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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: G4eCoulombScatteringModel.cc,v 1.40 2008/01/07 08:32:01 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-01-patch-02 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class file |
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32 | // |
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33 | // |
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34 | // File name: G4eCoulombScatteringModel |
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35 | // |
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36 | // Author: Vladimir Ivanchenko |
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37 | // |
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38 | // Creation date: 22.08.2005 |
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39 | // |
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40 | // Modifications: |
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41 | // 01.08.06 V.Ivanchenko extend upper limit of table to TeV and review the |
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42 | // logic of building - only elements from G4ElementTable |
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43 | // 08.08.06 V.Ivanchenko build internal table in ekin scale, introduce faclim |
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44 | // 19.08.06 V.Ivanchenko add inline function ScreeningParameter |
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45 | // 09.10.07 V.Ivanchenko reorganized methods, add cut dependence in scattering off e- |
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46 | // |
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47 | // Class Description: |
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48 | // |
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49 | // ------------------------------------------------------------------- |
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50 | // |
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51 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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52 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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53 | |
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54 | #include "G4eCoulombScatteringModel.hh" |
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55 | #include "Randomize.hh" |
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56 | #include "G4DataVector.hh" |
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57 | #include "G4ElementTable.hh" |
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58 | #include "G4PhysicsLogVector.hh" |
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59 | #include "G4ParticleChangeForGamma.hh" |
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60 | #include "G4Electron.hh" |
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61 | #include "G4Positron.hh" |
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62 | #include "G4Proton.hh" |
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63 | |
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64 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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65 | |
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66 | using namespace std; |
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67 | |
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68 | G4eCoulombScatteringModel::G4eCoulombScatteringModel( |
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69 | G4double thetaMin, G4double thetaMax, G4bool build, |
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70 | G4double tlim, const G4String& nam) |
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71 | : G4VEmModel(nam), |
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72 | cosThetaMin(cos(thetaMin)), |
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73 | cosThetaMax(cos(thetaMax)), |
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74 | q2Limit(tlim), |
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75 | theCrossSectionTable(0), |
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76 | lowKEnergy(keV), |
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77 | highKEnergy(TeV), |
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78 | alpha2(fine_structure_const*fine_structure_const), |
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79 | faclim(100.0), |
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80 | nbins(12), |
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81 | nmax(100), |
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82 | buildTable(build), |
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83 | isInitialised(false) |
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84 | { |
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85 | fNistManager = G4NistManager::Instance(); |
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86 | theElectron = G4Electron::Electron(); |
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87 | thePositron = G4Positron::Positron(); |
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88 | theProton = G4Proton::Proton(); |
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89 | a0 = alpha2*electron_mass_c2*electron_mass_c2/(0.885*0.885); |
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90 | G4double p0 = electron_mass_c2*classic_electr_radius; |
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91 | coeff = twopi*p0*p0; |
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92 | constn = 6.937e-6/(MeV*MeV); |
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93 | tkin = targetZ = targetA = mom2 = DBL_MIN; |
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94 | elecXSection = nucXSection = 0.0; |
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95 | ecut = DBL_MAX; |
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96 | particle = 0; |
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97 | for(size_t j=0; j<100; j++) {index[j] = -1;} |
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98 | } |
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99 | |
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100 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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101 | |
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102 | G4eCoulombScatteringModel::~G4eCoulombScatteringModel() |
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103 | { |
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104 | if(theCrossSectionTable) { |
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105 | theCrossSectionTable->clearAndDestroy(); |
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106 | delete theCrossSectionTable; |
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107 | } |
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108 | } |
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109 | |
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110 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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111 | |
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112 | void G4eCoulombScatteringModel::Initialise(const G4ParticleDefinition* p, |
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113 | const G4DataVector&) |
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114 | { |
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115 | // G4cout << "!!! G4eCoulombScatteringModel::Initialise for " |
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116 | // << p->GetParticleName() << " cos(TetMin)= " << cosThetaMin |
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117 | // << " cos(TetMax)= " << cosThetaMax <<G4endl; |
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118 | if(!isInitialised) { |
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119 | isInitialised = true; |
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120 | |
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121 | if(pParticleChange) |
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122 | fParticleChange = |
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123 | reinterpret_cast<G4ParticleChangeForGamma*>(pParticleChange); |
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124 | else |
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125 | fParticleChange = new G4ParticleChangeForGamma(); |
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126 | } else { |
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127 | return; |
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128 | } |
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129 | |
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130 | if(p->GetParticleType() == "nucleus") buildTable = false; |
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131 | if(!buildTable) return; |
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132 | |
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133 | // Compute log cross section table per atom |
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134 | if(!theCrossSectionTable) theCrossSectionTable = new G4PhysicsTable(); |
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135 | |
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136 | nbins = 2*G4int(log10(highKEnergy/lowKEnergy)); |
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137 | } |
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138 | |
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139 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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140 | |
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141 | G4double G4eCoulombScatteringModel::ComputeCrossSectionPerAtom( |
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142 | const G4ParticleDefinition* p, |
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143 | G4double kinEnergy, |
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144 | G4double Z, G4double A, |
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145 | G4double cutEnergy, G4double) |
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146 | { |
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147 | if(p == particle && kinEnergy == tkin && Z == targetZ && |
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148 | A == targetA && cutEnergy == ecut) return nucXSection; |
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149 | |
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150 | //G4cout << "### G4eCoulombScatteringModel::ComputeCrossSectionPerAtom for " |
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151 | // << p->GetParticleName() << " Z= " << Z << " A= " << A |
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152 | // << " e= " << kinEnergy << G4endl; |
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153 | |
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154 | nucXSection = ComputeElectronXSectionPerAtom(p,kinEnergy,Z,A,cutEnergy); |
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155 | |
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156 | // nuclear cross section |
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157 | if(theCrossSectionTable) { |
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158 | G4bool b; |
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159 | G4int iz = G4int(Z); |
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160 | G4int idx = index[iz]; |
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161 | |
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162 | // compute table for given Z |
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163 | if(-1 == idx) { |
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164 | idx = theCrossSectionTable->size(); |
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165 | index[iz] = idx; |
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166 | G4PhysicsLogVector* ptrVector |
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167 | = new G4PhysicsLogVector(lowKEnergy, highKEnergy, nbins); |
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168 | // G4cout << "New vector Z= " << iz << " A= " << A << " idx= " << idx << G4endl; |
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169 | G4double e, value; |
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170 | for(G4int i=0; i<=nbins; i++) { |
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171 | e = ptrVector->GetLowEdgeEnergy( i ) ; |
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172 | value = CalculateCrossSectionPerAtom(p, e, Z, A); |
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173 | ptrVector->PutValue( i, log(value) ); |
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174 | } |
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175 | theCrossSectionTable->push_back(ptrVector); |
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176 | } |
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177 | |
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178 | // take value from the table |
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179 | nucXSection += |
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180 | std::exp((((*theCrossSectionTable)[idx]))->GetValue(kinEnergy, b)); |
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181 | |
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182 | // compute value from scratch |
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183 | } else nucXSection += CalculateCrossSectionPerAtom(p, kinEnergy, Z, A); |
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184 | |
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185 | // G4cout << " cross(bn)= " << nucXSection/barn << G4endl; |
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186 | |
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187 | if(nucXSection < 0.0) nucXSection = 0.0; |
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188 | return nucXSection; |
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189 | } |
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190 | |
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191 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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192 | |
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193 | G4double G4eCoulombScatteringModel::ComputeElectronXSectionPerAtom( |
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194 | const G4ParticleDefinition* p, |
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195 | G4double kinEnergy, |
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196 | G4double Z, |
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197 | G4double A, |
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198 | G4double cutEnergy) |
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199 | { |
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200 | if(p == particle && kinEnergy == tkin && Z == targetZ && |
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201 | cutEnergy == ecut) return elecXSection; |
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202 | ecut = cutEnergy; |
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203 | elecXSection = 0.0; |
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204 | SetupParticle(p); |
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205 | G4double ekin = std::max(keV, kinEnergy); |
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206 | //G4double ekin = kinEnergy; |
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207 | SetupTarget(Z, A, ekin); |
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208 | |
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209 | G4double tmax = tkin; |
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210 | if(p == theElectron) tmax *= 0.5; |
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211 | else if(p != thePositron) { |
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212 | G4double ratio = electron_mass_c2/mass; |
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213 | G4double tau = tkin/mass; |
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214 | tmax = 2.0*electron_mass_c2*tau*(tau + 2.)/ |
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215 | (1.0 + 2.0*ratio*(tau + 1.0) + ratio*ratio); |
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216 | } |
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217 | |
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218 | cosTetMaxElec = cosTetMaxNuc; |
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219 | G4double t = std::min(cutEnergy, tmax); |
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220 | G4double mom21 = t*(t + 2.0*electron_mass_c2); |
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221 | G4double t1 = tkin - t; |
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222 | if(t1 > 0.0) { |
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223 | G4double mom22 = t1*(t1 + 2.0*mass); |
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224 | G4double ctm = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22); |
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225 | if(ctm > cosTetMaxElec && ctm <= 1.0) cosTetMaxElec = ctm; |
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226 | } |
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227 | |
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228 | if(cosTetMaxElec < cosThetaMin) { |
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229 | G4double x1 = 1.0 - cosThetaMin + screenZ; |
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230 | G4double x2 = 1.0 - cosTetMaxElec + screenZ; |
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231 | elecXSection = coeff*Z*chargeSquare*invbeta2* |
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232 | (cosThetaMin - cosTetMaxElec)/(x1*x2*mom2); |
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233 | } |
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234 | // G4cout << "cut= " << ecut << " e= " << tkin |
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235 | // << " croosE(barn)= " << elecXSection/barn |
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236 | // << " cosEl= " << cosTetMaxElec << " costmin= " << cosThetaMin << G4endl; |
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237 | return elecXSection; |
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238 | } |
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239 | |
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240 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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241 | |
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242 | G4double G4eCoulombScatteringModel::CalculateCrossSectionPerAtom( |
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243 | const G4ParticleDefinition* p, |
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244 | G4double kinEnergy, |
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245 | G4double Z, G4double A) |
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246 | { |
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247 | G4double cross = 0.0; |
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248 | SetupParticle(p); |
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249 | G4double ekin = std::max(keV, kinEnergy); |
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250 | //G4double ekin = kinEnergy; |
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251 | SetupTarget(Z, A, ekin); |
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252 | |
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253 | if(cosTetMaxNuc < cosThetaMin) { |
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254 | G4double x1 = 1.0 - cosThetaMin; |
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255 | G4double x2 = 1.0 - cosTetMaxNuc; |
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256 | G4double x3 = cosThetaMin - cosTetMaxNuc; |
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257 | G4double z1 = x1 + screenZ; |
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258 | G4double z2 = x2 + screenZ; |
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259 | G4double d = 1.0/formfactA - screenZ; |
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260 | G4double d1 = 1.0 - formfactA*screenZ; |
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261 | G4double zn1= x1 + d; |
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262 | G4double zn2= x2 + d; |
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263 | cross = coeff*Z*Z*chargeSquare*invbeta2 |
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264 | *(x3/(z1*z2) + x3/(zn1*zn2) + |
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265 | 2.0*std::log(z1*zn2/(z2*zn1))/d) / (mom2*d1*d1); |
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266 | } |
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267 | |
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268 | // G4cout << "CalculateCrossSectionPerAtom: e(MeV)= " << tkin |
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269 | // << " cross(b)= " << cross/barn << " ctmin= " << cosThetaMin |
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270 | // << " ctmax= " << cosTetMaxNuc << G4endl; |
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271 | |
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272 | return cross; |
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273 | } |
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274 | |
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275 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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276 | |
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277 | void G4eCoulombScatteringModel::SampleSecondaries( |
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278 | std::vector<G4DynamicParticle*>*, |
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279 | const G4MaterialCutsCouple* couple, |
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280 | const G4DynamicParticle* dp, |
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281 | G4double cutEnergy, |
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282 | G4double maxEnergy) |
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283 | { |
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284 | const G4Material* aMaterial = couple->GetMaterial(); |
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285 | const G4ParticleDefinition* p = dp->GetDefinition(); |
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286 | G4double kinEnergy = dp->GetKineticEnergy(); |
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287 | |
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288 | // Select atom and setup |
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289 | SetupParticle(p); |
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290 | const G4Element* elm = |
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291 | SelectRandomAtom(aMaterial,p,kinEnergy,cutEnergy,maxEnergy); |
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292 | G4double Z = elm->GetZ(); |
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293 | G4double A = elm->GetN(); |
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294 | |
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295 | G4double cross = |
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296 | ComputeCrossSectionPerAtom(p,kinEnergy,Z,A,cutEnergy,maxEnergy); |
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297 | |
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298 | G4double costm = cosTetMaxNuc; |
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299 | G4double formf = formfactA; |
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300 | if(G4UniformRand()*cross < elecXSection) { |
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301 | costm = cosTetMaxElec; |
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302 | formf = 0.0; |
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303 | } |
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304 | /* |
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305 | G4cout << "G4eCoul...SampleSecondaries: e(MeV)= " << tkin |
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306 | << " ctmin= " << cosThetaMin |
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307 | << " ctmaxN= " << cosTetMaxNuc |
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308 | << " ctmax= " << costm |
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309 | << " Z= " << Z << " A= " << A |
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310 | << " cross= " << cross/barn << " crossE= " << elecXSection/barn |
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311 | << G4endl; |
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312 | */ |
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313 | if(costm >= cosThetaMin) return; |
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314 | |
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315 | G4double x1 = 1. - cosThetaMin + screenZ; |
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316 | G4double x2 = 1. - costm; |
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317 | G4double x3 = cosThetaMin - costm; |
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318 | G4double grej, z, z1; |
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319 | do { |
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320 | z = G4UniformRand()*x3; |
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321 | z1 = (x1*x2 - screenZ*z)/(x1 + z); |
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322 | if(z1 < 0.0) z1 = 0.0; |
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323 | else if(z1 > 2.0) z1 = 2.0; |
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324 | grej = 1.0/(1.0 + formf*z1); |
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325 | } while ( G4UniformRand() > grej*grej ); |
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326 | |
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327 | G4double cost = 1.0 - z1; |
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328 | G4double sint= sqrt(z1*(2.0 - z1)); |
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329 | /* |
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330 | if(sint > 0.1) |
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331 | G4cout<<"## SampleSecondaries: e(MeV)= " << kinEnergy |
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332 | << " sint= " << sint << " Z= " << Z << " screenZ= " << screenZ |
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333 | << " cn= " << formf |
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334 | << G4endl; |
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335 | */ |
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336 | G4double phi = twopi * G4UniformRand(); |
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337 | |
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338 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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339 | G4ThreeVector newDirection(cos(phi)*sint,sin(phi)*sint,cost); |
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340 | newDirection.rotateUz(direction); |
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341 | |
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342 | fParticleChange->ProposeMomentumDirection(newDirection); |
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343 | |
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344 | return; |
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345 | } |
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346 | |
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347 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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348 | |
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349 | |
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