The neutron is believed to have some sort of internal structure. I'm
not up on current quark theory. The free neutron decays with a half
life of ~15 min according to:
n -> p + e + 1.29 MeV, (ignore neutrinos)
That's a lot of energy per unit mass. Fortunately the relatively long
decay time provides some kind of "get away from danger grace time".
However, in the event of a relatively high energy inelastic nuclear
collision, internal resonance states of the neutron might be excited
that might enhance the rate of decay. That would make high kinetic
energy neutrons more dangerous than might be expected from the value
of the kinetic energy alone. I'm thinking of processes that might take
place in less than a millisecond.
My questionis to any quark experts out there: Are internal resonance
states of the neutron known that might effectively 'catalyze' more
rapid release of neutron energy?