Detailed spectroscopy of 110Cd: Evidence for weak mixing and the emergence of γ-soft behavior

A study of the β⁺-electron capture decay of 110In into levels of 110Cd is combined with a reanalysis of data from a previous study of 110Cd with the (n,n′γ) reaction with monoenergetic neutrons. The γγ coincidences from the 110In decay leads to many new assignments of γ rays observed in the (n,n′γ) reaction, permitting the observation of weak low-energy transitions, and setting stringent upper limits on unobserved decay branches. The uncertainties on many of the lifetimes from the (n,n′γ) reaction are significantly reduced, and limits are established for the lifetimes of levels too long for a direct measurement. The absence of enhanced transitions between the previously assigned phonon states and the deformed intruder states strongly suggests that mixing between the configurations is generally weak, refuting the strong-mixing scenario as an explanation of the decay pattern of the excited 0⁺ states in 110Cd. The decay pattern of the nonintruder states is suggestive of a γ-soft rotor, or O(6) nucleus, rather than a vibrational, or U(5), pattern. The existence of a four-particle-six-hole proton excitation in 110Cd is also suggested.