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2 | // ******************************************************************** |
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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: G4WentzelOKandVIxSection.cc,v 1.12 2010/11/04 17:30:32 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: emstand-V09-03-25 $ |
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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: G4WentzelOKandVIxSection |
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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 | // |
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42 | // |
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43 | |
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44 | // ------------------------------------------------------------------- |
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45 | // |
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46 | |
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47 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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48 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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49 | |
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50 | #include "G4WentzelOKandVIxSection.hh" |
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51 | #include "Randomize.hh" |
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52 | #include "G4Electron.hh" |
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53 | #include "G4Positron.hh" |
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54 | #include "G4Proton.hh" |
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55 | #include "G4LossTableManager.hh" |
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56 | |
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57 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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58 | |
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59 | G4double G4WentzelOKandVIxSection::ScreenRSquare[] = {0.0}; |
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60 | G4double G4WentzelOKandVIxSection::FormFactor[] = {0.0}; |
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61 | |
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62 | using namespace std; |
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63 | |
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64 | G4WentzelOKandVIxSection::G4WentzelOKandVIxSection() : |
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65 | numlimit(0.1), |
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66 | nwarnings(0), |
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67 | nwarnlimit(50), |
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68 | alpha2(fine_structure_const*fine_structure_const) |
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69 | { |
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70 | fNistManager = G4NistManager::Instance(); |
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71 | fG4pow = G4Pow::GetInstance(); |
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72 | theElectron = G4Electron::Electron(); |
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73 | thePositron = G4Positron::Positron(); |
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74 | theProton = G4Proton::Proton(); |
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75 | lowEnergyLimit = 1.0*eV; |
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76 | G4double p0 = electron_mass_c2*classic_electr_radius; |
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77 | coeff = twopi*p0*p0; |
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78 | particle = 0; |
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79 | |
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80 | // Thomas-Fermi screening radii |
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81 | // Formfactors from A.V. Butkevich et al., NIM A 488 (2002) 282 |
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82 | |
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83 | if(0.0 == ScreenRSquare[0]) { |
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84 | G4double a0 = electron_mass_c2/0.88534; |
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85 | G4double constn = 6.937e-6/(MeV*MeV); |
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86 | |
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87 | ScreenRSquare[0] = alpha2*a0*a0; |
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88 | for(G4int j=1; j<100; ++j) { |
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89 | G4double x = a0*fG4pow->Z13(j); |
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90 | ScreenRSquare[j] = alpha2*x*x; |
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91 | x = fNistManager->GetA27(j); |
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92 | FormFactor[j] = constn*x*x; |
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93 | } |
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94 | } |
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95 | currentMaterial = 0; |
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96 | elecXSRatio = factB = formfactA = screenZ = 0.0; |
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97 | cosTetMaxElec = cosTetMaxNuc = invbeta2 = kinFactor = 1.0; |
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98 | |
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99 | Initialise(theElectron, 1.0); |
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100 | SetTargetMass(proton_mass_c2); |
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101 | } |
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102 | |
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103 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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104 | |
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105 | G4WentzelOKandVIxSection::~G4WentzelOKandVIxSection() |
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106 | {} |
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107 | |
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108 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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109 | |
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110 | void G4WentzelOKandVIxSection::Initialise(const G4ParticleDefinition* p, |
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111 | G4double CosThetaLim) |
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112 | { |
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113 | SetupParticle(p); |
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114 | tkin = mom2 = 0.0; |
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115 | ecut = etag = DBL_MAX; |
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116 | targetZ = 0; |
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117 | cosThetaMax = CosThetaLim; |
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118 | G4double a = |
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119 | G4LossTableManager::Instance()->FactorForAngleLimit()*CLHEP::hbarc/CLHEP::fermi; |
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120 | factorA2 = 0.5*a*a; |
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121 | currentMaterial = 0; |
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122 | } |
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123 | |
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124 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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125 | |
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126 | void G4WentzelOKandVIxSection::SetupParticle(const G4ParticleDefinition* p) |
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127 | { |
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128 | particle = p; |
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129 | mass = particle->GetPDGMass(); |
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130 | spin = particle->GetPDGSpin(); |
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131 | if(0.0 != spin) { spin = 0.5; } |
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132 | G4double q = std::fabs(particle->GetPDGCharge()/eplus); |
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133 | chargeSquare = q*q; |
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134 | charge3 = chargeSquare*q; |
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135 | tkin = 0.0; |
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136 | currentMaterial = 0; |
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137 | } |
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138 | |
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139 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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140 | |
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141 | G4double |
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142 | G4WentzelOKandVIxSection::SetupTarget(G4int Z, G4double cut) |
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143 | { |
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144 | G4double cosTetMaxNuc2 = cosTetMaxNuc; |
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145 | if(Z != targetZ || tkin != etag) { |
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146 | etag = tkin; |
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147 | targetZ = Z; |
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148 | if(targetZ > 99) { targetZ = 99; } |
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149 | SetTargetMass(fNistManager->GetAtomicMassAmu(targetZ)*amu_c2); |
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150 | kinFactor = coeff*targetZ*chargeSquare*invbeta2/mom2; |
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151 | |
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152 | screenZ = ScreenRSquare[targetZ]/mom2; |
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153 | if(Z > 1) { |
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154 | G4double tau = tkin/mass; |
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155 | screenZ *=std::min(Z*invbeta2, |
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156 | (1.13 +3.76*Z*Z*invbeta2*alpha2*std::sqrt(tau/(tau + fG4pow->Z23(Z))))); |
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157 | } |
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158 | if(targetZ == 1 && cosTetMaxNuc < 0.0 && particle == theProton) { |
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159 | cosTetMaxNuc = 0.0; |
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160 | } |
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161 | formfactA = FormFactor[targetZ]*mom2; |
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162 | |
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163 | // allowing do not compute scattering off e- |
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164 | cosTetMaxElec = 1.0; |
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165 | if(cut < DBL_MAX) { |
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166 | if(mass < MeV) { |
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167 | if(cosTetMaxNuc < 1.0 && cosTetMaxNuc > 0.0 && tkin < 10*cut) { |
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168 | cosTetMaxNuc2 *= 0.1*tkin/cut; |
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169 | } |
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170 | } |
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171 | ComputeMaxElectronScattering(cut); |
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172 | } |
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173 | } |
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174 | return cosTetMaxNuc2; |
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175 | } |
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176 | |
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177 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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178 | |
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179 | G4double |
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180 | G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom(G4double cosTMax) |
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181 | { |
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182 | G4double xsec = 0.0; |
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183 | if(cosTMax >= 1.0) { return xsec; } |
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184 | |
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185 | G4double xSection = 0.0; |
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186 | G4double x = 0; |
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187 | G4double y = 0; |
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188 | G4double x1= 0; |
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189 | G4double x2= 0; |
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190 | G4double xlog = 0.0; |
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191 | |
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192 | G4double costm = std::max(cosTMax,cosTetMaxElec); |
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193 | G4double fb = screenZ*factB; |
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194 | |
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195 | // scattering off electrons |
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196 | if(costm < 1.0) { |
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197 | x = (1.0 - costm)/screenZ; |
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198 | x1= x/(1 + x); |
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199 | if(x < numlimit) { |
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200 | x2 = 0.5*x*x; |
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201 | y = x2*(1.0 - 1.3333333*x + 3*x2); |
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202 | } else { |
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203 | xlog = log(1.0 + x); |
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204 | y = xlog - x1; |
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205 | } |
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206 | |
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207 | if(0.0 < factB) { |
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208 | if(x < numlimit) { y -= fb*x2*x*(0.6666667 - x); } |
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209 | else { y -= fb*(x + x1 - 2*xlog); } |
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210 | } |
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211 | |
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212 | if(y < 0.0) { |
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213 | ++nwarnings; |
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214 | if(nwarnings < nwarnlimit) { |
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215 | G4cout << "G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom scattering on e- <0" |
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216 | << G4endl; |
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217 | G4cout << "y= " << y |
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218 | << " e(MeV)= " << tkin << " p(MeV/c)= " << sqrt(mom2) |
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219 | << " Z= " << targetZ << " " |
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220 | << particle->GetParticleName() << G4endl; |
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221 | G4cout << " 1-costm= " << 1.0-costm << " screenZ= " << screenZ |
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222 | << " x= " << x << G4endl; |
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223 | } |
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224 | y = 0.0; |
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225 | } |
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226 | xSection = y; |
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227 | } |
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228 | /* |
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229 | G4cout << "G4WentzelVI:XS per A " << " Z= " << targetZ |
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230 | << " e(MeV)= " << tkin/MeV << " XSel= " << xSection |
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231 | << " cut(MeV)= " << ecut/MeV |
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232 | << " zmaxE= " << (1.0 - cosTetMaxElec)/screenZ |
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233 | << " zmaxN= " << (1.0 - cosThetaMax)/screenZ |
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234 | << " 1-costm= " << 1.0 - cosThetaMax << G4endl; |
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235 | */ |
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236 | // scattering off nucleus |
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237 | if(cosTMax < 1.0) { |
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238 | x = (1.0 - cosTMax)/screenZ; |
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239 | x1= x/(1 + x); |
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240 | if(x < numlimit) { |
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241 | x2 = 0.5*x*x; |
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242 | y = x2*(1.0 - 1.3333333*x + 3*x2); |
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243 | } else { |
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244 | xlog = log(1.0 + x); |
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245 | y = xlog - x1; |
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246 | } |
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247 | |
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248 | if(0.0 < factB) { |
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249 | if(x < numlimit) { y -= fb*x2*x*(0.6666667 - x); } |
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250 | else { y -= fb*(x + x1 - 2*xlog); } |
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251 | } |
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252 | if(y < 0.0) { |
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253 | ++nwarnings; |
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254 | if(nwarnings < nwarnlimit) { |
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255 | G4cout << "G4WentzelOKandVIxSection::ComputeTransportCrossSectionPerAtom scattering on e- <0" |
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256 | << G4endl; |
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257 | G4cout << "y= " << y |
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258 | << " e(MeV)= " << tkin << " Z= " << targetZ << " " |
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259 | << particle->GetParticleName() << G4endl; |
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260 | G4cout << " formfactA= " << formfactA << " screenZ= " << screenZ |
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261 | << " x= " << " x1= " << x1 <<G4endl; |
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262 | } |
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263 | y = 0.0; |
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264 | } |
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265 | xSection += y*targetZ; |
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266 | } |
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267 | xSection *= kinFactor; |
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268 | /* |
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269 | G4cout << "Z= " << targetZ << " XStot= " << xSection/barn |
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270 | << " screenZ= " << screenZ << " formF= " << formfactA |
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271 | << " for " << particle->GetParticleName() |
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272 | << " m= " << mass << " 1/v= " << sqrt(invbeta2) << " p= " << sqrt(mom2) |
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273 | << " x= " << x |
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274 | << G4endl; |
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275 | */ |
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276 | return xSection; |
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277 | } |
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278 | |
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279 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo.... |
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280 | |
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281 | G4ThreeVector |
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282 | G4WentzelOKandVIxSection::SampleSingleScattering(G4double cosTMin, |
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283 | G4double cosTMax, |
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284 | G4double elecRatio) |
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285 | { |
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286 | G4ThreeVector v(0.0,0.0,1.0); |
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287 | |
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288 | G4double formf = formfactA; |
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289 | G4double cost1 = cosTMin; |
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290 | G4double cost2 = cosTMax; |
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291 | if(elecRatio > 0.0) { |
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292 | if(G4UniformRand() <= elecRatio) { |
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293 | formf = 0.0; |
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294 | cost1 = std::max(cost1,cosTetMaxElec); |
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295 | cost2 = std::max(cost2,cosTetMaxElec); |
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296 | } |
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297 | } |
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298 | if(cost1 < cost2) { return v; } |
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299 | |
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300 | G4double w1 = 1. - cost1 + screenZ; |
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301 | G4double w2 = 1. - cost2 + screenZ; |
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302 | G4double z1 = w1*w2/(w1 + G4UniformRand()*(w2 - w1)) - screenZ; |
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303 | if(factB > 0.0 || formf > 0.0 || factD > 0.01) { |
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304 | G4double grej = (1. - z1*factB)/ |
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305 | ( (1.0 + z1*factD)*(1.0 + formf*z1)*(1.0 + formf*z1) ); |
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306 | if( G4UniformRand() > grej ) { return v; } |
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307 | } |
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308 | G4double cost = 1.0 - z1; |
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309 | if(cost > 1.0) { cost = 1.0; } |
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310 | else if(cost < -1.0) { cost =-1.0; } |
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311 | G4double sint = sqrt((1.0 - cost)*(1.0 + cost)); |
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312 | //G4cout << "sint= " << sint << G4endl; |
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313 | G4double phi = twopi*G4UniformRand(); |
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314 | G4double vx1 = sint*cos(phi); |
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315 | G4double vy1 = sint*sin(phi); |
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316 | |
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317 | // only direction is changed |
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318 | v.set(vx1,vy1,cost); |
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319 | return v; |
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320 | } |
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321 | |
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322 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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323 | |
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324 | void |
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325 | G4WentzelOKandVIxSection::ComputeMaxElectronScattering(G4double cutEnergy) |
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326 | { |
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327 | G4double tmax = tkin; |
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328 | if(mass > MeV) { |
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329 | G4double ratio = electron_mass_c2/mass; |
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330 | G4double tau = tkin/mass; |
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331 | tmax = 2.0*electron_mass_c2*tau*(tau + 2.)/ |
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332 | (1.0 + 2.0*ratio*(tau + 1.0) + ratio*ratio); |
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333 | cosTetMaxElec = 1.0 - std::min(cutEnergy, tmax)*electron_mass_c2/mom2; |
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334 | } else { |
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335 | |
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336 | if(particle == theElectron) { tmax *= 0.5; } |
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337 | G4double t = std::min(cutEnergy, tmax); |
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338 | G4double mom21 = t*(t + 2.0*electron_mass_c2); |
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339 | G4double t1 = tkin - t; |
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340 | //G4cout <<"tkin=" <<tkin<<" tmax= "<<tmax<<" t= " |
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341 | //<<t<< " t1= "<<t1<<" cut= "<<ecut<<G4endl; |
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342 | if(t1 > 0.0) { |
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343 | G4double mom22 = t1*(t1 + 2.0*mass); |
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344 | G4double ctm = (mom2 + mom22 - mom21)*0.5/sqrt(mom2*mom22); |
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345 | if(ctm < 1.0) { cosTetMaxElec = ctm; } |
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346 | //if(ctm < -1.0) { cosTetMaxElec = -1.0;} |
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347 | if(particle == theElectron && cosTetMaxElec < 0.0) { cosTetMaxElec = 0.0; } |
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348 | } |
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349 | } |
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350 | } |
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351 | |
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352 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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