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15 | // * use. Please see the license in the file LICENSE and URL above * |
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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4Penelope08GammaConversionModel.cc,v 1.4 2010/07/28 07:09:16 pandola Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-04-ref-00 $ |
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28 | // |
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29 | // Author: Luciano Pandola |
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30 | // |
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31 | // History: |
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32 | // -------- |
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33 | // 13 Jan 2010 L Pandola First implementation (updated to Penelope08) |
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34 | // |
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35 | |
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36 | #include "G4Penelope08GammaConversionModel.hh" |
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37 | #include "G4ParticleDefinition.hh" |
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38 | #include "G4MaterialCutsCouple.hh" |
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39 | #include "G4ProductionCutsTable.hh" |
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40 | #include "G4DynamicParticle.hh" |
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41 | #include "G4Element.hh" |
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42 | #include "G4Gamma.hh" |
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43 | #include "G4Electron.hh" |
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44 | #include "G4Positron.hh" |
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45 | #include "G4PhysicsFreeVector.hh" |
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46 | |
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47 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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48 | |
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49 | |
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50 | G4Penelope08GammaConversionModel::G4Penelope08GammaConversionModel(const G4ParticleDefinition*, |
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51 | const G4String& nam) |
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52 | :G4VEmModel(nam),logAtomicCrossSection(0),fEffectiveCharge(0),fMaterialInvScreeningRadius(0), |
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53 | fScreeningFunction(0),isInitialised(false) |
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54 | { |
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55 | fIntrinsicLowEnergyLimit = 2.0*electron_mass_c2; |
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56 | fIntrinsicHighEnergyLimit = 100.0*GeV; |
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57 | fSmallEnergy = 1.1*MeV; |
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58 | InitializeScreeningRadii(); |
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59 | |
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60 | // SetLowEnergyLimit(fIntrinsicLowEnergyLimit); |
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61 | SetHighEnergyLimit(fIntrinsicHighEnergyLimit); |
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62 | // |
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63 | verboseLevel= 0; |
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64 | // Verbosity scale: |
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65 | // 0 = nothing |
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66 | // 1 = warning for energy non-conservation |
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67 | // 2 = details of energy budget |
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68 | // 3 = calculation of cross sections, file openings, sampling of atoms |
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69 | // 4 = entering in methods |
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70 | } |
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71 | |
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72 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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73 | |
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74 | G4Penelope08GammaConversionModel::~G4Penelope08GammaConversionModel() |
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75 | { |
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76 | std::map <const G4int,G4PhysicsFreeVector*>::iterator i; |
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77 | if (logAtomicCrossSection) |
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78 | { |
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79 | for (i=logAtomicCrossSection->begin();i != logAtomicCrossSection->end();i++) |
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80 | if (i->second) delete i->second; |
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81 | delete logAtomicCrossSection; |
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82 | } |
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83 | if (fEffectiveCharge) |
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84 | delete fEffectiveCharge; |
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85 | if (fMaterialInvScreeningRadius) |
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86 | delete fMaterialInvScreeningRadius; |
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87 | if (fScreeningFunction) |
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88 | delete fScreeningFunction; |
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89 | } |
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90 | |
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91 | |
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92 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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93 | |
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94 | void G4Penelope08GammaConversionModel::Initialise(const G4ParticleDefinition*, |
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95 | const G4DataVector&) |
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96 | { |
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97 | if (verboseLevel > 3) |
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98 | G4cout << "Calling G4Penelope08GammaConversionModel::Initialise()" << G4endl; |
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99 | |
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100 | // logAtomicCrossSection is created only once, since it is never cleared |
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101 | if (!logAtomicCrossSection) |
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102 | logAtomicCrossSection = new std::map<const G4int,G4PhysicsFreeVector*>; |
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103 | |
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104 | //delete old material data... |
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105 | if (fEffectiveCharge) |
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106 | { |
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107 | delete fEffectiveCharge; |
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108 | fEffectiveCharge = 0; |
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109 | } |
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110 | if (fMaterialInvScreeningRadius) |
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111 | { |
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112 | delete fMaterialInvScreeningRadius; |
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113 | fMaterialInvScreeningRadius = 0; |
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114 | } |
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115 | if (fScreeningFunction) |
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116 | { |
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117 | delete fScreeningFunction; |
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118 | fScreeningFunction = 0; |
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119 | } |
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120 | //and create new ones |
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121 | fEffectiveCharge = new std::map<const G4Material*,G4double>; |
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122 | fMaterialInvScreeningRadius = new std::map<const G4Material*,G4double>; |
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123 | fScreeningFunction = new std::map<const G4Material*,std::pair<G4double,G4double> >; |
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124 | |
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125 | if (verboseLevel > 0) { |
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126 | G4cout << "Penelope Gamma Conversion model is initialized " << G4endl |
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127 | << "Energy range: " |
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128 | << LowEnergyLimit() / MeV << " MeV - " |
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129 | << HighEnergyLimit() / GeV << " GeV" |
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130 | << G4endl; |
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131 | } |
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132 | |
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133 | if(isInitialised) return; |
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134 | fParticleChange = GetParticleChangeForGamma(); |
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135 | isInitialised = true; |
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136 | } |
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137 | |
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138 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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139 | |
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140 | G4double G4Penelope08GammaConversionModel::ComputeCrossSectionPerAtom( |
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141 | const G4ParticleDefinition*, |
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142 | G4double energy, |
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143 | G4double Z, G4double, |
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144 | G4double, G4double) |
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145 | { |
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146 | // |
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147 | // Penelope model. |
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148 | // Cross section (including triplet production) read from database and managed |
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149 | // through the G4CrossSectionHandler utility. Cross section data are from |
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150 | // M.J. Berger and J.H. Hubbel (XCOM), Report NBSIR 887-3598 |
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151 | // |
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152 | |
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153 | if (energy < fIntrinsicLowEnergyLimit) |
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154 | return 0; |
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155 | |
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156 | G4int iZ = (G4int) Z; |
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157 | |
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158 | //read data files |
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159 | if (!logAtomicCrossSection->count(iZ)) |
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160 | ReadDataFile(iZ); |
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161 | //now it should be ok |
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162 | if (!logAtomicCrossSection->count(iZ)) |
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163 | { |
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164 | G4cout << "Problem in G4Penelope08GammaConversion::ComputeCrossSectionPerAtom" |
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165 | << G4endl; |
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166 | G4Exception(); |
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167 | } |
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168 | |
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169 | G4double cs = 0; |
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170 | G4double logene = std::log(energy); |
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171 | G4PhysicsFreeVector* theVec = logAtomicCrossSection->find(iZ)->second; |
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172 | |
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173 | G4double logXS = theVec->Value(logene); |
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174 | cs = std::exp(logXS); |
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175 | |
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176 | if (verboseLevel > 2) |
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177 | G4cout << "Gamma conversion cross section at " << energy/MeV << " MeV for Z=" << Z << |
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178 | " = " << cs/barn << " barn" << G4endl; |
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179 | return cs; |
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180 | } |
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181 | |
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182 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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183 | |
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184 | void |
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185 | G4Penelope08GammaConversionModel::SampleSecondaries(std::vector<G4DynamicParticle*>* fvect, |
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186 | const G4MaterialCutsCouple* couple, |
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187 | const G4DynamicParticle* aDynamicGamma, |
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188 | G4double, |
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189 | G4double) |
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190 | { |
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191 | // |
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192 | // Penelope model. |
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193 | // Final state is sampled according to the Bethe-Heitler model with Coulomb |
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194 | // corrections, according to the semi-empirical model of |
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195 | // J. Baro' et al., Radiat. Phys. Chem. 44 (1994) 531. |
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196 | // |
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197 | // The model uses the high energy Coulomb correction from |
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198 | // H. Davies et al., Phys. Rev. 93 (1954) 788 |
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199 | // and atomic screening radii tabulated from |
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200 | // J.H. Hubbel et al., J. Phys. Chem. Ref. Data 9 (1980) 1023 |
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201 | // for Z= 1 to 92. |
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202 | // |
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203 | if (verboseLevel > 3) |
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204 | G4cout << "Calling SamplingSecondaries() of G4Penelope08GammaConversionModel" << G4endl; |
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205 | |
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206 | G4double photonEnergy = aDynamicGamma->GetKineticEnergy(); |
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207 | |
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208 | // Always kill primary |
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209 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
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210 | fParticleChange->SetProposedKineticEnergy(0.); |
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211 | |
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212 | if (photonEnergy <= fIntrinsicLowEnergyLimit) |
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213 | { |
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214 | fParticleChange->ProposeLocalEnergyDeposit(photonEnergy); |
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215 | return ; |
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216 | } |
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217 | |
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218 | G4ParticleMomentum photonDirection = aDynamicGamma->GetMomentumDirection(); |
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219 | const G4Material* mat = couple->GetMaterial(); |
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220 | |
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221 | //check if material data are available |
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222 | if (!fEffectiveCharge->count(mat)) |
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223 | InitializeScreeningFunctions(mat); |
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224 | if (!fEffectiveCharge->count(mat)) |
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225 | { |
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226 | G4cout << "Problem in G4Penelope08GammaConversion::SampleSecondaries()" << G4endl; |
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227 | G4cout << "Unable to allocate the EffectiveCharge data" << G4endl; |
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228 | G4Exception(); |
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229 | } |
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230 | |
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231 | // eps is the fraction of the photon energy assigned to e- (including rest mass) |
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232 | G4double eps = 0; |
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233 | G4double eki = electron_mass_c2/photonEnergy; |
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234 | |
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235 | //Do it fast for photon energy < 1.1 MeV (close to threshold) |
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236 | if (photonEnergy < fSmallEnergy) |
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237 | eps = eki + (1.0-2.0*eki)*G4UniformRand(); |
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238 | else |
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239 | { |
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240 | //Complete calculation |
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241 | G4double effC = fEffectiveCharge->find(mat)->second; |
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242 | G4double alz = effC*fine_structure_const; |
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243 | G4double T = std::sqrt(2.0*eki); |
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244 | G4double F00=(-1.774-1.210e1*alz+1.118e1*alz*alz)*T |
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245 | +(8.523+7.326e1*alz-4.441e1*alz*alz)*T*T |
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246 | -(1.352e1+1.211e2*alz-9.641e1*alz*alz)*T*T*T |
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247 | +(8.946+6.205e1*alz-6.341e1*alz*alz)*T*T*T*T; |
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248 | |
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249 | G4double F0b = fScreeningFunction->find(mat)->second.second; |
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250 | G4double g0 = F0b + F00; |
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251 | G4double invRad = fMaterialInvScreeningRadius->find(mat)->second; |
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252 | G4double bmin = 4.0*eki/invRad; |
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253 | std::pair<G4double,G4double> scree = GetScreeningFunctions(bmin); |
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254 | G4double g1 = scree.first; |
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255 | G4double g2 = scree.second; |
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256 | G4double g1min = g1+g0; |
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257 | G4double g2min = g2+g0; |
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258 | G4double xr = 0.5-eki; |
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259 | G4double a1 = 2.*g1min*xr*xr/3.; |
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260 | G4double p1 = a1/(a1+g2min); |
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261 | |
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262 | G4bool loopAgain = false; |
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263 | //Random sampling of eps |
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264 | do{ |
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265 | loopAgain = false; |
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266 | if (G4UniformRand() <= p1) |
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267 | { |
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268 | G4double ru2m1 = 2.0*G4UniformRand()-1.0; |
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269 | if (ru2m1 < 0) |
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270 | eps = 0.5-xr*std::pow(std::abs(ru2m1),1./3.); |
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271 | else |
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272 | eps = 0.5+xr*std::pow(ru2m1,1./3.); |
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273 | G4double B = eki/(invRad*eps*(1.0-eps)); |
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274 | scree = GetScreeningFunctions(B); |
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275 | g1 = scree.first; |
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276 | g1 = std::max(g1+g0,0.); |
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277 | if (G4UniformRand()*g1min > g1) |
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278 | loopAgain = true; |
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279 | } |
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280 | else |
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281 | { |
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282 | eps = eki+2.0*xr*G4UniformRand(); |
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283 | G4double B = eki/(invRad*eps*(1.0-eps)); |
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284 | scree = GetScreeningFunctions(B); |
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285 | g2 = scree.second; |
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286 | g2 = std::max(g2+g0,0.); |
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287 | if (G4UniformRand()*g2min > g2) |
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288 | loopAgain = true; |
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289 | } |
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290 | }while(loopAgain); |
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291 | |
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292 | } |
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293 | if (verboseLevel > 4) |
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294 | G4cout << "Sampled eps = " << eps << G4endl; |
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295 | |
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296 | G4double electronTotEnergy = eps*photonEnergy; |
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297 | G4double positronTotEnergy = (1.0-eps)*photonEnergy; |
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298 | |
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299 | // Scattered electron (positron) angles. ( Z - axis along the parent photon) |
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300 | |
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301 | //electron kinematics |
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302 | G4double electronKineEnergy = std::max(0.,electronTotEnergy - electron_mass_c2) ; |
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303 | G4double costheta_el = G4UniformRand()*2.0-1.0; |
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304 | G4double kk = std::sqrt(electronKineEnergy*(electronKineEnergy+2.*electron_mass_c2)); |
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305 | costheta_el = (costheta_el*electronTotEnergy+kk)/(electronTotEnergy+costheta_el*kk); |
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306 | G4double phi_el = twopi * G4UniformRand() ; |
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307 | G4double dirX_el = std::sqrt(1.-costheta_el*costheta_el) * std::cos(phi_el); |
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308 | G4double dirY_el = std::sqrt(1.-costheta_el*costheta_el) * std::sin(phi_el); |
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309 | G4double dirZ_el = costheta_el; |
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310 | |
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311 | //positron kinematics |
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312 | G4double positronKineEnergy = std::max(0.,positronTotEnergy - electron_mass_c2) ; |
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313 | G4double costheta_po = G4UniformRand()*2.0-1.0; |
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314 | kk = std::sqrt(positronKineEnergy*(positronKineEnergy+2.*electron_mass_c2)); |
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315 | costheta_po = (costheta_po*positronTotEnergy+kk)/(positronTotEnergy+costheta_po*kk); |
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316 | G4double phi_po = twopi * G4UniformRand() ; |
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317 | G4double dirX_po = std::sqrt(1.-costheta_po*costheta_po) * std::cos(phi_po); |
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318 | G4double dirY_po = std::sqrt(1.-costheta_po*costheta_po) * std::sin(phi_po); |
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319 | G4double dirZ_po = costheta_po; |
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320 | |
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321 | // Kinematics of the created pair: |
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322 | // the electron and positron are assumed to have a symetric angular |
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323 | // distribution with respect to the Z axis along the parent photon |
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324 | G4double localEnergyDeposit = 0. ; |
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325 | |
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326 | if (electronKineEnergy > 0.0) |
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327 | { |
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328 | G4ThreeVector electronDirection ( dirX_el, dirY_el, dirZ_el); |
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329 | electronDirection.rotateUz(photonDirection); |
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330 | G4DynamicParticle* electron = new G4DynamicParticle (G4Electron::Electron(), |
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331 | electronDirection, |
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332 | electronKineEnergy); |
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333 | fvect->push_back(electron); |
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334 | } |
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335 | else |
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336 | { |
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337 | localEnergyDeposit += electronKineEnergy; |
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338 | electronKineEnergy = 0; |
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339 | } |
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340 | |
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341 | //Generate the positron. Real particle in any case, because it will annihilate. If below |
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342 | //threshold, produce it at rest |
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343 | if (positronKineEnergy < 0.0) |
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344 | { |
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345 | localEnergyDeposit += positronKineEnergy; |
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346 | positronKineEnergy = 0; //produce it at rest |
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347 | } |
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348 | G4ThreeVector positronDirection(dirX_po,dirY_po,dirZ_po); |
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349 | positronDirection.rotateUz(photonDirection); |
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350 | G4DynamicParticle* positron = new G4DynamicParticle(G4Positron::Positron(), |
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351 | positronDirection, positronKineEnergy); |
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352 | fvect->push_back(positron); |
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353 | |
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354 | //Add rest of energy to the local energy deposit |
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355 | fParticleChange->ProposeLocalEnergyDeposit(localEnergyDeposit); |
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356 | |
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357 | if (verboseLevel > 1) |
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358 | { |
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359 | G4cout << "-----------------------------------------------------------" << G4endl; |
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360 | G4cout << "Energy balance from G4Penelope08GammaConversion" << G4endl; |
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361 | G4cout << "Incoming photon energy: " << photonEnergy/keV << " keV" << G4endl; |
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362 | G4cout << "-----------------------------------------------------------" << G4endl; |
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363 | if (electronKineEnergy) |
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364 | G4cout << "Electron (explicitely produced) " << electronKineEnergy/keV << " keV" |
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365 | << G4endl; |
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366 | if (positronKineEnergy) |
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367 | G4cout << "Positron (not at rest) " << positronKineEnergy/keV << " keV" << G4endl; |
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368 | G4cout << "Rest masses of e+/- " << 2.0*electron_mass_c2/keV << " keV" << G4endl; |
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369 | if (localEnergyDeposit) |
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370 | G4cout << "Local energy deposit " << localEnergyDeposit/keV << " keV" << G4endl; |
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371 | G4cout << "Total final state: " << (electronKineEnergy+positronKineEnergy+ |
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372 | localEnergyDeposit+2.0*electron_mass_c2)/keV << |
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373 | " keV" << G4endl; |
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374 | G4cout << "-----------------------------------------------------------" << G4endl; |
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375 | } |
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376 | if (verboseLevel > 0) |
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377 | { |
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378 | G4double energyDiff = std::fabs(electronKineEnergy+positronKineEnergy+ |
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379 | localEnergyDeposit+2.0*electron_mass_c2-photonEnergy); |
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380 | if (energyDiff > 0.05*keV) |
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381 | G4cout << "Warning from G4Penelope08GammaConversion: problem with energy conservation: " |
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382 | << (electronKineEnergy+positronKineEnergy+ |
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383 | localEnergyDeposit+2.0*electron_mass_c2)/keV |
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384 | << " keV (final) vs. " << photonEnergy/keV << " keV (initial)" << G4endl; |
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385 | } |
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386 | } |
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387 | |
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388 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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389 | |
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390 | void G4Penelope08GammaConversionModel::ReadDataFile(const G4int Z) |
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391 | { |
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392 | if (verboseLevel > 2) |
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393 | { |
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394 | G4cout << "G4Penelope08GammaConversionModel::ReadDataFile()" << G4endl; |
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395 | G4cout << "Going to read Gamma Conversion data files for Z=" << Z << G4endl; |
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396 | } |
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397 | |
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398 | char* path = getenv("G4LEDATA"); |
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399 | if (!path) |
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400 | { |
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401 | G4String excep = |
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402 | "G4Penelope08GammaConversionModel - G4LEDATA environment variable not set!"; |
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403 | G4Exception(excep); |
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404 | } |
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405 | |
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406 | /* |
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407 | Read the cross section file |
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408 | */ |
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409 | std::ostringstream ost; |
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410 | if (Z>9) |
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411 | ost << path << "/penelope/pairproduction/pdgpp" << Z << ".p08"; |
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412 | else |
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413 | ost << path << "/penelope/pairproduction/pdgpp0" << Z << ".p08"; |
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414 | std::ifstream file(ost.str().c_str()); |
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415 | if (!file.is_open()) |
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416 | { |
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417 | G4String excep = "G4Penelope08GammaConversionModel - data file " + |
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418 | G4String(ost.str()) + " not found!"; |
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419 | G4Exception(excep); |
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420 | } |
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421 | |
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422 | //I have to know in advance how many points are in the data list |
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423 | //to initialize the G4PhysicsFreeVector() |
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424 | size_t ndata=0; |
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425 | G4String line; |
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426 | while( getline(file, line) ) |
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427 | ndata++; |
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428 | ndata -= 1; //remove one header line |
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429 | //G4cout << "Found: " << ndata << " lines" << G4endl; |
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430 | |
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431 | file.clear(); |
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432 | file.close(); |
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433 | file.open(ost.str().c_str()); |
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434 | G4int readZ =0; |
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435 | file >> readZ; |
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436 | |
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437 | if (verboseLevel > 3) |
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438 | G4cout << "Element Z=" << Z << G4endl; |
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439 | |
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440 | //check the right file is opened. |
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441 | if (readZ != Z) |
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442 | { |
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443 | G4cout << "G4Penelope08GammaConversionModel::ReadDataFile()" << G4endl; |
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444 | G4cout << "Corrupted data file for Z=" << Z << G4endl; |
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445 | G4Exception(); |
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446 | } |
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447 | |
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448 | G4PhysicsFreeVector* theVec = new G4PhysicsFreeVector(ndata); |
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449 | G4double ene=0,xs=0; |
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450 | for (size_t i=0;i<ndata;i++) |
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451 | { |
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452 | file >> ene >> xs; |
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453 | //dimensional quantities |
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454 | ene *= eV; |
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455 | xs *= barn; |
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456 | if (xs < 1e-40*cm2) //protection against log(0) |
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457 | xs = 1e-40*cm2; |
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458 | theVec->PutValue(i,std::log(ene),std::log(xs)); |
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459 | } |
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460 | file.close(); |
---|
461 | |
---|
462 | if (!logAtomicCrossSection) |
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463 | { |
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464 | G4cout << "G4Penelope08RayleighModel::ReadDataFile()" << G4endl; |
---|
465 | G4cout << "Problem with allocation of logAtomicCrossSection data table " << G4endl; |
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466 | G4Exception(); |
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467 | } |
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468 | logAtomicCrossSection->insert(std::make_pair(Z,theVec)); |
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469 | |
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470 | return; |
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471 | |
---|
472 | } |
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473 | |
---|
474 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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475 | |
---|
476 | void G4Penelope08GammaConversionModel::InitializeScreeningRadii() |
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477 | { |
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478 | G4double temp[99] = {1.2281e+02,7.3167e+01,6.9228e+01,6.7301e+01,6.4696e+01, |
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479 | 6.1228e+01,5.7524e+01,5.4033e+01,5.0787e+01,4.7851e+01,4.6373e+01, |
---|
480 | 4.5401e+01,4.4503e+01,4.3815e+01,4.3074e+01,4.2321e+01,4.1586e+01, |
---|
481 | 4.0953e+01,4.0524e+01,4.0256e+01,3.9756e+01,3.9144e+01,3.8462e+01, |
---|
482 | 3.7778e+01,3.7174e+01,3.6663e+01,3.5986e+01,3.5317e+01,3.4688e+01, |
---|
483 | 3.4197e+01,3.3786e+01,3.3422e+01,3.3068e+01,3.2740e+01,3.2438e+01, |
---|
484 | 3.2143e+01,3.1884e+01,3.1622e+01,3.1438e+01,3.1142e+01,3.0950e+01, |
---|
485 | 3.0758e+01,3.0561e+01,3.0285e+01,3.0097e+01,2.9832e+01,2.9581e+01, |
---|
486 | 2.9411e+01,2.9247e+01,2.9085e+01,2.8930e+01,2.8721e+01,2.8580e+01, |
---|
487 | 2.8442e+01,2.8312e+01,2.8139e+01,2.7973e+01,2.7819e+01,2.7675e+01, |
---|
488 | 2.7496e+01,2.7285e+01,2.7093e+01,2.6911e+01,2.6705e+01,2.6516e+01, |
---|
489 | 2.6304e+01,2.6108e+01,2.5929e+01,2.5730e+01,2.5577e+01,2.5403e+01, |
---|
490 | 2.5245e+01,2.5100e+01,2.4941e+01,2.4790e+01,2.4655e+01,2.4506e+01, |
---|
491 | 2.4391e+01,2.4262e+01,2.4145e+01,2.4039e+01,2.3922e+01,2.3813e+01, |
---|
492 | 2.3712e+01,2.3621e+01,2.3523e+01,2.3430e+01,2.3331e+01,2.3238e+01, |
---|
493 | 2.3139e+01,2.3048e+01,2.2967e+01,2.2833e+01,2.2694e+01,2.2624e+01, |
---|
494 | 2.2545e+01,2.2446e+01,2.2358e+01,2.2264e+01}; |
---|
495 | |
---|
496 | //copy temporary vector in class data member |
---|
497 | for (G4int i=0;i<99;i++) |
---|
498 | fAtomicScreeningRadius[i] = temp[i]; |
---|
499 | } |
---|
500 | |
---|
501 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
502 | |
---|
503 | void G4Penelope08GammaConversionModel::InitializeScreeningFunctions(const G4Material* material) |
---|
504 | { |
---|
505 | // This is subroutine GPPa0 of Penelope |
---|
506 | // |
---|
507 | // 1) calculate the effective Z for the purpose |
---|
508 | // |
---|
509 | G4double zeff = 0; |
---|
510 | G4int intZ = 0; |
---|
511 | G4int nElements = material->GetNumberOfElements(); |
---|
512 | const G4ElementVector* elementVector = material->GetElementVector(); |
---|
513 | |
---|
514 | //avoid calculations if only one building element! |
---|
515 | if (nElements == 1) |
---|
516 | { |
---|
517 | zeff = (*elementVector)[0]->GetZ(); |
---|
518 | intZ = (G4int) zeff; |
---|
519 | } |
---|
520 | else // many elements...let's do the calculation |
---|
521 | { |
---|
522 | const G4double* fractionVector = material->GetVecNbOfAtomsPerVolume(); |
---|
523 | |
---|
524 | G4double atot = 0; |
---|
525 | for (G4int i=0;i<nElements;i++) |
---|
526 | { |
---|
527 | G4double Zelement = (*elementVector)[i]->GetZ(); |
---|
528 | G4double Aelement = (*elementVector)[i]->GetA(); |
---|
529 | atot += Aelement*fractionVector[i]; |
---|
530 | zeff += Zelement*Aelement*fractionVector[i]; //average with the number of nuclei |
---|
531 | } |
---|
532 | atot /= material->GetTotNbOfAtomsPerVolume(); |
---|
533 | zeff /= (material->GetTotNbOfAtomsPerVolume()*atot); |
---|
534 | |
---|
535 | intZ = (G4int) (zeff+0.25); |
---|
536 | if (intZ <= 0) |
---|
537 | intZ = 1; |
---|
538 | if (intZ > 99) |
---|
539 | intZ = 99; |
---|
540 | } |
---|
541 | |
---|
542 | if (fEffectiveCharge) |
---|
543 | fEffectiveCharge->insert(std::make_pair(material,zeff)); |
---|
544 | |
---|
545 | // |
---|
546 | // 2) Calculate Coulomb Correction |
---|
547 | // |
---|
548 | G4double alz = fine_structure_const*zeff; |
---|
549 | G4double alzSquared = alz*alz; |
---|
550 | G4double fc = alzSquared*(0.202059-alzSquared* |
---|
551 | (0.03693-alzSquared* |
---|
552 | (0.00835-alzSquared*(0.00201-alzSquared* |
---|
553 | (0.00049-alzSquared* |
---|
554 | (0.00012-alzSquared*0.00003))))) |
---|
555 | +1.0/(alzSquared+1.0)); |
---|
556 | // |
---|
557 | // 3) Screening functions and low-energy corrections |
---|
558 | // |
---|
559 | G4double matRadius = 2.0/ fAtomicScreeningRadius[intZ-1]; |
---|
560 | if (fMaterialInvScreeningRadius) |
---|
561 | fMaterialInvScreeningRadius->insert(std::make_pair(material,matRadius)); |
---|
562 | |
---|
563 | std::pair<G4double,G4double> myPair(0,0); |
---|
564 | G4double f0a = 4.0*std::log(fAtomicScreeningRadius[intZ-1]); |
---|
565 | G4double f0b = f0a - 4.0*fc; |
---|
566 | myPair.first = f0a; |
---|
567 | myPair.second = f0b; |
---|
568 | |
---|
569 | if (fScreeningFunction) |
---|
570 | fScreeningFunction->insert(std::make_pair(material,myPair)); |
---|
571 | |
---|
572 | if (verboseLevel > 2) |
---|
573 | { |
---|
574 | G4cout << "Average Z for material " << material->GetName() << " = " << |
---|
575 | zeff << G4endl; |
---|
576 | G4cout << "Effective radius for material " << material->GetName() << " = " << |
---|
577 | fAtomicScreeningRadius[intZ-1] << " m_e*c/hbar --> BCB = " << |
---|
578 | matRadius << G4endl; |
---|
579 | G4cout << "Screening parameters F0 for material " << material->GetName() << " = " << |
---|
580 | f0a << "," << f0b << G4endl; |
---|
581 | } |
---|
582 | return; |
---|
583 | } |
---|
584 | |
---|
585 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
---|
586 | |
---|
587 | std::pair<G4double,G4double> |
---|
588 | G4Penelope08GammaConversionModel::GetScreeningFunctions(G4double B) |
---|
589 | { |
---|
590 | // This is subroutine SCHIFF of Penelope |
---|
591 | // |
---|
592 | // Screening Functions F1(B) and F2(B) in the Bethe-Heitler differential cross |
---|
593 | // section for pair production |
---|
594 | // |
---|
595 | std::pair<G4double,G4double> result(0.,0.); |
---|
596 | G4double BSquared = B*B; |
---|
597 | G4double f1 = 2.0-2.0*std::log(1.0+BSquared); |
---|
598 | G4double f2 = f1 - 6.66666666e-1; // (-2/3) |
---|
599 | if (B < 1.0e-10) |
---|
600 | f1 = f1-twopi*B; |
---|
601 | else |
---|
602 | { |
---|
603 | G4double a0 = 4.0*B*std::atan(1./B); |
---|
604 | f1 = f1 - a0; |
---|
605 | f2 += 2.0*BSquared*(4.0-a0-3.0*std::log((1.0+BSquared)/BSquared)); |
---|
606 | } |
---|
607 | G4double g1 = 0.5*(3.0*f1-f2); |
---|
608 | G4double g2 = 0.25*(3.0*f1+f2); |
---|
609 | |
---|
610 | result.first = g1; |
---|
611 | result.second = g2; |
---|
612 | |
---|
613 | return result; |
---|
614 | } |
---|