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// $Id: PrimaryGeneratorAction.cc,v 1.6 2006/06/29 16:50:44 gunter Exp $
// GEANT4 tag $Name:  $
//
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#include "PrimaryGeneratorAction.hh"

#include "DetectorConstruction.hh"
#include "G4Event.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"

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PrimaryGeneratorAction::PrimaryGeneratorAction (DetectorConstruction* det)
:detector(det)
{
  G4int n_particle = 1;
  particleGun  = new G4ParticleGun(n_particle);

  G4ParticleDefinition* particle
                 = G4ParticleTable::GetParticleTable()->FindParticle("e-");
  particleGun->SetParticleDefinition(particle);
  particleGun->SetParticleEnergy(5.*GeV);  
  particleGun->SetParticlePosition(initPos = G4ThreeVector(-1*cm,-1*cm,-1*cm));  
  particleGun->SetParticleMomentumDirection(G4ThreeVector(0.,0.,1.));
}

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

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void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
  //this function is called at the begin of event
  //
  if (particleGun->GetParticlePosition() == initPos) {
    G4double position = -0.5*(detector->GetfullLength());
    particleGun->SetParticlePosition(G4ThreeVector(0.*cm,0.*cm,position));
  }       
  particleGun->GeneratePrimaryVertex(anEvent);
}

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