Blocking of coupling to the 02 + excitation in 154Gd by the [505]11/2- neutron in 155Gd

Abstract

The concept that the first excited 0+ states in N = 90 nuclei arenot a ?-vibration but a second vacuum formed by the combination ofthe quadrupole pairing force and the low density of oblate orbitalsnear the Fermi surface is supported by the blocking of this collectivemode in 154Gd from coupling to the [505]11/2 ? single-particle quasi-neutronorbital in 155Gd. The coupling of this orbital to the 2+ ?-vibrationin 154Gd is observed since this coupling is not Pauli-blocked.