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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7 | // * conditions of the Geant4 Software License, included in the file * |
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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 | // |
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27 | // $Id: G4NeutronBetaDecayChannel.cc,v 1.7 2006/06/29 19:25:38 gunter Exp $ |
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28 | // GEANT4 tag $Name: geant4-09-03-cand-01 $ |
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29 | // |
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30 | // |
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31 | // ------------------------------------------------------------ |
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32 | // GEANT 4 class header file |
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33 | // |
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34 | // History: first implementation, based on object model of |
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35 | // 18 Sep 2001 H.Kurashige |
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36 | // |
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37 | // ------------------------------------------------------------ |
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38 | |
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39 | #include "G4ParticleDefinition.hh" |
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40 | #include "G4DecayProducts.hh" |
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41 | #include "G4VDecayChannel.hh" |
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42 | #include "G4NeutronBetaDecayChannel.hh" |
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43 | #include "Randomize.hh" |
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44 | #include "G4RotationMatrix.hh" |
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45 | #include "G4LorentzVector.hh" |
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46 | #include "G4LorentzRotation.hh" |
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47 | |
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48 | |
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49 | G4NeutronBetaDecayChannel::G4NeutronBetaDecayChannel( |
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50 | const G4String& theParentName, |
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51 | G4double theBR) |
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52 | :G4VDecayChannel("Neutron Decay"), |
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53 | aENuCorr(-0.102) |
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54 | { |
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55 | // set names for daughter particles |
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56 | if (theParentName == "neutron") { |
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57 | SetBR(theBR); |
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58 | SetParent("neutron"); |
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59 | SetNumberOfDaughters(3); |
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60 | SetDaughter(0, "e-"); |
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61 | SetDaughter(1, "anti_nu_e"); |
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62 | SetDaughter(2, "proton"); |
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63 | } else { |
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64 | #ifdef G4VERBOSE |
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65 | if (GetVerboseLevel()>0) { |
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66 | G4cout << "G4NeutronBetaDecayChannel:: constructor :"; |
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67 | G4cout << " parent particle is not muon but "; |
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68 | G4cout << theParentName << G4endl; |
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69 | } |
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70 | #endif |
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71 | } |
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72 | } |
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73 | |
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74 | G4NeutronBetaDecayChannel::~G4NeutronBetaDecayChannel() |
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75 | { |
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76 | } |
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77 | |
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78 | G4DecayProducts *G4NeutronBetaDecayChannel::DecayIt(G4double) |
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79 | { |
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80 | // This class describes free neutron beta decay kinemtics. |
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81 | // This version neglects neutron/electron polarization |
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82 | // without Coulomb effect |
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83 | |
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84 | #ifdef G4VERBOSE |
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85 | if (GetVerboseLevel()>1) G4cout << "G4NeutronBetaDecayChannel::DecayIt "; |
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86 | #endif |
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87 | |
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88 | if (parent == 0) FillParent(); |
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89 | if (daughters == 0) FillDaughters(); |
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90 | |
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91 | // parent mass |
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92 | G4double parentmass = parent->GetPDGMass(); |
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93 | |
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94 | //daughters'mass |
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95 | G4double daughtermass[3]; |
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96 | G4double sumofdaughtermass = 0.0; |
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97 | for (G4int index=0; index<3; index++){ |
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98 | daughtermass[index] = daughters[index]->GetPDGMass(); |
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99 | sumofdaughtermass += daughtermass[index]; |
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100 | } |
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101 | G4double xmax = parentmass-sumofdaughtermass; |
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102 | |
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103 | //create parent G4DynamicParticle at rest |
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104 | G4ThreeVector dummy; |
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105 | G4DynamicParticle * parentparticle = new G4DynamicParticle( parent, dummy, 0.0); |
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106 | |
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107 | //create G4Decayproducts |
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108 | G4DecayProducts *products = new G4DecayProducts(*parentparticle); |
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109 | delete parentparticle; |
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110 | |
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111 | // calculate daughter momentum |
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112 | G4double daughtermomentum[3]; |
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113 | |
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114 | // calcurate electron energy |
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115 | G4double x; // Ee |
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116 | G4double p; // Pe |
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117 | G4double m = daughtermass[0]; //Me |
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118 | G4double w; // cosine of e-nu angle |
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119 | G4double r; |
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120 | G4double r0; |
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121 | do { |
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122 | x = xmax*G4UniformRand(); |
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123 | p = std::sqrt(x*(x+2.0*m)); |
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124 | w = 1.0-2.0*G4UniformRand(); |
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125 | r = p*(x+m)*(xmax-x)*(xmax-x)*(1.0+aENuCorr*p/(x+m)*w); |
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126 | r0 = G4UniformRand()*(xmax+m)*(xmax+m)*xmax*xmax*(1.0+aENuCorr); |
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127 | } while (r < r0); |
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128 | |
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129 | //create daughter G4DynamicParticle |
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130 | // rotation materix to lab frame |
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131 | G4double costheta = 2.*G4UniformRand()-1.0; |
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132 | G4double theta = std::acos(costheta)*rad; |
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133 | G4double phi = twopi*G4UniformRand()*rad; |
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134 | G4RotationMatrix rm; |
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135 | rm.rotateY(theta); |
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136 | rm.rotateZ(phi); |
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137 | |
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138 | // daughter 0 (electron) in Z direction |
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139 | daughtermomentum[0] = p; |
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140 | G4ThreeVector direction0(0.0, 0.0, 1.0); |
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141 | direction0 = rm * direction0; |
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142 | G4DynamicParticle * daughterparticle0 |
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143 | = new G4DynamicParticle( daughters[0], direction0*daughtermomentum[0]); |
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144 | products->PushProducts(daughterparticle0); |
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145 | |
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146 | // daughter 1 (nutrino) in XZ plane |
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147 | G4double eNu = xmax-x; |
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148 | G4double cosn = w; |
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149 | G4double sinn = std::sqrt((1.0-cosn)*(1.0+cosn)); |
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150 | |
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151 | G4ThreeVector direction1(sinn, 0.0, cosn); |
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152 | direction1 = rm * direction1; |
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153 | G4DynamicParticle * daughterparticle1 |
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154 | = new G4DynamicParticle( daughters[1], direction1*eNu); |
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155 | products->PushProducts(daughterparticle1); |
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156 | |
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157 | // daughter 2 (proton) at REST |
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158 | G4ThreeVector direction2(0.0, 0.0, 0.0); |
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159 | G4DynamicParticle * daughterparticle2 |
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160 | = new G4DynamicParticle( daughters[2], direction2); |
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161 | products->PushProducts(daughterparticle2); |
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162 | |
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163 | |
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164 | // output message |
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165 | #ifdef G4VERBOSE |
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166 | if (GetVerboseLevel()>1) { |
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167 | G4cout << "G4NeutronBetaDecayChannel::DecayIt "; |
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168 | G4cout << " create decay products in rest frame " <<G4endl; |
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169 | products->DumpInfo(); |
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170 | } |
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171 | #endif |
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172 | return products; |
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173 | } |
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174 | |
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175 | |
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176 | |
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177 | |
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178 | |
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179 | |
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