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// $Id: G4ePolarizedBremsstrahlungModel.cc,v 1.4 2007/11/01 17:32:34 schaelic Exp $
// GEANT4 tag $Name: geant4-09-02-ref-02 $
//
// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4ePolarizedBremsstrahlungModel
//
// Author:        Karim Laihem
//
// Creation date: 12.03.2005
//
// Modifications:
//    19-08-06 addapted to accomodate geant481 structure
//
//
// Class Description:
//
//
// -------------------------------------------------------------------
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

#include "G4ePolarizedBremsstrahlungModel.hh"
#include "G4PolarizedBremsstrahlungCrossSection.hh"
#include "G4ParticleChangeForLoss.hh"
#include "G4PolarizationHelper.hh"

G4ePolarizedBremsstrahlungModel::G4ePolarizedBremsstrahlungModel(const G4ParticleDefinition* p,
                                               const G4String& nam)
  : G4eBremsstrahlungModel(p,nam),
    crossSectionCalculator(0)
{
}

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

G4ePolarizedBremsstrahlungModel::~G4ePolarizedBremsstrahlungModel()
{
  if (crossSectionCalculator) delete crossSectionCalculator;
}
  
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....

void G4ePolarizedBremsstrahlungModel::Initialise(const G4ParticleDefinition* p, 
							 const G4DataVector& d)
{
  G4eBremsstrahlungModel::Initialise(p,d);
  if (!crossSectionCalculator)
    crossSectionCalculator = new G4PolarizedBremsstrahlungCrossSection();
}


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


void G4ePolarizedBremsstrahlungModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp,
							const G4MaterialCutsCouple* couple,
							const G4DynamicParticle* dp,
							G4double tmin,
							G4double maxEnergy)
{
  G4eBremsstrahlungModel::SampleSecondaries(vdp,couple,dp,tmin,maxEnergy);
  G4int num = vdp->size();

  if(num > 0) {
    G4double lepEnergy0 = dp->GetKineticEnergy();
    G4double gamEnergy1 = (*vdp)[0]->GetKineticEnergy();
    G4double sintheta   = dp->GetMomentumDirection().cross((*vdp)[0]->GetMomentumDirection()).mag();
    if (sintheta>1.) sintheta=1.;


    G4StokesVector beamPol = dp->GetPolarization();

    // determine interaction plane
    G4ThreeVector  nInteractionFrame = 
      G4PolarizationHelper::GetFrame(dp->GetMomentumDirection(), 
		 fParticleChange->GetProposedMomentumDirection());

    // transform polarization into interaction frame
     beamPol.InvRotateAz(nInteractionFrame,dp->GetMomentumDirection());

    // calulcate polarization transfer
    crossSectionCalculator->SetMaterial(GetCurrentElement()->GetN(),  // number of nucleons
					GetCurrentElement()->GetZ(),
					GetCurrentElement()->GetfCoulomb());
    crossSectionCalculator->Initialize(lepEnergy0, gamEnergy1, sintheta,
				       beamPol, G4StokesVector::ZERO);

    // deterimine final state polarization
    G4StokesVector newBeamPol = crossSectionCalculator->GetPol2();
    newBeamPol.RotateAz(nInteractionFrame,
	fParticleChange->GetProposedMomentumDirection());
    fParticleChange->ProposePolarization(newBeamPol);

    if (num!=1) G4cout<<" WARNING "<<num<<" secondaries in polarized bremsstrahlung not supported!\n"; 
    for (G4int i=0; i<num; i++) {
      G4StokesVector photonPol = crossSectionCalculator->GetPol3();
      photonPol.SetPhoton();
      photonPol.RotateAz(nInteractionFrame,(*vdp)[i]->GetMomentumDirection());
      (*vdp)[i]->SetPolarization(photonPol.p1(),
				 photonPol.p2(),
				 photonPol.p3());
    }
  }
  return;
}
// The emitted gamma energy is sampled using a parametrized formula