1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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23 | // * acceptance of all terms of the Geant4 Software license. * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4PairProductionRelModel.hh,v 1.9 2010/10/26 10:35:22 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: emstand-V09-03-24 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class header file |
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32 | // |
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33 | // |
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34 | // File name: G4PairProductionRelModel |
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35 | // |
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36 | // Author: Andreas Schaelicke |
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37 | // |
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38 | // Creation date: 02.04.2009 |
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39 | // |
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40 | // Modifications: |
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41 | // |
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42 | // Class Description: |
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43 | // |
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44 | // Implementation of gamma convertion to e+e- in the field of a nucleus |
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45 | // relativistic approximation |
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46 | // |
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47 | |
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48 | // ------------------------------------------------------------------- |
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49 | // |
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50 | |
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51 | #ifndef G4PairProductionRelModel_h |
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52 | #define G4PairProductionRelModel_h 1 |
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53 | |
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54 | #include "G4VEmModel.hh" |
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55 | #include "G4PhysicsTable.hh" |
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56 | #include "G4NistManager.hh" |
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57 | |
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58 | class G4ParticleChangeForGamma; |
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59 | |
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60 | class G4PairProductionRelModel : public G4VEmModel |
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61 | { |
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62 | |
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63 | public: |
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64 | |
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65 | G4PairProductionRelModel(const G4ParticleDefinition* p = 0, |
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66 | const G4String& nam = "BetheHeitlerLPM"); |
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67 | |
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68 | virtual ~G4PairProductionRelModel(); |
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69 | |
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70 | virtual void Initialise(const G4ParticleDefinition*, const G4DataVector&); |
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71 | |
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72 | virtual G4double ComputeCrossSectionPerAtom( |
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73 | const G4ParticleDefinition*, |
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74 | G4double kinEnergy, |
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75 | G4double Z, |
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76 | G4double A=0., |
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77 | G4double cut=0., |
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78 | G4double emax=DBL_MAX); |
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79 | |
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80 | virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*, |
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81 | const G4MaterialCutsCouple*, |
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82 | const G4DynamicParticle*, |
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83 | G4double tmin, |
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84 | G4double maxEnergy); |
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85 | |
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86 | virtual void SetupForMaterial(const G4ParticleDefinition*, |
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87 | const G4Material*,G4double); |
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88 | |
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89 | // * fast inline functions * |
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90 | inline void SetCurrentElement(G4double /*Z*/); |
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91 | |
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92 | // set / get methods |
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93 | inline void SetLPMconstant(G4double val); |
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94 | inline G4double LPMconstant() const; |
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95 | |
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96 | inline void SetLPMflag(G4bool); |
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97 | inline G4bool LPMflag() const; |
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98 | |
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99 | protected: |
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100 | // screening functions |
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101 | inline G4double Phi1(G4double delta) const; |
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102 | inline G4double Phi2(G4double delta) const; |
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103 | inline G4double DeltaMax() const; |
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104 | inline G4double DeltaMin(G4double) const; |
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105 | // lpm functions |
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106 | void CalcLPMFunctions(G4double k, G4double eplus); |
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107 | |
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108 | // obsolete |
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109 | G4double ScreenFunction1(G4double ScreenVariable); |
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110 | G4double ScreenFunction2(G4double ScreenVariable); |
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111 | |
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112 | G4double ComputeXSectionPerAtom(G4double totalEnergy, G4double Z); |
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113 | |
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114 | G4double ComputeDXSectionPerAtom(G4double eplusEnergy, G4double totalEnergy, G4double Z); |
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115 | G4double ComputeRelDXSectionPerAtom(G4double eplusEnergy, G4double totalEnergy, G4double Z); |
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116 | |
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117 | // hide assignment operator |
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118 | G4PairProductionRelModel & operator=(const G4PairProductionRelModel &right); |
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119 | G4PairProductionRelModel(const G4PairProductionRelModel&); |
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120 | |
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121 | G4NistManager* nist; |
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122 | |
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123 | G4ParticleDefinition* theGamma; |
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124 | G4ParticleDefinition* theElectron; |
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125 | G4ParticleDefinition* thePositron; |
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126 | G4ParticleChangeForGamma* fParticleChange; |
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127 | |
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128 | G4double fLPMconstant; |
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129 | G4bool fLPMflag; |
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130 | |
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131 | // cash |
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132 | G4double z13, z23, lnZ; |
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133 | G4double Fel, Finel, fCoulomb; |
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134 | G4double currentZ; |
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135 | |
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136 | // LPM effect |
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137 | G4double lpmEnergy; |
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138 | G4double xiLPM, phiLPM, gLPM; |
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139 | |
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140 | // consts |
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141 | G4bool use_completescreening; |
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142 | |
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143 | static const G4double xgi[8], wgi[8]; |
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144 | static const G4double Fel_light[5]; |
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145 | static const G4double Finel_light[5]; |
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146 | static const G4double facFel; |
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147 | static const G4double facFinel; |
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148 | |
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149 | static const G4double preS1, logTwo; |
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150 | |
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151 | }; |
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152 | |
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153 | |
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154 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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155 | |
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156 | inline |
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157 | void G4PairProductionRelModel::SetLPMconstant(G4double val) |
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158 | { |
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159 | fLPMconstant = val; |
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160 | } |
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161 | |
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162 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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163 | |
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164 | inline |
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165 | G4double G4PairProductionRelModel::LPMconstant() const |
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166 | { |
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167 | return fLPMconstant; |
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168 | } |
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169 | |
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170 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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171 | |
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172 | inline |
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173 | void G4PairProductionRelModel::SetLPMflag(G4bool val) |
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174 | { |
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175 | fLPMflag = val; |
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176 | } |
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177 | |
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178 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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179 | |
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180 | inline |
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181 | G4bool G4PairProductionRelModel::LPMflag() const |
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182 | { |
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183 | return fLPMflag; |
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184 | } |
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185 | |
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186 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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187 | |
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188 | inline void G4PairProductionRelModel::SetCurrentElement(G4double Z) |
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189 | { |
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190 | if(Z != currentZ) { |
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191 | currentZ = Z; |
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192 | |
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193 | G4int iz = G4int(Z); |
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194 | z13 = nist->GetZ13(iz); |
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195 | z23 = z13*z13; |
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196 | lnZ = nist->GetLOGZ(iz); |
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197 | |
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198 | if (iz <= 4) { |
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199 | Fel = Fel_light[iz]; |
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200 | Finel = Finel_light[iz] ; |
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201 | } |
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202 | else { |
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203 | Fel = facFel - lnZ/3. ; |
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204 | Finel = facFinel - 2.*lnZ/3. ; |
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205 | } |
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206 | fCoulomb=GetCurrentElement()->GetfCoulomb(); |
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207 | } |
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208 | } |
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209 | |
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210 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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211 | |
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212 | inline G4double G4PairProductionRelModel::Phi1(G4double delta) const |
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213 | { |
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214 | G4double screenVal; |
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215 | |
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216 | if (delta > 1.) |
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217 | screenVal = 21.12 - 4.184*std::log(delta+0.952); |
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218 | else |
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219 | screenVal = 20.868 - delta*(3.242 - 0.625*delta); |
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220 | |
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221 | return screenVal; |
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222 | } |
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223 | |
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224 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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225 | |
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226 | inline G4double G4PairProductionRelModel::Phi2(G4double delta) const |
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227 | { |
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228 | G4double screenVal; |
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229 | |
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230 | if (delta > 1.) |
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231 | screenVal = 21.12 - 4.184*std::log(delta+0.952); |
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232 | else |
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233 | screenVal = 20.209 - delta*(1.930 + 0.086*delta); |
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234 | |
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235 | return screenVal; |
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236 | } |
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237 | |
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238 | inline G4double G4PairProductionRelModel::ScreenFunction1(G4double ScreenVariable) |
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239 | |
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240 | // compute the value of the screening function 3*PHI1 - PHI2 |
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241 | |
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242 | { |
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243 | G4double screenVal; |
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244 | |
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245 | if (ScreenVariable > 1.) |
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246 | screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952); |
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247 | else |
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248 | screenVal = 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable); |
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249 | |
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250 | return screenVal; |
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251 | } |
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252 | |
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253 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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254 | |
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255 | inline G4double G4PairProductionRelModel::ScreenFunction2(G4double ScreenVariable) |
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256 | |
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257 | // compute the value of the screening function 1.5*PHI1 + 0.5*PHI2 |
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258 | |
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259 | { |
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260 | G4double screenVal; |
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261 | |
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262 | if (ScreenVariable > 1.) |
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263 | screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952); |
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264 | else |
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265 | screenVal = 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable); |
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266 | |
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267 | return screenVal; |
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268 | } |
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269 | |
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270 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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271 | |
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272 | |
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273 | inline G4double G4PairProductionRelModel::DeltaMax() const |
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274 | { |
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275 | // k > 50 MeV |
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276 | G4double FZ = 8.*(lnZ/3. + fCoulomb); |
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277 | return std::exp( (42.24-FZ)/8.368 ) + 0.952; |
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278 | } |
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279 | |
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280 | inline G4double G4PairProductionRelModel::DeltaMin(G4double k) const |
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281 | { |
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282 | return 4.*136./z13*(electron_mass_c2/k); |
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283 | } |
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284 | |
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285 | |
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286 | |
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287 | #endif |
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