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 | // |
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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: G4PhotoElectricAngularGeneratorSauterGavrila |
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33 | // |
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34 | // Creation date: 10 May 2004 |
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35 | // |
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36 | // Modifications: |
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37 | // 10 May 2003 P. Rodrigues First implementation acording with new design |
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38 | // |
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39 | // Class Description: |
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40 | // |
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41 | // Concrete class for PhotoElectric Electron Angular Distribution Generation |
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42 | // This model is a re-implementation of the Photolectric angular distribution |
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43 | // developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect |
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44 | // |
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45 | // Class Description: End |
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46 | // |
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47 | // ------------------------------------------------------------------- |
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48 | // |
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49 | // |
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50 | |
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51 | #include "G4PhotoElectricAngularGeneratorSauterGavrila.hh" |
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52 | #include "Randomize.hh" |
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53 | |
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54 | // |
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55 | |
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56 | G4PhotoElectricAngularGeneratorSauterGavrila::G4PhotoElectricAngularGeneratorSauterGavrila(const G4String& name):G4VPhotoElectricAngularDistribution(name) |
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57 | {;} |
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58 | |
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59 | // |
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60 | |
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61 | G4PhotoElectricAngularGeneratorSauterGavrila::~G4PhotoElectricAngularGeneratorSauterGavrila() |
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62 | {;} |
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63 | |
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64 | // |
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65 | |
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66 | G4ThreeVector G4PhotoElectricAngularGeneratorSauterGavrila::GetPhotoElectronDirection(const G4ThreeVector& direction, const G4double eKineticEnergy, const G4ThreeVector&, const G4int) const |
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67 | { |
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68 | |
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69 | // Compute Theta distribution of the emitted electron, with respect to the |
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70 | // incident Gamma. |
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71 | // The Sauter-Gavrila distribution for the K-shell is used. (adapted from G4PhotoElectricEffect) |
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72 | |
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73 | G4double costeta = 1.; |
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74 | G4double Phi = twopi * G4UniformRand(); |
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75 | G4double cosphi = std::cos(Phi); |
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76 | G4double sinphi = std::sin(Phi); |
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77 | G4double sinteta = 0; |
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78 | G4double gamma = 1. + eKineticEnergy/electron_mass_c2; |
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79 | |
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80 | if (gamma > 5.) { |
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81 | G4ThreeVector direction (sinteta*cosphi, sinteta*sinphi, costeta); |
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82 | return costeta; |
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83 | } |
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84 | |
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85 | G4double beta = std::sqrt(gamma*gamma-1.)/gamma; |
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86 | G4double b = 0.5*gamma*(gamma-1.)*(gamma-2); |
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87 | |
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88 | G4double rndm,term,greject,grejsup; |
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89 | if (gamma < 2.) grejsup = gamma*gamma*(1.+b-beta*b); |
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90 | else grejsup = gamma*gamma*(1.+b+beta*b); |
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91 | |
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92 | do { rndm = 1.-2*G4UniformRand(); |
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93 | costeta = (rndm+beta)/(rndm*beta+1.); |
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94 | term = 1.-beta*costeta; |
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95 | greject = (1.-costeta*costeta)*(1.+b*term)/(term*term); |
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96 | } while(greject < G4UniformRand()*grejsup); |
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97 | |
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98 | |
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99 | sinteta = std::sqrt(1.-costeta*costeta); |
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100 | G4ThreeVector photoelectrondirection (sinteta*cosphi, sinteta*sinphi, costeta); |
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101 | photoelectrondirection.rotateUz(direction); |
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102 | return photoelectrondirection; |
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103 | } |
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104 | |
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105 | // |
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106 | |
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107 | void G4PhotoElectricAngularGeneratorSauterGavrila::PrintGeneratorInformation() const |
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108 | { |
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109 | G4cout << "\n" << G4endl; |
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110 | G4cout << "" << G4endl; |
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111 | G4cout << "Re-implementation of the photolectric angular distribution" << G4endl; |
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112 | G4cout << "developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect" << G4endl; |
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113 | G4cout << "It computes the theta distribution of the emitted electron, with respect to the" << G4endl; |
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114 | G4cout << "incident Gamma, using the Sauter-Gavrila distribution for the K-shell\n" << G4endl; |
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115 | } |
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