Nuclear structure studies for the astrophysical r-process

Abstract

The production of the heaviest elements in nature occurs via the r-process, i.e. a combination of rapid neutron captures, the inverse photodisintegrations, and slower β −-decays, β-delayed processes as well as fission and possibly interactions with intense neutrino fluxes. A correct understanding and modeling requires the knowledge of nuclear properties far from stability and a detailed prescription of the astrophysical environment. Experiments at radioactive ion beam facilities have played a pioneering role in exploring the characteristics of nuclear structure in terms of masses and β-decay properties. Initial examinations paid attention to highly unstable nuclei with magic neutron numbers and their β-decay properties, related to the location and height of r-process peaks, while recent activities focus on the evolution of shell effects at large distances from the valley of stability. We show in site-independent applications the effect of both types of nuclear properties on r-process abundances. Next, we explore also additional nuclear properties in calculations related to possibly “realistic” astrophysical sites representative for the two options of neutron-rich high entropy or low entropy environments like (i) the supernova neutrino wind and (ii) neutron star mergers or possibly also axial jets from proto-neutron stars in supernova explosions. We close with a list of remaining theoretical, experimental and observational challenges needed to overcome for a full understanding of the nature of the r-process.