electronScattering/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 "G4ParticleTable.hh"
0037 #include "G4SystemOfUnits.hh"
0038 #include "Randomize.hh"
0039
0040 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0041
0042 PrimaryGeneratorAction::PrimaryGeneratorAction(DetectorConstruction* DC)
0043   : fParticleGun(0), fDetector(DC), fGunMessenger(0)
0044 {
0045   fParticleGun = new G4ParticleGun(1);
0046
0047   G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
0048   G4ParticleDefinition* particle = particleTable->FindParticle("e-");
0049   fParticleGun->SetParticleDefinition(particle);
0050   fParticleGun->SetParticleEnergy(20. * MeV);
0051   fZ0 = -0.5 * (fDetector->GetThicknessWorld());
0052   fParticleGun->SetParticlePosition(G4ThreeVector(0 * cm, 0 * cm, fZ0));
0053   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
0054
0055   G4double radiusWorld = fDetector->GetRadiusWorld();
0056   fR2World = radiusWorld * radiusWorld;
0057   fRndmBeam = 420 * um;
0058
0059   // create a messenger for this class
0060   fGunMessenger = new PrimaryGeneratorMessenger(this);
0061 }
0062
0063 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0064
0065 PrimaryGeneratorAction::~PrimaryGeneratorAction()
0066 {
0067   delete fParticleGun;
0068   delete fGunMessenger;
0069 }
0070
0071 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0072
0073 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
0074 {
0075   // this function is called at the begining of event
0076   //
0077   // randomize beam, if requested.
0078   if (fRndmBeam > 0.) {
0079     G4double s_proj = fRndmBeam / std::sqrt(2.);
0080     G4double x0, y0;
0081     do {
0082       x0 = G4RandGauss::shoot(0., s_proj);
0083       y0 = G4RandGauss::shoot(0., s_proj);
0084     } while ((x0 * x0 + y0 * y0) > fR2World);
0085     fParticleGun->SetParticlePosition(G4ThreeVector(x0, y0, fZ0));
0086   }
0087
0088   fParticleGun->GeneratePrimaryVertex(anEvent);
0089 }
0090
0091 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......