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25 //
26 //
27 // -------------------------------------------------------------------
28 //
29 // GEANT4 Class file
30 //
31 //
32 // File name: G4RDModifiedTsai
33 //
34 // Author: Andreia Trindade (andreia@lip.pt)
35 // Pedro Rodrigues (psilva@lip.pt)
36 // Luis Peralta (luis@lip.pt)
37 //
38 // Creation date: 21 March 2003
39 //
40 // Modifications:
41 // 21 Mar 2003 A. Trindade First implementation acording with new design
42 // 24 Mar 2003 & Fix in Tsai generator in order to prevent theta generation above pi
43 //
44 // Class Description:
45 //
46 // Concrete base class for Bremsstrahlung Angular Distribution Generation - Tsai Model
47 //
48 // Class Description: End
49 //
50 // -------------------------------------------------------------------
51 //
52 //
53
54 #include "G4RDModifiedTsai.hh"
55 #include "Randomize.hh"
56 #include "G4PhysicalConstants.hh"
57 //
58
59 G4RDModifiedTsai::G4RDModifiedTsai(const G4String& name):G4RDVBremAngularDistribution(name)
60 {;}
61
62 //
63
64 G4RDModifiedTsai::~G4RDModifiedTsai()
65 {;}
66
67 //
68
69 G4double G4RDModifiedTsai::PolarAngle(const G4double initial_energy,
70 const G4double, // final_energy
71 const G4int ) // Z
72 {
73
74 // Sample gamma angle (Z - axis along the parent particle).
75 // Universal distribution suggested by L. Urban (Geant3 manual (1993)
76 // Phys211) derived from Tsai distribution (Rev Mod Phys 49,421(1977))
77
78 G4double totalEnergy = initial_energy + electron_mass_c2;
79
80 const G4double a1 = 0.625, a2 = 3.*a1, d = 27.;
81 G4double u, theta = 0;
82
83 do{
84 u = - std::log(G4UniformRand()*G4UniformRand());
85
86 if (9./(9.+d) > G4UniformRand()) u /= a1;
87 else u /= a2;
88
89 theta = u*electron_mass_c2/totalEnergy;
90 }while(u > (totalEnergy*pi/electron_mass_c2));
91
92 return theta;
93 }
94 //
95
96 void G4RDModifiedTsai::PrintGeneratorInformation() const
97 {
98
99 G4cout << "\n" << G4endl;
100 G4cout << "Bremsstrahlung Angular Generator is Modified Tsai" << G4endl;
101 G4cout << "Universal distribution suggested by L. Urban (Geant3 manual (1993) Phys211)" << G4endl;
102 G4cout << "Derived from Tsai distribution (Rev Mod Phys 49,421(1977)) \n" << G4endl;
103 }
104