B2a/src/PrimaryGeneratorAction.cc

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0025 //
0026 /// \file PrimaryGeneratorAction.cc
0027 /// \brief Implementation of the B2::PrimaryGeneratorAction class
0028
0029 #include "PrimaryGeneratorAction.hh"
0030
0031 #include "G4Box.hh"
0032 #include "G4LogicalVolume.hh"
0033 #include "G4LogicalVolumeStore.hh"
0034 #include "G4ParticleGun.hh"
0035 #include "G4ParticleTable.hh"
0036 #include "G4SystemOfUnits.hh"
0037
0038 namespace B2
0039 {
0040
0041 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0042
0043 PrimaryGeneratorAction::PrimaryGeneratorAction()
0044 {
0045   G4int nofParticles = 1;
0046   fParticleGun = new G4ParticleGun(nofParticles);
0047
0048   // default particle kinematic
0049
0050   G4ParticleDefinition* particleDefinition =
0051     G4ParticleTable::GetParticleTable()->FindParticle("proton");
0052
0053   fParticleGun->SetParticleDefinition(particleDefinition);
0054   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
0055   fParticleGun->SetParticleEnergy(3.0 * GeV);
0056 }
0057
0058 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0059
0060 PrimaryGeneratorAction::~PrimaryGeneratorAction()
0061 {
0062   delete fParticleGun;
0063 }
0064
0065 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0066
0067 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* event)
0068 {
0069   // This function is called at the begining of event
0070
0071   // In order to avoid dependence of PrimaryGeneratorAction
0072   // on DetectorConstruction class we get world volume
0073   // from G4LogicalVolumeStore.
0074
0075   G4double worldZHalfLength = 0;
0076   G4LogicalVolume* worldLV = G4LogicalVolumeStore::GetInstance()->GetVolume("World");
0077   G4Box* worldBox = nullptr;
0078   if (worldLV) worldBox = dynamic_cast<G4Box*>(worldLV->GetSolid());
0079   if (worldBox)
0080     worldZHalfLength = worldBox->GetZHalfLength();
0081   else {
0082     G4cerr << "World volume of box not found." << G4endl;
0083     G4cerr << "Perhaps you have changed geometry." << G4endl;
0084     G4cerr << "The gun will be place in the center." << G4endl;
0085   }
0086
0087   // Starting a primary particle close to the world boundary.
0088   //
0089   fParticleGun->SetParticlePosition(G4ThreeVector(0., 0., -worldZHalfLength + 1 * um));
0090
0091   fParticleGun->GeneratePrimaryVertex(event);
0092 }
0093
0094 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0095
0096 }  // namespace B2