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24 | // ******************************************************************** |
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25 | // |
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26 | // $Id: G4PolarizedMollerBhabhaModel.cc,v 1.4 2007/05/23 08:52:20 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-03 $ |
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28 | // ------------------------------------------------------------------- |
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29 | // |
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30 | // GEANT4 Class file |
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31 | // |
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32 | // File name: G4PolarizedMollerBhabhaModel |
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33 | // |
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34 | // Author: A.Schaelicke on base of Vladimir Ivanchenko code |
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35 | // |
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36 | // Creation date: 10.11.2005 |
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37 | // |
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38 | // Modifications: |
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39 | // |
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40 | // 20-08-05, modified interface (A.Schaelicke) |
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41 | // |
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42 | // Class Description: |
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43 | // |
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44 | // Implementation of energy loss and delta-electron production by e+/e- |
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45 | // (including polarization effects) |
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46 | // |
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47 | // ------------------------------------------------------------------- |
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48 | // |
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49 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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50 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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51 | |
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52 | #include "G4PolarizedMollerBhabhaModel.hh" |
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53 | #include "G4Electron.hh" |
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54 | #include "G4Positron.hh" |
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55 | #include "G4ParticleChangeForLoss.hh" |
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56 | #include "Randomize.hh" |
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57 | |
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58 | #include "G4PolarizationManager.hh" |
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59 | #include "G4PolarizationHelper.hh" |
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60 | #include "G4PolarizedBhabhaCrossSection.hh" |
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61 | #include "G4PolarizedMollerCrossSection.hh" |
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62 | |
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63 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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64 | |
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65 | G4PolarizedMollerBhabhaModel::G4PolarizedMollerBhabhaModel(const G4ParticleDefinition* p, |
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66 | const G4String& nam) |
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67 | : G4MollerBhabhaModel(p,nam) |
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68 | { |
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69 | |
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70 | // G4cout<<" particle==electron "<<(p==theElectron)<<G4endl; |
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71 | isElectron=(p==theElectron); // necessary due to wrong order in G4MollerBhabhaModel constructor! |
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72 | |
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73 | if (p==0) { |
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74 | |
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75 | } |
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76 | if (!isElectron) { |
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77 | G4cout<<" buildBhabha cross section "<<isElectron<<G4endl; |
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78 | crossSectionCalculator = new G4PolarizedBhabhaCrossSection(); |
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79 | } else { |
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80 | G4cout<<" buildMoller cross section "<<isElectron<<G4endl; |
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81 | crossSectionCalculator = new G4PolarizedMollerCrossSection(); |
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82 | } |
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83 | } |
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84 | |
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85 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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86 | |
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87 | G4PolarizedMollerBhabhaModel::~G4PolarizedMollerBhabhaModel() |
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88 | { |
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89 | if (crossSectionCalculator) { |
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90 | delete crossSectionCalculator; |
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91 | } |
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92 | } |
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93 | |
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94 | |
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95 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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96 | |
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97 | G4double G4PolarizedMollerBhabhaModel::ComputeCrossSectionPerElectron( |
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98 | const G4ParticleDefinition* pd, |
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99 | G4double kinEnergy, |
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100 | G4double cut, |
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101 | G4double emax) |
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102 | { |
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103 | G4double xs = |
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104 | G4MollerBhabhaModel::ComputeCrossSectionPerElectron(pd,kinEnergy, |
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105 | cut,emax); |
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106 | // G4cout<<"calc eIoni xsec "<<xs<<G4endl; |
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107 | // G4cout<<" "<<kinEnergy<<" "<<cut<<" "<<emax<<G4endl; |
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108 | G4double factor=1.; |
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109 | if (xs!=0) { |
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110 | // G4cout<<"calc asym"<<G4endl; |
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111 | G4double tmax = MaxSecondaryEnergy(pd, kinEnergy); |
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112 | tmax = std::min(emax, tmax); |
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113 | |
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114 | if (std::fabs(cut/emax-1.)<1.e-10) return xs; |
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115 | |
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116 | if(cut < tmax) { |
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117 | |
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118 | G4double xmin = cut/kinEnergy; |
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119 | G4double xmax = tmax/kinEnergy; |
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120 | // G4cout<<"calc asym "<<xmin<<","<<xmax<<G4endl; |
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121 | G4double gam = kinEnergy/electron_mass_c2 + 1.0; |
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122 | |
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123 | G4double crossPol=crossSectionCalculator-> |
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124 | TotalXSection(xmin,xmax,gam, |
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125 | theBeamPolarization, |
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126 | theTargetPolarization); |
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127 | G4double crossUnpol=crossSectionCalculator-> |
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128 | TotalXSection(xmin,xmax,gam, |
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129 | G4StokesVector::ZERO, |
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130 | G4StokesVector::ZERO); |
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131 | if (crossUnpol>0.) factor=crossPol/crossUnpol; |
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132 | // G4cout<<" factor="<<factor<<G4endl; |
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133 | } |
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134 | } |
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135 | return xs*factor; |
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136 | } |
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137 | |
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138 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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139 | |
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140 | void G4PolarizedMollerBhabhaModel::SampleSecondaries(std::vector<G4DynamicParticle*>* vdp, |
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141 | const G4MaterialCutsCouple* , |
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142 | const G4DynamicParticle* dp, |
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143 | G4double tmin, |
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144 | G4double maxEnergy) |
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145 | { |
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146 | // *** obtain and save target and beam polarization *** |
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147 | G4PolarizationManager * polarizationManger = G4PolarizationManager::GetInstance(); |
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148 | |
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149 | const G4Track * aTrack = fParticleChange->GetCurrentTrack(); |
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150 | |
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151 | // obtain polarization of the beam |
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152 | theBeamPolarization = dp->GetPolarization(); |
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153 | |
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154 | // obtain polarization of the media |
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155 | G4VPhysicalVolume* aPVolume = aTrack->GetVolume(); |
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156 | G4LogicalVolume* aLVolume = aPVolume->GetLogicalVolume(); |
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157 | const G4bool targetIsPolarized = polarizationManger->IsPolarized(aLVolume); |
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158 | theTargetPolarization = polarizationManger->GetVolumePolarization(aLVolume); |
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159 | |
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160 | // transfer target polarization in interaction frame |
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161 | if (targetIsPolarized) |
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162 | theTargetPolarization.rotateUz(dp->GetMomentumDirection()); |
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163 | |
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164 | |
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165 | |
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166 | |
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167 | G4double tmax = std::min(maxEnergy, MaxSecondaryKinEnergy(dp)); |
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168 | if(tmin >= tmax) return; |
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169 | // if(tmin > tmax) tmin = tmax; |
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170 | |
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171 | G4double polL = theBeamPolarization.z()*theTargetPolarization.z(); |
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172 | polL=std::fabs(polL); |
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173 | G4double polT = theBeamPolarization.x()*theTargetPolarization.x() + |
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174 | theBeamPolarization.y()*theTargetPolarization.y(); |
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175 | polT=std::fabs(polT); |
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176 | |
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177 | G4double kineticEnergy = dp->GetKineticEnergy(); |
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178 | G4double energy = kineticEnergy + electron_mass_c2; |
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179 | G4double totalMomentum = std::sqrt(kineticEnergy*(energy + electron_mass_c2)); |
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180 | G4double xmin = tmin/kineticEnergy; |
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181 | G4double xmax = tmax/kineticEnergy; |
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182 | G4double gam = energy/electron_mass_c2; |
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183 | G4double gamma2 = gam*gam; |
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184 | G4double gmo = gam - 1.; |
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185 | G4double gmo2 = gmo*gmo; |
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186 | G4double gmo3 = gmo2*gmo; |
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187 | G4double gpo = gam + 1.; |
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188 | G4double gpo2 = gpo*gpo; |
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189 | G4double gpo3 = gpo2*gpo; |
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190 | G4double x, y, q, grej, grej2; |
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191 | G4double z = 0.; |
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192 | G4double xs = 0., phi =0.; |
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193 | G4ThreeVector direction = dp->GetMomentumDirection(); |
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194 | |
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195 | //(Polarized) Moller (e-e-) scattering |
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196 | if (isElectron) { |
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197 | // *** dice according to polarized cross section |
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198 | G4double G = ((2.0*gam - 1.0)/gamma2)*(1. - polT - polL*gam); |
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199 | G4double H = (sqr(gam - 1.0)/gamma2)*(1. + polT + polL*((gam + 3.)/(gam - 1.))); |
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200 | |
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201 | y = 1.0 - xmax; |
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202 | grej = 1.0 - G*xmax + xmax*xmax*(H + (1.0 - G*y)/(y*y)); |
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203 | grej2 = 1.0 - G*xmin + xmin*xmin*(H + (1.0 - G*y)/(y*y)); |
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204 | if (grej2 > grej) grej = grej2; |
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205 | G4double prefM = gamma2*classic_electr_radius*classic_electr_radius/(gmo2*(gam + 1.0)); |
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206 | grej *= prefM; |
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207 | do { |
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208 | q = G4UniformRand(); |
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209 | x = xmin*xmax/(xmin*(1.0 - q) + xmax*q); |
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210 | if (crossSectionCalculator) { |
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211 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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212 | theTargetPolarization,1); |
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213 | xs=crossSectionCalculator->XSection(G4StokesVector::ZERO, |
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214 | G4StokesVector::ZERO); |
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215 | z=xs*sqr(x)*4.; |
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216 | if (grej < z) { |
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217 | G4cout<<"WARNING : error in Moller rejection routine! \n" |
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218 | <<" z = "<<z<<" grej="<<grej<<"\n"; |
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219 | } |
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220 | } else { |
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221 | G4cout<<"No calculator in Moller scattering"<<G4endl; |
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222 | } |
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223 | } while(grej * G4UniformRand() > z); |
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224 | //Bhabha (e+e-) scattering |
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225 | } else { |
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226 | // *** dice according to polarized cross section |
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227 | y = xmax*xmax; |
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228 | grej = 0.; |
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229 | grej += y*y*gmo3*(1. + (polL + polT)*(gam + 3.)/gmo); |
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230 | grej += -2.*xmin*xmin*xmin*gam*gmo2*(1. - (polL + polT)*(gam + 3.)/gmo); |
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231 | grej += y*y*gmo*(3.*gamma2 + 6.*gam + 4.)*(1. + (polL*(3.*gam + 1.)*(gamma2 + gam + 1.) + polT*((gam + 2.)*gamma2 + 1.))/(gmo*(3.*gam*(gam + 2.) + 4.))); |
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232 | grej /= gpo3; |
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233 | grej += -xmin*(2.*gamma2 + 4.*gam + 1.)*(1. - gam*(polL*(2.*gam + 1.) + polT)/(2.*gam*(gam + 2.) + 1.))/gpo2; |
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234 | grej += gamma2/(gamma2 - 1.); |
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235 | G4double prefB = classic_electr_radius*classic_electr_radius/(gam - 1.0); |
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236 | grej *= prefB; |
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237 | |
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238 | do { |
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239 | q = G4UniformRand(); |
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240 | x = xmin*xmax/(xmin*(1.0 - q) + xmax*q); |
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241 | if (crossSectionCalculator) { |
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242 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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243 | theTargetPolarization,1); |
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244 | xs=crossSectionCalculator->XSection(G4StokesVector::ZERO, |
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245 | G4StokesVector::ZERO); |
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246 | z=xs*sqr(x)*4.; |
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247 | } else { |
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248 | G4cout<<"No calculator in Bhabha scattering"<<G4endl; |
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249 | } |
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250 | |
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251 | if(z > grej) { |
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252 | G4cout<<"&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&"<<G4endl; |
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253 | G4cout << "G4PolarizedMollerBhabhaModel::SampleSecondaries Warning! "<<G4endl |
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254 | << "Majorant " << grej << " < " |
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255 | << z << " for x= " << x<<G4endl |
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256 | << " e+e- (Bhabha) scattering"<<" at KinEnergy "<<kineticEnergy<<G4endl; |
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257 | G4cout<<"&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&"<<G4endl; |
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258 | } |
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259 | } while(grej * G4UniformRand() > z); |
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260 | } |
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261 | // |
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262 | // |
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263 | // polar asymmetries (due to transverse polarizations) |
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264 | // |
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265 | // |
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266 | if (crossSectionCalculator) { |
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267 | // grej*=1./(sqr(x)*sqr(gamma2-1))*sqr(gam*(1+gam)); |
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268 | grej=xs*2.; |
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269 | do { |
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270 | phi = twopi * G4UniformRand() ; |
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271 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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272 | theTargetPolarization,1); |
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273 | xs=crossSectionCalculator->XSection(G4StokesVector::ZERO, |
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274 | G4StokesVector::ZERO); |
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275 | if(xs > grej) { |
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276 | if (isElectron){ |
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277 | G4cout << "G4PolarizedMollerBhabhaModel::SampleSecondaries Warning! "<<G4endl |
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278 | << "Majorant " << grej << " < " |
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279 | << xs << " for phi= " << phi<<G4endl |
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280 | << " e-e- (Moller) scattering"<< G4endl |
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281 | <<"PHI DICING"<<G4endl; |
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282 | } else { |
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283 | G4cout << "G4PolarizedMollerBhabhaModel::SampleSecondaries Warning! "<<G4endl |
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284 | << "Majorant " << grej << " < " |
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285 | << xs << " for phi= " << phi<<G4endl |
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286 | << " e+e- (Bhabha) scattering"<< G4endl |
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287 | <<"PHI DICING"<<G4endl; |
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288 | } |
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289 | } |
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290 | } while(grej * G4UniformRand() > xs); |
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291 | } |
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292 | |
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293 | // fix kinematics of delta electron |
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294 | G4double deltaKinEnergy = x * kineticEnergy; |
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295 | G4double deltaMomentum = |
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296 | std::sqrt(deltaKinEnergy * (deltaKinEnergy + 2.0*electron_mass_c2)); |
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297 | G4double cost = deltaKinEnergy * (energy + electron_mass_c2) / |
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298 | (deltaMomentum * totalMomentum); |
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299 | G4double sint = 1.0 - cost*cost; |
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300 | if(sint > 0.0) sint = std::sqrt(sint); |
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301 | |
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302 | |
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303 | G4ThreeVector deltaDirection(-sint*std::cos(phi),-sint*std::sin(phi), cost) ; |
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304 | deltaDirection.rotateUz(direction); |
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305 | |
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306 | // primary change |
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307 | kineticEnergy -= deltaKinEnergy; |
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308 | fParticleChange->SetProposedKineticEnergy(kineticEnergy); |
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309 | |
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310 | if(kineticEnergy > DBL_MIN) { |
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311 | G4ThreeVector dir = totalMomentum*direction - deltaMomentum*deltaDirection; |
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312 | direction = dir.unit(); |
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313 | fParticleChange->SetProposedMomentumDirection(direction); |
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314 | } |
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315 | |
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316 | // create G4DynamicParticle object for delta ray |
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317 | G4DynamicParticle* delta = new G4DynamicParticle(theElectron,deltaDirection,deltaKinEnergy); |
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318 | vdp->push_back(delta); |
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319 | |
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320 | // get interaction frame |
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321 | G4ThreeVector nInteractionFrame = |
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322 | G4PolarizationHelper::GetFrame(direction,deltaDirection); |
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323 | |
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324 | if (crossSectionCalculator) { |
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325 | // calculate mean final state polarizations |
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326 | |
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327 | theBeamPolarization.InvRotateAz(nInteractionFrame,direction); |
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328 | theTargetPolarization.InvRotateAz(nInteractionFrame,direction); |
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329 | crossSectionCalculator->Initialize(x,gam,phi,theBeamPolarization, |
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330 | theTargetPolarization,2); |
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331 | |
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332 | // electron/positron |
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333 | fPositronPolarization=crossSectionCalculator->GetPol2(); |
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334 | fPositronPolarization.RotateAz(nInteractionFrame,direction); |
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335 | |
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336 | fParticleChange->ProposePolarization(fPositronPolarization); |
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337 | |
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338 | // electron |
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339 | fElectronPolarization=crossSectionCalculator->GetPol3(); |
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340 | fElectronPolarization.RotateAz(nInteractionFrame,deltaDirection); |
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341 | delta->SetPolarization(fElectronPolarization.x(), |
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342 | fElectronPolarization.y(), |
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343 | fElectronPolarization.z()); |
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344 | } |
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345 | else { |
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346 | fPositronPolarization=G4ThreeVector(); |
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347 | fElectronPolarization=G4ThreeVector(); |
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348 | } |
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349 | } |
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350 | |
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351 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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