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.
