Why do some nuclei decay by Neutron Emission?

Question

Alright so I am confused somewhat about Neutron Heavy Nuclei not decaying, or more specifically why it is that Neutron Heavy Nuclei sometimes decay by emitting Neutrons.

Someone has already answered why neutron-heavy nuclei decay in general, weak force beta decay basically happens until it can't, but I do not understand why neutron heavy nuclei can, sometimes, emit Neutrons. I am talking about the light elements that have neutron upon neutron upon neutron. Hydrogen Isotopes beyond Tritium decay by Neutron Emission, why? Why doesn't it decay by beta decay? Why do other neutron heavy light elements perform neutron emission?

Answer 1

I’m not an expert but I’ll attempt to answer this. The reason is simply that emitting nucleons is a strong force interaction, while beta decay is a weak interaction, and the strong force is orders of magnitudes faster then the weak force, and therefore typically acts on a much shorter timescale. It’s similar to the reason why deuterium fusion rarely produces helium-4.