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25 //
26 // G4MuonRadiativeDecayChannelWithSpin
27 //
28 // Class description:
29 //
30 // This class describes radiative muon decay kinematics, but
31 // gives incorrect energy spectrum for neutrinos.
32 // Samples Radiative Muon Decay.
33 // References:
34 // - TRIUMF/TWIST Technote TN-55:
35 // "Radiative muon decay" by P. Depommier and A. Vacheret
36 // - Yoshitaka Kuno and Yasuhiro Okada
37 // "Muon Decays and Physics Beyond the Standard Model"
38 // Rev. Mod. Phys. 73, 151 (2001)
39
40 // Author: P.Gumplinger - Triumf, 25 July 2007
41 // Revision: D. Mingming - Center for HEP, Tsinghua Univ., 10 August 2011
42 // --------------------------------------------------------------------
43 #ifndef G4MuonRadiativeDecayChannelWithSpin_hh
44 #define G4MuonRadiativeDecayChannelWithSpin_hh 1
45
46 #include "G4ThreeVector.hh"
47 #include "G4VDecayChannel.hh"
48 #include "Randomize.hh"
49 #include "globals.hh"
50
51 #include <CLHEP/Units/PhysicalConstants.h>
52
53 class G4MuonRadiativeDecayChannelWithSpin : public G4VDecayChannel
54 {
55 public:
56 G4MuonRadiativeDecayChannelWithSpin(const G4String& theParentName, G4double theBR);
57 ~G4MuonRadiativeDecayChannelWithSpin() override = default;
58
59 G4DecayProducts* DecayIt(G4double) override;
60
61 protected:
62 // Copy constructor and assignment operator
63 G4MuonRadiativeDecayChannelWithSpin(const G4MuonRadiativeDecayChannelWithSpin&) = default;
64 G4MuonRadiativeDecayChannelWithSpin& operator=(const G4MuonRadiativeDecayChannelWithSpin&);
65
66 private:
67 G4MuonRadiativeDecayChannelWithSpin() = default;
68
69 G4double fron(G4double Pmu, G4double x, G4double y, G4double cthetaE, G4double cthetaG,
70 G4double cthetaEG);
71
72 // Generates random vectors, uniformly distributed over the surface
73 // of a sphere of given radius
74 void rn3dim(G4double& x, G4double& y, G4double& z, G4double xlong);
75
76 G4double atan4(G4double x, G4double y);
77 };
78
79 // ------------------------
80 // Inline methods
81 // ------------------------
82
83 inline void G4MuonRadiativeDecayChannelWithSpin::rn3dim(G4double& x, G4double& y, G4double& z,
84 G4double xlong)
85 {
86 G4double a = 0.;
87 G4double b = 0.;
88 G4double c = 0.;
89 G4double r = 0.;
90
91 do {
92 a = G4UniformRand() - 0.5;
93 b = G4UniformRand() - 0.5;
94 c = G4UniformRand() - 0.5;
95 r = a * a + b * b + c * c;
96 } while (r > 0.25); // Loop checking, 09.08.2015, K.Kurashige
97
98 G4double rinv = xlong / (std::sqrt(r));
99 x = a * rinv;
100 y = b * rinv;
101 z = c * rinv;
102
103 return;
104 }
105
106 inline G4double G4MuonRadiativeDecayChannelWithSpin::atan4(G4double x, G4double y)
107 {
108 G4double phi = 0.;
109
110 if (x == 0. && y > 0.) {
111 phi = 0.5 * CLHEP::pi;
112 }
113 else if (x == 0. && y < 0.) {
114 phi = 1.5 * CLHEP::pi;
115 }
116 else if (y == 0. && x > 0.) {
117 phi = 0.;
118 }
119 else if (y == 0. && x < 0.) {
120 phi = CLHEP::pi;
121 }
122 else if (x > 0.) {
123 phi = std::atan(y / x);
124 }
125 else if (x < 0.) {
126 phi = std::atan(y / x) + CLHEP::pi;
127 }
128
129 return phi;
130 }
131
132 #endif
133