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//
// $Id: G4GammaConversionToMuons.icc,v 1.1 2002/04/19 14:44:33 hbu Exp $
// GEANT4 tag $Name: geant4-05-00 $
//
//         ------------ G4GammaConversionToMuons physics process ------
//         by H.Burkhardt, S. Kelner and R. Kokoulin, April 2002
// -----------------------------------------------------------------------------

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

inline G4bool G4GammaConversionToMuons::IsApplicable(
                                        const G4ParticleDefinition& particle)
{
   return ( &particle == G4Gamma::Gamma() );
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

inline G4double G4GammaConversionToMuons::GetCrossSectionPerAtom(
                                   const G4DynamicParticle* aDynamicGamma,
                                         G4Element*         anElement)

// gives the total cross section per atom in GEANT4 internal units
{
   G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
   G4double AtomicZ = anElement->GetZ();
   G4double AtomicA = anElement->GetA()/(g/mole);
   G4double crossSection =
        ComputeCrossSectionPerAtom(GammaEnergy,AtomicZ,AtomicA);
   return crossSection;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

inline G4double G4GammaConversionToMuons::GetMeanFreePath(const G4Track& aTrack,
                                              G4double, G4ForceCondition*)

// returns the photon mean free path in GEANT4 internal units
// (MeanFreePath is a private member of the class)

{
   const G4DynamicParticle* aDynamicGamma = aTrack.GetDynamicParticle();
   G4double GammaEnergy = aDynamicGamma->GetKineticEnergy();
   G4Material* aMaterial = aTrack.GetMaterial();

   if (GammaEnergy <  LowestEnergyLimit)
     MeanFreePath = DBL_MAX;
   else
     MeanFreePath = ComputeMeanFreePath(GammaEnergy,aMaterial);

   return MeanFreePath;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

inline G4double G4GammaConversionToMuons::ComputeMeanFreePath(
                            G4double GammaEnergy, G4Material* aMaterial)

// computes and returns the photon mean free path in GEANT4 internal units
{
  const G4ElementVector* theElementVector = aMaterial->GetElementVector();
  const G4double* NbOfAtomsPerVolume = aMaterial->GetVecNbOfAtomsPerVolume();

  G4double SIGMA = 0 ;

  for ( size_t i=0 ; i < aMaterial->GetNumberOfElements() ; i++ )
  {
    G4double AtomicZ = (*theElementVector)[i]->GetZ();
    G4double AtomicA = (*theElementVector)[i]->GetA()/(g/mole);
    SIGMA += NbOfAtomsPerVolume[i] *
      ComputeCrossSectionPerAtom(GammaEnergy,AtomicZ,AtomicA);
  }
  return SIGMA > DBL_MIN ? 1./SIGMA : DBL_MAX;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......