Nuclear astrophysics and the Oslo method : A study on experimental and theoretical radiative neutron-capture rates and their role in heavy-element nucleosynthesis

Abstract

The subject of heavy-element nucleosynthesis still holds many mysteries. Part is due to the difficulty of simulating the astrophysical scenarios where it takes place, and part is because the relevant properties of the involved nuclei are mostly unknown for some of the main nucleosynthesis processes. Neutron-capture rates are one of these properties, and while described by theoretical models, these do not necessarily agree with each other or with experimental results. Experimental data are therefore central to both the correct simulation of heavy-element nucleosynthesis, and the development of more predictive models. Experimental nuclear level densities and γ-ray strength functions are in this regard interesting quantities in the context of nuclear structure and because they provide the input for calculating neutron-capture rates for exotic, neutron-rich nuclei. These two quantities can be obtained by analyzing data from particle-γ experiments using the Oslo method. Thanks to the results from three experiments carried out at the Oslo Cyclotron Laboratory and from a sensitivity study of the rapid neutron-capture process using a model-consistent approach, we are able to better explain the creation of heavy elements in the universe.