1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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9 | // * include a list of copyright holders. * |
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11 | // * Neither the authors of this software system, nor their employing * |
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12 | // * institutes,nor the agencies providing financial support for this * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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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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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: G4WentzelVIModel.cc,v 1.60 2010/06/01 11:13:31 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-04-beta-cand-01 $ |
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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: G4WentzelVIModel |
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35 | // |
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36 | // Author: V.Ivanchenko |
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37 | // |
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38 | // Creation date: 09.04.2008 from G4MuMscModel |
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39 | // |
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40 | // Modifications: |
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41 | // 27-05-2010 V.Ivanchenko added G4WentzelOKandVIxSection class to |
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42 | // compute cross sections and sample scattering angle |
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43 | // |
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44 | // |
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45 | // Class Description: |
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46 | // |
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47 | // Implementation of the model of multiple scattering based on |
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48 | // G.Wentzel, Z. Phys. 40 (1927) 590. |
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49 | // H.W.Lewis, Phys Rev 78 (1950) 526. |
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50 | // J.M. Fernandez-Varea et al., NIM B73 (1993) 447. |
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51 | // L.Urban, CERN-OPEN-2006-077. |
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52 | |
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53 | // ------------------------------------------------------------------- |
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54 | // |
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55 | |
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56 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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57 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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58 | |
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59 | #include "G4WentzelVIModel.hh" |
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60 | #include "Randomize.hh" |
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61 | #include "G4ParticleChangeForMSC.hh" |
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62 | #include "G4PhysicsTableHelper.hh" |
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63 | #include "G4ElementVector.hh" |
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64 | #include "G4ProductionCutsTable.hh" |
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65 | #include "G4LossTableManager.hh" |
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66 | #include "G4Pow.hh" |
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67 | |
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68 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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69 | |
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70 | using namespace std; |
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71 | |
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72 | G4WentzelVIModel::G4WentzelVIModel(const G4String& nam) : |
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73 | G4VMscModel(nam), |
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74 | theLambdaTable(0), |
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75 | numlimit(0.1), |
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76 | currentCouple(0), |
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77 | cosThetaMin(1.0), |
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78 | isInitialized(false), |
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79 | inside(false) |
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80 | { |
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81 | invsqrt12 = 1./sqrt(12.); |
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82 | tlimitminfix = 1.e-6*mm; |
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83 | lowEnergyLimit = 1.0*eV; |
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84 | particle = 0; |
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85 | nelments = 5; |
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86 | xsecn.resize(nelments); |
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87 | prob.resize(nelments); |
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88 | theManager = G4LossTableManager::Instance(); |
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89 | fG4pow = G4Pow::GetInstance(); |
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90 | wokvi = new G4WentzelOKandVIxSection(); |
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91 | } |
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92 | |
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93 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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94 | |
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95 | G4WentzelVIModel::~G4WentzelVIModel() |
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96 | { |
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97 | delete wokvi; |
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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 | void G4WentzelVIModel::Initialise(const G4ParticleDefinition* p, |
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103 | const G4DataVector& cuts) |
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104 | { |
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105 | // reset parameters |
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106 | SetupParticle(p); |
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107 | currentRange = 0.0; |
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108 | cosThetaMax = cos(PolarAngleLimit()); |
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109 | wokvi->Initialise(p, cosThetaMax); |
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110 | /* |
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111 | G4cout << "G4WentzelVIModel: factorA2(GeV^2) = " << factorA2/(GeV*GeV) |
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112 | << " 1-cos(ThetaLimit)= " << 1 - cosThetaMax |
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113 | << G4endl; |
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114 | */ |
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115 | currentCuts = &cuts; |
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116 | |
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117 | // set values of some data members |
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118 | if(!isInitialized) { |
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119 | isInitialized = true; |
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120 | fParticleChange = GetParticleChangeForMSC(); |
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121 | InitialiseSafetyHelper(); |
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122 | } |
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123 | } |
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124 | |
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125 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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126 | |
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127 | G4double G4WentzelVIModel::ComputeCrossSectionPerAtom( |
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128 | const G4ParticleDefinition* p, |
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129 | G4double kinEnergy, |
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130 | G4double Z, G4double, |
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131 | G4double cutEnergy, G4double) |
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132 | { |
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133 | G4double xsec = 0.0; |
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134 | if(p != particle) { SetupParticle(p); } |
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135 | if(kinEnergy < lowEnergyLimit) { return xsec; } |
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136 | DefineMaterial(CurrentCouple()); |
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137 | cosTetMaxNuc = wokvi->SetupKinematic(kinEnergy, currentMaterial); |
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138 | if(cosTetMaxNuc < 1.0) { |
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139 | cosTetMaxNuc = wokvi->SetupTarget(G4int(Z), cutEnergy); |
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140 | xsec = wokvi->ComputeTransportCrossSectionPerAtom(cosTetMaxNuc); |
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141 | /* |
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142 | G4cout << "G4WentzelVIModel::CS: Z= " << G4int(Z) << " e(MeV)= " << kinEnergy |
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143 | << " 1-cosN= " << 1 - costm << " xsec(bn)= " << xsec/barn |
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144 | << " " << particle->GetParticleName() << G4endl; |
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145 | */ |
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146 | } |
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147 | return xsec; |
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148 | } |
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149 | |
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150 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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151 | |
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152 | G4double G4WentzelVIModel::ComputeTruePathLengthLimit( |
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153 | const G4Track& track, |
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154 | G4PhysicsTable* theTable, |
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155 | G4double currentMinimalStep) |
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156 | { |
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157 | G4double tlimit = currentMinimalStep; |
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158 | const G4DynamicParticle* dp = track.GetDynamicParticle(); |
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159 | G4StepPoint* sp = track.GetStep()->GetPreStepPoint(); |
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160 | G4StepStatus stepStatus = sp->GetStepStatus(); |
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161 | //G4cout << "G4WentzelVIModel::ComputeTruePathLengthLimit stepStatus= " |
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162 | // << stepStatus << G4endl; |
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163 | |
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164 | // initialisation for 1st step |
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165 | if(stepStatus == fUndefined) { |
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166 | inside = false; |
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167 | SetupParticle(dp->GetDefinition()); |
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168 | } |
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169 | |
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170 | // initialisation for each step, lambda may be computed from scratch |
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171 | preKinEnergy = dp->GetKineticEnergy(); |
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172 | DefineMaterial(track.GetMaterialCutsCouple()); |
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173 | theLambdaTable = theTable; |
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174 | lambdaeff = GetLambda(preKinEnergy); |
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175 | currentRange = |
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176 | theManager->GetRangeFromRestricteDEDX(particle,preKinEnergy,currentCouple); |
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177 | cosTetMaxNuc = wokvi->SetupKinematic(preKinEnergy, currentMaterial); |
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178 | |
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179 | // extra check for abnormal situation |
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180 | // this check needed to run MSC with eIoni and eBrem inactivated |
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181 | if(tlimit > currentRange) { tlimit = currentRange; } |
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182 | |
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183 | // stop here if small range particle |
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184 | if(inside) { return tlimit; } |
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185 | |
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186 | // pre step |
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187 | G4double presafety = sp->GetSafety(); |
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188 | |
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189 | // compute presafety again if presafety <= 0 and no boundary |
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190 | // i.e. when it is needed for optimization purposes |
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191 | if(stepStatus != fGeomBoundary && presafety < tlimitminfix) { |
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192 | presafety = ComputeSafety(sp->GetPosition(), tlimit); |
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193 | } |
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194 | /* |
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195 | G4cout << "e(MeV)= " << preKinEnergy/MeV |
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196 | << " " << particle->GetParticleName() |
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197 | << " CurLimit(mm)= " << tlimit/mm <<" safety(mm)= " << presafety/mm |
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198 | << " R(mm)= " <<currentRange/mm |
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199 | << " L0(mm^-1)= " << lambdaeff*mm |
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200 | <<G4endl; |
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201 | */ |
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202 | // far from geometry boundary |
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203 | if(currentRange < presafety) { |
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204 | inside = true; |
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205 | return tlimit; |
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206 | } |
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207 | |
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208 | // natural limit for high energy |
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209 | G4double rlimit = std::max(facrange*currentRange, |
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210 | 0.7*(1.0 - cosTetMaxNuc)*lambdaeff); |
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211 | |
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212 | // low-energy e- |
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213 | if(cosThetaMax > cosTetMaxNuc) { |
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214 | rlimit = std::min(rlimit, facsafety*presafety); |
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215 | } |
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216 | |
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217 | // cut correction |
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218 | G4double rcut = currentCouple->GetProductionCuts()->GetProductionCut(1); |
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219 | //G4cout << "rcut= " << rcut << " rlimit= " << rlimit << " presafety= " << presafety |
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220 | // << " 1-cosThetaMax= " <<1-cosThetaMax << " 1-cosTetMaxNuc= " << 1-cosTetMaxNuc |
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221 | // << G4endl; |
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222 | if(rcut > rlimit) { rlimit = std::min(rlimit, rcut*sqrt(rlimit/rcut)); } |
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223 | |
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224 | if(rlimit < tlimit) { tlimit = rlimit; } |
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225 | |
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226 | tlimit = std::max(tlimit, tlimitminfix); |
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227 | |
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228 | // step limit in infinite media |
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229 | tlimit = std::min(tlimit, 20*currentMaterial->GetRadlen()); |
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230 | /* |
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231 | G4cout << particle->GetParticleName() << " e= " << preKinEnergy |
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232 | << " L0= " << lambdaeff << " R= " << currentRange |
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233 | << "tlimit= " << tlimit |
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234 | << " currentMinimalStep= " << currentMinimalStep << G4endl; |
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235 | */ |
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236 | return tlimit; |
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237 | } |
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238 | |
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239 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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240 | |
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241 | G4double G4WentzelVIModel::ComputeGeomPathLength(G4double truelength) |
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242 | { |
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243 | tPathLength = truelength; |
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244 | zPathLength = tPathLength; |
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245 | |
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246 | if(lambdaeff > 0.0) { |
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247 | G4double tau = tPathLength/lambdaeff; |
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248 | //G4cout << "ComputeGeomPathLength: tLength= " << tPathLength |
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249 | // << " Leff= " << lambdaeff << " tau= " << tau << G4endl; |
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250 | // small step |
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251 | if(tau < numlimit) { |
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252 | zPathLength *= (1.0 - 0.5*tau + tau*tau/6.0); |
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253 | |
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254 | // medium step |
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255 | } else { |
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256 | G4double e1 = 0.0; |
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257 | if(currentRange > tPathLength) { |
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258 | e1 = theManager->GetEnergy(particle, |
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259 | currentRange-tPathLength, |
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260 | currentCouple); |
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261 | } |
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262 | e1 = 0.5*(e1 + preKinEnergy); |
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263 | cosTetMaxNuc = wokvi->SetupKinematic(e1, currentMaterial); |
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264 | lambdaeff = GetLambda(e1); |
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265 | zPathLength = lambdaeff*(1.0 - exp(-tPathLength/lambdaeff)); |
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266 | } |
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267 | } |
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268 | //G4cout<<"Comp.geom: zLength= "<<zPathLength<<" tLength= "<<tPathLength<<G4endl; |
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269 | return zPathLength; |
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270 | } |
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271 | |
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272 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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273 | |
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274 | G4double G4WentzelVIModel::ComputeTrueStepLength(G4double geomStepLength) |
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275 | { |
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276 | // initialisation of single scattering x-section |
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277 | xtsec = 0.0; |
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278 | |
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279 | // pathalogical case |
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280 | if(lambdaeff <= 0.0) { |
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281 | zPathLength = geomStepLength; |
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282 | tPathLength = geomStepLength; |
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283 | return tPathLength; |
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284 | } |
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285 | |
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286 | G4double tau = geomStepLength/lambdaeff; |
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287 | |
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288 | // step defined by transportation |
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289 | if(geomStepLength != zPathLength) { |
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290 | |
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291 | // step defined by transportation |
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292 | zPathLength = geomStepLength; |
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293 | tPathLength = zPathLength*(1.0 + 0.5*tau + tau*tau/3.0); |
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294 | |
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295 | // energy correction for a big step |
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296 | if(tau > numlimit) { |
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297 | G4double e1 = 0.0; |
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298 | if(currentRange > tPathLength) { |
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299 | e1 = theManager->GetEnergy(particle, |
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300 | currentRange-tPathLength, |
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301 | currentCouple); |
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302 | } |
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303 | e1 = 0.5*(e1 + preKinEnergy); |
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304 | cosTetMaxNuc = wokvi->SetupKinematic(e1, currentMaterial); |
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305 | lambdaeff = GetLambda(e1); |
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306 | tau = zPathLength/lambdaeff; |
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307 | |
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308 | if(tau < 0.999999) { tPathLength = -lambdaeff*log(1.0 - tau); } |
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309 | else { tPathLength = currentRange; } |
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310 | } |
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311 | } |
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312 | |
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313 | // check of step length |
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314 | // define threshold angle between single and multiple scattering |
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315 | cosThetaMin = 1.0 - 1.5*tPathLength/lambdaeff; |
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316 | |
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317 | // recompute transport cross section - do not change energy |
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318 | // anymore - cannot be applied for big steps |
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319 | if(cosThetaMin > cosTetMaxNuc) { |
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320 | |
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321 | // new computation |
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322 | G4double xsec = ComputeXSectionPerVolume(); |
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323 | //G4cout << "%%%% xsec= " << xsec << " xtsec= " << xtsec << G4endl; |
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324 | if(xtsec > 0.0) { |
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325 | if(xsec > 0.0) { lambdaeff = 1./xsec; } |
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326 | else { lambdaeff = DBL_MAX; } |
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327 | |
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328 | tau = zPathLength*xsec; |
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329 | if(tau < numlimit) { tPathLength = zPathLength*(1.0 + 0.5*tau + tau*tau/3.0); } |
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330 | else if(tau < 0.999999) { tPathLength = -lambdaeff*log(1.0 - tau); } |
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331 | else { tPathLength = currentRange; } |
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332 | } |
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333 | } |
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334 | |
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335 | if(tPathLength > currentRange) { tPathLength = currentRange; } |
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336 | if(tPathLength < zPathLength) { tPathLength = zPathLength; } |
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337 | /* |
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338 | G4cout <<"Comp.true: zLength= "<<zPathLength<<" tLength= "<<tPathLength |
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339 | <<" Leff(mm)= "<<lambdaeff/mm<<" sig0(1/mm)= " << xtsec <<G4endl; |
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340 | G4cout << particle->GetParticleName() << " 1-cosThetaMin= " << 1-cosThetaMin |
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341 | << " 1-cosTetMaxNuc= " << 1-cosTetMaxNuc |
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342 | << " e(MeV)= " << preKinEnergy/MeV << G4endl; |
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343 | */ |
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344 | return tPathLength; |
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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 | void G4WentzelVIModel::SampleScattering(const G4DynamicParticle* dynParticle, |
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350 | G4double safety) |
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351 | { |
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352 | //G4cout << "!##! G4WentzelVIModel::SampleScattering for " |
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353 | // << particle->GetParticleName() << G4endl; |
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354 | |
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355 | // ignore scattering for zero step length and energy below the limit |
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356 | if(dynParticle->GetKineticEnergy() < lowEnergyLimit || |
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357 | tPathLength <= DBL_MIN || lambdaeff <= DBL_MIN) |
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358 | { return; } |
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359 | |
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360 | G4double invlambda = 0.0; |
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361 | if(lambdaeff < DBL_MAX) { invlambda = 0.5/lambdaeff; } |
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362 | |
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363 | // use average kinetic energy over the step |
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364 | G4double cut = (*currentCuts)[currentMaterialIndex]; |
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365 | /* |
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366 | G4cout <<"SampleScat: E0(MeV)= "<< preKinEnergy/MeV |
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367 | << " Leff= " << lambdaeff <<" sig0(1/mm)= " << xtsec |
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368 | << " x1= " << tPathLength*invlambda << " safety= " << safety << G4endl; |
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369 | */ |
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370 | |
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371 | G4double length = tPathLength; |
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372 | G4double lengthlim = tPathLength*1.e-6; |
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373 | |
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374 | // step limit due msc |
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375 | G4double x0 = length; |
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376 | // large scattering angle case - two step approach |
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377 | if(tPathLength*invlambda > 0.5 && length > tlimitminfix) { x0 *= 0.5; } |
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378 | |
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379 | // step limit due single scattering |
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380 | G4double x1 = length; |
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381 | if(xtsec > 0.0) { x1 = -log(G4UniformRand())/xtsec; } |
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382 | |
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383 | const G4ElementVector* theElementVector = |
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384 | currentMaterial->GetElementVector(); |
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385 | G4int nelm = currentMaterial->GetNumberOfElements(); |
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386 | |
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387 | // geometry |
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388 | G4double sint, cost, phi; |
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389 | G4ThreeVector oldDirection = dynParticle->GetMomentumDirection(); |
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390 | G4ThreeVector temp(0.0,0.0,1.0); |
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391 | |
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392 | // current position and direction relative to the end point |
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393 | // because of magnetic field geometry is computed relatively to the |
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394 | // end point of the step |
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395 | G4ThreeVector dir(0.0,0.0,1.0); |
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396 | G4ThreeVector pos(0.0,0.0,-zPathLength); |
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397 | G4double mscfac = zPathLength/tPathLength; |
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398 | |
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399 | // start a loop |
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400 | do { |
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401 | G4double step = x0; |
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402 | G4bool singleScat = false; |
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403 | |
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404 | // single scattering case |
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405 | if(x1 < x0) { |
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406 | step = x1; |
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407 | singleScat = true; |
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408 | } |
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409 | |
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410 | // new position |
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411 | pos += step*mscfac*dir; |
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412 | |
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413 | // added multiple scattering |
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414 | G4double z; |
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415 | G4double tet2 = step*invlambda; |
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416 | do { z = -tet2*log(G4UniformRand()); } while (z >= 1.0); |
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417 | |
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418 | cost = 1.0 - 2.0*z; |
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419 | sint = sqrt((1.0 - cost)*(1.0 + cost)); |
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420 | phi = twopi*G4UniformRand(); |
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421 | G4double vx1 = sint*cos(phi); |
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422 | G4double vy1 = sint*sin(phi); |
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423 | |
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424 | // lateral displacement |
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425 | if (latDisplasment && safety > tlimitminfix) { |
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426 | G4double rms = invsqrt12*sqrt(2.0*tet2); |
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427 | G4double dx = step*(0.5*vx1 + rms*G4RandGauss::shoot(0.0,1.0)); |
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428 | G4double dy = step*(0.5*vy1 + rms*G4RandGauss::shoot(0.0,1.0)); |
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429 | G4double dz; |
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430 | G4double d = (dx*dx + dy*dy)/(step*step); |
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431 | if(d < numlimit) { dz = -0.5*step*d*(1.0 + 0.25*d); } |
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432 | else if(d < 1.0) { dz = -step*(1.0 - sqrt(1.0 - d));} |
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433 | else { dx = dy = dz = 0.0; } |
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434 | |
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435 | // change position |
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436 | temp.set(dx,dy,dz); |
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437 | temp.rotateUz(dir); |
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438 | pos += temp; |
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439 | } |
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440 | |
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441 | // direction is changed |
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442 | temp.set(vx1,vy1,cost); |
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443 | temp.rotateUz(dir); |
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444 | dir = temp; |
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445 | |
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446 | if(singleScat) { |
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447 | |
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448 | // select element |
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449 | G4int i = 0; |
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450 | if(nelm > 1) { |
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451 | G4double qsec = G4UniformRand()*xtsec; |
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452 | for (; i<nelm; ++i) { if(xsecn[i] >= qsec) { break; } } |
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453 | if(i >= nelm) { i = nelm - 1; } |
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454 | } |
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455 | G4double cosTetM = |
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456 | wokvi->SetupTarget(G4int((*theElementVector)[i]->GetZ()), cut); |
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457 | temp = wokvi->SampleSingleScattering(cosThetaMin, cosTetM, prob[i]); |
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458 | temp.rotateUz(dir); |
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459 | |
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460 | // renew direction |
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461 | dir = temp; |
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462 | |
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463 | // new single scatetring |
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464 | x1 = -log(G4UniformRand())/xtsec; |
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465 | } |
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466 | |
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467 | // update step |
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468 | length -= step; |
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469 | |
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470 | } while (length > lengthlim); |
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471 | |
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472 | dir.rotateUz(oldDirection); |
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473 | pos.rotateUz(oldDirection); |
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474 | |
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475 | //G4cout << "G4WentzelVIModel sampling of scattering is done" << G4endl; |
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476 | // end of sampling ------------------------------- |
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477 | |
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478 | fParticleChange->ProposeMomentumDirection(dir); |
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479 | |
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480 | // lateral displacement |
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481 | if (latDisplasment) { |
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482 | G4double r = pos.mag(); |
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483 | |
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484 | /* |
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485 | G4cout << " r(mm)= " << r << " safety= " << safety |
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486 | << " trueStep(mm)= " << tPathLength |
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487 | << " geomStep(mm)= " << zPathLength |
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488 | << G4endl; |
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489 | */ |
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490 | |
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491 | if(r > tlimitminfix) { |
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492 | pos /= r; |
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493 | ComputeDisplacement(fParticleChange, pos, r, safety); |
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494 | } |
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495 | } |
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496 | //G4cout << "G4WentzelVIModel::SampleScattering end" << G4endl; |
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497 | } |
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498 | |
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499 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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500 | |
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501 | G4double G4WentzelVIModel::ComputeXSectionPerVolume() |
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502 | { |
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503 | // prepare recomputation of x-sections |
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504 | const G4ElementVector* theElementVector = currentMaterial->GetElementVector(); |
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505 | const G4double* theAtomNumDensityVector = |
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506 | currentMaterial->GetVecNbOfAtomsPerVolume(); |
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507 | G4int nelm = currentMaterial->GetNumberOfElements(); |
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508 | if(nelm > nelments) { |
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509 | nelments = nelm; |
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510 | xsecn.resize(nelm); |
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511 | prob.resize(nelm); |
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512 | } |
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513 | G4double cut = (*currentCuts)[currentMaterialIndex]; |
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514 | cosTetMaxNuc = wokvi->GetCosThetaNuc(); |
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515 | |
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516 | // check consistency |
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517 | xtsec = 0.0; |
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518 | if(cosTetMaxNuc > cosThetaMin) { return 0.0; } |
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519 | |
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520 | // loop over elements |
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521 | G4double xs = 0.0; |
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522 | for (G4int i=0; i<nelm; ++i) { |
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523 | G4double costm = |
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524 | wokvi->SetupTarget(G4int((*theElementVector)[i]->GetZ()), cut); |
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525 | G4double density = theAtomNumDensityVector[i]; |
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526 | |
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527 | G4double esec = 0.0; |
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528 | if(costm < cosThetaMin) { |
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529 | |
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530 | // recompute the transport x-section |
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531 | xs += density*wokvi->ComputeTransportCrossSectionPerAtom(cosThetaMin); |
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532 | |
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533 | // recompute the total x-section |
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534 | G4double nsec = wokvi->ComputeNuclearCrossSection(cosThetaMin, costm); |
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535 | esec = wokvi->ComputeElectronCrossSection(cosThetaMin, costm); |
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536 | nsec += esec; |
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537 | if(nsec > 0.0) { esec /= nsec; } |
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538 | xtsec += nsec*density; |
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539 | } |
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540 | xsecn[i] = xtsec; |
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541 | prob[i] = esec; |
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542 | //G4cout << i << " xs= " << xs << " xtsec= " << xtsec << " 1-cosThetaMin= " << 1-cosThetaMin |
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543 | // << " 1-cosTetMaxNuc2= " <<1-cosTetMaxNuc2<< G4endl; |
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544 | } |
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545 | |
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546 | //G4cout << "ComputeXS result: xsec(1/mm)= " << xs |
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547 | // << " txsec(1/mm)= " << xtsec <<G4endl; |
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548 | return xs; |
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549 | } |
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550 | |
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551 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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