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26 // 26 //
27 // ------------------------------------------- 27 // -------------------------------------------------------------------
28 // 28 //
29 // GEANT4 Class file 29 // GEANT4 Class file
30 // 30 //
31 // 31 //
32 // File name: G4DipBustGenerator 32 // File name: G4DipBustGenerator
33 // 33 //
34 // Author: Vladimir Grichine 34 // Author: Vladimir Grichine
35 // 35 //
36 // Creation date: 17 May 2011 36 // Creation date: 17 May 2011
37 // 37 //
38 // Modifications: 38 // Modifications:
39 // 39 //
40 // 17.07.2018 optimisations, using G4Pow in S 40 // 17.07.2018 optimisations, using G4Pow in SampleCosTheta() method M.Novak
41 // 41 //
42 // Class Description: 42 // Class Description:
43 // 43 //
44 // Bremsstrahlung Angular Distribution Generat 44 // Bremsstrahlung Angular Distribution Generation
45 // suggested the dipole approximation in the 45 // suggested the dipole approximation in the rest frame of electron
46 // busted in the laboratory frame. 46 // busted in the laboratory frame.
47 // 47 //
48 // Class Description: End 48 // Class Description: End
49 // 49 //
50 // ------------------------------------------- 50 // -------------------------------------------------------------------
51 // 51 //
52 52
53 #include "G4DipBustGenerator.hh" 53 #include "G4DipBustGenerator.hh"
54 #include "Randomize.hh" 54 #include "Randomize.hh"
55 // #include "G4Log.hh" 55 // #include "G4Log.hh"
56 // #include "G4Exp.hh" 56 // #include "G4Exp.hh"
57 #include "G4Pow.hh" 57 #include "G4Pow.hh"
58 #include <CLHEP/Units/PhysicalConstants.h> 58 #include <CLHEP/Units/PhysicalConstants.h>
59 59
60 //....oooOO0OOooo........oooOO0OOooo........oo 60 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
61 61
62 G4DipBustGenerator::G4DipBustGenerator(const G 62 G4DipBustGenerator::G4DipBustGenerator(const G4String&)
63 : G4VEmAngularDistribution("DipBustGen") 63 : G4VEmAngularDistribution("DipBustGen")
64 {} 64 {}
65 65
66 //....oooOO0OOooo........oooOO0OOooo........oo 66 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
67 67
68 G4DipBustGenerator::~G4DipBustGenerator() = de << 68 G4DipBustGenerator::~G4DipBustGenerator()
>> 69 {}
69 70
70 //....oooOO0OOooo........oooOO0OOooo........oo 71 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
71 72
72 G4double G4DipBustGenerator::SampleCosTheta(co 73 G4double G4DipBustGenerator::SampleCosTheta(const G4double kinEnergy)
73 { 74 {
74 const G4double c = 4. - 8.*G4UniformR 75 const G4double c = 4. - 8.*G4UniformRand();
75 const G4double delta = 0.5*(std::sqrt(c*c 76 const G4double delta = 0.5*(std::sqrt(c*c+4.) + std::abs(c));
76 const G4double signc = (c < 0.) ? -1.0 : 77 const G4double signc = (c < 0.) ? -1.0 : 1.0;
77 // const G4double cofA = -signc*G4Exp(G4Log( 78 // const G4double cofA = -signc*G4Exp(G4Log(delta)/3.0);
78 const G4double cofA = -signc*G4Pow::GetI 79 const G4double cofA = -signc*G4Pow::GetInstance()->A13(delta);
79 const G4double cosTheta = std::min(1.,std::m 80 const G4double cosTheta = std::min(1.,std::max(-1.,cofA - 1./cofA));
80 const G4double tau = kinEnergy/CLHEP::e 81 const G4double tau = kinEnergy/CLHEP::electron_mass_c2;
81 const G4double beta = std::sqrt(tau*(tau 82 const G4double beta = std::sqrt(tau*(tau + 2.))/(tau + 1.);
82 83
83 return (cosTheta + beta)/(1. + cosTheta*beta 84 return (cosTheta + beta)/(1. + cosTheta*beta);
84 } 85 }
85 86
86 //....oooOO0OOooo........oooOO0OOooo........oo 87 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
87 88
88 G4ThreeVector& 89 G4ThreeVector&
89 G4DipBustGenerator::SampleDirection(const G4Dy 90 G4DipBustGenerator::SampleDirection(const G4DynamicParticle* dp, G4double,
90 G4int, co 91 G4int, const G4Material*)
91 { 92 {
92 const G4double cosTheta = SampleCosTheta(dp- 93 const G4double cosTheta = SampleCosTheta(dp->GetKineticEnergy());
93 94
94 const G4double sinTheta = std::sqrt((1. - co 95 const G4double sinTheta = std::sqrt((1. - cosTheta)*(1. + cosTheta));
95 const G4double phi = CLHEP::twopi*G4Uni 96 const G4double phi = CLHEP::twopi*G4UniformRand();
96 97
97 fLocalDirection.set(sinTheta*std::cos(phi), 98 fLocalDirection.set(sinTheta*std::cos(phi), sinTheta*std::sin(phi),cosTheta);
98 fLocalDirection.rotateUz(dp->GetMomentumDire 99 fLocalDirection.rotateUz(dp->GetMomentumDirection());
99 100
100 return fLocalDirection; 101 return fLocalDirection;
101 } 102 }
102 103
103 //....oooOO0OOooo........oooOO0OOooo........oo 104 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
104 105
105 G4double G4DipBustGenerator::PolarAngle(G4doub 106 G4double G4DipBustGenerator::PolarAngle(G4double eTkin,
106 G4dou 107 G4double, // final_energy
107 G4int 108 G4int ) // Z
108 { 109 {
109 const G4double cosTheta = SampleCosTheta(eTk 110 const G4double cosTheta = SampleCosTheta(eTkin);
110 G4double theta = std::acos(cosTheta); 111 G4double theta = std::acos(cosTheta);
111 theta = std::min(std::max(theta, 0.), CLHEP: 112 theta = std::min(std::max(theta, 0.), CLHEP::pi);
112 return theta; 113 return theta;
113 } 114 }
114 115
115 //....oooOO0OOooo........oooOO0OOooo........oo 116 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
116 117
117 void G4DipBustGenerator::SamplePairDirections( 118 void G4DipBustGenerator::SamplePairDirections(const G4DynamicParticle* dp,
118 119 G4double elecKinEnergy,
119 120 G4double posiKinEnergy,
120 121 G4ThreeVector& dirElectron,
121 122 G4ThreeVector& dirPositron,
122 123 G4int, const G4Material*)
123 { 124 {
124 const G4double phi = CLHEP::twopi * G4Unifo 125 const G4double phi = CLHEP::twopi * G4UniformRand();
125 const G4double sinp = std::sin(phi); 126 const G4double sinp = std::sin(phi);
126 const G4double cosp = std::cos(phi); 127 const G4double cosp = std::cos(phi);
127 128
128 G4double cost = SampleCosTheta(elecKinEnergy 129 G4double cost = SampleCosTheta(elecKinEnergy);
129 G4double sint = std::sqrt((1. - cost)*(1. + 130 G4double sint = std::sqrt((1. - cost)*(1. + cost));
130 131
131 dirElectron.set(sint*cosp, sint*sinp, cost); 132 dirElectron.set(sint*cosp, sint*sinp, cost);
132 dirElectron.rotateUz(dp->GetMomentumDirectio 133 dirElectron.rotateUz(dp->GetMomentumDirection());
133 134
134 cost = SampleCosTheta(posiKinEnergy); 135 cost = SampleCosTheta(posiKinEnergy);
135 sint = std::sqrt((1. - cost)*(1. + cost)); 136 sint = std::sqrt((1. - cost)*(1. + cost));
136 137
137 dirPositron.set(-sint*cosp, -sint*sinp, cost 138 dirPositron.set(-sint*cosp, -sint*sinp, cost);
138 dirPositron.rotateUz(dp->GetMomentumDirectio 139 dirPositron.rotateUz(dp->GetMomentumDirection());
139 } 140 }
140 141
141 //....oooOO0OOooo........oooOO0OOooo........oo 142 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
142 143
143 void G4DipBustGenerator::PrintGeneratorInforma 144 void G4DipBustGenerator::PrintGeneratorInformation() const
144 { 145 {
145 G4cout << "\n" << G4endl; 146 G4cout << "\n" << G4endl;
146 G4cout << "Angular Generator based on classi 147 G4cout << "Angular Generator based on classical formula from" << G4endl;
147 G4cout << "J.D. Jackson, Classical Electrody 148 G4cout << "J.D. Jackson, Classical Electrodynamics, Wiley, New York 1975"
148 << G4endl; 149 << G4endl;
149 } 150 }
150 151
151 //....oooOO0OOooo........oooOO0OOooo........oo 152 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
152 153