extended/visualization/userVisAction/src/B1PrimaryGeneratorAction.cc

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// $Id: B1PrimaryGeneratorAction.cc 69587 2013-05-08 14:26:03Z gcosmo $
//
/// \file B1PrimaryGeneratorAction.cc
/// \brief Implementation of the B1PrimaryGeneratorAction class

#include "B1PrimaryGeneratorAction.hh"

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

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B1PrimaryGeneratorAction* B1PrimaryGeneratorAction::fgInstance = 0;

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const B1PrimaryGeneratorAction* B1PrimaryGeneratorAction::Instance()
{
// Static acces function via G4RunManager 

  return fgInstance;
}      

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B1PrimaryGeneratorAction::B1PrimaryGeneratorAction()
: G4VUserPrimaryGeneratorAction(),
  fParticleGun(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);
  
  fgInstance = this;
}

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B1PrimaryGeneratorAction::~B1PrimaryGeneratorAction()
{
  delete fParticleGun;
  fgInstance = 0;
}

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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;
  G4LogicalVolume* envLV
    = G4LogicalVolumeStore::GetInstance()->GetVolume("Envelope");
  G4Box* envBox = NULL;
  if ( envLV ) envBox = dynamic_cast<G4Box*>(envLV->GetSolid());
  if ( envBox ) {
    envSizeXY = envBox->GetXHalfLength()*2.;
    envSizeZ = envBox->GetZHalfLength()*2.;
  }  
  else  {
    G4cerr << "Envelope volume of box shape not found." << G4endl;
    G4cerr << "Perhaps you have changed geometry." << G4endl;
    G4cerr << "The gun will be place in the center." << G4endl;
  }

  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);
}

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