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// $Id: G4DNAElectronElasticScatteringInWater.icc,v 1.4 2006/06/29 19:34:02 gunter Exp $
// GEANT4 tag $Name: geant4-08-02 $
//

#ifdef    G4DNAELECTRONELASTICSCATTERINGINWATER_HH
 template<typename TotalCrossSectionPolicy, typename FinalStatesPolicy>
 G4VParticleChange *                      G4DNAElectronElasticScatteringInWater<TotalCrossSectionPolicy, FinalStatesPolicy> :: PostStepDoIt(const G4Track & aTrack, const G4Step & aStep)
 {
  this->aParticleChange.Initialize(aTrack);
  
  G4double k;
  k=aTrack.GetDynamicParticle()->GetKineticEnergy();
 
  G4double cosTheta;
  const G4int z(10); // H2O number of electrons
  
  cosTheta=FinalStatesPolicy::RandomizeCosTheta(k, z);
 
  G4double phi;
  phi=2*pi*G4UniformRand();
  
  G4ThreeVector zVers(aTrack.GetDynamicParticle()->GetMomentumDirection());
  G4ThreeVector xVers(zVers.orthogonal());
  G4ThreeVector yVers(zVers.cross(xVers));
  
  G4double xDir;
  G4double yDir;
  
  xDir=std::sqrt(1-cosTheta*cosTheta);
  yDir=xDir;
  xDir*=std::cos(phi);
  yDir*=std::sin(phi);
  
  G4ThreeVector zPrimeVers((xDir*xVers + yDir*yVers + cosTheta*zVers).unit());
 
  this->aParticleChange.ProposeEnergy(k);
  this->aParticleChange.ProposeMomentumDirection(zPrimeVers);
  this->aParticleChange.SetNumberOfSecondaries(0);
  
  return G4VDNAProcessInWater<TotalCrossSectionPolicy, FinalStatesPolicy>::PostStepDoIt(aTrack, aStep);
 }
#endif /* G4DNAELECTRONELASTICSCATTERINGINWATER_HH */