fanoCavity/src/PrimaryGeneratorAction.cc

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0025 //
0026 /// \file PrimaryGeneratorAction.cc
0027 /// \brief Implementation of the PrimaryGeneratorAction class
0028
0029 #include "PrimaryGeneratorAction.hh"
0030
0031 #include "DetectorConstruction.hh"
0032 #include "PrimaryGeneratorMessenger.hh"
0033
0034 #include "G4Event.hh"
0035 #include "G4ParticleDefinition.hh"
0036 #include "G4ParticleGun.hh"
0037 #include "G4ParticleTable.hh"
0038 #include "G4PhysicalConstants.hh"
0039 #include "G4SystemOfUnits.hh"
0040 #include "Randomize.hh"
0041
0042 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0043
0044 PrimaryGeneratorAction::PrimaryGeneratorAction(DetectorConstruction* det)
0045   : fParticleGun(0), fDetector(det), fGunMessenger(0)
0046 {
0047   fParticleGun = new G4ParticleGun(1);
0048   G4ParticleDefinition* particle = G4ParticleTable::GetParticleTable()->FindParticle("gamma");
0049   fParticleGun->SetParticleDefinition(particle);
0050   fParticleGun->SetParticleEnergy(1.25 * MeV);
0051   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
0052
0053   fRBeam = 1.;
0054
0055   // create a messenger for this class
0056   fGunMessenger = new PrimaryGeneratorMessenger(this);
0057 }
0058
0059 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0060
0061 PrimaryGeneratorAction::~PrimaryGeneratorAction()
0062 {
0063   delete fParticleGun;
0064   delete fGunMessenger;
0065 }
0066
0067 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0068
0069 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
0070 {
0071   // this function is called at the begining of event
0072   //
0073   G4double z0 = -0.5 * (fDetector->GetTotalThickness());
0074   G4double x0 = 0. * cm, y0 = 0. * cm;
0075
0076   // beam width
0077   //
0078   if (fRBeam > 0.) {
0079     G4double beam = fRBeam * (fDetector->GetWallRadius());
0080     G4double r = beam * std::sqrt(G4UniformRand());
0081     G4double theta = twopi * G4UniformRand();
0082     x0 = r * std::cos(theta);
0083     y0 = r * std::sin(theta);
0084   }
0085   fParticleGun->SetParticlePosition(G4ThreeVector(x0, y0, z0));
0086   fParticleGun->GeneratePrimaryVertex(anEvent);
0087 }
0088
0089 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......