B2b/src/PrimaryGeneratorAction.cc

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0027 /// \file B2/B2b/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 #include "globals.hh"
0039
0040 namespace B2
0041 {
0042
0043 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0044
0045 PrimaryGeneratorAction::PrimaryGeneratorAction()
0046 {
0047   G4int nofParticles = 1;
0048   fParticleGun = new G4ParticleGun(nofParticles);
0049
0050   // default particle kinematic
0051
0052   G4ParticleDefinition* particleDefinition =
0053     G4ParticleTable::GetParticleTable()->FindParticle("proton");
0054
0055   fParticleGun->SetParticleDefinition(particleDefinition);
0056   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
0057   fParticleGun->SetParticleEnergy(3.0 * GeV);
0058 }
0059
0060 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0061
0062 PrimaryGeneratorAction::~PrimaryGeneratorAction()
0063 {
0064   delete fParticleGun;
0065 }
0066
0067 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0068
0069 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* event)
0070 {
0071   // This function is called at the begining of event
0072
0073   // In order to avoid dependence of PrimaryGeneratorAction
0074   // on DetectorConstruction class we get world volume
0075   // from G4LogicalVolumeStore.
0076
0077   G4double worldZHalfLength = 0;
0078   G4LogicalVolume* worldLV = G4LogicalVolumeStore::GetInstance()->GetVolume("World");
0079   G4Box* worldBox = nullptr;
0080   if (worldLV) worldBox = dynamic_cast<G4Box*>(worldLV->GetSolid());
0081   if (worldBox)
0082     worldZHalfLength = worldBox->GetZHalfLength();
0083   else {
0084     G4cerr << "World volume of box not found." << G4endl;
0085     G4cerr << "Perhaps you have changed geometry." << G4endl;
0086     G4cerr << "The gun will be place in the center." << G4endl;
0087   }
0088
0089   // Starting a primary particle close to the world boundary.
0090   //
0091   fParticleGun->SetParticlePosition(G4ThreeVector(0., 0., -worldZHalfLength + 1 * um));
0092
0093   fParticleGun->GeneratePrimaryVertex(event);
0094 }
0095
0096 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0097
0098 }  // namespace B2