Phase change near $N=70$ in the wave function of the $I^{\pi }=11/2^{-}$ isomers along the cadmium-isotope chain

Abstract

The electromagnetic features of the $11/2^{-}$ isomers in the ${}^{111-127}$Cd isotopes are reproduced by numerically optimized shell-model wave-functions. A sudden phase change of the wave functions at $N=70$ is identified and further confirmed by the evolution of B(E2, $7/2_1^{-}\to 11/2_1^{-}$) values. This phase change gives rise to different linear relations for the $Q$ and $\mu$ values with $N<70$ and $N>70$, as needed to reproduce the experimental data. The particle-hole transformation properties for $h_{11/2}$ neutrons in a well-isolated subshell involving degenerate $s_{1/2}$, $d_{3/2}$, $d_{5/2}$ and $h_{11/2}$ orbits is suggested as a possible explanation for this phase change.

Comments: 5 pages, 3 figures, regular article