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2 | // ******************************************************************** |
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3 | // * License and Disclaimer * |
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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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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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24 | // ******************************************************************** |
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25 | // |
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26 | // |
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27 | // ------------------------------------------------------------------- |
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28 | // |
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29 | // GEANT4 Class file |
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30 | // |
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31 | // |
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32 | // File name: G4Generator2BS |
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33 | // |
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34 | // Author: Andreia Trindade (andreia@lip.pt) |
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35 | // Pedro Rodrigues (psilva@lip.pt) |
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36 | // Luis Peralta (luis@lip.pt) |
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37 | // |
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38 | // Creation date: 2 June 2003 |
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39 | // |
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40 | // Modifications: |
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41 | // 02 Jun 2003 First implementation acording with new design |
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42 | // 05 Nov 2003 MGP Fixed std namespace |
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43 | // 17 Nov 2003 MGP Fixed compilation problem on Windows |
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44 | // |
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45 | // Class Description: |
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46 | // |
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47 | // Concrete base class for Bremsstrahlung Angular Distribution Generation - 2BS Distribution |
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48 | // |
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49 | // Class Description: End |
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50 | // |
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51 | // ------------------------------------------------------------------- |
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52 | // |
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53 | // |
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54 | |
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55 | #include "G4Generator2BS.hh" |
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56 | #include "Randomize.hh" |
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57 | // |
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58 | |
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59 | G4Generator2BS::G4Generator2BS(const G4String& name):G4VBremAngularDistribution(name) |
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60 | {;} |
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61 | |
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62 | // |
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63 | |
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64 | G4Generator2BS::~G4Generator2BS() |
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65 | {;} |
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66 | |
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67 | // |
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68 | |
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69 | G4double G4Generator2BS::PolarAngle(const G4double initial_energy, |
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70 | const G4double final_energy, |
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71 | const G4int Z) |
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72 | { |
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73 | |
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74 | // Adapted from "Improved bremsstrahlung photon angular sampling in the EGS4 code system" |
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75 | // by Alex F. Bielajew, Rahde Mohan anc Chen-Shou Chui, PIRS-0203 |
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76 | // Ionizing Radiation Standards |
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77 | // Institute for National Measurement Standards |
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78 | // National Research Council of Canada |
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79 | // Departement of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York |
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80 | |
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81 | |
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82 | G4double theta = 0; |
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83 | |
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84 | G4double initialTotalEnergy = (initial_energy+electron_mass_c2)/electron_mass_c2; |
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85 | G4double finalTotalEnergy = (final_energy+electron_mass_c2)/electron_mass_c2; |
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86 | EnergyRatio = finalTotalEnergy/initialTotalEnergy; |
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87 | G4double gMaxEnergy = (pi*initialTotalEnergy)*(pi*initialTotalEnergy); |
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88 | |
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89 | G4double Zeff = std::sqrt(static_cast<G4double>(Z) * (static_cast<G4double>(Z) + 1.0)); |
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90 | z = (0.00008116224*(std::pow(Zeff,0.3333333))); |
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91 | |
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92 | // Rejection arguments |
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93 | rejection_argument1 = (1.0+EnergyRatio*EnergyRatio); |
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94 | rejection_argument2 = - 2.0*EnergyRatio + 3.0*rejection_argument1; |
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95 | rejection_argument3 = ((1-EnergyRatio)/(2.0*initialTotalEnergy*EnergyRatio))* |
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96 | ((1-EnergyRatio)/(2.0*initialTotalEnergy*EnergyRatio)); |
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97 | |
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98 | // Calculate rejection function at 0, 1 and Emax |
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99 | G4double gfunction0 = RejectionFunction(0); |
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100 | G4double gfunction1 = RejectionFunction(1); |
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101 | G4double gfunctionEmax = RejectionFunction(gMaxEnergy); |
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102 | |
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103 | |
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104 | // Calculate Maximum value |
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105 | G4double gMaximum = std::max(gfunction0,gfunction1); |
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106 | gMaximum = std::max(gMaximum,gfunctionEmax); |
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107 | |
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108 | G4double rand, gfunctionTest, randTest; |
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109 | |
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110 | do{ |
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111 | rand = G4UniformRand(); |
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112 | rand = rand/(1-rand+1.0/gMaxEnergy); |
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113 | gfunctionTest = RejectionFunction(rand); |
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114 | randTest = G4UniformRand(); |
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115 | |
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116 | }while(randTest > (gfunctionTest/gMaximum)); |
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117 | |
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118 | theta = std::sqrt(rand)/initialTotalEnergy; |
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119 | |
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120 | |
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121 | return theta; |
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122 | } |
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123 | // |
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124 | |
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125 | G4double G4Generator2BS::RejectionFunction(G4double value) const |
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126 | { |
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127 | |
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128 | G4double argument = (1+value)*(1+value); |
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129 | |
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130 | G4double gfunction = (4+std::log(rejection_argument3+(z/argument)))* |
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131 | ((4*EnergyRatio*value/argument)-rejection_argument1)+rejection_argument2; |
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132 | |
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133 | return gfunction; |
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134 | |
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135 | } |
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136 | |
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137 | void G4Generator2BS::PrintGeneratorInformation() const |
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138 | { |
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139 | G4cout << "\n" << G4endl; |
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140 | G4cout << "Bremsstrahlung Angular Generator is 2BS Generator from 2BS Koch & Motz distribution (Rev Mod Phys 31(4), 920 (1959))" << G4endl; |
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141 | G4cout << "Sampling algorithm adapted from PIRS-0203" << G4endl; |
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142 | G4cout << "\n" << G4endl; |
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143 | } |
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144 | |
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