Nuclear Reactions with Short-Lived Nuclear Beams

拟议的项目将涉及利用短寿命放射性核束(RNB)研究核反应，以及开发仪器、技术和仪器以促进RNB研究。具体实验将侧重于利用6He、8Li、7Be、8B等短寿束的低能核反应，研究接近核稳定极限的丰中子和丰质子核的结构和反应机理。这些研究是一个非常成功的计划的继续，目的是阐明在稳定极限下出现的对于弱束缚系统的奇特的“核晕”结构对库仑势垒附近的聚变、转移、非弹性激发和分裂几率的影响。这里特别令人感兴趣的是到连续统和在连续统内的高阶耦合对各种反应机制的影响，因为连续统的接近是弱束缚系统的特征之一，定义了弱束缚系统的特征。这项工作将主要与圣母大学(UND)的TwinSol设施一起进行，尽管橡树岭国家实验室和(可能)国家超导回旋实验室的RNB设施也可用于特定实验。我们还建议利用UND提供的束流和实验设备的几乎独特的能力来非常准确地测量Ge同位素上的(3He，n)反应。从这项实验中获得的数据，与耶鲁大学已经在进行的其他实验的结果相结合，将使与76Ge的无中微子双衰变相关的核矩阵元素的值有很大的改善。这反过来将允许更准确地确定中微子的质量。该提案对研究生、本科和高中教育以及发展具有技术素养的劳动力的更广泛影响如下。拟议的工作将涉及密歇根大学(UM)和圣母大学(University Of Notre Dame)的研究生和本科生，以及来自密歇根大学和圣母大学附近其他几所学校(主要是本科生)的教职员工和学生。这些学生在使用先进的、最先进的计算方法、核加速器、辐射探测器、真空和低温技术以及超导离子-光磁系统方面的“动手”培训，已经对培养一支精通技术的劳动力队伍产生了重要影响。最后，我们将继续并扩大一个非常成功的项目，让来自社会经济困难的密歇根州新布法罗学区的高中生参与与物理相关的研究。该计划包括三个部分：在NBHS开发符合密歇根州立大学这一领域标准的核物理课程；由NBHS的所有物理科学专业的学生每年参观圣母大学核物理实验室；为有兴趣了解物理职业的精选(和高度上进的)NBHS学生举办为期一周的住宿式“核物理夏令营”。暑期计划的安排是为了让学生可以直接与物理研究生和本科生互动，以及来自附近几所学院和大学的教职员工，他们可以分享他们作为职业的物理知识和经验。

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.