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PrimaryGeneratorAction.cc
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29 //
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32 
33 #include "PrimaryGeneratorAction.hh"
34 
35 #include "DetectorConstruction.hh"
36 #include "PrimaryGeneratorMessenger.hh"
37 
38 #include "G4Event.hh"
39 #include "G4ParticleTable.hh"
40 #include "G4ParticleDefinition.hh"
41 #include "G4SystemOfUnits.hh"
42 #include "Randomize.hh"
43 
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45 
46 PrimaryGeneratorAction::PrimaryGeneratorAction(DetectorConstruction* DC)
47 :G4VUserPrimaryGeneratorAction(),
48  fParticleGun(0),fDetector(DC),fRndmBeam(0),fGunMessenger(0)
49 {
50  G4int n_particle = 1;
51  fParticleGun = new G4ParticleGun(n_particle);
52  SetDefaultKinematic();
53 
54  //create a messenger for this class
55  fGunMessenger = new PrimaryGeneratorMessenger(this);
56 }
57 
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59 
60 PrimaryGeneratorAction::~PrimaryGeneratorAction()
61 {
62  delete fParticleGun;
63  delete fGunMessenger;
64 }
65 
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67 
68 void PrimaryGeneratorAction::SetDefaultKinematic()
69 {
70  // default particle kinematic
71  //
72  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
73  G4ParticleDefinition* particle
74  = particleTable->FindParticle("e-");
75  fParticleGun->SetParticleDefinition(particle);
76  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(1.,0.,0.));
77  fParticleGun->SetParticleEnergy(30.*MeV);
78  G4double x0 = -0.5*(fDetector->GetWorldSizeX());
79  fParticleGun->SetParticlePosition(G4ThreeVector(x0, 0.0, 0.0));
80 }
81 
82 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
83 
84 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
85 {
86  //this function is called at the begining of event
87  //
88  //randomize the beam, if requested.
89  if (fRndmBeam > 0.)
90  {
91  G4ThreeVector oldPosition = fParticleGun->GetParticlePosition();
92  G4double rbeam = 0.5*(fDetector->GetAbsorberSizeYZ())*fRndmBeam;
93  G4double x0 = oldPosition.x();
94  G4double y0 = oldPosition.y() + (2*G4UniformRand()-1.)*rbeam;
95  G4double z0 = oldPosition.z() + (2*G4UniformRand()-1.)*rbeam;
96  fParticleGun->SetParticlePosition(G4ThreeVector(x0,y0,z0));
97  fParticleGun->GeneratePrimaryVertex(anEvent);
98  fParticleGun->SetParticlePosition(oldPosition);
99  }
100  else fParticleGun->GeneratePrimaryVertex(anEvent);
101 }
102 
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