Nuclear Reactions with Short-Lived Nuclear Beams

点击翻译按钮获取中文摘要

The proposed project will involve the study of nuclear reactions utilizing short-lived radioactive nuclear beams (RNBs) together with the development of instrumentation, techniques, and apparatus to facilitate RNB studies. Specific experiments will emphasize the investigation of the structure and reaction mechanisms of neutron- and proton-rich nuclei near the limits of nuclear stability using low-energy nuclear reactions with short-lived beams such as 6He, 8Li, 7Be, 8B, etc.. These studies are a continuation of a very successful program to elucidate the effect that the exotic "nuclear halo" structure, which appears for weakly-bound systems at the limits of stability, has on fusion, transfer, inelastic excitation, and breakup probabilities near the Coulomb barrier. Of particular interest here is the influence that higher-order couplings to and within the continuum have on the various reaction mechanisms, since proximity of the continuum is one of the characteristic, defining features of weakly-bound systems. The work will be carried out primarily with the TwinSol facility at the University of Notre Dame (UND), although the RNB facilities at Oak Ridge National Laboratory and (possibly) at the National Superconducting Cyclotron Laboratory may also be utilized for specific experiments. We also propose to make use of the nearly unique capabilities of the beams and experimental equipment available at UND to very accurately measure the (3He,n) reaction on Ge isotopes. The data obtained from this experiment, when combined with the results from other experiments already underway at Yale University, will enable a much-improved value for the nuclear matrix element relevant for neutrinoless double decay of 76Ge. This in turn will allow for a more accurate determination of the mass of the neutrino.The broader impact of the proposal on graduate, undergraduate, and high school education, as well as the development of a technologically literate workforce, is as follows. The proposed work will involve graduate and undergraduate students from the University of Michigan (UM) and the University of Notre Dame, together with faculty members and students from several other (primarily undergraduate) schools located in close proximity to UM and UND. The "hands-on" training of these students in the use of advanced, state-of-the-art computational methods, nuclear accelerators, radiation detectors, vacuum and cryogenic techniques, and superconducting ion-optical magnetic systems has already had an important impact on the development of a technologically-literate workforce. Finally, we will continue and expand a highly successful program that involves high-school students from the socio-economically-challenged New Buffalo, MI school district in physics-related research. This program has three components: the development of a nuclear-physics curriculum at NBHS that satisfies State of Michigan standards in this area, a yearly tour of the Notre Dame nuclear physics laboratory by all the physical-sciences students at NBHS, and a one-week residential "nuclear physics summer camp" for selected (and highly-motivated) NBHS students interested in learning about careers in physics. The summer program is arranged so that the students can interact directly with physics graduate and undergraduate students, and faculty from several nearby colleges and universities who can share their knowledge and experiences of physics as a career.