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G4ModifiedTsai.cc
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26 // $Id: G4ModifiedTsai.cc 110415 2018-05-23 06:44:31Z gcosmo $
27 //
28 // -------------------------------------------------------------------
29 //
30 // GEANT4 Class file
31 //
32 //
33 // File name: G4ModifiedTsai
34 //
35 // Author: Andreia Trindade (andreia@lip.pt)
36 // Pedro Rodrigues (psilva@lip.pt)
37 // Luis Peralta (luis@lip.pt)
38 //
39 // Creation date: 21 March 2003
40 //
41 // Modifications:
42 // 21 Mar 2003 A.Trindade First implementation acording with new design
43 // 24 Mar 2003 A.Trindade Fix in Tsai generator in order to prevent theta
44 // generation above pi
45 // 13 Oct 2010 V.Ivanchenko Moved to standard and improved comment
46 // 26.04.2011 V.Grichine Clean-up of PolarAngle method
47 //
48 // Class Description:
49 //
50 // Bremsstrahlung Angular Distribution Generation
51 // suggested by L.Urban (Geant3 manual (1993) Phys211)
52 // Derived from Tsai distribution (Rev Mod Phys 49,421(1977))
53 //
54 // Class Description: End
55 //
56 // -------------------------------------------------------------------
57 //
58 
59 #include "G4ModifiedTsai.hh"
60 #include "Randomize.hh"
61 #include "G4Log.hh"
63 
64 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
65 
67  : G4VEmAngularDistribution("AngularGenUrban")
68 {}
69 
70 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
71 
73 {}
74 
75 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
76 
79  G4double, G4int, const G4Material*)
80 {
81  // Sample gamma angle (Z - axis along the parent particle).
83  G4double sint = std::sqrt((1 - cost)*(1 + cost));
85 
86  fLocalDirection.set(sint*std::cos(phi), sint*std::sin(phi), cost);
88 
89  return fLocalDirection;
90 }
91 
92 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
93 
95 {
96  // Universal distribution suggested by L. Urban (Geant3 manual (1993)
97  // Phys211) derived from Tsai distribution (Rev Mod Phys 49,421(1977))
98 
99  G4double uMax = 2*(1. + kinEnergy/CLHEP::electron_mass_c2);
100 
101  static const G4double a1 = 1.6;
102  static const G4double a2 = a1/3.;
103  static const G4double border = 0.25;
104  G4double u;
105  CLHEP::HepRandomEngine* rndmEngine = G4Random::getTheEngine();
106 
107  do {
108  G4double uu = -G4Log(rndmEngine->flat()*rndmEngine->flat());
109  u = (border > rndmEngine->flat()) ? uu*a1 : uu*a2;
110 
111  // Loop checking, 03-Aug-2015, Vladimir Ivanchenko
112  } while(u > uMax);
113 
114  return 1.0 - 2.0*u*u/(uMax*uMax);
115 }
116 
117 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
118 
120  G4double elecKinEnergy,
121  G4double posiKinEnergy,
122  G4ThreeVector& dirElectron,
123  G4ThreeVector& dirPositron,
124  G4int, const G4Material*)
125 {
127  G4double sinp = std::sin(phi);
128  G4double cosp = std::cos(phi);
129 
130  G4double cost = SampleCosTheta(elecKinEnergy);
131  G4double sint = std::sqrt((1. - cost)*(1. + cost));
132 
133  dirElectron.set(sint*cosp, sint*sinp, cost);
134  dirElectron.rotateUz(dp->GetMomentumDirection());
135 
136  cost = SampleCosTheta(posiKinEnergy);
137  sint = std::sqrt((1. - cost)*(1. + cost));
138 
139  dirPositron.set(-sint*cosp, -sint*sinp, cost);
140  dirPositron.rotateUz(dp->GetMomentumDirection());
141 }
142 
143 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
144 
146 {
147  G4cout << "\n" << G4endl;
148  G4cout << "Bremsstrahlung Angular Generator is Modified Tsai" << G4endl;
149  G4cout << "Distribution suggested by L.Urban (Geant3 manual (1993) Phys211)"
150  << G4endl;
151  G4cout << "Derived from Tsai distribution (Rev Mod Phys 49,421(1977)) \n"
152  << G4endl;
153 }
154 
155 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void set(double x, double y, double z)
G4double SampleCosTheta(G4double kinEnergy)
static unsigned border[]
Definition: csz_inflate.cc:298
virtual void PrintGeneratorInformation() const final
#define G4endl
Definition: G4ios.hh:61
const G4ThreeVector & GetMomentumDirection() const
Hep3Vector & rotateUz(const Hep3Vector &)
Definition: ThreeVector.cc:38
virtual ~G4ModifiedTsai()
G4double G4Log(G4double x)
Definition: G4Log.hh:230
double G4double
Definition: G4Types.hh:76
virtual double flat()=0
static constexpr double electron_mass_c2
virtual void SamplePairDirections(const G4DynamicParticle *dp, G4double elecKinEnergy, G4double posiKinEnergy, G4ThreeVector &dirElectron, G4ThreeVector &dirPositron, G4int Z=0, const G4Material *mat=nullptr) final
#define G4UniformRand()
Definition: Randomize.hh:53
static constexpr double twopi
Definition: SystemOfUnits.h:55
int G4int
Definition: G4Types.hh:78
G4double GetKineticEnergy() const
G4GLOB_DLL std::ostream G4cout
virtual G4ThreeVector & SampleDirection(const G4DynamicParticle *dp, G4double out_energy, G4int Z, const G4Material *mat=nullptr) final
G4ModifiedTsai(const G4String &name="")