseForElement (const G4ParticleDefinition *, G4int Z)
virtual G4double	ComputeDEDXPerVolume (const G4Material *, const G4ParticleDefinition *, G4double kineticEnergy, G4double cutEnergy=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 *, G4double cut=0.0)
virtual G4double	MinEnergyCut (const G4ParticleDefinition *, const G4MaterialCutsCouple *)
virtual void	SetupForMaterial (const G4ParticleDefinition *, const G4Material *, G4double kineticEnergy)
virtual void	DefineForRegion (const G4Region *)
void	InitialiseElementSelectors (const G4ParticleDefinition *, const G4DataVector &)
std::vector < G4EmElementSelector * > *	GetElementSelectors ()
void	SetElementSelectors (std::vector< G4EmElementSelector * > *)
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)
G4int	SelectRandomAtomNumber (const G4Material *)
void	SetParticleChange (G4VParticleChange *, G4VEmFluctuationModel *f=0)
void	SetCrossSectionTable (G4PhysicsTable *, G4bool isLocal)
G4ElementData *	GetElementData ()
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
G4bool	UseAngularGeneratorFlag () const
void	SetAngularGeneratorFlag (G4bool)
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	SetForceBuildTable (G4bool val)
void	SetMasterThread (G4bool val)
G4bool	IsMaster () const
G4double	MaxSecondaryKinEnergy (const G4DynamicParticle *dynParticle)
const G4String &	GetName () const
void	SetCurrentCouple (const G4MaterialCutsCouple *)
const G4Element *	GetCurrentElement () const

Additional Inherited Members
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 inherited from G4VEmModel
G4ElementData *	fElementData
G4VParticleChange *	pParticleChange
G4PhysicsTable *	xSectionTable
const std::vector< G4double > *	theDensityFactor
const std::vector< G4int > *	theDensityIdx
size_t	idxTable

Detailed Description

Definition at line 60 of file G4eeToTwoGammaModel.hh.

Constructor & Destructor Documentation

G4eeToTwoGammaModel::G4eeToTwoGammaModel	(	const G4ParticleDefinition *	p = 0,
		const G4String &	nam = "eplus2gg"
	)

Definition at line 87 of file G4eeToTwoGammaModel.cc.

References G4Gamma::Gamma().

  : G4VEmModel(nam),
    pi_rcl2(pi*classic_electr_radius*classic_electr_radius),
    isInitialised(false)
{
  theGamma = G4Gamma::Gamma();
  fParticleChange = 0;
}

G4eeToTwoGammaModel::~G4eeToTwoGammaModel ( )

virtual

Definition at line 99 of file G4eeToTwoGammaModel.cc.

{}

Member Function Documentation

G4double G4eeToTwoGammaModel::ComputeCrossSectionPerAtom ( const G4ParticleDefinition *  p, G4double  kinEnergy, G4double  Z, G4double  A = 0., G4double  cutEnergy = 0., G4double  maxEnergy = DBL_MAX  )

virtual

Reimplemented from G4VEmModel.

Definition at line 137 of file G4eeToTwoGammaModel.cc.

References ComputeCrossSectionPerElectron().

{
  // Calculates the cross section per atom of annihilation into two photons
  
  G4double cross = Z*ComputeCrossSectionPerElectron(p,kineticEnergy);
  return cross;  
}

G4double G4eeToTwoGammaModel::ComputeCrossSectionPerElectron ( const G4ParticleDefinition *  , G4double  kinEnergy, G4double  cutEnergy = 0., G4double  maxEnergy = DBL_MAX  )

virtual

Reimplemented in G4PolarizedAnnihilationModel.

Definition at line 114 of file G4eeToTwoGammaModel.cc.

References python.hepunit::electron_mass_c2, python.hepunit::eV, G4Log(), G4InuclParticleNames::gam, and G4INCL::Math::max().

Referenced by ComputeCrossSectionPerAtom(), G4PolarizedAnnihilationModel::ComputeCrossSectionPerElectron(), and CrossSectionPerVolume().

{
  // Calculates the cross section per electron of annihilation into two photons
  // from the Heilter formula.

  G4double ekin  = std::max(eV,kineticEnergy);   

  G4double tau   = ekin/electron_mass_c2;
  G4double gam   = tau + 1.0;
  G4double gamma2= gam*gam;
  G4double bg2   = tau * (tau+2.0);
  G4double bg    = sqrt(bg2);

  G4double cross = pi_rcl2*((gamma2+4*gam+1.)*G4Log(gam+bg) - (gam+3.)*bg)
                 / (bg2*(gam+1.));
  return cross;  
}

G4double G4eeToTwoGammaModel::CrossSectionPerVolume ( const G4Material *  material, const G4ParticleDefinition *  p, G4double  kineticEnergy, G4double  cutEnergy, G4double  maxEnergy  )

virtual

Reimplemented from G4VEmModel.

Definition at line 150 of file G4eeToTwoGammaModel.cc.

References ComputeCrossSectionPerElectron(), and G4Material::GetElectronDensity().

{
  // Calculates the cross section per volume of annihilation into two photons
  
  G4double eDensity = material->GetElectronDensity();
  G4double cross = eDensity*ComputeCrossSectionPerElectron(p,kineticEnergy);
  return cross;
}

void G4eeToTwoGammaModel::Initialise ( const G4ParticleDefinition *  , const G4DataVector &    )

virtual

Implements G4VEmModel.

Reimplemented in G4PolarizedAnnihilationModel.

Definition at line 104 of file G4eeToTwoGammaModel.cc.

References G4VEmModel::GetParticleChangeForGamma().

{
  if(isInitialised) { return; }
  fParticleChange = GetParticleChangeForGamma();
  isInitialised = true;
}

void G4eeToTwoGammaModel::SampleSecondaries ( std::vector< G4DynamicParticle * > *  vdp, const G4MaterialCutsCouple *  , const G4DynamicParticle *  dp, G4double  tmin, G4double  maxEnergy  )

virtual

!! likely problematic direction to be checked

Implements G4VEmModel.

Reimplemented in G4PolarizedAnnihilationModel.

Definition at line 165 of file G4eeToTwoGammaModel.cc.

References python.hepunit::electron_mass_c2, fStopAndKill, G4cout, G4endl, G4Exp(), G4Log(), G4UniformRand, G4InuclParticleNames::gam, G4DynamicParticle::GetKineticEnergy(), G4DynamicParticle::GetMomentumDirection(), G4VParticleChange::ProposeTrackStatus(), CLHEP::Hep3Vector::rotateUz(), G4DynamicParticle::SetPolarization(), G4ParticleChangeForGamma::SetProposedKineticEnergy(), python.hepunit::twopi, CLHEP::Hep3Vector::unit(), CLHEP::Hep3Vector::x(), CLHEP::Hep3Vector::y(), and CLHEP::Hep3Vector::z().

{
  G4double PositKinEnergy = dp->GetKineticEnergy();
  G4DynamicParticle *aGamma1, *aGamma2;
   
  // Case at rest
  if(PositKinEnergy == 0.0) {
    G4double cost = 2.*G4UniformRand()-1.;
    G4double sint = sqrt((1. - cost)*(1. + cost));
    G4double phi  = twopi * G4UniformRand();
    G4ThreeVector dir(sint*cos(phi), sint*sin(phi), cost);
    phi = twopi * G4UniformRand();
    G4ThreeVector pol(cos(phi), sin(phi), 0.0);
    pol.rotateUz(dir);
    aGamma1 = new G4DynamicParticle(theGamma, dir, electron_mass_c2);
    aGamma1->SetPolarization(pol.x(),pol.y(),pol.z());
    aGamma2 = new G4DynamicParticle(theGamma,-dir, electron_mass_c2);
    aGamma1->SetPolarization(-pol.x(),-pol.y(),-pol.z());

  } else {

    G4ThreeVector PositDirection = dp->GetMomentumDirection();

    G4double tau     = PositKinEnergy/electron_mass_c2;
    G4double gam     = tau + 1.0;
    G4double tau2    = tau + 2.0;
    G4double sqgrate = sqrt(tau/tau2)*0.5;
    G4double sqg2m1  = sqrt(tau*tau2);

    // limits of the energy sampling
    G4double epsilmin = 0.5 - sqgrate;
    G4double epsilmax = 0.5 + sqgrate;
    G4double epsilqot = epsilmax/epsilmin;

    //
    // sample the energy rate of the created gammas
    //
    G4double epsil, greject;

    do {
      epsil = epsilmin*G4Exp(G4Log(epsilqot)*G4UniformRand());
      greject = 1. - epsil + (2.*gam*epsil-1.)/(epsil*tau2*tau2);
    } while( greject < G4UniformRand() );

    //
    // scattered Gamma angles. ( Z - axis along the parent positron)
    //

    G4double cost = (epsil*tau2-1.)/(epsil*sqg2m1);
    if(std::abs(cost) > 1.0) {
      G4cout << "### G4eeToTwoGammaModel WARNING cost= " << cost
         << " positron Ekin(MeV)= " << PositKinEnergy
         << " gamma epsil= " << epsil
         << G4endl;
      if(cost > 1.0) cost = 1.0;
      else cost = -1.0; 
    }
    G4double sint = sqrt((1.+cost)*(1.-cost));
    G4double phi  = twopi * G4UniformRand();

    //
    // kinematic of the created pair
    //

    G4double TotalAvailableEnergy = PositKinEnergy + 2.0*electron_mass_c2;
    G4double Phot1Energy = epsil*TotalAvailableEnergy;

    G4ThreeVector Phot1Direction(sint*cos(phi), sint*sin(phi), cost);
    Phot1Direction.rotateUz(PositDirection);
    aGamma1 = new G4DynamicParticle (theGamma,Phot1Direction, Phot1Energy);
    phi = twopi * G4UniformRand();
    G4ThreeVector pol1(cos(phi), sin(phi), 0.0);
    pol1.rotateUz(Phot1Direction);
    aGamma1->SetPolarization(pol1.x(),pol1.y(),pol1.z());

    G4double Phot2Energy =(1.-epsil)*TotalAvailableEnergy;
    G4double PositP= sqrt(PositKinEnergy*(PositKinEnergy+2.*electron_mass_c2));
    G4ThreeVector dir = PositDirection*PositP - Phot1Direction*Phot1Energy;
    G4ThreeVector Phot2Direction = dir.unit();

    // create G4DynamicParticle object for the particle2
    aGamma2 = new G4DynamicParticle (theGamma,Phot2Direction, Phot2Energy);

    //!!! likely problematic direction to be checked
    aGamma2->SetPolarization(-pol1.x(),-pol1.y(),-pol1.z());
  }
  /*
    G4cout << "Annihilation in fly: e0= " << PositKinEnergy
    << " m= " << electron_mass_c2
    << " e1= " << Phot1Energy 
    << " e2= " << Phot2Energy << " dir= " <<  dir 
    << " -> " << Phot1Direction << " " 
    << Phot2Direction << G4endl;
  */
 
  vdp->push_back(aGamma1);
  vdp->push_back(aGamma2);
  fParticleChange->SetProposedKineticEnergy(0.);
  fParticleChange->ProposeTrackStatus(fStopAndKill);
}

---

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

• G4eeToTwoGammaModel.hh
• G4eeToTwoGammaModel.cc