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//
// $Id: G3toG4PrimaryGeneratorAction.cc,v 1.5 2006/06/29 17:20:26 gunter Exp $
// GEANT4 tag $Name: geant4-09-03-cand-01 $
//

#include "globals.hh"
#include "Randomize.hh"
#include "G3toG4PrimaryGeneratorAction.hh"
#include "G4Event.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"

G3toG4PrimaryGeneratorAction::G3toG4PrimaryGeneratorAction(){
  G4int n_particle = 1;
  particleGun = new G4ParticleGun(n_particle);

  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4String particleName;
  G4ParticleDefinition* particle 
    = particleTable->FindParticle(particleName="chargedgeantino");
  particleGun->SetParticleDefinition(particle);
  G4ThreeVector direction(0, 0, 1);
  particleGun->SetParticleMomentumDirection(direction.unit());
  particleGun->SetParticleEnergy(1.*GeV);
  particleGun->SetParticlePosition(G4ThreeVector(0.*cm, 0.*cm,0.*cm));
}

G3toG4PrimaryGeneratorAction::~G3toG4PrimaryGeneratorAction(){
  delete particleGun;
}

void 
G3toG4PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent){
  //G4ThreeVector direction = GetRandomDirection();
  //particleGun->SetParticleMomentumDirection( direction.unit() ) ;
  G4cout << ">>>>>>>> Primary direction: " 
         << particleGun->GetParticleMomentumDirection() << G4endl;
  particleGun->GeneratePrimaryVertex(anEvent);
}

G4ThreeVector 
G3toG4PrimaryGeneratorAction::GetRandomDirection() {

  G4ThreeVector retval;

  G4double CosTheta;
  G4double SinTheta;

  G4double Phi;
  G4double SinPhi;
  G4double CosPhi;

  G4double rand;

  rand = G4UniformRand();

  CosTheta = 2.0*rand -1.0;
  SinTheta = std::sqrt (1.-CosTheta*CosTheta);
  rand = G4UniformRand();
  Phi = twopi*rand;
  SinPhi = std::sin (Phi);
  CosPhi = std::cos (Phi);
  retval.setX(SinTheta*CosPhi);
  retval.setY(SinTheta*SinPhi);
  retval.setZ(CosTheta);

  return retval;
}