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// -------------------------------------------------------------------
//
//
// GEANT4 Class header file
//
//
// File name:     G4WentzelVIModel
//
// Author:        V.Ivanchenko 
//
// Creation date: 09.04.2008 from G4MuMscModel
//
// Modifications:
// 27-05-2010 V.Ivanchenko added G4WentzelOKandVIxSection class to
//              compute cross sections and sample scattering angle
//
// Class Description:
//
// Implementation of the model of multiple scattering based on
// G.Wentzel, Z. Phys. 40 (1927) 590.
// H.W.Lewis, Phys Rev 78 (1950) 526.
// J.M. Fernandez-Varea et al., NIM B73 (1993) 447.
// L.Urban, CERN-OPEN-2006-077.

// -------------------------------------------------------------------
//

#ifndef G4WentzelVIModel_h
#define G4WentzelVIModel_h 1

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

#include "G4VMscModel.hh"
#include "G4MaterialCutsCouple.hh"
#include "G4WentzelOKandVIxSection.hh"

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

class G4WentzelVIModel : public G4VMscModel
{

public:

  explicit G4WentzelVIModel(G4bool comb=true, const G4String& nam = "WentzelVIUni");

  ~G4WentzelVIModel() override;

  void Initialise(const G4ParticleDefinition*, const G4DataVector&) override;

  void InitialiseLocal(const G4ParticleDefinition*, 
		       G4VEmModel* masterModel) override;

  void StartTracking(G4Track*) override;

  G4double ComputeCrossSectionPerAtom(const G4ParticleDefinition*,
				      G4double KineticEnergy,
				      G4double AtomicNumber,
				      G4double AtomicWeight=0., 
				      G4double cut = DBL_MAX,
				      G4double emax= DBL_MAX) override;

  G4ThreeVector& SampleScattering(const G4ThreeVector&, 
				  G4double safety) override;

  G4double 
  ComputeTruePathLengthLimit(const G4Track& track,
			     G4double& currentMinimalStep) override;

  G4double ComputeGeomPathLength(G4double truePathLength) override;

  G4double ComputeTrueStepLength(G4double geomStepLength) override;

  // defines low energy limit on energy transfer to atomic electron
  void SetFixedCut(G4double);

  // low energy limit on energy transfer to atomic electron
  G4double GetFixedCut() const;

  // access to cross section class
  void SetWVICrossSection(G4WentzelOKandVIxSection*);

  G4WentzelOKandVIxSection* GetWVICrossSection();

  void SetUseSecondMoment(G4bool);

  G4bool UseSecondMoment() const;

  G4PhysicsTable* GetSecondMomentTable();

  G4double SecondMoment(const G4ParticleDefinition*,
			const G4MaterialCutsCouple*,
			G4double kineticEnergy);

  void SetSingleScatteringFactor(G4double);

  void DefineMaterial(const G4MaterialCutsCouple*);

  G4WentzelVIModel & operator=(const G4WentzelVIModel &right) = delete;
  G4WentzelVIModel(const G4WentzelVIModel&) = delete;

protected:

  G4double ComputeTransportXSectionPerVolume(G4double cosTheta);

  inline void SetupParticle(const G4ParticleDefinition*);

private:

  G4double ComputeSecondMoment(const G4ParticleDefinition*,
			       G4double kineticEnergy);

protected:

  G4WentzelOKandVIxSection* wokvi;
  const G4MaterialCutsCouple* currentCouple = nullptr;
  const G4Material* currentMaterial = nullptr;

  const G4ParticleDefinition* particle = nullptr;
  G4ParticleChangeForMSC* fParticleChange = nullptr;
  const G4DataVector* currentCuts = nullptr;
  G4PhysicsTable* fSecondMoments = nullptr;

  G4double lowEnergyLimit;
  G4double tlimitminfix;
  G4double ssFactor = 1.05;
  G4double invssFactor = 1.0;

  // cache kinematics
  G4double preKinEnergy = 0.0;
  G4double tPathLength = 0.0;
  G4double zPathLength = 0.0;
  G4double lambdaeff = 0.0;
  G4double currentRange = 0.0; 
  G4double cosTetMaxNuc = 0.0;

  G4double fixedCut = -1.0;

  // cache kinematics
  G4double effKinEnergy = 0.0;

  // single scattering parameters
  G4double cosThetaMin = 1.0;
  G4double cosThetaMax = -1.0;
  G4double xtsec = 0.0;

  G4int  currentMaterialIndex = 0;
  size_t idx2 = 0;

  // data for single scattering mode
  G4int nelments = 0;

  // flags
  G4bool   singleScatteringMode;
  G4bool   isCombined;
  G4bool   useSecondMoment;

  std::vector<G4double> xsecn;
  std::vector<G4double> prob;
};

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

inline void G4WentzelVIModel::SetupParticle(const G4ParticleDefinition* p)
{
  // Initialise mass and charge
  if(p != particle) {
    particle = p;
    wokvi->SetupParticle(p);
  }
}

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

inline void G4WentzelVIModel::SetFixedCut(G4double val)
{
  fixedCut = val;
}

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

inline G4double G4WentzelVIModel::GetFixedCut() const
{
  return fixedCut;
}

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

inline void G4WentzelVIModel::SetWVICrossSection(G4WentzelOKandVIxSection* ptr)
{
  if(ptr != wokvi) {
    delete wokvi;
    wokvi = ptr;
  }
}

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

inline G4WentzelOKandVIxSection* G4WentzelVIModel::GetWVICrossSection()
{
  return wokvi;
}

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

inline void G4WentzelVIModel::SetUseSecondMoment(G4bool val)
{
  useSecondMoment = val;
}

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

inline G4bool G4WentzelVIModel::UseSecondMoment() const
{
  return useSecondMoment;
}

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

inline G4PhysicsTable* G4WentzelVIModel::GetSecondMomentTable()
{
  return fSecondMoments;
}

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

inline G4double 
G4WentzelVIModel::SecondMoment(const G4ParticleDefinition* part,
			       const G4MaterialCutsCouple* couple,
			       G4double ekin)
{
  G4double x = 0.0;
  if(useSecondMoment) { 
    DefineMaterial(couple);
    x = (fSecondMoments) ?  
      (*fSecondMoments)[(*theDensityIdx)[currentMaterialIndex]]->Value(ekin, idx2)
      *(*theDensityFactor)[currentMaterialIndex]/(ekin*ekin)
      : ComputeSecondMoment(part, ekin);
  }
  return x;
}

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

#endif