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// $Id$
//

#ifndef G4DNAScreenedRutherfordElasticModel_h
#define G4DNAScreenedRutherfordElasticModel_h 1

#include <CLHEP/Units/SystemOfUnits.h>

#include "G4VEmModel.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4ProductionCutsTable.hh"
#include "G4NistManager.hh"

class G4DNAScreenedRutherfordElasticModel : public G4VEmModel
{

public:

  G4DNAScreenedRutherfordElasticModel(const G4ParticleDefinition* p = 0, 
		          const G4String& nam = "DNAScreenedRutherfordElasticModel");

  virtual ~G4DNAScreenedRutherfordElasticModel();

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

  virtual G4double CrossSectionPerVolume(const G4Material* material,
					   const G4ParticleDefinition* p,
					   G4double ekin,
					   G4double emin,
					   G4double emax);

  virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*,
				 const G4MaterialCutsCouple*,
				 const G4DynamicParticle*,
				 G4double tmin,
				 G4double maxEnergy);

  inline void SetKillBelowThreshold (G4double threshold);		 
  G4double GetKillBelowThreshold () { return killBelowEnergy; }		 

protected:

  G4ParticleChangeForGamma* fParticleChangeForGamma;

private:
  // Water density table
  const std::vector<G4double>* fpWaterDensity;

  G4double killBelowEnergy;  
  G4double lowEnergyLimit;  
  G4double intermediateEnergyLimit;
  G4double highEnergyLimit; 
  G4bool isInitialised;
  G4int verboseLevel;
  
  // Cross section
  
  G4double RutherfordCrossSection(G4double energy, G4double z);
  
  G4double ScreeningFactor(G4double energy, G4double z);
  
  // Final state according to Brenner & Zaider

  G4double BrennerZaiderRandomizeCosTheta(G4double k);
  G4double CalculatePolynomial(G4double k, std::vector<G4double>& vec);
  std::vector<G4double> betaCoeff;
  std::vector<G4double> deltaCoeff;
  std::vector<G4double> gamma035_10Coeff;
  std::vector<G4double> gamma10_100Coeff;
  std::vector<G4double> gamma100_200Coeff;
   
  // Final state according to Screened Rutherford

  G4double ScreenedRutherfordRandomizeCosTheta(G4double k, G4double z);

  //
   
  G4DNAScreenedRutherfordElasticModel & operator=(const  G4DNAScreenedRutherfordElasticModel &right);
  G4DNAScreenedRutherfordElasticModel(const  G4DNAScreenedRutherfordElasticModel&);

};

inline void G4DNAScreenedRutherfordElasticModel::SetKillBelowThreshold (G4double threshold) 
{ 
    killBelowEnergy = threshold; 
    if (threshold < 9*CLHEP::eV)
     G4Exception ("*** WARNING : the G4DNAScreenedRutherfordElasticModel class is not validated below 9 eV !","",JustWarning,"") ;   
}		 

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#endif