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//
// $Id: G4eplusAnnihilation.icc,v 1.8 2001/09/17 17:07:11 maire Exp $
// GEANT4 tag $Name: geant4-05-02-patch-01 $
//
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// 10-01-97, crossection table + meanfreepath table, M.Maire
// 17-03-97, merge 'in fly' and 'at rest', M.Maire
// 28-05-01, V.Ivanchenko minor changes to provide ANSI -wall compilation 
// 17-09-01, migration of Materials to pure STL (mma) 
// 
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inline G4bool G4eplusAnnihilation::IsApplicable(
                                           const G4ParticleDefinition& particle)
{
   return ( &particle == G4Positron::Positron() ); 
}

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inline G4double G4eplusAnnihilation::GetCrossSectionPerAtom(
                                           G4DynamicParticle* aDynamicPositron,
                                           G4Element*         anElement)
 
// return the total cross section per atom in GEANT4 internal units

{
   G4double crossSection;
   G4double PositronEnergy = aDynamicPositron->GetKineticEnergy();
   G4bool isOutRange ;

   if (PositronEnergy > HighestEnergyLimit)
     crossSection = 0. ;
   else {
     if (PositronEnergy < LowestEnergyLimit) PositronEnergy = 1.01*LowestEnergyLimit;
     crossSection = (*theCrossSectionTable)(anElement->GetIndex())->
                    GetValue( PositronEnergy, isOutRange );
   }

   return crossSection; 
}

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inline G4double G4eplusAnnihilation::GetMeanFreePath(const G4Track& aTrack,
                                                     G4double,
                                                     G4ForceCondition*)
 
// returns the positron mean free path in GEANT4 internal units

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

  G4double MeanFreePath;
  G4bool isOutRange ;

  if (PositronEnergy > HighestEnergyLimit) MeanFreePath = DBL_MAX;
  else 
    {
     if (PositronEnergy < LowestEnergyLimit)
                                    PositronEnergy = 1.01*LowestEnergyLimit;
     MeanFreePath = (*theMeanFreePathTable)(aMaterial->GetIndex())->
                    GetValue( PositronEnergy, isOutRange );
    }

  return MeanFreePath; 
} 

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inline G4double G4eplusAnnihilation::ComputeMeanFreePath(
                                                       G4double PositKinEnergy,
                                                       G4Material* aMaterial)

// returns the positron mean free path in GEANT4 internal units

{
  const G4ElementVector* theElementVector = aMaterial->GetElementVector();
  const G4double* NbOfAtomsPerVolume = aMaterial->GetVecNbOfAtomsPerVolume();   

  G4double SIGMA = 0 ;

  for (size_t elm=0 ; elm < aMaterial->GetNumberOfElements() ; elm++ )
     {             
        SIGMA += NbOfAtomsPerVolume[elm] * 
                 ComputeCrossSectionPerAtom(PositKinEnergy,
                                            (*theElementVector)[elm]->GetZ());
     }       

  return SIGMA > DBL_MIN ? 1./SIGMA : DBL_MAX;
}

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inline G4double G4eplusAnnihilation::GetMeanLifeTime(const G4Track&,
                                                     G4ForceCondition*)
 
// returns the annihilation mean life time in GEANT4 internal units

{
   return 0.0; 
} 

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