Nuclear Reaction Theory

Pawel Danielewicz和Filomena Nunes计划在他们互补的专业知识的基础上进行核反应理论的研究。重点是可以影响当代和未来加速器实验的理论，包括碎片化设施，如NSCL， RIKEN和GSI，以及低能耗设施，如世界各地的各种ISOL设施和最重要的地方规划的FRIB。具体目标包括一个完整的三体方法来捕获反应，应用于三α聚变反应，实现非平衡格林函数方法，首先是中心反应，以及继续研究核能泛函的对称部分。还计划研究多粒子最终态反应的发射源，库仑解离的基准方法（包括相对论效应）和变形核的镜像对称性研究以及对波函数渐近性的影响。利用基于Faddeev超球面方法的r-矩阵方法的新发展，探讨了三个带电粒子的低能捕获。要实现的非平衡格林函数方法，在其特定的极限下产生随时间变化的哈特里-福克和玻尔兹曼方程方法，并提供了将这两种方法推广到反应能量范围的可能性，结合了短程相关和不同量子效应的影响。在静态极限下，该方法提供了包含短程相关性的核结构描述。该项目与国家科学院实验项目的利益重叠，因此，将有可能继续与当地实验人员密切合作。此外，研究人员将继续受益于国家科学实验室核理论小组其他成员在核结构方面的专业知识，以及部分设在他们大学的核天体物理联合研究所成员在核天体物理方面的专业知识。计划研究的长期广泛目标是：1)推进直接反应理论，包括稀有同位素束的反应；2)发展用于反应模拟的量子输运理论；3)发展可靠地从反应中提取体性质和单粒子性质的方法。研究生将参与到这些努力的不同方面。该研究计划完全符合核科学咨询委员会长期计划中核社区确定的优先事项。正如这里所计划的，新的核反应方法对于充分利用新的稀有同位素设施是重要的，因为核反应将不可避免地继续成为研究感兴趣的外来核的主要工具。此外，这些设施中测量统计量的增加将对反应模型的准确性提出更高的要求。该计划的影响超出了核反应，因为它加强了核反应与核天体物理学、核反应与介观物理之间的联系。关于第一个问题，研究人员计划探索影响天体物理模型中核反应速率的过程，以及与中子星有关的致密核物质的特性。在与介观物理的联系方面，研究人员计划通过推进核反应的量子输运理论来缩小外围反应和中心反应描述之间的差距，这是一个与原子陷阱物理学、电子在纳米结构上的输运和早期宇宙加热相似的框架。

Pawel Danielewicz and Filomena Nunes plan to carry out research on nuclear reaction theory, building on their complimentary expertise. The emphasis is on theory that can impact experiments done at contemporary and future accelerators, including fragmentation facilities such as NSCL, RIKEN and GSI, and low-energy facilities such as the various ISOL facilities worldwide and foremost locally planned FRIB. The specific objectives include a full three-body approach to capture reactions, with application to the triple-alpha fusion reaction, implementation of the nonequilibrium Green's function approach, at first to central reactions, and the continued investigation of the symmetry part of the nuclear energy functional. Also planned are the study of emission sources in reactions with multiparticle final states, benchmarking methods for Coulomb dissociation (including relativistic effects) and the study of mirror symmetry in deformed nuclei and implications for the asymptotics of the wavefunctions. The low energy capture of three charged particles will be approached using a new development of the R-matrix method built on the Faddeev hyper-spherical method. Nonequilibrium Green's function method, to be implemented, yields both time-dependent Hartree-Fock and Boltzmann-equation methods in its particular limits and offers the possibility of generalizing those two approaches across the energy range for reactions, incorporating both effects of short-range correlations and different quantal effects. In the static limit, the method provides a description of nuclear structure incorporating short-range correlations. The project overlaps with the interests of the experimental program at the NSCL and, thus, will make it possible to continue a close collaboration with the local experimentalists. The investigators will moreover continue to benefit from the expertise in nuclear structure of other members of the NSCL Nuclear Theory Group and from the expertise in nuclear astrophysics of the members of the Joint Institute for Nuclear Astrophysics, housed partly at their University.The long-term broad objectives that the planned research is directed at are: 1) advancing direct reaction theory, including reactions with rare isotope beams, 2) developing quantum transport theory for use in reaction simulations and 3) developing methods for a reliable extraction of bulk properties and single particle properties from reactions. Graduate students are going to be involved in the different facets of each of these efforts. The research plan fits well within the priorities set by nuclear community in the Long Range Plan of the Nuclear Science Advisory Committee. Novel approaches to nuclear reactions, as planned here, are important for a full utilization of the new rare isotope facilities because nuclear reactions will inevitably continue to be the main tool to study the exotic nuclei of interest. Moreover, the increased measurement statistics in these facilities will impose a larger demand on the accuracy of the reaction models. The plan has impact beyond nuclear reactions, as it enhances connections between nuclear reactions and nuclear astrophysics, and between nuclear reactions and mesoscopic physics. Concerning the first, the investigators plan to explore processes that impact nuclear reaction rates in astrophysical modeling as well as properties of dense nuclear matter that pertain to neutron stars. Concerning the connection to mesoscopic physics, the researchers plan to close the gap between the description of peripheral and central reactions by advancing quantum transport theory for nuclear reactions, a framework with parallels in the physics of atomic traps, transport of electrons across nanostructures and heating of the early Universe.