1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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4 | // * * |
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5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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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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10 | // * * |
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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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16 | // * for the full disclaimer and the limitation of liability. * |
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17 | // * * |
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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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20 | // * By using, copying, modifying or distributing the software (or * |
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21 | // * any work based on the software) you agree to acknowledge its * |
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22 | // * use in resulting scientific publications, and indicate your * |
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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: G4AdjointComptonModel.cc,v 1.6 2009/12/16 17:50:03 gunter Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-03 $ |
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28 | // |
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29 | #include "G4AdjointComptonModel.hh" |
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30 | #include "G4AdjointCSManager.hh" |
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31 | |
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32 | |
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33 | #include "G4Integrator.hh" |
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34 | #include "G4TrackStatus.hh" |
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35 | #include "G4ParticleChange.hh" |
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36 | #include "G4AdjointElectron.hh" |
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37 | #include "G4AdjointGamma.hh" |
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38 | #include "G4Gamma.hh" |
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39 | #include "G4KleinNishinaCompton.hh" |
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40 | |
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41 | |
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42 | //////////////////////////////////////////////////////////////////////////////// |
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43 | // |
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44 | G4AdjointComptonModel::G4AdjointComptonModel(): |
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45 | G4VEmAdjointModel("AdjointCompton") |
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46 | |
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47 | { SetApplyCutInRange(false); |
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48 | SetUseMatrix(true); |
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49 | SetUseMatrixPerElement(true); |
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50 | SetUseOnlyOneMatrixForAllElements(true); |
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51 | theAdjEquivOfDirectPrimPartDef =G4AdjointGamma::AdjointGamma(); |
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52 | theAdjEquivOfDirectSecondPartDef=G4AdjointElectron::AdjointElectron(); |
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53 | theDirectPrimaryPartDef=G4Gamma::Gamma(); |
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54 | second_part_of_same_type=false; |
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55 | theDirectEMModel=new G4KleinNishinaCompton(G4Gamma::Gamma(),"ComptonDirectModel"); |
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56 | |
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57 | } |
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58 | //////////////////////////////////////////////////////////////////////////////// |
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59 | // |
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60 | G4AdjointComptonModel::~G4AdjointComptonModel() |
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61 | {;} |
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62 | //////////////////////////////////////////////////////////////////////////////// |
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63 | // |
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64 | void G4AdjointComptonModel::SampleSecondaries(const G4Track& aTrack, |
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65 | G4bool IsScatProjToProjCase, |
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66 | G4ParticleChange* fParticleChange) |
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67 | { |
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68 | if (!UseMatrix) return RapidSampleSecondaries(aTrack,IsScatProjToProjCase,fParticleChange); |
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69 | |
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70 | //A recall of the compton scattering law is |
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71 | //Egamma2=Egamma1/(1+(Egamma1/E0_electron)(1.-cos_th)) |
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72 | //Therefore Egamma2_max= Egamma2(cos_th=1) = Egamma1 |
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73 | //Therefore Egamma2_min= Egamma2(cos_th=-1) = Egamma1/(1+2.(Egamma1/E0_electron)) |
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74 | |
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75 | |
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76 | const G4DynamicParticle* theAdjointPrimary =aTrack.GetDynamicParticle(); |
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77 | G4double adjointPrimKinEnergy = theAdjointPrimary->GetKineticEnergy(); |
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78 | if (adjointPrimKinEnergy>HighEnergyLimit*0.999){ |
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79 | return; |
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80 | } |
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81 | |
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82 | |
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83 | //Sample secondary energy |
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84 | //----------------------- |
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85 | G4double gammaE1; |
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86 | gammaE1 = SampleAdjSecEnergyFromCSMatrix(adjointPrimKinEnergy, |
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87 | IsScatProjToProjCase); |
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88 | |
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89 | |
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90 | //gammaE2 |
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91 | //----------- |
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92 | |
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93 | G4double gammaE2 = adjointPrimKinEnergy; |
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94 | if (!IsScatProjToProjCase) gammaE2 = gammaE1 - adjointPrimKinEnergy; |
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95 | |
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96 | |
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97 | |
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98 | |
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99 | |
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100 | |
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101 | //Cos th |
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102 | //------- |
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103 | // G4cout<<"Compton scattering "<<gammaE1<<'\t'<<gammaE2<<G4endl; |
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104 | G4double cos_th = 1.+ electron_mass_c2*(1./gammaE1 -1./gammaE2); |
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105 | if (!IsScatProjToProjCase) { |
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106 | G4double p_elec=theAdjointPrimary->GetTotalMomentum(); |
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107 | cos_th = (gammaE1 - gammaE2*cos_th)/p_elec; |
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108 | } |
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109 | G4double sin_th = 0.; |
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110 | if (std::abs(cos_th)>1){ |
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111 | //G4cout<<"Problem in compton scattering with cos_th "<<cos_th<<G4endl; |
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112 | if (cos_th>0) { |
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113 | cos_th=1.; |
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114 | } |
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115 | else cos_th=-1.; |
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116 | sin_th=0.; |
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117 | } |
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118 | else sin_th = std::sqrt(1.-cos_th*cos_th); |
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119 | |
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120 | |
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121 | |
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122 | |
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123 | //gamma0 momentum |
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124 | //-------------------- |
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125 | |
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126 | |
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127 | G4ThreeVector dir_parallel=theAdjointPrimary->GetMomentumDirection(); |
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128 | G4double phi =G4UniformRand()*2.*3.1415926; |
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129 | G4ThreeVector gammaMomentum1 = gammaE1*G4ThreeVector(std::cos(phi)*sin_th,std::sin(phi)*sin_th,cos_th); |
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130 | gammaMomentum1.rotateUz(dir_parallel); |
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131 | // G4cout<<gamma0Energy<<'\t'<<gamma0Momentum<<G4endl; |
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132 | |
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133 | |
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134 | //It is important to correct the weight of particles before adding the secondary |
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135 | //------------------------------------------------------------------------------ |
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136 | CorrectPostStepWeight(fParticleChange, |
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137 | aTrack.GetWeight(), |
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138 | adjointPrimKinEnergy, |
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139 | gammaE1, |
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140 | IsScatProjToProjCase); |
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141 | |
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142 | if (!IsScatProjToProjCase){ //kill the primary and add a secondary |
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143 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
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144 | fParticleChange->AddSecondary(new G4DynamicParticle(theAdjEquivOfDirectPrimPartDef,gammaMomentum1)); |
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145 | //G4cout<<"gamma0Momentum "<<gamma0Momentum<<G4endl; |
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146 | } |
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147 | else { |
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148 | fParticleChange->ProposeEnergy(gammaE1); |
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149 | fParticleChange->ProposeMomentumDirection(gammaMomentum1.unit()); |
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150 | } |
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151 | |
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152 | |
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153 | } |
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154 | //////////////////////////////////////////////////////////////////////////////// |
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155 | // |
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156 | void G4AdjointComptonModel::RapidSampleSecondaries(const G4Track& aTrack, |
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157 | G4bool IsScatProjToProjCase, |
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158 | G4ParticleChange* fParticleChange) |
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159 | { |
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160 | |
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161 | const G4DynamicParticle* theAdjointPrimary =aTrack.GetDynamicParticle(); |
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162 | DefineCurrentMaterial(aTrack.GetMaterialCutsCouple()); |
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163 | |
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164 | |
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165 | G4double adjointPrimKinEnergy = theAdjointPrimary->GetKineticEnergy(); |
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166 | |
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167 | |
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168 | if (adjointPrimKinEnergy>HighEnergyLimit*0.999){ |
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169 | return; |
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170 | } |
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171 | |
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172 | |
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173 | G4double diffCSUsed=currentMaterial->GetElectronDensity()*twopi_mc2_rcl2; |
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174 | G4double gammaE1=0.; |
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175 | G4double gammaE2=0.; |
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176 | if (!IsScatProjToProjCase){ |
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177 | |
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178 | G4double Emax = GetSecondAdjEnergyMaxForProdToProjCase(adjointPrimKinEnergy); |
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179 | G4double Emin= GetSecondAdjEnergyMinForProdToProjCase(adjointPrimKinEnergy);; |
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180 | if (Emin>=Emax) return; |
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181 | G4double f1=(Emin-adjointPrimKinEnergy)/Emin; |
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182 | G4double f2=(Emax-adjointPrimKinEnergy)/Emax/f1; |
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183 | gammaE1=adjointPrimKinEnergy/(1.-f1*std::pow(f2,G4UniformRand()));; |
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184 | gammaE2=gammaE1-adjointPrimKinEnergy; |
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185 | diffCSUsed= diffCSUsed*(1.+2.*std::log(1.+electron_mass_c2/adjointPrimKinEnergy))*adjointPrimKinEnergy/gammaE1/gammaE2; |
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186 | |
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187 | |
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188 | } |
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189 | else { G4double Emax = GetSecondAdjEnergyMaxForScatProjToProjCase(adjointPrimKinEnergy); |
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190 | G4double Emin = GetSecondAdjEnergyMinForScatProjToProjCase(adjointPrimKinEnergy,currentTcutForDirectSecond); |
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191 | if (Emin>=Emax) return; |
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192 | gammaE2 =adjointPrimKinEnergy; |
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193 | gammaE1=Emin*std::pow(Emax/Emin,G4UniformRand()); |
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194 | diffCSUsed= diffCSUsed/gammaE1; |
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195 | |
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196 | } |
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197 | |
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198 | |
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199 | |
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200 | |
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201 | //Weight correction |
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202 | //----------------------- |
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203 | //First w_corr is set to the ratio between adjoint total CS and fwd total CS |
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204 | G4double w_corr=G4AdjointCSManager::GetAdjointCSManager()->GetPostStepWeightCorrection(); |
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205 | |
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206 | //Then another correction is needed due to the fact that a biaised differential CS has been used rather than the |
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207 | //one consistent with the direct model |
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208 | |
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209 | |
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210 | G4double diffCS = DiffCrossSectionPerAtomPrimToScatPrim(gammaE1, gammaE2,1,0.); |
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211 | if (diffCS >0) diffCS /=G4direct_CS; // here we have the normalised diffCS |
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212 | diffCS*=theDirectEMProcess->GetLambda(gammaE1,currentCouple); |
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213 | //diffCS*=theDirectEMModel->CrossSectionPerVolume(currentMaterial,G4Gamma::Gamma(),gammaE1,0.,2.*gammaE1); |
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214 | //G4cout<<"diffCS/diffCSUsed "<<diffCS/diffCSUsed<<'\t'<<gammaE1<<'\t'<<gammaE2<<G4endl; |
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215 | |
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216 | w_corr*=diffCS/diffCSUsed; |
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217 | |
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218 | G4double new_weight = aTrack.GetWeight()*w_corr; |
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219 | fParticleChange->SetParentWeightByProcess(false); |
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220 | fParticleChange->SetSecondaryWeightByProcess(false); |
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221 | fParticleChange->ProposeParentWeight(new_weight); |
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222 | |
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223 | |
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224 | |
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225 | //Cos th |
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226 | //------- |
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227 | |
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228 | G4double cos_th = 1.+ electron_mass_c2*(1./gammaE1 -1./gammaE2); |
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229 | if (!IsScatProjToProjCase) { |
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230 | G4double p_elec=theAdjointPrimary->GetTotalMomentum(); |
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231 | cos_th = (gammaE1 - gammaE2*cos_th)/p_elec; |
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232 | } |
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233 | G4double sin_th = 0.; |
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234 | if (std::abs(cos_th)>1){ |
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235 | //G4cout<<"Problem in compton scattering with cos_th "<<cos_th<<G4endl; |
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236 | if (cos_th>0) { |
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237 | cos_th=1.; |
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238 | } |
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239 | else cos_th=-1.; |
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240 | sin_th=0.; |
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241 | } |
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242 | else sin_th = std::sqrt(1.-cos_th*cos_th); |
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243 | |
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244 | |
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245 | |
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246 | |
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247 | //gamma0 momentum |
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248 | //-------------------- |
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249 | |
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250 | |
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251 | G4ThreeVector dir_parallel=theAdjointPrimary->GetMomentumDirection(); |
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252 | G4double phi =G4UniformRand()*2.*3.1415926; |
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253 | G4ThreeVector gammaMomentum1 = gammaE1*G4ThreeVector(std::cos(phi)*sin_th,std::sin(phi)*sin_th,cos_th); |
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254 | gammaMomentum1.rotateUz(dir_parallel); |
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255 | |
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256 | |
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257 | |
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258 | |
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259 | if (!IsScatProjToProjCase){ //kill the primary and add a secondary |
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260 | fParticleChange->ProposeTrackStatus(fStopAndKill); |
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261 | fParticleChange->AddSecondary(new G4DynamicParticle(theAdjEquivOfDirectPrimPartDef,gammaMomentum1)); |
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262 | //G4cout<<"gamma0Momentum "<<gamma0Momentum<<G4endl; |
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263 | } |
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264 | else { |
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265 | fParticleChange->ProposeEnergy(gammaE1); |
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266 | fParticleChange->ProposeMomentumDirection(gammaMomentum1.unit()); |
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267 | } |
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268 | |
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269 | |
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270 | |
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271 | } |
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272 | |
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273 | |
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274 | //////////////////////////////////////////////////////////////////////////////// |
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275 | // |
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276 | //The implementation here is correct for energy loss process, for the photoelectric and compton scattering the method should be redefine |
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277 | G4double G4AdjointComptonModel::DiffCrossSectionPerAtomPrimToSecond( |
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278 | G4double gamEnergy0, |
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279 | G4double kinEnergyElec, |
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280 | G4double Z, |
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281 | G4double A) |
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282 | { |
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283 | G4double gamEnergy1 = gamEnergy0 - kinEnergyElec; |
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284 | G4double dSigmadEprod=0.; |
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285 | if (gamEnergy1>0.) dSigmadEprod=DiffCrossSectionPerAtomPrimToScatPrim(gamEnergy0,gamEnergy1,Z,A); |
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286 | return dSigmadEprod; |
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287 | } |
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288 | |
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289 | |
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290 | //////////////////////////////////////////////////////////////////////////////// |
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291 | // |
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292 | G4double G4AdjointComptonModel::DiffCrossSectionPerAtomPrimToScatPrim( |
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293 | G4double gamEnergy0, |
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294 | G4double gamEnergy1, |
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295 | G4double Z, |
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296 | G4double ) |
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297 | { //Based on Klein Nishina formula |
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298 | // In the forward case (see G4KleinNishinaModel) the cross section is parametrised while |
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299 | // the secondaries are sampled from the |
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300 | // Klein Nishida differential cross section |
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301 | // The used diffrential cross section here is therefore the cross section multiplied by the normalised |
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302 | //differential Klein Nishida cross section |
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303 | |
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304 | |
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305 | //Klein Nishida Cross Section |
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306 | //----------------------------- |
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307 | G4double epsilon = gamEnergy0 / electron_mass_c2 ; |
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308 | G4double one_plus_two_epsi =1.+2.*epsilon; |
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309 | G4double gamEnergy1_max = gamEnergy0; |
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310 | G4double gamEnergy1_min = gamEnergy0/one_plus_two_epsi; |
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311 | if (gamEnergy1 >gamEnergy1_max || gamEnergy1<gamEnergy1_min) { |
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312 | /*G4cout<<"the differential CS is null"<<G4endl; |
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313 | G4cout<<gamEnergy0<<G4endl; |
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314 | G4cout<<gamEnergy1<<G4endl; |
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315 | G4cout<<gamEnergy1_min<<G4endl;*/ |
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316 | return 0.; |
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317 | } |
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318 | |
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319 | |
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320 | G4double epsi2 = epsilon *epsilon ; |
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321 | G4double one_plus_two_epsi_2=one_plus_two_epsi*one_plus_two_epsi; |
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322 | |
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323 | |
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324 | G4double CS=std::log(one_plus_two_epsi)*(1.- 2.*(1.+epsilon)/epsi2); |
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325 | CS+=4./epsilon +0.5*(1.-1./one_plus_two_epsi_2); |
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326 | CS/=epsilon; |
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327 | //Note that the pi*re2*Z factor is neglected because it is suppresed when computing dCS_dE1/CS; |
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328 | // in the differential cross section |
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329 | |
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330 | |
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331 | //Klein Nishida Differential Cross Section |
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332 | //----------------------------------------- |
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333 | G4double epsilon1 = gamEnergy1 / electron_mass_c2 ; |
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334 | G4double v= epsilon1/epsilon; |
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335 | G4double term1 =1.+ 1./epsilon -1/epsilon1; |
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336 | G4double dCS_dE1= 1./v +v + term1*term1 -1.; |
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337 | dCS_dE1 *=1./epsilon/gamEnergy0; |
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338 | |
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339 | |
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340 | //Normalised to the CS used in G4 |
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341 | //------------------------------- |
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342 | |
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343 | G4direct_CS = theDirectEMModel->ComputeCrossSectionPerAtom(G4Gamma::Gamma(), |
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344 | gamEnergy0, |
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345 | Z, 0., 0.,0.); |
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346 | |
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347 | dCS_dE1 *= G4direct_CS/CS; |
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348 | /* G4cout<<"the differential CS is not null"<<G4endl; |
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349 | G4cout<<gamEnergy0<<G4endl; |
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350 | G4cout<<gamEnergy1<<G4endl;*/ |
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351 | |
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352 | return dCS_dE1; |
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353 | |
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354 | |
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355 | } |
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356 | |
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357 | //////////////////////////////////////////////////////////////////////////////// |
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358 | // |
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359 | G4double G4AdjointComptonModel::GetSecondAdjEnergyMaxForScatProjToProjCase(G4double PrimAdjEnergy) |
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360 | { G4double inv_e_max = 1./PrimAdjEnergy - 2./electron_mass_c2; |
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361 | G4double e_max = HighEnergyLimit; |
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362 | if (inv_e_max > 0. ) e_max=std::min(1./inv_e_max,HighEnergyLimit); |
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363 | return e_max; |
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364 | } |
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365 | //////////////////////////////////////////////////////////////////////////////// |
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366 | // |
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367 | G4double G4AdjointComptonModel::GetSecondAdjEnergyMinForProdToProjCase(G4double PrimAdjEnergy) |
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368 | { G4double half_e=PrimAdjEnergy/2.; |
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369 | G4double term=std::sqrt(half_e*(electron_mass_c2+half_e)); |
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370 | G4double emin=half_e+term; |
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371 | return emin; |
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372 | } |
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373 | //////////////////////////////////////////////////////////////////////////////// |
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374 | // |
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375 | G4double G4AdjointComptonModel::AdjointCrossSection(const G4MaterialCutsCouple* aCouple, |
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376 | G4double primEnergy, |
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377 | G4bool IsScatProjToProjCase) |
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378 | { |
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379 | if (UseMatrix) return G4VEmAdjointModel::AdjointCrossSection(aCouple,primEnergy,IsScatProjToProjCase); |
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380 | DefineCurrentMaterial(aCouple); |
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381 | |
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382 | |
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383 | G4double Cross=0.; |
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384 | G4double Emax_proj =0.; |
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385 | G4double Emin_proj =0.; |
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386 | if (!IsScatProjToProjCase ){ |
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387 | Emax_proj = GetSecondAdjEnergyMaxForProdToProjCase(primEnergy); |
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388 | Emin_proj = GetSecondAdjEnergyMinForProdToProjCase(primEnergy); |
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389 | if (Emax_proj>Emin_proj ){ |
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390 | Cross= std::log((Emax_proj-primEnergy)*Emin_proj/Emax_proj/(Emin_proj-primEnergy)) |
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391 | *(1.+2.*std::log(1.+electron_mass_c2/primEnergy)); |
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392 | } |
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393 | } |
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394 | else { |
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395 | Emax_proj = GetSecondAdjEnergyMaxForScatProjToProjCase(primEnergy); |
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396 | Emin_proj = GetSecondAdjEnergyMinForScatProjToProjCase(primEnergy,0.); |
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397 | if (Emax_proj>Emin_proj) { |
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398 | Cross = std::log(Emax_proj/Emin_proj); |
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399 | //+0.5*primEnergy*primEnergy(1./(Emin_proj*Emin_proj) - 1./(Emax_proj*Emax_proj)); neglected at the moment |
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400 | } |
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401 | |
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402 | |
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403 | } |
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404 | |
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405 | Cross*=currentMaterial->GetElectronDensity()*twopi_mc2_rcl2; |
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406 | lastCS=Cross; |
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407 | return Cross; |
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408 | } |
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