Theoretical Nuclear Structure Physics

理论核结构物理

• 批准号: 0140300
• 负责人: Jerry Draayer
• 金额: $ 18.5万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0140300&HistoricalAwards=false
• 关键词: Theoretical; Nuclear; Structure; Physics

0140300DraayerThe nuclear theory program at Louisiana State University (LSU) in Baton Rouge is focused on understanding the structure of atomic nuclei; specifically, we examine key ingredients of the strong interaction that binds nucleons (neutron and protons) in the nucleus. There is both a basic science and an applied aspect to what we do: On the basic science side we probe the "nuclear soup" - trying to understand how the strong interaction, which can be drilled down to a consideration of the structure of the nucleons themselves, manifests itself in the nuclear medium. This is important since we cannot claim we really understand an object unless we can tear it apart and put it back together again. We know, for example, that nuclear display certain characteristic features, such as independent particle behavior near closed shells and collective rotations - like that of a quantum top - away from closed shells. The drivers of these simple characteristics, which the composite system filters from the complex nucleon-nucleon interaction, remain elusive and hence a roadblock to a deeper understanding of the structure of atomic nuclei. On the complementary applied science side, one can gain a better appreciation for practical implications of what we do by asking a very general but important question: "Is it important to understand systems and related processes that are responsible for most of the energy stored in the universe?" If it is important to understand at a deeper level this "ultimate source of energy", then the study of nuclear physics, as well as the training of students who will shepherd future developments in this area, has real value to our nation and humankind. It is within this larger framework that we see and do our work. We are particularly interested in the structure of rare earth and actinide nuclei because in these nuclei that the collective modes are strongly enhanced through the involvement of a large fraction of the total number of constituent nucleons. Such studies require theoretical tools beyond those of the usual shell and collective models, which nonetheless by virtue of their successes provide guidance and limits on all new approaches. Our research exploits symmetry methods, from point groups to q-deformed and infinite-dimensional algebras, as well as non-linear dynamics. The proposed work, which will continue our ongoing program, is organized into three areas: 1) shell-model and related investigations; 2) group theory and algebraic methods; and 3) collective motion and nonlinear dynamics. Recent successes in each of these areas include, respectively: 1) the articulation of "twist" and "scissors + twist" modes as collective M1 transitions in strongly deformed nuclei; 2) an algebraic solution of the generalized pairing problem, inclusive of non-degenerate single-particle energies; and 3) the evolution of deformation in nuclei to solitons (dubbed rotons) on the surface of a liquid drop. The training of graduate students, most from abroad, has been and will continue to be an important complementary educational and out-reach feature of our program. To date, the PhD student profile in theoretical nuclear physics program at LSU is: 1 African- American (the first in physics to graduate from LSU), 1 Korean, 1 Pakistani, 4 Germans, 1 Indonesian, 1 Ukrainian, 1 Romanian, 4 Bulgarian, and 2 Armenian.

0140300Draayer 位于巴吞鲁日的路易斯安那州立大学 (LSU) 的核理论项目专注于理解原子核的结构；具体来说，我们研究了原子核中结合核子（中子和质子）的强相互作用的关键成分。 我们所做的工作既有基础科学，也有应用方面：在基础科学方面，我们探索“核汤”——试图了解强相互作用如何在核介质中表现出来，这种强相互作用可以深入考虑核子本身的结构。 这很重要，因为我们不能声称我们真正理解了一个物体，除非我们能把它拆开并重新组合起来。 例如，我们知道核表现出某些特征，例如靠近封闭壳层的独立粒子行为和远离封闭壳层的集体旋转（如量子顶部的旋转）。 复合系统从复杂的核子-核子相互作用中过滤掉这些简单特征的驱动因素仍然难以捉摸，因此成为更深入理解原子核结构的障碍。 在互补的应用科学方面，通过提出一个非常普遍但重要的问题，人们可以更好地理解我们所做的事情的实际意义：“了解负责宇宙中存储的大部分能量的系统和相关过程是否重要？” 如果更深入地了解这种“终极能源”很重要，那么核物理的研究以及对引领该领域未来发展的学生的培训对我们的国家和人类具有真正的价值。 我们正是在这个更大的框架内看待并开展我们的工作。我们对稀土和锕系元素核的结构特别感兴趣，因为在这些核中，集体模式通过参与大部分组成核子总数而得到强烈增强。 此类研究需要超越通常的外壳和集体模型的理论工具，尽管如此，它们的成功为所有新方法提供了指导和限制。 我们的研究利用了对称方法，从点群到 q 变形和无限维代数，以及非线性动力学。 拟议的工作将继续我们正在进行的计划，分为三个领域：1）壳模型和相关研究； 2）群论和代数方法； 3）集体运动和非线性动力学。 最近在每个领域取得的成功分别包括：1）将“扭曲”和“剪刀+扭曲”模式明确表达为强变形核中的集体 M1 跃迁； 2）广义配对问题的代数解，包括非简并单粒子能量； 3）液滴表面原子核变形演化为孤子（称为旋子）。 研究生的培训（大部分来自国外）已经并将继续成为我们项目的重要补充教育和推广功能。 迄今为止，路易斯安那州立大学理论核物理项目的博士生概况为：1 名非裔美国人（第一个从路易斯安那州立大学物理学专业毕业的人）、1 名韩国人、1 名巴基斯坦人、4 名德国人、1 名印度尼西亚人、1 名乌克兰人、1 名罗马尼亚人、4 名保加利亚人和 2 名亚美尼亚人。