Intruder And Multiphonon States In ~(108)Cd

摘要

~(108)Cd was investigated using the powerful combination of two complementary experimental techniques: γγ-spectroscopy following the β-decay of ~(108)In and the non-selective (α, n) fusion evaporation reaction. This resulted in the observation of 120 new states and more than 580 new transitions. 30 new spin assignments and more than 80 multipole mixing ratios were derived from γγ-angular correlation analyses and eight effective lifetimes stem from a Doppler Shift Attenuation (DSA) analysis following the fusion evaporation reaction. The proton 2p-2h excited intruder band, which is typical for near proton-magic nuclei with a sizable imbalance between valence protons and neutrons, was established up to the 4~+ member including lower limits for the absolute E2 transition strengths of interband and intraband decays. The heavily suppressed absolute E2 transition strength out of the proposed intruder band indicates pure bands with little mixing. These findings are compared to neighboring Cd isotopes and related six quasi-proton structures. An analysis of the multi-phonon structures observed in ~(108)Cd and heavier Cd isotopes shows that the chain of even mass cadmium isotopes may form a transitional path between the vibrational U(5) and gamma-unstable O(6) dynamical symmetry with 108Cd closer to the gamma-soft case.