G4eeToTwoGammaModel

public G4VEmModel

Implementation of e+ annihilation into 2 gamma
The secondaries Gamma energies are sampled using the Heitler cross section.
A modified version of the random number techniques of Butcher & Messel is used (Nuc Phys 20(1960),15).

GEANT4 internal units.
Note 1: The initial electron is assumed free and at rest.
Note 2: The annihilation processes producing one or more than two photons are ignored, as negligible compared to the two photons process.

class

public:

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

  virtual ~G4eeToTwoGammaModel();

  virtual void Initialise(const G4ParticleDefinition*, 
              const G4DataVector&) override;

  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) final;

  virtual G4double CrossSectionPerVolume(const G4Material*,
                     const G4ParticleDefinition*,
                     G4double kineticEnergy,
                     G4double cutEnergy,
                     G4double maxEnergy) final;

  virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*,
                 const G4MaterialCutsCouple*,
                 const G4DynamicParticle*,
                 G4double tmin,
                 G4double maxEnergy) override;

private:

  // hide assignment operator
  G4eeToTwoGammaModel & operator=(const  G4eeToTwoGammaModel &right) = delete;
  G4eeToTwoGammaModel(const  G4eeToTwoGammaModel&) = delete;