From detailed spectroscopy of ${}^{110}\mathrm{Cd}$ and ${}^{112}\mathrm{Cd}$ following the ${\beta }^{+}/\mathrm{EC}$ decay of ${}^{110,112}\mathrm{In}$ and the ${\beta }^{-}$ decay of ${}^{112}\mathrm{Ag}$, the presence of very weak decay branches from nonyrast states is revealed. In ${}^{112}\mathrm{Cd}$, $2_5^{+}\to 0_4^{+}$ and $4_6^{+}\to 2_5^{+}$ transitions are observed that yield $B(E2;2_5^{+}\to 0_4^{+})=34\pm 15$ W.u. and $B(E2;4_6^{+}\to 2_5^{+})=77\pm 30$ W.u., respectively, clearly indicating a collective structure. In ${}^{110}\mathrm{Cd}$, a weak decay branch from the $4_6^{+}$ level to the $2_5^{+}$ level is observed, and from a lifetime measurement following the $(n,n^{\prime }\gamma )$ reaction, $B(E2;4_6^{+}\to 2_5^{+})=55\pm 14$ W.u. is determined. A new branch is also observed for the decay of the $6_4^{+}$ level to the $4_6^{+}$ state, indicating that the sequence $2_5^{+}$, $4_6^{+}$, and $6_4^{+}$ forms part of a collective structure. The presence of $3_3^{+}$ and $5_2^{+}$ levels spaced between the previous sequence is highly suggestive of a $\gamma$ band built on the $0_2^{+}$ shape-coexisting intruder state. The $0_4^{+}$ levels in ${}^{110,112,114}\mathrm{Cd}$ have preferred decays to the lowest $2^{+}$ members of the intruder bands, and for ${}^{114}\mathrm{Cd}$ a previous measurement had established an enhanced $B(E2;0_4^{+}\to 2_3^{+})$. The energy systematics of the $0_2^{+}$, $0_3^{+}$, and $0_4^{+}$ levels all display the characteristic parabolic-shaped pattern, suggesting that they are built on multiparticle-multihole proton excitations. The results are compared with beyond-mean-field calculations that reproduce qualitatively the observed levels and their decays and suggest that the $0_1^{+}$, $0_2^{+}$, $0_3^{+}$, and $0_4^{+}$ levels and the excited states built on them possess different deformations.

• Received 29 June 2019
• Revised 26 December 2019
• Accepted 20 February 2020

DOI:https://doi.org/10.1103/PhysRevC.101.044302