Average properties of nuclear states in the quasi-continuum region

Abstract

Intense effort to explore the atomic nucleus has persisted through the past century. Despite of the great efforts, there still remains many open questions regarding the properties of the nucleus. In particular, the low energy region of excited nuclei is a poorly known area. In this thesis we have used two complimentary techniques to investigate nuclear structure in the low energy region. Through 3He induced reactions we apply the so-called Oslo method to extract nuclear properties at excitation energies below the neutron separation threshold. Beyond the neutron threshold we have used photo-neutron experiments and studied nuclei with energies up to 13 MeV. The new experimental data reviles special excitation modes of the nucleus, also known as resonances, some of which cannot be explained by existing theoretical models. Furthermore, radiative neutron capture cross sections, relevant for astrophysical calculations, are extracted by use of the reaction code TALYS. Astrophysical reaction rates are also calculated, and we find that resonance features in the low energy region of excited nuclei have a significant impact on the reaction rates.