Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei

Università degli Studi di Milano and INFN, Sezione di Milano, Milano, Italy

Published online: 11 May 2016

Abstract

The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as ^47,49Ca, ¹³³Sb and ²¹⁰Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of ²³⁵U and ²⁴¹Pu targets), with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of ¹³³Sb, a new microscopic “hybrid” model is introduced: it is based on the coupling between core excitations (both collective and non-collective) of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.