Theoretical Nuclear Structure Physics

0140300Draayer位于巴吞鲁日的路易斯安那州立大学(LSU)的核理论课程专注于了解原子核的结构；具体地说，我们研究结合原子核中的核子(中子和质子)的强相互作用的关键成分。我们所做的既有基础科学方面的问题，也有应用方面的问题：在基础科学方面，我们探索“核汤”--试图理解强相互作用--可以归结为对核子本身结构的考虑--是如何在核介质中表现出来的。这一点很重要，因为我们不能声称我们真的了解一个物体，除非我们能将它拆开并重新组装起来。例如，我们知道，核显示出某些特征特征，例如闭合壳层附近的独立粒子行为和集体旋转--就像量子顶部的旋转--远离闭合壳层。复合系统从复杂的核子-核子相互作用中过滤出来的这些简单特征的驱动因素仍然难以捉摸，因此是深入理解原子核结构的障碍。在互补的应用科学方面，人们可以通过问一个非常普遍但重要的问题来更好地理解我们所做的事情的实际影响：“理解负责宇宙中储存的大部分能量的系统和相关过程是否重要？”如果在更深的层面上理解这一“终极能源”很重要，那么研究核物理，以及培养引领这一领域未来发展的学生，对我们的国家和人类都具有真正的价值。我们正是在这个更大的框架内看到并开展我们的工作。我们特别感兴趣的是稀土原子核和吖系元素原子核的结构，因为在这些原子核中，通过很大一部分组成核子的参与，集体模得到了极大的增强。这类研究需要超越通常的壳模型和集体模型的理论工具，尽管如此，这些模型的成功为所有新方法提供了指导和限制。我们的研究使用了对称方法，从点群到q变形和无限维代数，以及非线性动力学。这项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。最近在这些领域取得的成功分别包括：1)强变形核中集体M1跃迁的“扭转”和“剪刀+扭转”模式的表达；2)广义配对问题的代数解，包括非简并的单粒子能量；以及3)核中形变到液滴表面孤子(称为Roton)的演化。对大多数来自国外的研究生的培训一直是并将继续是我们项目的一个重要的补充教育和延伸的特点。到目前为止，路易斯安那州立大学理论核物理项目的博士生概况是：1名非裔美国人(第一个从路易斯安那州立大学毕业的物理学专业学生)，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。

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.