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Re: Question Cf 252 Neutron Source (Eric)
Re: Feedback Re: Cf 252 Neutron Source (Michael H. Kelsey)
Date: 06 Oct, 2011
From: Michael H. Kelsey <Michael H. Kelsey>

On Wed, 20 Jul 2011 03:45:02 GMT, Michael H. Kelsey wrote:
> On Tue, 19 Jul 2011 23:06:05 GMT, Eric wrote:
> 
> > I need to define a Cf 252 neutron source, and haven't been successful.
> > In previous sims, I've been dealing mostly with monoenergetic things
> > (ie, Cs137, I would just define a 662 kev gamma and call it good), but
> > there should be a range of values for Cf 252.
> > 
> > I've defined the source using something like:
> > ----------------------------------------------------
> > particleGun->SetParticleEnergy(some value*eV);
> > particleGun-> SetParticlePosition(G4ThreeVector(0.,0.,0);
> > particleGun->SetParticleMomentumDirection(G4ThreeVector(0.,0.,1));
> > 
> > G4int Z=98, A=252;
> > G4double ionCharge = 1.*eplus;
> > G4double excitEnergy= 0.*keV;
> > 
> > G4ParticleDefinition* ion =
> > G4ParticleTable::GetParticleTable()->GetIon(Z,A,excitEnergy);
> > particleGun->SetParticleDefinition(ion);
> > particleGun->SetParticleCharge(ionCharge);
> > 
> > particleGun-> GeneratePrimaryVertex(anEvent);
> > ----------------------------------------------------
> > 
> > Which gives me an ion, in the simulation, of Cf252, but doesn't emit a
> > range of low energy neutrons. I haven't found a good example showing how
> > to do this... anyone have any insight?
> 
> Take a look at examples/extended/radioactivedecay/rdecay01. You need to
> have included G4RadioactiveDecay in your PhysicsList, and you need to
> enable it for your geometry (either all volumes or just your source).

Well, I'm now suitably embarrassed :-( This week, I've started working with a Cf-252 source in my own simulation, and the advice I gave you won't work, at least not in GEANT4 9.4. With |/grdm/verbose 1|, I get the following message:

  G4RadioactiveDecay::DecayIt : Cf252[0.0] is not a valid nucleus for the RDM

So apparently in 9.4 RDM doesn't know how to deal with spontaneous fission and neutron emission. I will inquire further with the experts and see if this is going to be resolved in 9.5.

-- Michael Kelsey

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1 None: Re: Cf 252 Neutron Source   (michel maire - 07 Oct, 2011)
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