Configuration Mixing of Two-Quasiparticle States inCf250

The interaction of a $K^{\pi }=5^{-}$ two-quasiproton band with a $K^{\pi }=5^{-}$ two-quasineutron band in ${}_{}{}^{250}{}_{}{}^{}\mathrm{Cf}$ has been observed using proton and neutron transfer reactions and radioactive-decay measurements. Configuration-mixing calculations using a two-body neutron-proton force give an interaction matrix element in good agreement with the value derived from our measurements.