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25 //
26 //
27 // GEANT4 Class file
28 //
29 //
30 // File name: G4OrePowellAtRestModel
31 //
32 // Author: I.Semeniouk & D.Bernard
33 //
34 // Creation date: 04 Juin 2024
35 //
36 // -------------------------------------------------------------------
37 //
38
39 #include "G4OrePowellAtRestModel.hh"
40 #include "G4DynamicParticle.hh"
41 #include "G4Material.hh"
42 #include "Randomize.hh"
43 #include "G4Gamma.hh"
44 #include "G4RandomDirection.hh"
45 #include "G4ThreeVector.hh"
46 #include "G4PhysicalConstants.hh"
47 #include "G4SystemOfUnits.hh"
48
49 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
50
51 G4OrePowellAtRestModel::G4OrePowellAtRestModel() : G4VPositronAtRestModel("OrePowell") {}
52
53 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
54
55 void G4OrePowellAtRestModel::SampleSecondaries(
56 std::vector<G4DynamicParticle*>& secParticles,
57 G4double&, const G4Material*) const
58 {
59 static const G4double PositronMass = CLHEP::electron_mass_c2;
60 const G4double ymax = 8.1;
61
62 CLHEP::HepRandomEngine* rndmEngine = G4Random::getTheEngine();
63
64 G4double cos12;
65 G4double cos13;
66 G4double sin12;
67 G4double sin13;
68 G4double r1;
69 G4double r2;
70 G4double r3;
71 G4double pdf;
72
73 G4double rndmv2[2];
74 G4double rndmv1;
75
76 do {
77 rndmv1 = rndmEngine->flat();
78
79 do {
80 rndmEngine->flatArray(2, rndmv2);
81 // energies of photon1 and photon2 normalized to electron rest mass
82 r1 = rndmv2[0];
83 r2 = rndmv2[1];
84 // energy conservation, with positronium assumed = 2 * electron rest mass
85 r3 = 2.0 - (r1+r2);
86 // cosine of angles between photons, from momentum conservation
87 cos12=(r3*r3 - r1*r1 -r2*r2)/(2*r1*r2);
88 cos13=(r2*r2 - r1*r1 -r3*r3)/(2*r1*r3);
89 // request both cosines < 1.
90 } while ( std::abs(cos12) > 1 || std::abs(cos13) > 1 );
91
92 sin12 = std::sqrt((1 + cos12)*(1 - cos12));
93 sin13 = -std::sqrt((1 + cos13)*(1 - cos13));
94
95 G4double cos23=cos12*cos13+sin12*sin13;
96
97 pdf = (1 - cos12)*(1 - cos12) + (1 - cos13)*(1 - cos13) + (1 - cos23)*(1 - cos23);
98 } while ( pdf < ymax * rndmv1 );
99 // END of Sampling
100
101 // photon directions in the decay plane, photon 1 along z, x perp to the plane.
102 G4ThreeVector PhotonMomentum1(0., 0., 1.);
103 G4ThreeVector PhotonMomentum2(0.,sin12,cos12);
104 G4ThreeVector PhotonMomentum3(0.,sin13,cos13);
105
106 // First Gamma direction
107 G4ThreeVector dir1 = G4RandomDirection();
108
109 PhotonMomentum1.rotateUz(dir1);
110 PhotonMomentum2.rotateUz(dir1);
111 PhotonMomentum3.rotateUz(dir1);
112
113 auto aGamma1 = new G4DynamicParticle(G4Gamma::Gamma(), PhotonMomentum1,
114 r1 * PositronMass);
115
116 //Random polarization
117 G4double phi1 = CLHEP::twopi * G4UniformRand();
118 G4ThreeVector pol1(std::cos(phi1),std::sin(phi1),0.0);
119 pol1.rotateUz(PhotonMomentum1);
120 aGamma1->SetPolarization(pol1);
121 secParticles.push_back(aGamma1);
122
123 auto aGamma2 = new G4DynamicParticle(G4Gamma::Gamma(), PhotonMomentum2,
124 r2 * PositronMass);
125
126 G4double phi2 = CLHEP::twopi * G4UniformRand();
127 G4ThreeVector pol2(std::cos(phi2),std::sin(phi2),0.0);
128 pol2.rotateUz(PhotonMomentum2);
129 aGamma2->SetPolarization(pol2);
130 secParticles.push_back(aGamma2);
131
132 auto aGamma3 = new G4DynamicParticle(G4Gamma::Gamma(), PhotonMomentum3,
133 r3 * PositronMass);
134
135 G4double phi3 = CLHEP::twopi * G4UniformRand();
136 G4ThreeVector pol3(std::cos(phi3),std::sin(phi3),0.0);
137 pol3.rotateUz(PhotonMomentum3);
138 aGamma3->SetPolarization(pol3);
139 secParticles.push_back(aGamma3);
140
141 }
142
143 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
144
145 void G4OrePowellAtRestModel::PrintGeneratorInformation() const
146 {
147 G4cout << "Orel Powell AtRest positron 3-gamma annihilation model" << G4endl;
148 }
149
150 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
151