//
// ********************************************************************
// * DISCLAIMER                                                       *
// *                                                                  *
// * The following disclaimer summarizes all the specific disclaimers *
// * of contributors to this software. The specific disclaimers,which *
// * govern, are listed with their locations in:                      *
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// *                                                                  *
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//
// $Id: PrimaryGeneratorAction.cc,v 1.1 2004/06/14 10:09:27 maire Exp $
// GEANT4 tag $Name: geant4-06-02 $
// 
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#include "PrimaryGeneratorAction.hh"

#include "DetectorConstruction.hh"

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

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PrimaryGeneratorAction::PrimaryGeneratorAction(DetectorConstruction* det)
:detector(det)					       
{
  particleGun  = new G4ParticleGun(1);
  G4ParticleDefinition* particle
           = G4ParticleTable::GetParticleTable()->FindParticle("mu+");
  particleGun->SetParticleDefinition(particle);
  particleGun->SetParticleEnergy(10*TeV);    
  particleGun->SetParticleMomentumDirection(G4ThreeVector(1.,0.,0.));
}

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

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void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
  //this function is called at the begining of event
  //
  G4double halfSize = 0.5*(detector->GetSize());
  G4double x0 = - halfSize;
  
  //randomize (y0,z0)
  //
  G4double beam = 0.8*halfSize; 
  G4double y0 = (2*G4UniformRand()-1.)*beam;
  G4double z0 = (2*G4UniformRand()-1.)*beam;
  
  particleGun->SetParticlePosition(G4ThreeVector(x0,y0,z0));
  particleGun->GeneratePrimaryVertex(anEvent);
}

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