#include "PrimaryGeneratorAction.hh"
#include "G4LogicalVolumeStore.hh"
#include "G4LogicalVolume.hh"
#include "G4Box.hh"
#include "G4RunManager.hh"
#include "G4GeneralParticleSource.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

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PrimaryGeneratorAction::PrimaryGeneratorAction()
: G4VUserPrimaryGeneratorAction(),
  fGPS(0)
{
  // Initialize the general particle source
  fGPS = new G4GeneralParticleSource();

  // Set the particle type to gamma
  G4ParticleDefinition* particle
    = G4ParticleTable::GetParticleTable()->FindParticle("gamma");
  fGPS->SetParticleDefinition(particle);

  // Set the energy of the gamma particles to 511 keV
  fGPS->GetCurrentSource()->GetEneDist()->SetMonoEnergy(511 * keV);

  // Set the initial position of the particles (e.g., at the origin)
  fGPS->SetParticlePosition(G4ThreeVector(0., 0., 0.));

  // Optionally, set the direction of the particles (e.g., along the z-axis)
  fGPS->GetCurrentSource()->GetAngDist()->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
}

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PrimaryGeneratorAction::~PrimaryGeneratorAction()
{
  delete fGPS;
}

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void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
  // Generate the primary vertex for the event
  fGPS->GeneratePrimaryVertex(anEvent);
}