Collaborative Research: Nuclear Reaction and Structure Studies with Radioactive and Stable Beams

该奖项资助的研究旨在促进更好地理解原子核，原子核是宇宙中所有正常物质的基本组成部分。 它们是如何在大爆炸之后形成的，它们现在又是如何相互作用来改变它们的基本元素性质的？ 是否存在由非常奇特的原子核组成的新形式的物质，我们如何制造和研究这些物质？ 为此，该小组将开发核科学中的特殊新技术，并培养未来的科学家，以帮助回答其中的一些问题。 一个重要的培训组成部分将是密歇根州新水牛高中教师和学生的良好和非常成功的推广活动的延续，该活动已向这些学生介绍了科学领域有趣，重要和令人兴奋的职业生涯。 这项研究中开发和使用的技术将应用于其他重要领域，如国土安全（核恐怖主义）、核废料的安全储存和监测，以及包括放射治疗在内的核医学应用。后者包括与这项研究直接相关的新模式：离子束的产生和成像，以治疗特定形式的癌症肿瘤。近50%的研究生和其他在该小组过去的研究项目中接受过培训的人员目前正在从事核安全或核医学方面的工作，预计这将由于目前的资助而继续下去。拟议的项目将涉及利用稳定和短寿命放射性核束进行核反应的研究，以及仪器、技术、和设备，以促进这种研究。 这包括使用在圣母大学运行的TwinSol低能放射性离子束设施，该设施由密歇根大学和圣母大学联合开发。 具体的实验将强调调查的结构和反应机制的中子和质子丰富的核附近的核稳定性的极限，以阐明的效果，外来的“核晕”结构，这似乎是弱约束系统的稳定性的极限，对融合，转移，非弹性激发，和附近的库仑势垒破裂概率。 这里特别感兴趣的是，高阶耦合和连续内的各种反应机制的影响，因为接近连续是弱束缚系统的特征定义功能。 这些研究将在TwinSol与国家超导回旋加速器实验室（NSCL）的一个小组合作进行，利用原型有源靶时间投影室（AT-TPC）。 一个相关的计划将使用最近在NSCL的再加速束流设施（ReA 3）投入使用的完整的AT-TPC。 此外，在UM研究小组及其同事的主要指导下，UM-UND合作将继续推进氘代中子发生器的开发和应用，用于涉及中子的核测量。 这将包括选定的测量（d，n）和（3 He，n）反应涉及稳定和不稳定的光束，特别是7 Be（d，n），这是在天体物理学的兴趣。 由于这些探测器允许中子光谱和截面测量，而无需中子飞行时间，因此当与适用于核天体物理测量的高强度、低能量、非脉冲加速器一起使用时，它们具有特别的优势。 后者包括最近在ND安装的新的5 MV加速器，我们将与ND的核天体物理组一起进行这些实验，特别是几个关键的（A，n）测量。 该小组最近开发的独特的中子探测器阵列在核科学以及国土安全和核不扩散方面都有广泛的应用潜力。一如以往，拟议的工作将涉及来自ND和UM的研究生和本科生，以及位于这些大学附近的几所主要本科学校的教师和学生。因此，拟议研究的高度技术性将大大有助于培养一支懂技术的工作队伍。

The research funded by this award is designed to promote a better understanding of atomic nuclei, the basic building blocks of all normal matter in the Universe. How did they form following the Big Bang, and how do they now interact to change their basic elemental nature? Are there new forms of matter made up from very exotic types of atomic nuclei and how might we make and study these? To this end the group will develop special new techniques in nuclear science, as well as train future scientists that can help answer some of these questions. One important training component will be a continuation of the well-established and highly successful outreach to faculty and students at New Buffalo High School in Michigan that has introduced these students to interesting, important, and exciting careers in the sciences. The technology developed and used in this research will have applications in other important areas, such as homeland security (nuclear terrorism), the safe storage and monitoring of nuclear wastes, and applications in nuclear medicine, including radiation therapy. The latter includes a new modality directly related to this research: the production and imaging of ion beams to treat particular forms of cancer tumors. Nearly 50% of graduate students and other personnel trained in the group's past research projects are currently pursuing careers in nuclear security or nuclear medicine, and it is anticipated that this will continue as a result of the present grant.The proposed project will involve the study of nuclear reactions utilizing stable as well as short-lived radioactive nuclear beams, together with the development of instrumentation, techniques, and apparatus to facilitate such studies. This includes use of the TwinSol low-energy radioactive ion-beam facility in operation at the University of Notre Dame (ND), developed jointly by the University of Michigan (UM) and ND. Specific experiments will emphasize the investigation of the structure and reaction mechanisms of neutron- and proton-rich nuclei near the limits of nuclear stability 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 to the continuum is the characteristic defining feature of weakly-bound systems. These studies will be carried out at TwinSol in collaboration with a group from the National Superconducting Cyclotron Laboratory (NSCL), utilizing a prototype active-target time-projection chamber (AT-TPC). A related program will use the full AT-TPC recently commissioned at the reaccelerated beam facility (ReA3) at NSCL. In addition, the UM-UND collaboration, under the primary direction of the UM research group and their colleagues, will continue advanced development and application of deuterated scintillators for nuclear measurements involving neutrons. This will include selected measurements of (d,n) and (3He,n) reactions involving both stable and unstable beams, and in particular 7Be(d,n) which is of interest in astrophysics. Since these detectors permit neutron spectroscopy and cross section measurements without neutron time-of-flight, they have a particular advantage when used with the high-intensity, low-energy, non-pulsed accelerators suitable for nuclear astrophysics measurements. The latter includes the new 5 MV accelerator recently installed at ND and we will pursue such experiments, and in particular several key (A,n) measurements, together with the nuclear astrophysics group at ND. The unique neutron detector array the group has recently developed has potential for wide-spread applications both in nuclear science as well as in homeland-security and nuclear non-proliferation. As in the past, the proposed work will involve graduate and undergraduate students from ND and UM, together with faculty members and students from several primarily undergraduate schools located in close proximity to these universities. The highly-technical nature of the proposed research will thus contribute significantly to the training of a technically-literate work force.