sdcounters/src/PrimaryGeneratorAction.cc

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0025 //
0026 // The `molcounters` example(s) are provided as part of Geant4-DNA
0027 // and any report or published result obtained using it shall cite
0028 // the respective Geant4-DNA collaboration publications.
0029 //
0030 // Reports or results obtained using the spatially-aware `MoleculeCounter`
0031 // provided in this example, shall further cite:
0032 //
0033 // Velten & Tomé, Radiation Physics and Chemistry, 2023 (10.1016/j.radphyschem.2023.111194)
0034 //
0035 //
0036 // Author: Christian Velten (2025)
0037 //
0038
0039 #include "PrimaryGeneratorAction.hh"
0040
0041 #include "G4ParticleDefinition.hh"
0042 #include "G4ParticleGun.hh"
0043 #include "G4ParticleTable.hh"
0044 #include "G4SystemOfUnits.hh"
0045 #include "Randomize.hh"
0046 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0047 PrimaryGeneratorAction::PrimaryGeneratorAction() : G4VUserPrimaryGeneratorAction()
0048 {
0049   G4int n_particle = 1;
0050   fParticleGun = std::make_unique<G4ParticleGun>(n_particle);
0051
0052   // default particle kinematic
0053   G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
0054   G4ParticleDefinition* particle = particleTable->FindParticle("e-");
0055   fParticleGun->SetParticleDefinition(particle);
0056   fParticleGun->SetParticlePosition(G4ThreeVector(0., 0., 0.));
0057   fParticleGun->SetParticleEnergy(100 * keV);
0058   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
0059 }
0060 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0061 void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
0062 {
0063   auto phi = CLHEP::twopi * G4UniformRand();
0064   auto cosTheta = 2 * G4UniformRand() - 1;
0065   auto sinTheta = std::sqrt(1 - cosTheta * cosTheta);
0066   auto ux = sinTheta * std::cos(phi);
0067   auto uy = sinTheta * std::sin(phi);
0068   auto uz = cosTheta;
0069
0070   fParticleGun->SetParticleMomentumDirection(G4ThreeVector(ux, uy, uz));
0071   fParticleGun->GeneratePrimaryVertex(anEvent);
0072 }
0073 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......