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25 // 25 //
>> 26 // $Id$
26 // 27 //
27 // ------------------------------------------- 28 // -------------------------------------------------------------------
28 // 29 //
29 // GEANT4 Class file 30 // GEANT4 Class file
30 // 31 //
31 // 32 //
32 // File name: G4DipBustGenerator 33 // File name: G4DipBustGenerator
33 // 34 //
34 // Author: Vladimir Grichine << 35 // Author: Vladimir Grichine
35 // << 36 //
36 // Creation date: 17 May 2011 37 // Creation date: 17 May 2011
37 // 38 //
38 // Modifications: << 39 // Modifications:
39 // << 40 //
40 // 17.07.2018 optimisations, using G4Pow in S <<
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 "G4PhysicalConstants.hh"
54 #include "Randomize.hh" 55 #include "Randomize.hh"
55 // #include "G4Log.hh" <<
56 // #include "G4Exp.hh" <<
57 #include "G4Pow.hh" <<
58 #include <CLHEP/Units/PhysicalConstants.h> <<
59 <<
60 //....oooOO0OOooo........oooOO0OOooo........oo <<
61 56
62 G4DipBustGenerator::G4DipBustGenerator(const G 57 G4DipBustGenerator::G4DipBustGenerator(const G4String&)
63 : G4VEmAngularDistribution("DipBustGen") 58 : G4VEmAngularDistribution("DipBustGen")
>> 59 {}
>> 60
>> 61 G4DipBustGenerator::~G4DipBustGenerator()
64 {} 62 {}
65 63
66 //....oooOO0OOooo........oooOO0OOooo........oo << 64 G4ThreeVector&
>> 65 G4DipBustGenerator::SampleDirection(const G4DynamicParticle* dp,
>> 66 G4double, G4int, const G4Material*)
>> 67 {
>> 68 G4double c, cosTheta, delta, cofA, signc = 1., a, power = 1./3.;
67 69
68 G4DipBustGenerator::~G4DipBustGenerator() = de << 70 G4double eTkin = dp->GetKineticEnergy();
69 71
70 //....oooOO0OOooo........oooOO0OOooo........oo << 72 c = 4. - 8.*G4UniformRand();
>> 73 a = c;
>> 74
>> 75 if( c < 0. )
>> 76 {
>> 77 signc = -1.;
>> 78 a = -c;
>> 79 }
>> 80 delta = std::sqrt(a*a+4.);
>> 81 delta += a;
>> 82 delta *= 0.5;
71 83
72 G4double G4DipBustGenerator::SampleCosTheta(co << 84 cofA = -signc*std::pow(delta, power);
73 { <<
74 const G4double c = 4. - 8.*G4UniformR <<
75 const G4double delta = 0.5*(std::sqrt(c*c <<
76 const G4double signc = (c < 0.) ? -1.0 : <<
77 // const G4double cofA = -signc*G4Exp(G4Log( <<
78 const G4double cofA = -signc*G4Pow::GetI <<
79 const G4double cosTheta = std::min(1.,std::m <<
80 const G4double tau = kinEnergy/CLHEP::e <<
81 const G4double beta = std::sqrt(tau*(tau <<
82 85
83 return (cosTheta + beta)/(1. + cosTheta*beta << 86 cosTheta = cofA - 1./cofA;
84 } <<
85 87
86 //....oooOO0OOooo........oooOO0OOooo........oo << 88 G4double tau = eTkin/electron_mass_c2;
>> 89 G4double beta = std::sqrt(tau*(tau + 2.))/(tau + 1.);
87 90
88 G4ThreeVector& << 91 cosTheta = (cosTheta + beta)/(1 + cosTheta*beta);
89 G4DipBustGenerator::SampleDirection(const G4Dy <<
90 G4int, co <<
91 { <<
92 const G4double cosTheta = SampleCosTheta(dp- <<
93 92
94 const G4double sinTheta = std::sqrt((1. - co << 93 G4double sinTheta = std::sqrt((1 - cosTheta)*(1 + cosTheta));
95 const G4double phi = CLHEP::twopi*G4Uni << 94 G4double phi = twopi*G4UniformRand();
96 95
97 fLocalDirection.set(sinTheta*std::cos(phi), 96 fLocalDirection.set(sinTheta*std::cos(phi), sinTheta*std::sin(phi),cosTheta);
98 fLocalDirection.rotateUz(dp->GetMomentumDire 97 fLocalDirection.rotateUz(dp->GetMomentumDirection());
99 98
100 return fLocalDirection; 99 return fLocalDirection;
101 } <<
102 <<
103 //....oooOO0OOooo........oooOO0OOooo........oo <<
104 100
105 G4double G4DipBustGenerator::PolarAngle(G4doub <<
106 G4dou <<
107 G4int <<
108 { <<
109 const G4double cosTheta = SampleCosTheta(eTk <<
110 G4double theta = std::acos(cosTheta); <<
111 theta = std::min(std::max(theta, 0.), CLHEP: <<
112 return theta; <<
113 } 101 }
114 102
115 //....oooOO0OOooo........oooOO0OOooo........oo << 103 G4double G4DipBustGenerator::PolarAngle(const G4double eTkin,
116 << 104 const G4double, // final_energy
117 void G4DipBustGenerator::SamplePairDirections( << 105 const G4int ) // Z
118 <<
119 <<
120 <<
121 <<
122 <<
123 { 106 {
124 const G4double phi = CLHEP::twopi * G4Unifo << 107 G4double c, cosTheta, delta, cofA, signc = 1., a, power = 1./3.;
125 const G4double sinp = std::sin(phi); << 108 G4double gamma, beta, theta;
126 const G4double cosp = std::cos(phi); <<
127 <<
128 G4double cost = SampleCosTheta(elecKinEnergy <<
129 G4double sint = std::sqrt((1. - cost)*(1. + <<
130 <<
131 dirElectron.set(sint*cosp, sint*sinp, cost); <<
132 dirElectron.rotateUz(dp->GetMomentumDirectio <<
133 109
134 cost = SampleCosTheta(posiKinEnergy); << 110 c = 4. - 8.*G4UniformRand();
135 sint = std::sqrt((1. - cost)*(1. + cost)); << 111 a = c;
>> 112
>> 113 if( c < 0. )
>> 114 {
>> 115 signc = -1.;
>> 116 a = -c;
>> 117 }
>> 118 delta = std::sqrt(a*a+4.);
>> 119 delta += a;
>> 120 delta *= 0.5;
>> 121
>> 122 cofA = -signc*std::pow(delta, power);
>> 123
>> 124 cosTheta = cofA - 1./cofA;
>> 125
>> 126 gamma = 1. + eTkin/electron_mass_c2;
>> 127 beta = std::sqrt(1. - 1./gamma/gamma);
>> 128
>> 129 cosTheta = (cosTheta + beta)/(1 + cosTheta*beta);
>> 130
>> 131 theta = std::acos(cosTheta);
>> 132
>> 133 if( theta < 0. ) theta = 0.;
>> 134 if( theta > pi ) theta = pi;
>> 135 // G4cout <<"theta = "<<theta<<"; ";
136 136
137 dirPositron.set(-sint*cosp, -sint*sinp, cost << 137 return theta;
138 dirPositron.rotateUz(dp->GetMomentumDirectio <<
139 } 138 }
140 139
141 //....oooOO0OOooo........oooOO0OOooo........oo <<
142 <<
143 void G4DipBustGenerator::PrintGeneratorInforma 140 void G4DipBustGenerator::PrintGeneratorInformation() const
144 { 141 {
145 G4cout << "\n" << G4endl; 142 G4cout << "\n" << G4endl;
146 G4cout << "Angular Generator based on classi 143 G4cout << "Angular Generator based on classical formula from" << G4endl;
147 G4cout << "J.D. Jackson, Classical Electrody << 144 G4cout << "J.D. Jackson, Classical Electrodynamics, Wiley, New York 1975"
148 << G4endl; 145 << G4endl;
149 } << 146 }
150 <<
151 //....oooOO0OOooo........oooOO0OOooo........oo <<
152 147