Geant4  9.6.p02
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ExN06PrimaryGeneratorAction.cc
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27 // $Id$
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31 
34 
35 #include "Randomize.hh"
36 
37 #include "G4Event.hh"
38 #include "G4ParticleGun.hh"
39 #include "G4ParticleTable.hh"
40 #include "G4ParticleDefinition.hh"
41 #include "G4SystemOfUnits.hh"
42 
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46 {
47  G4int n_particle = 1;
48  particleGun = new G4ParticleGun(n_particle);
49 
50  //create a messenger for this class
51  gunMessenger = new ExN06PrimaryGeneratorMessenger(this);
52 
53  //default kinematic
54  //
56  G4ParticleDefinition* particle = particleTable->FindParticle("e+");
57 
58  particleGun->SetParticleDefinition(particle);
59  particleGun->SetParticleTime(0.0*ns);
60  particleGun->SetParticlePosition(G4ThreeVector(0.0*cm,0.0*cm,0.0*cm));
61  particleGun->SetParticleMomentumDirection(G4ThreeVector(1.,0.,0.));
62  particleGun->SetParticleEnergy(500.0*keV);
63 }
64 
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66 
68 {
69  delete particleGun;
70  delete gunMessenger;
71 }
72 
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74 
76 {
77  particleGun->GeneratePrimaryVertex(anEvent);
78 }
79 
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81 
83 {
84  G4double angle = G4UniformRand() * 360.0*deg;
85  SetOptPhotonPolar(angle);
86 }
87 
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91 {
92  if (particleGun->GetParticleDefinition()->GetParticleName() != "opticalphoton")
93  {
94  G4cout << "--> warning from PrimaryGeneratorAction::SetOptPhotonPolar() :"
95  "the particleGun is not an opticalphoton" << G4endl;
96  return;
97  }
98 
99  G4ThreeVector normal (1., 0., 0.);
100  G4ThreeVector kphoton = particleGun->GetParticleMomentumDirection();
101  G4ThreeVector product = normal.cross(kphoton);
102  G4double modul2 = product*product;
103 
104  G4ThreeVector e_perpend (0., 0., 1.);
105  if (modul2 > 0.) e_perpend = (1./std::sqrt(modul2))*product;
106  G4ThreeVector e_paralle = e_perpend.cross(kphoton);
107 
108  G4ThreeVector polar = std::cos(angle)*e_paralle + std::sin(angle)*e_perpend;
109  particleGun->SetParticlePolarization(polar);
110 }
111 
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