| 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: 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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