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25 //
26 //
27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4RDPhotoElectricAngularGeneratorSauterGavrila
33 //
34 // Creation date: 10 May 2004
35 //
36 // Modifications:
37 // 10 May 2003 P. Rodrigues First implementation acording with new design
38 //
39 // Class Description:
40 //
41 // Concrete class for PhotoElectric Electron Angular Distribution Generation
42 // This model is a re-implementation of the Photolectric angular distribution
43 // developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect
44 //
45 // Class Description: End
46 //
47 // -------------------------------------------------------------------
48 //
49 //
50
51 #include "G4RDPhotoElectricAngularGeneratorSauterGavrila.hh"
52 #include "Randomize.hh"
53 #include "G4PhysicalConstants.hh"
54
55 //
56
57 G4RDPhotoElectricAngularGeneratorSauterGavrila::G4RDPhotoElectricAngularGeneratorSauterGavrila(const G4String& name):G4RDVPhotoElectricAngularDistribution(name)
58 {;}
59
60 //
61
62 G4RDPhotoElectricAngularGeneratorSauterGavrila::~G4RDPhotoElectricAngularGeneratorSauterGavrila()
63 {;}
64
65 //
66
67 G4ThreeVector G4RDPhotoElectricAngularGeneratorSauterGavrila::GetPhotoElectronDirection(const G4ThreeVector& direction, const G4double eKineticEnergy, const G4ThreeVector&, const G4int) const
68 {
69
70 // Compute Theta distribution of the emitted electron, with respect to the
71 // incident Gamma.
72 // The Sauter-Gavrila distribution for the K-shell is used. (adapted from G4PhotoElectricEffect)
73
74 G4double costeta = 1.;
75 G4double Phi = twopi * G4UniformRand();
76 G4double cosphi = std::cos(Phi);
77 G4double sinphi = std::sin(Phi);
78 G4double sinteta = 0;
79 G4double gamma = 1. + eKineticEnergy/electron_mass_c2;
80
81 if (gamma > 5.) {
82 G4ThreeVector direction (sinteta*cosphi, sinteta*sinphi, costeta);
83 return direction;
84 }
85
86 G4double beta = std::sqrt(gamma*gamma-1.)/gamma;
87 G4double b = 0.5*gamma*(gamma-1.)*(gamma-2);
88
89 G4double rndm,term,greject,grejsup;
90 if (gamma < 2.) grejsup = gamma*gamma*(1.+b-beta*b);
91 else grejsup = gamma*gamma*(1.+b+beta*b);
92
93 do { rndm = 1.-2*G4UniformRand();
94 costeta = (rndm+beta)/(rndm*beta+1.);
95 term = 1.-beta*costeta;
96 greject = (1.-costeta*costeta)*(1.+b*term)/(term*term);
97 } while(greject < G4UniformRand()*grejsup);
98
99
100 sinteta = std::sqrt(1.-costeta*costeta);
101 G4ThreeVector photoelectrondirection (sinteta*cosphi, sinteta*sinphi, costeta);
102 photoelectrondirection.rotateUz(direction);
103 return photoelectrondirection;
104 }
105
106 //
107
108 void G4RDPhotoElectricAngularGeneratorSauterGavrila::PrintGeneratorInformation() const
109 {
110 G4cout << "\n" << G4endl;
111 G4cout << "" << G4endl;
112 G4cout << "Re-implementation of the photolectric angular distribution" << G4endl;
113 G4cout << "developed my M. Maire for the Standard EM Physics G4PhotoElectricEffect" << G4endl;
114 G4cout << "It computes the theta distribution of the emitted electron, with respect to the" << G4endl;
115 G4cout << "incident Gamma, using the Sauter-Gavrila distribution for the K-shell\n" << G4endl;
116 }
117