Local suppression of collectivity in the N=80 isotones at the Z=58 subshell closure

Abstract

Background: Recent data on N = 80 isotones have suggested that the proton π(1g7/2) subshell closure at Z = 58 has an impact on the properties of low-lying collective states. Purpose: Knowledge of the B(E2; 2+ 1 → 0+ 1 ) value of 140Nd is needed in order to test this conjecture. Method: The unstable, neutron-rich nucleus 140Nd was investigated via projectile Coulomb excitation at the REX-ISOLDE facility with the MINIBALL spectrometer. Results: The B(E2) value of 33(2) W.u. expands the N = 80 systematics beyond the Z = 58 subshell closure. Conclusions: The measurement demonstrates that the reduced collectivity of 138Ce is a local effect possibly due to the Z = 58 subshell closure and requests refined theoretical calculations. The latter predict a smoothly increasing trend.