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 | // |
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28 | // Physics model class G4LElastic |
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29 | // |
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30 | // |
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31 | // G4 Model: Low-energy Elastic scattering |
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32 | // F.W. Jones, TRIUMF, 04-JUN-96 |
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33 | // |
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34 | // use -scheme for elastic scattering: HPW, 20th June 1997 |
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35 | // most of the code comes from the old Low-energy Elastic class |
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36 | // |
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37 | // 25-JUN-98 FWJ: replaced missing Initialize for ParticleChange. |
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38 | // 14-DEC-05 V.Ivanchenko: restore 1.19 version (7.0) |
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39 | // 23-JAN-07 V.Ivanchenko: add protection inside sqrt |
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40 | // |
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41 | |
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42 | #include "globals.hh" |
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43 | #include "G4LElastic.hh" |
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44 | #include "Randomize.hh" |
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45 | #include "G4ParticleTable.hh" |
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46 | #include "G4IonTable.hh" |
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47 | |
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48 | |
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49 | G4HadFinalState* |
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50 | G4LElastic::ApplyYourself(const G4HadProjectile& aTrack, G4Nucleus& targetNucleus) |
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51 | { |
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52 | if(getenv("debug_LElastic")) verboseLevel = 5; |
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53 | theParticleChange.Clear(); |
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54 | const G4HadProjectile* aParticle = &aTrack; |
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55 | G4double atno2 = targetNucleus.GetN(); |
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56 | G4double zTarget = targetNucleus.GetZ(); |
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57 | theParticleChange.SetEnergyChange(aTrack.GetKineticEnergy()); |
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58 | theParticleChange.SetMomentumChange(aTrack.Get4Momentum().vect().unit()); |
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59 | |
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60 | // Elastic scattering off Hydrogen |
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61 | |
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62 | G4DynamicParticle* aSecondary = 0; |
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63 | if (atno2 < 1.5) { |
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64 | const G4ParticleDefinition* aParticleType = aParticle->GetDefinition(); |
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65 | if (aParticleType == G4PionPlus::PionPlus()) |
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66 | aSecondary = LightMedia.PionPlusExchange(aParticle, targetNucleus); |
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67 | else if (aParticleType == G4PionMinus::PionMinus()) |
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68 | aSecondary = LightMedia.PionMinusExchange(aParticle, targetNucleus); |
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69 | else if (aParticleType == G4KaonPlus::KaonPlus()) |
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70 | aSecondary = LightMedia.KaonPlusExchange(aParticle, targetNucleus); |
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71 | else if (aParticleType == G4KaonZeroShort::KaonZeroShort()) |
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72 | aSecondary = LightMedia.KaonZeroShortExchange(aParticle,targetNucleus); |
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73 | else if (aParticleType == G4KaonZeroLong::KaonZeroLong()) |
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74 | aSecondary = LightMedia.KaonZeroLongExchange(aParticle, targetNucleus); |
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75 | else if (aParticleType == G4KaonMinus::KaonMinus()) |
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76 | aSecondary = LightMedia.KaonMinusExchange(aParticle, targetNucleus); |
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77 | else if (aParticleType == G4Proton::Proton()) |
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78 | aSecondary = LightMedia.ProtonExchange(aParticle, targetNucleus); |
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79 | else if (aParticleType == G4AntiProton::AntiProton()) |
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80 | aSecondary = LightMedia.AntiProtonExchange(aParticle, targetNucleus); |
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81 | else if (aParticleType == G4Neutron::Neutron()) |
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82 | aSecondary = LightMedia.NeutronExchange(aParticle, targetNucleus); |
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83 | else if (aParticleType == G4AntiNeutron::AntiNeutron()) |
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84 | aSecondary = LightMedia.AntiNeutronExchange(aParticle, targetNucleus); |
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85 | else if (aParticleType == G4Lambda::Lambda()) |
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86 | aSecondary = LightMedia.LambdaExchange(aParticle, targetNucleus); |
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87 | else if (aParticleType == G4AntiLambda::AntiLambda()) |
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88 | aSecondary = LightMedia.AntiLambdaExchange(aParticle, targetNucleus); |
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89 | else if (aParticleType == G4SigmaPlus::SigmaPlus()) |
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90 | aSecondary = LightMedia.SigmaPlusExchange(aParticle, targetNucleus); |
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91 | else if (aParticleType == G4SigmaMinus::SigmaMinus()) |
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92 | aSecondary = LightMedia.SigmaMinusExchange(aParticle, targetNucleus); |
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93 | else if (aParticleType == G4AntiSigmaPlus::AntiSigmaPlus()) |
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94 | aSecondary = LightMedia.AntiSigmaPlusExchange(aParticle,targetNucleus); |
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95 | else if (aParticleType == G4AntiSigmaMinus::AntiSigmaMinus()) |
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96 | aSecondary= LightMedia.AntiSigmaMinusExchange(aParticle,targetNucleus); |
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97 | else if (aParticleType == G4XiZero::XiZero()) |
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98 | aSecondary = LightMedia.XiZeroExchange(aParticle, targetNucleus); |
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99 | else if (aParticleType == G4XiMinus::XiMinus()) |
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100 | aSecondary = LightMedia.XiMinusExchange(aParticle, targetNucleus); |
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101 | else if (aParticleType == G4AntiXiZero::AntiXiZero()) |
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102 | aSecondary = LightMedia.AntiXiZeroExchange(aParticle, targetNucleus); |
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103 | else if (aParticleType == G4AntiXiMinus::AntiXiMinus()) |
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104 | aSecondary = LightMedia.AntiXiMinusExchange(aParticle, targetNucleus); |
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105 | else if (aParticleType == G4OmegaMinus::OmegaMinus()) |
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106 | aSecondary = LightMedia.OmegaMinusExchange(aParticle, targetNucleus); |
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107 | else if (aParticleType == G4AntiOmegaMinus::AntiOmegaMinus()) |
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108 | aSecondary= LightMedia.AntiOmegaMinusExchange(aParticle,targetNucleus); |
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109 | else if (aParticleType == G4KaonPlus::KaonPlus()) |
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110 | aSecondary = LightMedia.KaonPlusExchange(aParticle, targetNucleus); |
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111 | } |
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112 | |
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113 | // Has a charge or strangeness exchange occurred? |
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114 | if (aSecondary) { |
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115 | aSecondary->SetMomentum(aParticle->Get4Momentum().vect()); |
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116 | theParticleChange.SetStatusChange(stopAndKill); |
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117 | theParticleChange.AddSecondary(aSecondary); |
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118 | } |
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119 | // G4cout << "Entering elastic scattering 1"<<G4endl; |
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120 | |
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121 | G4double p = aParticle->GetTotalMomentum()/GeV; |
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122 | if (verboseLevel > 1) |
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123 | G4cout << "G4LElastic::DoIt: Incident particle p=" << p << " GeV" << G4endl; |
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124 | |
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125 | if (p < 0.01) return &theParticleChange; |
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126 | |
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127 | // G4cout << "Entering elastic scattering 2"<<G4endl; |
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128 | // Compute the direction of elastic scattering. |
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129 | // It is planned to replace this code with a method based on |
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130 | // parameterized functions and a Monte Carlo method to invert the CDF. |
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131 | |
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132 | G4double ran = G4UniformRand(); |
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133 | G4double aa, bb, cc, dd, rr; |
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134 | if (atno2 <= 62.) { |
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135 | aa = std::pow(atno2, 1.63); |
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136 | bb = 14.5*std::pow(atno2, 0.66); |
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137 | cc = 1.4*std::pow(atno2, 0.33); |
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138 | dd = 10.; |
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139 | } |
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140 | else { |
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141 | aa = std::pow(atno2, 1.33); |
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142 | bb = 60.*std::pow(atno2, 0.33); |
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143 | cc = 0.4*std::pow(atno2, 0.40); |
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144 | dd = 10.; |
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145 | } |
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146 | aa = aa/bb; |
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147 | cc = cc/dd; |
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148 | rr = (aa + cc)*ran; |
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149 | if (verboseLevel > 1) { |
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150 | G4cout << "DoIt: aa,bb,cc,dd,rr" << G4endl; |
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151 | G4cout << aa << " " << bb << " " << cc << " " << dd << " " << rr << G4endl; |
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152 | } |
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153 | G4double t1 = -std::log(ran)/bb; |
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154 | G4double t2 = -std::log(ran)/dd; |
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155 | if (verboseLevel > 1) { |
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156 | G4cout << "t1,Fctcos " << t1 << " " << Fctcos(t1, aa, bb, cc, dd, rr) << |
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157 | G4endl; |
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158 | G4cout << "t2,Fctcos " << t2 << " " << Fctcos(t2, aa, bb, cc, dd, rr) << |
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159 | G4endl; |
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160 | } |
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161 | G4double eps = 0.001; |
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162 | G4int ind1 = 10; |
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163 | G4double t; |
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164 | G4int ier1; |
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165 | ier1 = Rtmi(&t, t1, t2, eps, ind1, |
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166 | aa, bb, cc, dd, rr); |
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167 | if (verboseLevel > 1) { |
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168 | G4cout << "From Rtmi, ier1=" << ier1 << G4endl; |
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169 | G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << |
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170 | G4endl; |
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171 | } |
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172 | if (ier1 != 0) t = 0.25*(3.*t1 + t2); |
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173 | if (verboseLevel > 1) { |
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174 | G4cout << "t, Fctcos " << t << " " << Fctcos(t, aa, bb, cc, dd, rr) << |
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175 | G4endl; |
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176 | } |
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177 | G4double phi = G4UniformRand()*twopi; |
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178 | rr = 0.5*t/(p*p); |
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179 | if (rr > 1.) rr = 0.; |
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180 | if (verboseLevel > 1) |
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181 | G4cout << "rr=" << rr << G4endl; |
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182 | G4double cost = 1. - rr; |
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183 | G4double sint = std::sqrt(std::max(rr*(2. - rr), 0.)); |
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184 | if (sint == 0.) return &theParticleChange; |
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185 | // G4cout << "Entering elastic scattering 3"<<G4endl; |
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186 | if (verboseLevel > 1) G4cout << "cos(t)=" << cost << " std::sin(t)=" << sint << G4endl; |
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187 | // Scattered particle referred to axis of incident particle |
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188 | G4double m1=aParticle->GetDefinition()->GetPDGMass(); |
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189 | G4int Z=static_cast<G4int>(zTarget+.5); |
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190 | G4int A=static_cast<G4int>(atno2); |
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191 | if(G4UniformRand()<atno2-A) A++; |
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192 | //G4cout << " ion info "<<atno2 << " "<<A<<" "<<Z<<" "<<zTarget<<G4endl; |
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193 | G4double m2=G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z)->GetPDGMass(); |
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194 | // non relativistic approximation |
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195 | G4double a=1+m2/m1; |
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196 | G4double b=-2.*p*cost; |
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197 | G4double c=p*p*(1-m2/m1); |
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198 | G4double p1 = (-b+std::sqrt(std::max(0.0,b*b-4.*a*c)))/(2.*a); |
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199 | G4double px = p1*sint*std::sin(phi); |
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200 | G4double py = p1*sint*std::cos(phi); |
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201 | G4double pz = p1*cost; |
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202 | |
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203 | // relativistic calculation |
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204 | G4double etot = std::sqrt(m1*m1+p*p)+m2; |
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205 | a = etot*etot-p*p*cost*cost; |
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206 | b = 2*p*p*(m1*cost*cost-etot); |
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207 | c = p*p*p*p*sint*sint; |
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208 | |
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209 | G4double de = (-b-std::sqrt(std::max(0.0,b*b-4.*a*c)))/(2.*a); |
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210 | G4double e1 = std::sqrt(p*p+m1*m1)-de; |
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211 | G4double p12=e1*e1-m1*m1; |
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212 | p1 = std::sqrt(std::max(1.*eV*eV,p12)); |
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213 | px = p1*sint*std::sin(phi); |
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214 | py = p1*sint*std::cos(phi); |
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215 | pz = p1*cost; |
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216 | |
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217 | if (verboseLevel > 1) |
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218 | { |
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219 | G4cout << "Relevant test "<<p<<" "<<p1<<" "<<cost<<" "<<de<<G4endl; |
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220 | G4cout << "p1/p = "<<p1/p<<" "<<m1<<" "<<m2<<" "<<a<<" "<<b<<" "<<c<<G4endl; |
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221 | G4cout << "rest = "<< b*b<<" "<<4.*a*c<<" "<<G4endl; |
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222 | G4cout << "make p1 = "<< p12<<" "<<e1*e1<<" "<<m1*m1<<" "<<G4endl; |
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223 | } |
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224 | // Incident particle |
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225 | G4double pxinc = p*aParticle->Get4Momentum().vect().unit().x(); |
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226 | G4double pyinc = p*aParticle->Get4Momentum().vect().unit().y(); |
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227 | G4double pzinc = p*aParticle->Get4Momentum().vect().unit().z(); |
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228 | if (verboseLevel > 1) { |
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229 | G4cout << "NOM SCAT " << px << " " << py << " " << pz << G4endl; |
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230 | G4cout << "INCIDENT " << pxinc << " " << pyinc << " " << pzinc << G4endl; |
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231 | } |
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232 | |
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233 | // Transform scattered particle to reflect direction of incident particle |
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234 | G4double pxnew, pynew, pznew; |
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235 | Defs1(p, px, py, pz, pxinc, pyinc, pzinc, &pxnew, &pynew, &pznew); |
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236 | // Normalize: |
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237 | G4double pxre=pxinc-pxnew; |
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238 | G4double pyre=pyinc-pynew; |
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239 | G4double pzre=pzinc-pznew; |
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240 | G4ThreeVector it0(pxnew*GeV, pynew*GeV, pznew*GeV); |
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241 | if(p1>0) |
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242 | { |
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243 | pxnew = pxnew/p1; |
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244 | pynew = pynew/p1; |
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245 | pznew = pznew/p1; |
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246 | } |
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247 | else |
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248 | { |
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249 | //G4double pphi = 2*pi*G4UniformRand(); |
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250 | //G4double ccth = 2*G4UniformRand()-1; |
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251 | pxnew = 0;//std::sin(std::acos(ccth))*std::sin(pphi); |
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252 | pynew = 0;//std::sin(std::acos(ccth))*std::cos(phi); |
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253 | pznew = 1;//ccth; |
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254 | } |
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255 | if (verboseLevel > 1) { |
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256 | G4cout << "DoIt: returning new momentum vector" << G4endl; |
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257 | G4cout << "DoIt: "<<pxinc << " " << pyinc << " " << pzinc <<" "<<p<< G4endl; |
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258 | G4cout << "DoIt: "<<pxnew << " " << pynew << " " << pznew <<" "<<p<< G4endl; |
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259 | } |
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260 | |
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261 | if (aSecondary) |
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262 | { |
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263 | aSecondary->SetMomentumDirection(pxnew, pynew, pznew); |
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264 | } |
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265 | else |
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266 | { |
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267 | try |
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268 | { |
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269 | theParticleChange.SetMomentumChange(pxnew, pynew, pznew); |
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270 | theParticleChange.SetEnergyChange(std::sqrt(m1*m1+it0.mag2())-m1); |
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271 | } |
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272 | catch(G4HadronicException) |
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273 | { |
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274 | std::cerr << "GHADException originating from components of G4LElastic"<<std::cout; |
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275 | throw; |
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276 | } |
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277 | G4ParticleDefinition * theDef = G4ParticleTable::GetParticleTable()->FindIon(Z,A,0,Z); |
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278 | G4ThreeVector it(pxre*GeV, pyre*GeV, pzre*GeV); |
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279 | G4DynamicParticle * aSec = |
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280 | new G4DynamicParticle(theDef, it.unit(), it.mag2()/(2.*m2)); |
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281 | theParticleChange.AddSecondary(aSec); |
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282 | // G4cout << "Final check ###### "<<p<<" "<<it.mag()<<" "<<p1<<G4endl; |
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283 | } |
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284 | return &theParticleChange; |
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285 | } |
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286 | |
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287 | |
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288 | // The following is a "translation" of a root-finding routine |
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289 | // from GEANT3.21/GHEISHA. Some of the labelled block structure has |
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290 | // been retained for clarity. This routine will not be needed after |
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291 | // the planned revisions to DoIt(). |
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292 | |
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293 | G4int |
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294 | G4LElastic::Rtmi(G4double* x, G4double xli, G4double xri, G4double eps, |
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295 | G4int iend, |
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296 | G4double aa, G4double bb, G4double cc, G4double dd, |
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297 | G4double rr) |
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298 | { |
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299 | G4int ier = 0; |
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300 | G4double xl = xli; |
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301 | G4double xr = xri; |
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302 | *x = xl; |
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303 | G4double tol = *x; |
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304 | G4double f = Fctcos(tol, aa, bb, cc, dd, rr); |
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305 | if (f == 0.) return ier; |
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306 | G4double fl, fr; |
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307 | fl = f; |
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308 | *x = xr; |
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309 | tol = *x; |
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310 | f = Fctcos(tol, aa, bb, cc, dd, rr); |
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311 | if (f == 0.) return ier; |
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312 | fr = f; |
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313 | |
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314 | // Error return in case of wrong input data |
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315 | if (fl*fr >= 0.) { |
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316 | ier = 2; |
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317 | return ier; |
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318 | } |
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319 | |
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320 | // Basic assumption fl*fr less than 0 is satisfied. |
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321 | // Generate tolerance for function values. |
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322 | G4int i = 0; |
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323 | G4double tolf = 100.*eps; |
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324 | |
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325 | // Start iteration loop |
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326 | label4: |
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327 | i++; |
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328 | |
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329 | // Start bisection loop |
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330 | for (G4int k = 1; k <= iend; k++) { |
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331 | *x = 0.5*(xl + xr); |
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332 | tol = *x; |
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333 | f = Fctcos(tol, aa, bb, cc, dd, rr); |
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334 | if (f == 0.) return 0; |
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335 | if (f*fr < 0.) { // Interchange xl and xr in order to get the |
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336 | tol = xl; // same Sign in f and fr |
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337 | xl = xr; |
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338 | xr = tol; |
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339 | tol = fl; |
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340 | fl = fr; |
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341 | fr = tol; |
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342 | } |
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343 | tol = f - fl; |
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344 | G4double a = f*tol; |
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345 | a = a + a; |
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346 | if (a < fr*(fr - fl) && i <= iend) goto label17; |
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347 | xr = *x; |
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348 | fr = f; |
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349 | |
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350 | // Test on satisfactory accuracy in bisection loop |
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351 | tol = eps; |
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352 | a = std::abs(xr); |
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353 | if (a > 1.) tol = tol*a; |
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354 | if (std::abs(xr - xl) <= tol && std::abs(fr - fl) <= tolf) goto label14; |
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355 | } |
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356 | // End of bisection loop |
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357 | |
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358 | // No convergence after iend iteration steps followed by iend |
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359 | // successive steps of bisection or steadily increasing function |
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360 | // values at right bounds. Error return. |
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361 | ier = 1; |
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362 | |
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363 | label14: |
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364 | if (std::abs(fr) > std::abs(fl)) { |
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365 | *x = xl; |
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366 | f = fl; |
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367 | } |
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368 | return ier; |
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369 | |
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370 | // Computation of iterated x-value by inverse parabolic interp |
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371 | label17: |
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372 | G4double a = fr - f; |
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373 | G4double dx = (*x - xl)*fl*(1. + f*(a - tol)/(a*(fr - fl)))/tol; |
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374 | G4double xm = *x; |
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375 | G4double fm = f; |
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376 | *x = xl - dx; |
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377 | tol = *x; |
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378 | f = Fctcos(tol, aa, bb, cc, dd, rr); |
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379 | if (f == 0.) return ier; |
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380 | |
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381 | // Test on satisfactory accuracy in iteration loop |
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382 | tol = eps; |
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383 | a = std::abs(*x); |
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384 | if (a > 1) tol = tol*a; |
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385 | if (std::abs(dx) <= tol && std::abs(f) <= tolf) return ier; |
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386 | |
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387 | // Preparation of next bisection loop |
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388 | if (f*fl < 0.) { |
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389 | xr = *x; |
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390 | fr = f; |
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391 | } |
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392 | else { |
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393 | xl = *x; |
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394 | fl = f; |
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395 | xr = xm; |
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396 | fr = fm; |
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397 | } |
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398 | goto label4; |
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399 | } |
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400 | |
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401 | |
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402 | // Test function for root-finder |
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403 | |
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404 | G4double |
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405 | G4LElastic::Fctcos(G4double t, |
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406 | G4double aa, G4double bb, G4double cc, G4double dd, |
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407 | G4double rr) |
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408 | { |
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409 | const G4double expxl = -82.; |
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410 | const G4double expxu = 82.; |
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411 | |
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412 | G4double test1 = -bb*t; |
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413 | if (test1 > expxu) test1 = expxu; |
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414 | if (test1 < expxl) test1 = expxl; |
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415 | |
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416 | G4double test2 = -dd*t; |
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417 | if (test2 > expxu) test2 = expxu; |
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418 | if (test2 < expxl) test2 = expxl; |
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419 | |
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420 | return aa*std::exp(test1) + cc*std::exp(test2) - rr; |
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421 | } |
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422 | |
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423 | |
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424 | void |
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425 | G4LElastic::Defs1(G4double p, G4double px, G4double py, G4double pz, |
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426 | G4double pxinc, G4double pyinc, G4double pzinc, |
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427 | G4double* pxnew, G4double* pynew, G4double* pznew) |
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428 | { |
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429 | // Transform scattered particle to reflect direction of incident particle |
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430 | G4double pt2 = pxinc*pxinc + pyinc*pyinc; |
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431 | if (pt2 > 0.) { |
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432 | G4double cost = pzinc/p; |
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433 | G4double sint1 = std::sqrt(std::abs((1. - cost )*(1.+cost))); |
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434 | G4double sint2 = std::sqrt(pt2)/p; |
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435 | G4double sint = 0.5*(sint1 + sint2); |
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436 | G4double ph = pi*0.5; |
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437 | if (pyinc < 0.) ph = pi*1.5; |
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438 | if (std::abs(pxinc) > 1.e-6) ph = std::atan2(pyinc, pxinc); |
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439 | G4double cosp = std::cos(ph); |
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440 | G4double sinp = std::sin(ph); |
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441 | if (verboseLevel > 1) { |
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442 | G4cout << "cost sint " << cost << " " << sint << G4endl; |
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443 | G4cout << "cosp sinp " << cosp << " " << sinp << G4endl; |
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444 | } |
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445 | *pxnew = cost*cosp*px - sinp*py + sint*cosp*pz; |
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446 | *pynew = cost*sinp*px + cosp*py + sint*sinp*pz; |
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447 | *pznew = -sint*px +cost*pz; |
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448 | } |
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449 | else { |
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450 | G4double cost=pzinc/p; |
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451 | *pxnew = cost*px; |
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452 | *pynew = py; |
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453 | *pznew = cost*pz; |
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454 | } |
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455 | } |
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