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25 //
26 /// \file eventgenerator/particleGun/src/PrimaryGeneratorAction4.cc
27 /// \brief Implementation of the PrimaryGeneratorAction4 class
28 //
29 //
30 //
31 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
32 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
33
34 #include "PrimaryGeneratorAction4.hh"
35
36 #include "PrimaryGeneratorAction.hh"
37
38 #include "G4Event.hh"
39 #include "G4ParticleDefinition.hh"
40 #include "G4ParticleGun.hh"
41 #include "G4ParticleTable.hh"
42 #include "G4PhysicalConstants.hh"
43 #include "G4SystemOfUnits.hh"
44 #include "Randomize.hh"
45
46 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
47
48 PrimaryGeneratorAction4::PrimaryGeneratorAction4(G4ParticleGun* gun) : fParticleGun(gun)
49 {
50 // vertex volume
51 //
52 G4double Rmin = 2. * mm;
53 G4double Rmax = 8. * mm;
54 fRmin3 = Rmin * Rmin * Rmin;
55 fRmax3 = Rmax * Rmax * Rmax;
56
57 // opening angle
58 //
59 G4double alphaMin = 0. * deg;
60 G4double alphaMax = 60. * deg;
61 fCosAlphaMin = std::cos(alphaMin);
62 fCosAlphaMax = std::cos(alphaMax);
63 }
64
65 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
66
67 void PrimaryGeneratorAction4::GeneratePrimaries(G4Event* anEvent)
68 {
69 // vertex position uniform in spherical shell
70 //
71 G4double cosTheta = 2 * G4UniformRand() - 1; // cosTheta uniform in [0, pi]
72 G4double sinTheta = std::sqrt(1. - cosTheta * cosTheta);
73 G4double phi = twopi * G4UniformRand(); // phi uniform in [0, 2*pi]
74 G4ThreeVector ur(sinTheta * std::cos(phi), sinTheta * std::sin(phi), cosTheta);
75
76 G4double R3 = fRmin3 + G4UniformRand() * (fRmax3 - fRmin3);
77 G4double R = std::pow(R3, 1. / 3);
78
79 fParticleGun->SetParticlePosition(R * ur);
80
81 // particle direction uniform around ur
82 //
83 // 1- in World frame
84 // cosAlpha uniform in [cos(alphaMin), cos(alphaMax)]
85 G4double cosAlpha = fCosAlphaMin - G4UniformRand() * (fCosAlphaMin - fCosAlphaMax);
86 G4double sinAlpha = std::sqrt(1. - cosAlpha * cosAlpha);
87 G4double psi = twopi * G4UniformRand(); // psi uniform in (0,2*pi)
88 G4ThreeVector dir(sinAlpha * std::cos(psi), sinAlpha * std::sin(psi), cosAlpha);
89
90 // 2- rotate dir (rotateUz transforms uz to ur)
91 dir.rotateUz(ur);
92
93 fParticleGun->SetParticleMomentumDirection(dir);
94
95 // energy
96 //
97 fParticleGun->SetParticleEnergy(1 * MeV);
98
99 // create vertex
100 //
101 fParticleGun->GeneratePrimaryVertex(anEvent);
102 }
103 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
104