On "Sub-Threshold" Reactions Involving Nuclear Fission

We analyze reactions of several types that are naively below threshold but can proceed because of the release of binding energy from nuclear fission and occasionally the formation of Coulombic bound states. These reactions include (i) photofission with pion production and (ii) charged current neutrino-nucleus reactions that lead to fission and/or formation of a Coulomb bound state of a $\mu^-$ with the nucleus of a fission fragment. We comment on the possible experimental observation of these reactions.