Muon-induced prompt fission of uranium

The prompt-fission probabilities of muonic ²³⁸U in radiationless dipole and quadrupole transitions of the muon are calculated. The 3d → 1s transition is found to dominate, in agreement with experiment. A measured drastic enhancement in the $\text{Γ}{}_{\mathrm{<mtext>n</mtext>}}\text{Γ}{}_{\mathrm{<mtext>f</mtext>}}$ ratio compared to photofission data is reproduced in terms of the increase of the fission barrier in the presence of the muon.