G4WentzelVIModel.hh

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// $Id: G4WentzelVIModel.hh 96934 2016-05-18 09:10:41Z gcosmo $
//
// -------------------------------------------------------------------
//
//
// 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

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

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class G4WentzelVIModel : public G4VMscModel
{

public:

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

  virtual ~G4WentzelVIModel();

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

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

  virtual void StartTracking(G4Track*) override;

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

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

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

  virtual G4double ComputeGeomPathLength(G4double truePathLength) override;

  virtual G4double ComputeTrueStepLength(G4double geomStepLength) override;

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

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

  // access to cross section class
  inline G4WentzelOKandVIxSection* GetWVICrossSection();

  inline void SetUseSecondMoment(G4bool);

  inline G4bool UseSecondMoment() const;

  inline G4PhysicsTable* GetSecondMomentTable();

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

  void SetSingleScatteringFactor(G4double);

protected:

  inline void DefineMaterial(const G4MaterialCutsCouple*);

private:

  G4double ComputeTransportXSectionPerVolume(G4double cosTheta);

  G4double ComputeSecondMoment(const G4ParticleDefinition*,
                               G4double kineticEnergy);

  inline void SetupParticle(const G4ParticleDefinition*);

  //  hide assignment operator
  G4WentzelVIModel & operator=(const  G4WentzelVIModel &right) = delete;
  G4WentzelVIModel(const  G4WentzelVIModel&) = delete;

protected:

  G4WentzelOKandVIxSection* wokvi;

  G4double tlimitminfix;
  G4double ssFactor;
  G4double invssFactor;

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

  // cache material
  G4int    currentMaterialIndex;
  const G4MaterialCutsCouple* currentCouple;
  const G4Material* currentMaterial;

  const G4ParticleDefinition* particle;

  // flags
  G4bool   singleScatteringMode;

private:

  G4ParticleChangeForMSC*   fParticleChange;
  const G4DataVector*       currentCuts;

  G4double invsqrt12;
  G4double fixedCut;

  // cache kinematics
  G4double effKinEnergy;

  // single scattering parameters
  G4double cosThetaMin;
  G4double cosThetaMax;

  G4PhysicsTable* fSecondMoments;
  size_t          idx2;

  // data for single scattering mode
  G4int minNCollisions;
  G4int nelments;
  std::vector<G4double> xsecn;
  std::vector<G4double> prob;

  G4double xtsec;
  G4double numlimit;

  // projectile
  G4double lowEnergyLimit;

  // flags
  G4bool   isCombined;
  G4bool   useSecondMoment;
};

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inline
void G4WentzelVIModel::DefineMaterial(const G4MaterialCutsCouple* cup) 
{ 
  if(cup != currentCouple) {
    currentCouple = cup;
    SetCurrentCouple(cup); 
    currentMaterial = cup->GetMaterial();
    currentMaterialIndex = currentCouple->GetIndex(); 
  }
}

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

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

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

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

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

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

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

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

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#endif