Nuclear Physics Data Relevant to r-Process Nucleosynthesis

Abstract

Abstract. The production of about half of the heavy elements in nature occurs via the r-process, i.e. a combination of rapid neutron captures, inverse photodisintegrations, and slower β -decays, β -delayed processes as well as fission and possibly interactions with neutrino fluxes. A correct understanding and modelling of this nucleosynthesis process requires the knowledge of nuclear properties far from stability and a detailed description of the astrophysical environments. 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 short-lived "waiting-point" nuclei with magic neutron numbers related to the location and height of the solar-system r-process abundance peaks, while more recent activities, mainly in the 132 Sn region, focus on the evolution of shell effects as a function of isospin. In this context, shape transitions and the erosion of the classical shell gaps with possible occurrence of new magic numbers play an important role. Consequences of improved theoretical and experimental nuclear data on calculations of the r-process matter flow will be presented, and the applicability of the long-lived actinides 232 Th and 238 U as cosmo-chronometers will be discussed.