Nuclear Reaction Theory

核反应理论

• 批准号: 1068571
• 负责人: Pawel Danielewicz
• 金额: $ 55.5万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1068571&HistoricalAwards=false
• 关键词: Nuclear; Reaction; Theory

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.

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。 重点是理论，可以影响在当代和未来的加速器，包括碎片设施，如NSCL，RIKEN和GSI，和低能量的设施，如各种ISOL设施世界各地和最重要的本地计划FRIB实验。 具体目标包括一个完整的三体方法捕获反应，与应用程序的三α融合反应，实施非平衡绿色函数的方法，首先是中央反应，并继续调查的对称性部分的核能功能。 还计划研究多粒子终态反应中的发射源、库仑解离的基准方法（包括相对论效应）以及变形核中的镜像对称性研究以及对波函数渐近性的影响。利用建立在Faddeev超球方法基础上的R-矩阵方法的新发展，对三个带电粒子的低能俘获进行了研究。 非平衡绿色的功能方法，要实施，产生时间依赖的Hartree-Fock和玻尔兹曼方程的方法在其特定的限制，并提供了可能性，概括这两种方法在整个能量范围内的反应，将两种影响的短程相关性和不同的量子效应。 在静态极限，该方法提供了一个描述的核结构纳入短程相关。该项目与NSCL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NSCL核理论小组其他成员的核结构专业知识，以及核天体物理学联合研究所成员的核天体物理学专业知识，该研究所部分设在他们的大学。计划研究的长期广泛目标是：1）推进直接反应理论，包括与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）发展从反应中可靠提取体性质和单粒子性质的方法。 研究生将参与这些努力的不同方面。 这项研究计划完全符合核科学咨询委员会长期计划中核界设定的优先事项。正如这里计划的那样，核反应的新方法对于充分利用新的稀有同位素设施非常重要，因为核反应将不可避免地继续成为研究感兴趣的奇异核的主要工具。 此外，在这些设施中增加的测量统计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之间的联系，以及核反应与介观物理学之间的联系。 关于第一个问题，研究人员计划探索影响天体物理建模中核反应速率的过程，以及与中子星有关的致密核物质的性质。关于与介观物理学的联系，研究人员计划通过推进核反应的量子传输理论来缩小外围和中心反应描述之间的差距，这是一个与原子陷阱物理学相似的框架，电子在纳米结构中的传输和早期宇宙的加热。