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

非技术描述自从核裂变的历史性发现证明了当原子成分(中子和质子)之间的强键被打破时可以释放出巨大的能量以来，理论核物理学家一直在基于这些成分之间的强力的知识来寻求对原子核性质的全面解释。这个项目利用劳伦斯利弗莫尔国家实验室(LLNL)的仪器、计算能力和理论专业知识来开发一个理论框架，将提高我们对这些力量的理解。当这一目标实现时，就有可能预测在极端条件下发生的反应，从恒星爆炸到核反应堆内部。提高我们对核反应的了解将有助于我们进一步了解“核燃料”的天体物理过程，并安全和经济地利用核现象来支持广泛的人道主义需求。未来核科学和技术的进步为越来越多的医学、工业、能源和国家安全应用提供了希望。先进仪器的发展和核同位素在疾病治疗中的应用提供了两个依赖于原子核基本性质的突出例子。除了提供使用LLNL的设施和专业知识外，该项目还将为PI和一名博士后研究员提供培训和独特的研究经验，间接造福于研究生和本科生。该项目旨在极大地扩大核反应理论的范围和影响，目的是预测实验上无法接触到的核和反应的性质，同时支持和通报现有和即将到来的放射性束流设施的实验。其目标是开发和实施一种对称性指导的理论，该理论将能够对较重核物种的反应进行开创性的从头算研究，同时考虑到参与核的具有挑战性的结构。这将通过利用已知在原子核中占主导地位的近似对称性来实现。在这种方法中，靶中的所有参与粒子和入射的质子或中子在量子多粒子系统和复合核的‘壳模型’概念中被同等对待。此外，还将使用最先进的手征有效场理论来研究质子和中子之间的相互作用。路易斯安那州立大学和LLNL的理论和实验核物理学家的独特专业知识相结合，有望实现新的预测，用于无法进行实验的过程，这可以促进与中微子和聚变相关的研究，是推进关于天体物理过程以及自然界基本对称性的知识的关键。反过来，这可以帮助解决当今物理学中最基本的两个问题：元素的起源，以及中微子是否是它自己的反粒子。虽然拟议的应用侧重于具体的重要问题，但新的发展将产生更广泛的影响，因为核能和国家安全领域的多物理模拟有类似的需求。作为这项研究的一部分，未来的领导者将接受低能量核科学研究方面的培训，同时在千万亿级计算设施的大规模并行环境中学习和工作。

Non-technical DescriptionEver 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 DescriptionThis 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.