| Project Detail |
Nuclear fission, the splitting of an atomic nucleus into two or more fragments, plays an essential role in both applied and fundamental science. However, even 85 years after its discovery, it remains a challenging puzzle for nuclear theorists. A crucial piece of this puzzle is the angular momentum of fission fragments, a measure of fragments rotation that has a substantial impact on the emission of neutrons and photons during the deexcitation process. Recent research on the subject has reignited a long-standing debate on several fundamental questions. One key problem involves establishing a comprehensive microscopic theory of angular momentum distributions for the full range of fragments masses and charges. These distributions are a major input in the data evaluation process employed to generate the large nuclear data libraries used in fundamental science and nuclear technology. However, due to the lack of a comprehensive theory, those evaluations still rely on simplified and occasionally inaccurate phenomenological inputs. The principal aim of this project is to predict angular momentum distributions using state-of-the-art nuclear density functional theory. Combining symmetry-restoration techniques and the time-dependent generator coordinate method, we will compute angular momentum distributions in fragments for the neutron-induced fission of two crucial actinides, 239Pu and 235U. Subsequently, we will explore the impact of nuclear excitation on these distributions by extending the finite-temperature formalism to fission fragments. The resulting database, first of its kind, will encompass microscopic angular momentum distributions as functions of the incident neutron energy and the nuclear excitation energy. Finally, we will evaluate the influence of these distributions on predicted fission spectra, employing the Hauser-Feschbach simulator YAHFC, thus paving the way for fission modeling based on microscopic theory. |
