G4BetheHeitlerModel.hh

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// $Id$
//
// -------------------------------------------------------------------
//
// GEANT4 Class header file
//
//
// File name:     G4BetheHeitlerModel
//
// Author:        Vladimir Ivanchenko on base of Michel Maire code
//
// Creation date: 19.04.2005
//
// Modifications:
// 02-02-06 Remove InitialiseCrossSectionPerAtom();
//
// Class Description:
//
// Implementation of gamma convertion to e+e- in the field of a nucleus 
// 
 
// -------------------------------------------------------------------
//
 
#ifndef G4BetheHeitlerModel_h
#define G4BetheHeitlerModel_h 1
 
#include "G4VEmModel.hh"
#include "G4PhysicsTable.hh"
 
class G4ParticleChangeForGamma;
 
class G4BetheHeitlerModel : public G4VEmModel
{
 
public:
 
  G4BetheHeitlerModel(const G4ParticleDefinition* p = 0, 
              const G4String& nam = "BetheHeitler");
 
  virtual ~G4BetheHeitlerModel();
 
  virtual void Initialise(const G4ParticleDefinition*, const G4DataVector&);
 
  virtual G4double ComputeCrossSectionPerAtom(
                                const G4ParticleDefinition*,
                                      G4double kinEnergy, 
                                      G4double Z, 
                                      G4double A=0., 
                                      G4double cut=0.,
                                      G4double emax=DBL_MAX);
 
  virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*,
                 const G4MaterialCutsCouple*,
                 const G4DynamicParticle*,
                 G4double tmin,
                 G4double maxEnergy);
 
private:
 
  G4double ScreenFunction1(G4double ScreenVariable);
 
  G4double ScreenFunction2(G4double ScreenVariable);
 
  // hide assignment operator
  G4BetheHeitlerModel & operator=(const G4BetheHeitlerModel &right);
  G4BetheHeitlerModel(const  G4BetheHeitlerModel&);
 
  G4ParticleDefinition*     theGamma;
  G4ParticleDefinition*     theElectron;
  G4ParticleDefinition*     thePositron;
  G4ParticleChangeForGamma* fParticleChange;
};
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
 
inline G4double G4BetheHeitlerModel::ScreenFunction1(G4double ScreenVariable)
 
// compute the value of the screening function 3*PHI1 - PHI2
 
{
   G4double screenVal;
 
   if (ScreenVariable > 1.)
     screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
   else
     screenVal = 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable);
 
   return screenVal;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
 
inline G4double G4BetheHeitlerModel::ScreenFunction2(G4double ScreenVariable)
 
// compute the value of the screening function 1.5*PHI1 - 0.5*PHI2
 
{
   G4double screenVal;
 
   if (ScreenVariable > 1.)
     screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
   else
     screenVal = 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable);
 
   return screenVal;
}
 
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
 
#endif