Nuclear deformations in the region of the A=160 r-process abundance peak

Abstract

In the abundance spectrum of r-process nuclei the most prominent features are the peaks that form when the r-process flow passes through the closed neutron shells. However, there are also other features in the abundance spectrum that cannot be explained by shell effects; for example, the peak in the region of the rare-earth nuclei around mass A=160. It has been argued that this peak is related to the deformation maximum of the neutron-rich isotopes. In recent years, both experimental and theoretical work has been carried out to study the deformation of neutron-rich rare-earth nuclei and to search for the point of maximum deformation. This work has focused on the nuclei around 170Dy with the aim of understanding the evolution of collectivity in the neutron shell with 82<N<126. These investigations will be discussed in terms of the Harris parameters of the variable moment of inertia model. Finally, we will discuss the possibility of reaching further into the neutron-rich rare-earth region in the future at the new experimental facilities using radioactive beams.