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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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 | // $Id: G4FinalStateElasticScreenedRutherford.cc,v 1.7 2009/06/11 15:47:08 mantero Exp $ |
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27 | // GEANT4 tag $Name: geant4-09-03 $ |
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28 | |
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29 | #include "G4FinalStateElasticScreenedRutherford.hh" |
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30 | |
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31 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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32 | |
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33 | G4FinalStateElasticScreenedRutherford::G4FinalStateElasticScreenedRutherford() |
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34 | { |
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35 | lowEnergyLimit = 200 * eV; |
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36 | highEnergyLimit = 10 * MeV; |
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37 | |
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38 | G4cout << G4endl; |
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39 | G4cout << "*******************************************************************************" << G4endl; |
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40 | G4cout << "*******************************************************************************" << G4endl; |
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41 | G4cout << " The class G4FinalStateElasticScreenedRutherford is NOT SUPPORTED ANYMORE. " << G4endl; |
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42 | G4cout << " It will be REMOVED with the next major release of Geant4. " << G4endl; |
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43 | G4cout << " Please consult: https://twiki.cern.ch/twiki/bin/view/Geant4/LoweProcesses" << G4endl; |
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44 | G4cout << "*******************************************************************************" << G4endl; |
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45 | G4cout << "*******************************************************************************" << G4endl; |
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46 | G4cout << G4endl; |
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47 | } |
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48 | |
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49 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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50 | |
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51 | G4FinalStateElasticScreenedRutherford::~G4FinalStateElasticScreenedRutherford() |
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52 | {} |
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53 | |
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54 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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55 | |
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56 | const G4FinalStateProduct& G4FinalStateElasticScreenedRutherford::GenerateFinalState(const G4Track& track, const G4Step& ) |
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57 | { |
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58 | product.Clear(); |
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59 | |
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60 | G4double k = track.GetDynamicParticle()->GetKineticEnergy(); |
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61 | |
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62 | const G4int z = 10; |
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63 | |
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64 | G4double cosTheta = RandomizeCosTheta(k, z); |
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65 | |
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66 | G4double phi = 2. * pi * G4UniformRand(); |
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67 | |
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68 | G4ThreeVector zVers = track.GetDynamicParticle()->GetMomentumDirection(); |
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69 | G4ThreeVector xVers = zVers.orthogonal(); |
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70 | G4ThreeVector yVers = zVers.cross(xVers); |
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71 | |
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72 | G4double xDir = std::sqrt(1. - cosTheta*cosTheta); |
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73 | G4double yDir = xDir; |
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74 | xDir *= std::cos(phi); |
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75 | yDir *= std::sin(phi); |
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76 | |
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77 | G4ThreeVector zPrimeVers((xDir*xVers + yDir*yVers + cosTheta*zVers)); |
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78 | |
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79 | product.ModifyPrimaryParticle(zPrimeVers,k); |
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80 | |
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81 | return product; |
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82 | } |
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83 | |
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84 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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85 | |
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86 | G4double G4FinalStateElasticScreenedRutherford::RandomizeCosTheta(G4double k, G4int z) const |
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87 | { |
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88 | |
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89 | // d sigma_el sigma_Ruth(K) |
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90 | // ------------ (K) ~ ----------------------------- |
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91 | // d Omega (1 + 2 n(K) - cos(theta))^2 |
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92 | // |
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93 | // We extract cos(theta) distributed as (1 + 2 n(K) - cos(theta))^-2 |
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94 | // |
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95 | // Maximum is for theta=0: 1/(4 n(K)^2) (When n(K) is positive, that is always satisfied within the validity of the process) |
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96 | // |
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97 | // Phys. Med. Biol. 45 (2000) 3171-3194 |
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98 | |
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99 | G4double n = ScreeningFactor(k, z); |
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100 | |
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101 | G4double oneOverMax = (4. * n*n); |
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102 | |
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103 | G4double cosTheta; |
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104 | G4double fCosTheta; |
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105 | |
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106 | do |
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107 | { |
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108 | cosTheta = 2. * G4UniformRand() - 1.; |
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109 | fCosTheta = (1 + 2.*n - cosTheta); |
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110 | fCosTheta = oneOverMax / (fCosTheta*fCosTheta); |
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111 | } |
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112 | while (fCosTheta < G4UniformRand()); |
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113 | |
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114 | return cosTheta; |
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115 | } |
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116 | |
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117 | //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo...... |
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118 | |
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119 | G4double G4FinalStateElasticScreenedRutherford::ScreeningFactor(G4double k, G4int z) const |
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120 | { |
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121 | // |
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122 | // alpha_1 + beta_1 ln(K/eV) constK Z^(2/3) |
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123 | // n(T) = -------------------------- ----------------- |
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124 | // K/(m_e c^2) 2 + K/(m_e c^2) |
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125 | // |
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126 | // Where K is the electron non-relativistic kinetic energy |
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127 | // |
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128 | // n(T) > 0 for T < ~ 400 MeV |
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129 | // |
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130 | // Nucl. Instr. Meth. 155 (1978) 145-156 |
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131 | |
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132 | const G4double alpha_1 = 1.64; |
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133 | const G4double beta_1 = -0.0825; |
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134 | const G4double constK = 1.7E-5; |
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135 | |
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136 | G4double numerator = (alpha_1 + beta_1 * std::log(k/eV)) * constK * std::pow(static_cast<double>(z), 2./3.); |
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137 | |
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138 | k /= electron_mass_c2; |
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139 | |
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140 | G4double denominator; |
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141 | denominator = k * (2 + k); |
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142 | |
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143 | G4double result = 0.; |
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144 | if (denominator != 0.) |
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145 | { |
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146 | result = numerator / denominator; |
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147 | } |
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148 | else |
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149 | { |
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150 | G4Exception("G4FinalStateElasticScreenedRutherford::ScreeningFactor - denominator = 0"); |
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151 | } |
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152 | return result; |
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153 | } |
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