Undergrad Neutrons and neutron interactions

[Bashayer Abdullah]

TL;DR

Does one neutron or more than one make different when they interact with the nuclei?

Does one neutron or more than one make different when they interact with the nuclei? what is the result that could happen if one neutron or neutrons hit the nuclei? I'm not sure but I think the neutrons are the most confusing particles to deal with.

I wish you guys can help me

Thanks

 

[vanhees71]

I don't know, what you are after, but neutrons are not so puzzling after all. From the point of view of the strong interaction it's (almost) just like a proton.

 

[mfb]

You mean more than one neutron hitting a nucleus at the same time (within the nuclear interaction time)? That is incredibly unlikely. A nucleus can absorb two neutrons at the same, or absorb one and scatter one, scatter both, and various other options depending on the energies.

 

[Bashayer Abdullah]

You mean more than one neutron hitting a nucleus at the same time (within the nuclear interaction time)? That is incredibly unlikely. A nucleus can absorb two neutrons at the same, or absorb one and scatter one, scatter both, and various other options depending on the energies.

Thank you for your reply,
And yes that was exactly what I mean in my question
Do you mean the energy of the nuclei? And what about if the nuclei was light or heavy?

 

[mfb]

What can happen depends on the type and state of the initial nucleus and the overall energy involved (which mainly depends on the energy of the neutrons). There is no general pattern that would depend on the mass of the nucleus.

 

[snorkack]

You mean more than one neutron hitting a nucleus at the same time (within the nuclear interaction time)? That is incredibly unlikely.

Difficult, but must happens at relevant amount. Otherwise, why doesn´ t r-process terminate at He-3?
Think of it. One neutron beta decays to proton and picks up two neutrons - to triton.
And H-4 is unbound. t beta decay halflife is 12 years, far above the 10 minute half-life of neutron or of the explosive disassembly time of kilonova.
Even if a few t decay to He-3, first of all the best reaction path for neutron capture of He-3 is (n, p) back to t, not (n, γ) to α. And even if a few α do form, He-5 is unbound again.

On the other hand, if you somehow could add two neutrons at a nucleus within a nuclear interaction time... note that while He-5 is unbound, He-6 is bound (and beta active).

So how does r-process get across the long-lived neutron dripline nuclei t and α?

 

[mfb]

The r-process doesn't involve helium at all. It starts with nuclei around iron.