1 | // |
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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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9 | // * include a list of copyright holders. * |
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11 | // * Neither the authors of this software system, nor their employing * |
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13 | // * work make any representation or warranty, express or implied, * |
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14 | // * regarding this software system or assume any liability for its * |
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15 | // * use. Please see the license in the file LICENSE and URL above * |
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18 | // * This code implementation is the result of the scientific and * |
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19 | // * technical work of the GEANT4 collaboration. * |
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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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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: G4hPairProductionModel.cc,v 1.1 2008/03/06 11:47:11 vnivanch Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-02-ref-02 $ |
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28 | // |
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29 | // ------------------------------------------------------------------- |
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30 | // |
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31 | // GEANT4 Class file |
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32 | // |
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33 | // |
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34 | // File name: G4hPairProductionModel |
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35 | // |
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36 | // Author: Vladimir Ivanchenko on base of G4MuPairProductionModel |
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37 | // |
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38 | // Creation date: 28.02.2008 |
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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 | // Class Description: |
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45 | // |
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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 "G4hPairProductionModel.hh" |
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53 | |
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54 | using namespace std; |
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55 | |
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56 | G4hPairProductionModel::G4hPairProductionModel(const G4ParticleDefinition* p, |
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57 | const G4String& nam) |
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58 | : G4MuPairProductionModel(p, nam) |
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59 | {} |
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60 | |
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61 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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62 | |
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63 | G4hPairProductionModel::~G4hPairProductionModel() |
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64 | {} |
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65 | |
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66 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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67 | |
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68 | G4double G4hPairProductionModel::ComputeDMicroscopicCrossSection( |
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69 | G4double tkin, |
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70 | G4double Z, |
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71 | G4double pairEnergy) |
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72 | // differential cross section |
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73 | { |
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74 | G4double bbbtf= 183. ; |
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75 | G4double bbbh = 202.4 ; |
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76 | G4double g1tf = 1.95e-5 ; |
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77 | G4double g2tf = 5.3e-5 ; |
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78 | G4double g1h = 4.4e-5 ; |
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79 | G4double g2h = 4.8e-5 ; |
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80 | |
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81 | G4double totalEnergy = tkin + particleMass; |
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82 | G4double residEnergy = totalEnergy - pairEnergy; |
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83 | G4double massratio = particleMass/electron_mass_c2 ; |
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84 | G4double massratio2 = massratio*massratio ; |
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85 | G4double cross = 0.; |
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86 | |
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87 | SetCurrentElement(Z); |
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88 | |
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89 | G4double c3 = 0.75*sqrte*particleMass; |
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90 | if (residEnergy <= c3*z13) return cross; |
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91 | |
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92 | G4double c7 = 4.*electron_mass_c2; |
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93 | G4double c8 = 6.*particleMass*particleMass; |
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94 | G4double alf = c7/pairEnergy; |
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95 | G4double a3 = 1. - alf; |
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96 | if (a3 <= 0.) return cross; |
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97 | |
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98 | // zeta calculation |
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99 | G4double bbb,g1,g2; |
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100 | if( Z < 1.5 ) { bbb = bbbh ; g1 = g1h ; g2 = g2h ; } |
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101 | else { bbb = bbbtf; g1 = g1tf; g2 = g2tf; } |
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102 | |
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103 | G4double zeta = 0; |
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104 | G4double zeta1 = 0.073*log(totalEnergy/(particleMass+g1*z23*totalEnergy))-0.26; |
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105 | if ( zeta1 > 0.) |
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106 | { |
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107 | G4double zeta2 = 0.058*log(totalEnergy/(particleMass+g2*z13*totalEnergy))-0.14; |
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108 | zeta = zeta1/zeta2 ; |
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109 | } |
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110 | |
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111 | G4double z2 = Z*(Z+zeta); |
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112 | G4double screen0 = 2.*electron_mass_c2*sqrte*bbb/(z13*pairEnergy); |
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113 | G4double a0 = totalEnergy*residEnergy; |
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114 | G4double a1 = pairEnergy*pairEnergy/a0; |
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115 | G4double bet = 0.5*a1; |
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116 | G4double xi0 = 0.25*massratio2*a1; |
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117 | G4double del = c8/a0; |
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118 | |
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119 | G4double rta3 = sqrt(a3); |
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120 | G4double tmnexp = alf/(1. + rta3) + del*rta3; |
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121 | if(tmnexp >= 1.0) return cross; |
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122 | |
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123 | G4double tmn = log(tmnexp); |
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124 | G4double sum = 0.; |
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125 | |
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126 | // Gaussian integration in ln(1-ro) ( with 8 points) |
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127 | for (G4int i=0; i<8; i++) |
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128 | { |
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129 | G4double a4 = exp(tmn*xgi[i]); // a4 = (1.-asymmetry) |
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130 | G4double a5 = a4*(2.-a4) ; |
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131 | G4double a6 = 1.-a5 ; |
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132 | G4double a7 = 1.+a6 ; |
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133 | G4double a9 = 3.+a6 ; |
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134 | G4double xi = xi0*a5 ; |
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135 | G4double xii = 1./xi ; |
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136 | G4double xi1 = 1.+xi ; |
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137 | G4double screen = screen0*xi1/a5 ; |
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138 | G4double yeu = 5.-a6+4.*bet*a7 ; |
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139 | G4double yed = 2.*(1.+3.*bet)*log(3.+xii)-a6-a1*(2.-a6) ; |
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140 | G4double ye1 = 1.+yeu/yed ; |
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141 | G4double ale=log(bbb/z13*sqrt(xi1*ye1)/(1.+screen*ye1)) ; |
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142 | G4double cre = 0.5*log(1.+2.25*z23*xi1*ye1/massratio2) ; |
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143 | G4double be; |
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144 | |
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145 | if (xi <= 1.e3) be = ((2.+a6)*(1.+bet)+xi*a9)*log(1.+xii)+(a5-bet)/xi1-a9; |
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146 | else be = (3.-a6+a1*a7)/(2.*xi); |
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147 | |
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148 | G4double fe = (ale-cre)*be; |
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149 | if ( fe < 0.) fe = 0. ; |
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150 | |
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151 | G4double ymu = 4.+a6 +3.*bet*a7 ; |
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152 | G4double ymd = a7*(1.5+a1)*log(3.+xi)+1.-1.5*a6 ; |
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153 | G4double ym1 = 1.+ymu/ymd ; |
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154 | G4double alm_crm = log(bbb*massratio/(1.5*z23*(1.+screen*ym1))); |
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155 | G4double a10,bm; |
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156 | if ( xi >= 1.e-3) |
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157 | { |
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158 | a10 = (1.+a1)*a5 ; |
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159 | bm = (a7*(1.+1.5*bet)-a10*xii)*log(xi1)+xi*(a5-bet)/xi1+a10; |
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160 | } else { |
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161 | bm = (5.-a6+bet*a9)*(xi/2.); |
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162 | } |
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163 | |
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164 | G4double fm = alm_crm*bm; |
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165 | if ( fm < 0.) fm = 0. ; |
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166 | |
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167 | sum += wgi[i]*a4*(fe+fm/massratio2); |
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168 | } |
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169 | |
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170 | cross = -tmn*sum*factorForCross*z2*residEnergy/(totalEnergy*pairEnergy); |
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171 | |
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172 | return cross; |
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173 | } |
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174 | |
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175 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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