B2a/src/PrimaryGeneratorAction.cc

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0027 /// \file B2/B2a/src/PrimaryGeneratorAction.cc
0028 /// \brief Implementation of the B2::PrimaryGeneratorAction class
0029
0030 #include "PrimaryGeneratorAction.hh"
0031
0032 #include "G4Box.hh"
0033 #include "G4LogicalVolume.hh"
0034 #include "G4LogicalVolumeStore.hh"
0035 #include "G4ParticleGun.hh"
0036 #include "G4ParticleTable.hh"
0037 #include "G4SystemOfUnits.hh"
0038
0039 namespace B2
0040 {
0041
0042 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0043
0044 PrimaryGeneratorAction::PrimaryGeneratorAction()
0045 {
0046   G4int nofParticles = 1;
0047   fParticleGun = new G4ParticleGun(nofParticles);
0048
0049   // default particle kinematic
0050
0051   G4ParticleDefinition* particleDefinition =
0052     G4ParticleTable::GetParticleTable()->FindParticle("proton");
0053
0054   fParticleGun->SetParticleDefinition(particleDefinition);
0055   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
0056   fParticleGun->SetParticleEnergy(3.0 * GeV);
0057 }
0058
0059 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0060
0061 PrimaryGeneratorAction::~PrimaryGeneratorAction()
0062 {
0063   delete fParticleGun;
0064 }
0065
0066 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0067
0068 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* event)
0069 {
0070   // This function is called at the begining of event
0071
0072   // In order to avoid dependence of PrimaryGeneratorAction
0073   // on DetectorConstruction class we get world volume
0074   // from G4LogicalVolumeStore.
0075
0076   G4double worldZHalfLength = 0;
0077   G4LogicalVolume* worldLV = G4LogicalVolumeStore::GetInstance()->GetVolume("World");
0078   G4Box* worldBox = nullptr;
0079   if (worldLV) worldBox = dynamic_cast<G4Box*>(worldLV->GetSolid());
0080   if (worldBox)
0081     worldZHalfLength = worldBox->GetZHalfLength();
0082   else {
0083     G4cerr << "World volume of box not found." << G4endl;
0084     G4cerr << "Perhaps you have changed geometry." << G4endl;
0085     G4cerr << "The gun will be place in the center." << G4endl;
0086   }
0087
0088   // Starting a primary particle close to the world boundary.
0089   //
0090   fParticleGun->SetParticlePosition(G4ThreeVector(0., 0., -worldZHalfLength + 1 * um));
0091
0092   fParticleGun->GeneratePrimaryVertex(event);
0093 }
0094
0095 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0096
0097 }  // namespace B2