Radioactive Neutron Source Cf252

How can I make neutron radioactive source Cf252 in GEANT4 simulation?

With G4ParticleGun, write your PrimaryGeneratorAction to set the particle definition in the first event, not during initialization. But note that you’re going to get quite low efficiency: First, radioactive decays are isotropic, so you won’t get a “neutron beam”. Second, the Cf-252 spontaneous fission rate is only 3.9%, so you’re going to get almost entirely alpha decay chains, not neutrons.

If you really only care about the neutrons, you might want to consider using G4GeneralParticleSource, and creating an energy histogram for the neutron spectrum. You won’t get the correlations or the neutron multiplicity that you would from Cf-252 decays, but if your target is relatively far from the source, that’s probably not a big deal.

You may have a look at examples/extended/hadronic/NeutronSource

@maire @mkelsey I am new to GEANT4 and using geant4.10.05 version.

I am using NeutronSource example and I did one line modification in file.

> void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
  //particle type
  if (fParticleGun->GetParticleDefinition() == G4Geantino::Geantino()) {
    //G4int Z = 95, A = 241;
    G4int Z = 98, A = 252;   //This is one line modification
    G4double ionCharge   = 0.*eplus;
    G4double excitEnergy = 0.*keV;

    G4ParticleDefinition* ion
       = G4IonTable::GetIonTable()->GetIon(Z,A,excitEnergy);

I am not getting any generated neutron even after running 10,00,000 events. Also, I tried to make a histogram of the generated alpha particles and I found it empty. But when I am using the Am-Be source, in that case, around 100 neutrons are generated for 10k events.

Do I need to add some PhysicsList? Thanks very much in advance.

Here, a macro for NeutronSource and its printout.
kumar.mac.txt (358 Bytes)
kumar.out.txt (5.0 KB)

@maire @mkelsey Thank you very much for your help.

This macro file is working in GEANT4.10.06 or above release but not working with the lower release. The reason behind this is available at Spontaneous fission in GEANT4