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39 // 41 // 40 // Class Description: 42 // Class Description: 41 // 43 // 42 // Implementation of gamma conversion to e+e- << 44 // Implementation of gamma convertion to e+e- in the field of a nucleus 43 // For details see Physics Reference Manual << 45 // 44 46 45 // ------------------------------------------- 47 // ------------------------------------------------------------------- 46 // 48 // 47 49 48 #ifndef G4BetheHeitlerModel_h 50 #ifndef G4BetheHeitlerModel_h 49 #define G4BetheHeitlerModel_h 1 51 #define G4BetheHeitlerModel_h 1 50 52 51 #include "G4VEmModel.hh" 53 #include "G4VEmModel.hh" 52 #include "G4PhysicsTable.hh" 54 #include "G4PhysicsTable.hh" 53 #include "G4Log.hh" 55 #include "G4Log.hh" 54 56 55 #include <vector> << 56 << 57 class G4ParticleChangeForGamma; 57 class G4ParticleChangeForGamma; 58 class G4Pow; 58 class G4Pow; 59 class G4EmElementXS; << 60 59 61 class G4BetheHeitlerModel : public G4VEmModel 60 class G4BetheHeitlerModel : public G4VEmModel 62 { 61 { 63 62 64 public: 63 public: 65 64 66 explicit G4BetheHeitlerModel(const G4Particl << 65 explicit G4BetheHeitlerModel(const G4ParticleDefinition* p = 0, 67 const G4String& << 66 const G4String& nam = "BetheHeitler"); 68 67 69 ~G4BetheHeitlerModel() override; << 68 virtual ~G4BetheHeitlerModel(); >> 69 >> 70 virtual void Initialise(const G4ParticleDefinition*, >> 71 const G4DataVector&) override; >> 72 >> 73 virtual void InitialiseLocal(const G4ParticleDefinition*, >> 74 G4VEmModel* masterModel) override; >> 75 >> 76 virtual G4double ComputeCrossSectionPerAtom( >> 77 const G4ParticleDefinition*, >> 78 G4double kinEnergy, >> 79 G4double Z, >> 80 G4double A=0., >> 81 G4double cut=0., >> 82 G4double emax=DBL_MAX) override; >> 83 >> 84 virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*, >> 85 const G4MaterialCutsCouple*, >> 86 const G4DynamicParticle*, >> 87 G4double tmin, >> 88 G4double maxEnergy) override; 70 89 71 void Initialise(const G4ParticleDefinition*, << 90 private: 72 91 73 void InitialiseLocal(const G4ParticleDefinit << 92 G4double ScreenFunction1(G4double ScreenVariable); 74 G4VEmModel* masterModel) override; << 75 93 76 G4double ComputeCrossSectionPerAtom(const G4 << 94 G4double ScreenFunction2(G4double ScreenVariable); 77 G4double kinEnergy, << 78 G4double Z, << 79 G4double A=0., << 80 G4double cut=0., << 81 G4double emax=DBL_MAX) override; << 82 << 83 void SampleSecondaries(std::vector<G4Dynamic << 84 const G4MaterialCutsCouple*, << 85 const G4DynamicParticle*, << 86 G4double tmin, << 87 G4double maxEnergy) override; << 88 95 89 // hide assignment operator 96 // hide assignment operator 90 G4BetheHeitlerModel & operator=(const G4Beth 97 G4BetheHeitlerModel & operator=(const G4BetheHeitlerModel &right) = delete; 91 G4BetheHeitlerModel(const G4BetheHeitlerMod 98 G4BetheHeitlerModel(const G4BetheHeitlerModel&) = delete; 92 99 93 protected: << 100 G4Pow* g4calc; >> 101 G4ParticleDefinition* theGamma; >> 102 G4ParticleDefinition* theElectron; >> 103 G4ParticleDefinition* thePositron; >> 104 G4ParticleChangeForGamma* fParticleChange; >> 105 }; 94 106 95 inline G4double ScreenFunction1(const G4doub << 107 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... 96 108 97 inline G4double ScreenFunction2(const G4doub << 109 inline G4double G4BetheHeitlerModel::ScreenFunction1(G4double ScreenVariable) 98 110 99 inline void ScreenFunction12(const G4double << 111 // compute the value of the screening function 3*PHI1 - PHI2 100 112 101 void InitialiseElementData(); << 113 { 102 << 114 G4double screenVal; 103 struct ElementData { << 104 G4double fDeltaMaxLow; << 105 G4double fDeltaMaxHigh; << 106 }; << 107 << 108 static const G4int gMaxZet; << 109 << 110 G4Pow* fG4Calc; << 111 const G4ParticleDefinition* fTheGamma; << 112 const G4ParticleDefinition* fTheElectr << 113 const G4ParticleDefinition* fThePositr << 114 G4ParticleChangeForGamma* fParticleC << 115 G4EmElementXS* fXSection{ << 116 115 117 G4bool isFirstInstance{false}; << 116 if (ScreenVariable > 1.) 118 G4bool useEPICS2017{false}; << 117 screenVal = 42.24 - 8.368*G4Log(ScreenVariable+0.952); >> 118 else >> 119 screenVal = 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable); 119 120 120 static std::vector<ElementData*> gElementDa << 121 return screenVal; 121 }; << 122 } 122 123 123 // << 124 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... 124 // Bethe screening functions for the elastic ( << 125 // Bethe's phi1, phi2 coherent screening funct << 126 // by using (the universal) atomic form factor << 127 // Fermi model of the atom (using numerical so << 128 // screening function instead of Moliere's ana << 129 // numerical results can be well approximated << 130 // especially near the delta=1 limit) by: << 131 // ## if delta <= 1.4 << 132 // phi1(delta) = 20.806 - delta*(3.190 - 0.57 << 133 // phi2(delta) = 20.234 - delta*(2.126 - 0.09 << 134 // ## if delta > 1.4 << 135 // phi1(delta) = phi2(delta) = 21.0190 - 4.14 << 136 // with delta = 136mc^2kZ^{-1/3}/[E(Eg-E)] = 1 << 137 // Eg is the initial photon energy, E is the t << 138 // the e-/e+ pair, eps0 = mc^2/Eg and eps = E/ << 139 125 140 // Compute the value of the screening function << 126 inline G4double G4BetheHeitlerModel::ScreenFunction2(G4double ScreenVariable) 141 inline G4double G4BetheHeitlerModel::ScreenFun << 142 { << 143 return (delta > 1.4) ? 42.038 - 8.29*G4Log(d << 144 : 42.184 - delta*(7.444 << 145 } << 146 127 147 // Compute the value of the screening function << 128 // compute the value of the screening function 1.5*PHI1 - 0.5*PHI2 148 inline G4double G4BetheHeitlerModel::ScreenFun << 149 { << 150 return (delta > 1.4) ? 42.038 - 8.29*G4Log(d << 151 : 41.326 - delta*(5.848 << 152 } << 153 129 154 // Same as ScreenFunction1 and ScreenFunction2 << 155 inline void G4BetheHeitlerModel::ScreenFunctio << 156 << 157 { 130 { 158 if (delta > 1.4) { << 131 G4double screenVal; 159 f1 = 42.038 - 8.29*G4Log(delta + 0.958); << 132 160 f2 = f1; << 133 if (ScreenVariable > 1.) 161 } else { << 134 screenVal = 42.24 - 8.368*G4Log(ScreenVariable+0.952); 162 f1 = 42.184 - delta*(7.444 - 1.623*delta); << 135 else 163 f2 = 41.326 - delta*(5.848 - 0.902*delta); << 136 screenVal = 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable); 164 } << 137 >> 138 return screenVal; 165 } 139 } >> 140 >> 141 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... 166 142 167 #endif 143 #endif 168 144