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/// \file electromagnetic/TestEm16/src/PrimaryGeneratorAction.cc
/// \brief Implementation of the PrimaryGeneratorAction class
//
//
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#include "PrimaryGeneratorAction.hh"

#include "DetectorConstruction.hh"

#include "G4Event.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"
#include "G4SystemOfUnits.hh"

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PrimaryGeneratorAction::PrimaryGeneratorAction(DetectorConstruction* DC)
:G4VUserPrimaryGeneratorAction(),fParticleGun(0),fDetector(DC)
{
  fParticleGun  = new G4ParticleGun(1);
  G4ParticleDefinition* particle
           = G4ParticleTable::GetParticleTable()->FindParticle("e+");
  fParticleGun->SetParticleDefinition(particle);
  fParticleGun->SetParticleEnergy(10*GeV);

  //set the initial gun position and direction.
  G4double x0 = -0.5*(fDetector->GetSize());
  G4double y0 = 0.*cm, z0 = 0.*cm;
  fParticleGun->SetParticlePosition(G4ThreeVector(x0,y0,z0));
  fParticleGun->SetParticleMomentumDirection(G4ThreeVector(1.,0.,0.));
}

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

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void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
  //this function is called at the beginning of event
  fParticleGun->GeneratePrimaryVertex(anEvent);
}

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