Vibrational, intruder structures in ¹¹⁶Cd

Decay properties of multiphonon quadrupole vibrational states and intruder structures in ¹¹⁶Cd have been examined with the (n,n′ γ) reaction, γ-ray excitation functions, angular distributions, and γ-γ coincidences have been measured. Lifetimes of many levels were determined with the Doppler-shift attenuation method, exposing the degree of collectivity of the intruder structure and the three-phonon states. In combination with other recent results, this new information reveals that the intruder picture is well supported in the Cd nuclei. However, a puzzle not present in the lighter Cd nuclei emerges in ¹¹⁶Cd; strong configuration mixing between intruder and multiphonon vibrational excitations cannot describe the observed decays of the lowest 0⁺ excited states.