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/// \file B1PrimaryGeneratorAction.cc
/// \brief Implementation of the B1PrimaryGeneratorAction class

#include "B1PrimaryGeneratorAction.hh"

#include "G4Box.hh"
#include "G4LogicalVolume.hh"
#include "G4LogicalVolumeStore.hh"
#include "G4ParticleDefinition.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"
#include "G4RunManager.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"

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B1PrimaryGeneratorAction::B1PrimaryGeneratorAction()
  : G4VUserPrimaryGeneratorAction(), fParticleGun(0), fEnvelopeBox(0)
{
  G4int n_particle = 1;
  fParticleGun = new G4ParticleGun(n_particle);

  // default particle kinematic
  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4String particleName;
  G4ParticleDefinition* particle = particleTable->FindParticle(particleName = "gamma");
  fParticleGun->SetParticleDefinition(particle);
  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(0., 0., 1.));
  fParticleGun->SetParticleEnergy(6. * MeV);
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

B1PrimaryGeneratorAction::~B1PrimaryGeneratorAction()
{
  delete fParticleGun;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

void B1PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
  // this function is called at the begining of ecah event
  //

  // In order to avoid dependence of PrimaryGeneratorAction
  // on DetectorConstruction class we get Envelope volume
  // from G4LogicalVolumeStore.

  G4double envSizeXY = 0;
  G4double envSizeZ = 0;

  if (!fEnvelopeBox) {
    G4LogicalVolume* envLV = G4LogicalVolumeStore::GetInstance()->GetVolume("Envelope");
    if (envLV) fEnvelopeBox = dynamic_cast<G4Box*>(envLV->GetSolid());
  }

  if (fEnvelopeBox) {
    envSizeXY = fEnvelopeBox->GetXHalfLength() * 2.;
    envSizeZ = fEnvelopeBox->GetZHalfLength() * 2.;
  }
  else {
    G4ExceptionDescription msg;
    msg << "Envelope volume of box shape not found.\n";
    msg << "Perhaps you have changed geometry.\n";
    msg << "The gun will be place at the center.";
    G4Exception("B1PrimaryGeneratorAction::GeneratePrimaries()", "MyCode0002", JustWarning, msg);
  }

  G4double size = 0.8;
  G4double x0 = size * envSizeXY * (G4UniformRand() - 0.5);
  G4double y0 = size * envSizeXY * (G4UniformRand() - 0.5);
  G4double z0 = -0.5 * envSizeZ;

  fParticleGun->SetParticlePosition(G4ThreeVector(x0, y0, z0));

  fParticleGun->GeneratePrimaryVertex(anEvent);
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
