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//
/// \file fpPrimaryGeneratorAction.cc
/// \brief Implementation of the fpPrimaryGeneratorAction class

#include "fpPrimaryGeneratorAction.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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fpPrimaryGeneratorAction::fpPrimaryGeneratorAction()
: G4VUserPrimaryGeneratorAction(),
  fgun(0)
 
{
   fgun  = new G4ParticleGun();
  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4String particleName;
  G4ParticleDefinition* particle
      = particleTable->FindParticle(particleName = "neutron");
  fgun->SetParticleDefinition(particle);
  
}

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fpPrimaryGeneratorAction::~fpPrimaryGeneratorAction()
{
  delete fgun;
}

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void fpPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
  fgun->SetParticleEnergy(0.144*MeV);

//
//  Neutron Surface Source Uniform Emitting by Area 
//
/*
  rand1 = FLRNDM(XDUMMY)
      rand2 = FLRNDM(XDUMMY)
      IF(rand1.ge.rand2)then
      radius = 3.5 * rand1
      else
      radius = 3.5 * rand2
      endif
      thi = 360 * FLRNDM(XDUMMY) * 3.1415926535 * 2 / 360.
      XBEAM = radius * cos(thi)
      YBEAM = radius * sin(thi)
      ZBEAM = -3.5
      XFLK(NPFLKA) = XBEAM
      YFLK(NPFLKA) = YBEAM
      ZFLK(NPFLKA) = ZBEAM
*/
  double rand1 = G4UniformRand();
  double rand2 = G4UniformRand();
  double xx, yy, zz;
  double radius;
  if (rand1 >= rand2)
      radius = 5 * rand1*cm;
  else
      radius = 5 * rand2*cm;
  double thi = 360 * G4UniformRand() * 3.1415926535 * 2 / 360.;
      xx = radius * cos(thi);
      yy = radius * sin(thi);
      zz = -2.6 * cm;


  fgun->SetParticlePosition(G4ThreeVector(xx,yy,zz));
  fgun->SetParticleMomentumDirection(G4ThreeVector(0, 0, 1));
  
  

  fgun->GeneratePrimaryVertex(anEvent);
}

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