Systematic study of low-spin states in even Cd nuclei

Low-lying low-spin collective states in even ${}_{}{}^{106\mathrm{-}112}{}_{}{}^{}\mathrm{Cd}$ and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Cd}$ were investigated using in-beam and off-beam γ-ray and conversion-electron spectroscopy. New spin assignments and decay branching ratios for the levels in ${}_{}{}^{106}{}_{}{}^{}\mathrm{Cd}$, ${}_{}{}^{108}{}_{}{}^{}\mathrm{Cd}$, ${}_{}{}^{110}{}_{}{}^{}\mathrm{Cd}$, and ${}_{}{}^{112}{}_{}{}^{}\mathrm{Cd}$ were obtained. The present results essentially complement the level systematics from ${}_{}{}^{106}{}_{}{}^{}\mathrm{Cd}$ to ${}_{}{}^{120}{}_{}{}^{}\mathrm{Cd}$. From the new data, it is inferred that two sets of low-lying $0^{+}$ states having different excitation characteristics cross between ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$ and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Cd}$. No corresponding crossing occurs on the neutron deficient side. New evidence for the existence of the proton-intruder states has been found.