RII Track-4: Ab initio modeling of nuclear reactions for studies of nucleosynthesis and fundamental symmetries in nature

Louisiana State University, Baton Rouge LA

Investigators

Abstract

Non-technical Description Ever since the history-making discovery of nuclear fission, which demonstrated the huge amount of energy that can be released when the strong bonds between the atomic constituents (neutrons and protons) are broken, theoretical nuclear physicists have searched for a comprehensive explanation of the properties of the atomic nucleus based on knowledge of the strong force between these constituents. This project takes advantage of the instrumentation, computing capabilities, and theoretical expertise at the Lawrence Livermore National Laboratory (LLNL) to develop a theoretical framework that will improve our understanding of these forces. When this goal is achieved, it will be possible to predict reactions that take place under extreme conditions, from stellar explosions to the interior of nuclear reactors. Improving our knowledge of nuclear reactions will help us further understand 'nuclei-fueled' astrophysical processes, and safely and economically harness nuclear phenomena in support of the broad scope of humanitarian needs. Future advances in nuclear science and technology hold promise for a growing number of applications for medicine, industry, energy, and national security. The development of advanced instrumentation and applications of nuclear isotopes in disease treatments provide two prominent examples that rely on elementary properties of atomic nuclei. In addition to providing access to the facilities and expertise at LLNL, this project will provide training and unique research experiences for the PI and a postdoctoral fellow, with indirect benefits to graduate and undergraduate students. Technical Description This project aims to dramatically expand the reach as well as the impact of nuclear reaction theory with the aim of predicting properties of experimentally inaccessible nuclei and reactions, while supporting and informing experiments at current and upcoming radioactive beam facilities. The goal is to develop and implement a symmetry-guided theory that will enable pioneering ab initio investigations of reactions for heavier nuclear species, while accounting for the challenging structure of the participating nuclei. This will be achieved by capitalizing on approximate symmetries known to dominate in nuclei. In this approach all participating particles in the target and incoming proton or neutron are treated on the same footing within a 'shell model' concept of the quantum many-particle system and the compound nucleus. In addition, state-of-the-art chiral effective field theory interactions between protons and neutrons will be employed. New predictions, possible through the unique combination of expertise of theoretical and experimental nuclear physicists at Louisiana State University and LLNL are anticipated for processes inaccessible to experiments, which can facilitate neutrino- and fusion-related research and are key to advancing knowledge about astrophysical processes, as well as of fundamental symmetries in nature. This, in turn, can help address two of the most fundamental questions of physics today: the origin of elements, and if the neutrino is its own antiparticle. While the proposed applications focus on specific important questions, the new developments will have wider impact, as multi-physics simulations in the areas of nuclear energy and national security have similar needs. As part of this research, future leaders will be trained in research in low-energy nuclear science, while learning and working in massively parallel environments at petascale computing facilities.