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// $Id: G4DNAIonizationInWater.icc,v 1.4 2006/06/29 19:34:45 gunter Exp $
// GEANT4 tag $Name: geant4-08-02 $
//

#ifdef    G4DNAIONIZATIONINWATER_HH
#include "G4Electron.hh"

 template<typename TotalCrossSectionPolicy, typename FinalStatesPolicy>
 G4VParticleChange* G4DNAIonizationInWater<TotalCrossSectionPolicy, FinalStatesPolicy> :: PostStepDoIt(const G4Track & aTrack, const G4Step & aStep)
 {
  const G4int z(10); // H2O number of electrons

  this->aParticleChange.Initialize(aTrack);

  const G4DynamicParticle* aDynamicParticle = aTrack.GetDynamicParticle();
  G4double k = aDynamicParticle->GetKineticEnergy();
  G4ParticleMomentum primaryDirection = aDynamicParticle->GetMomentumDirection();
  G4double particleMass = aDynamicParticle->GetDefinition()->GetPDGMass();
  G4double TotalEnergy = k + particleMass;
  G4double Psquare = k*(TotalEnergy+particleMass);
  G4double TotalMomentum = std::sqrt(Psquare);


  G4int ionizationShell(TotalCrossSectionPolicy::RandomizePartialCrossSection(k,z));
  G4double secondaryKinetic(FinalStatesPolicy::RandomizeEjectedElectronEnergy(k,ionizationShell));
  G4double bindingEnergy(FinalStatesPolicy::EnergyConstant(ionizationShell));
 
  //Direction of the secondary electron
  G4double cosTheta = 0.;
  G4double phi = 0.; 
  FinalStatesPolicy::RandomizeEjectedElectronDirection(k,secondaryKinetic, cosTheta, phi);
  G4double sinTheta = std::sqrt(1.-cosTheta*cosTheta);
  G4double dirx = sinTheta*std::cos(phi),diry = sinTheta*std::sin(phi),dirz = cosTheta;
  G4ThreeVector DeltaDirection(dirx,diry,dirz);
  DeltaDirection.rotateUz(primaryDirection);


  G4double DeltaTotalMomentum = std::sqrt(secondaryKinetic*(secondaryKinetic +
                                                     2.*electron_mass_c2 ));

   //Primary Particle Direction
      G4double finalPx = TotalMomentum*primaryDirection.x()
                        - DeltaTotalMomentum*DeltaDirection.x();
      G4double finalPy = TotalMomentum*primaryDirection.y()
                        - DeltaTotalMomentum*DeltaDirection.y();
      G4double finalPz = TotalMomentum*primaryDirection.z()
                        - DeltaTotalMomentum*DeltaDirection.z();
      G4double finalMomentum =
                std::sqrt(finalPx*finalPx+finalPy*finalPy+finalPz*finalPz);
      finalPx /= finalMomentum;
      finalPy /= finalMomentum;
      finalPz /= finalMomentum;

  this->aParticleChange.ProposeMomentumDirection( finalPx,finalPy,finalPz );
  this->aParticleChange.ProposeEnergy(k-bindingEnergy-secondaryKinetic);
  this->aParticleChange.ProposeLocalEnergyDeposit(bindingEnergy);
  this->aParticleChange.SetNumberOfSecondaries(1);

  G4DynamicParticle* aElectron = new G4DynamicParticle(G4Electron::Electron(),DeltaDirection,secondaryKinetic);
  this->aParticleChange.AddSecondary(aElectron);

  return G4VDNAProcessInWater<TotalCrossSectionPolicy, FinalStatesPolicy>::PostStepDoIt(aTrack, aStep);
 }
#endif /* G4DNAIONIZATIONINWATER_HH */