| 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 direction;
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| 83 | // Bugzilla 1120
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| 84 | // SI on 05/09/2010 as suggested by JG 04/09/10
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| 85 | }
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| 86 |
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| 87 | G4double beta = std::sqrt(gamma*gamma-1.)/gamma;
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| 88 | G4double b = 0.5*gamma*(gamma-1.)*(gamma-2);
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| 89 |
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| 90 | G4double rndm,term,greject,grejsup;
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| 91 | if (gamma < 2.) grejsup = gamma*gamma*(1.+b-beta*b);
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| 92 | else grejsup = gamma*gamma*(1.+b+beta*b);
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| 93 |
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| 94 | do { rndm = 1.-2*G4UniformRand();
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| 95 | costeta = (rndm+beta)/(rndm*beta+1.);
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| 96 | term = 1.-beta*costeta;
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| 97 | greject = (1.-costeta*costeta)*(1.+b*term)/(term*term);
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| 98 | } while(greject < G4UniformRand()*grejsup);
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| 99 |
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| 100 |
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| 101 | sinteta = std::sqrt(1.-costeta*costeta);
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| 102 | G4ThreeVector photoelectrondirection (sinteta*cosphi, sinteta*sinphi, costeta);
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| 103 | photoelectrondirection.rotateUz(direction);
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| 104 | return photoelectrondirection;
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| 105 | }
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| 106 |
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| 107 | //
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| 108 |
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| 109 | void G4PhotoElectricAngularGeneratorSauterGavrila::PrintGeneratorInformation() const
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| 110 | {
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| 111 | G4cout << "\n" << G4endl;
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| 112 | G4cout << "" << G4endl;
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| 113 | G4cout << "Re-implementation of the photolectric angular distribution" << G4endl;
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| 114 | G4cout << "developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect" << G4endl;
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| 115 | G4cout << "It computes the theta distribution of the emitted electron, with respect to the" << G4endl;
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| 116 | G4cout << "incident Gamma, using the Sauter-Gavrila distribution for the K-shell\n" << G4endl;
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| 117 | }
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