Structure and Electromagnetic Moments Of Exotic Nuclei

奇异核的结构和电磁矩

• 批准号: 1067906
• 负责人: Jolie Cizewski
• 金额: $ 75万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1067906&HistoricalAwards=false
• 关键词: Structure; Electromagnetic; Moments; Exotic; Nuclei

One of the frontier areas of nuclear physics is the study of the structure of atomic nuclei far from the valley of stability. In atomic nuclei the single-particle orbitals are expected to change as a function of neutron and proton number, and in addition are very sensitive to the presence of deformation. Single-particle characteristics can be probed in single-particle transfer reactions. Light-ion transfer reactions will be studied with beam energies near the Coulomb barrier and about 40-MeV per nucleon. Studies will concentrate on neutron-rich nuclei near the N=50 and N=82 neutron shell closures and light nuclei important to understand nucleosynthesis in stars. These studies will be carried out with accelerated beams of rare isotopes at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University, the Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory and the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. One focus is to extract spectroscopic strengths with reduced dependence on theoretical model parameters. Another challenge in nuclear structure physics is to understand the balance between a microscopic description of the nuclear wave function and a model based on collective motions of the nucleons within the nucleus. This balance changes as a function of excitation energy and angular momentum and may be quite different in nuclei away from the valley of stability from the observed behavior of nuclei near stability. The focus of the second component of this proposal addresses, via measurements of the magnetic moments of excited states, the interplay of single-particle configurations with an underlying spherical or deformed core. The technique of Coulomb excitation in inverse kinematics is well established and has been tested on radioactive beams (RIBs). However, recent high statistics experiments carried out with heavier nuclei than in the past, and with higher energy beams, have uncovered several issues that need to be addressed before the methods are tried at the new RIB facilities. Semi-magic Tin-126 will be studied at HRIBF. A new program of research to be established at the ATLAS facility will focus initially on the low-lying states of Samarium-150 and Gadolinium-152 and on the efficacy of alpha transfer reactions. The structure of the proposed activities is designed to have as large an impact as possible on the education and training of graduate and undergraduate students, as well as postdoctoral associates. The project will also serve to enhance the diversity of the nuclear science workforce by including early career scientists who are women or come from other under-represented backgrounds. The participation of these early career scholars in the forefront research would prepare them for careers in higher education and basic and applied research, in national laboratories and industry. The anticipated nuclear physics results are also of importance in astronomy, to understand the abundance of elements observed in the cosmos; in condensed matter physics, to understand the microscopic components of the transient hyperfine field; and for nuclear energy and national security, to understand properties of and reactions on fission fragments.

核物理学的前沿领域之一是研究远离稳定谷的原子核的结构。 在原子核中，单粒子轨道预计会作为中子和质子数的函数而变化，此外，对形变的存在非常敏感。 单粒子特性可以在单粒子转移反应中探测。轻离子转移反应将与库仑势垒附近的束能量和约40兆电子伏的每个核子进行研究。研究将集中在N=50和N=82中子壳闭合附近的富中子核和对理解恒星核合成很重要的轻核。 这些研究将在密歇根州立大学的国家超导回旋加速器实验室（NSCL）、阿贡国家实验室的阿贡串列直线加速器系统（ATLAS）和橡树岭国家实验室的Holifield放射性离子束设施（HRIBF）用稀有同位素加速束进行。 一个焦点是提取光谱强度，减少对理论模型参数的依赖。 核结构物理学的另一个挑战是理解原子核波函数的微观描述和基于原子核内核子集体运动的模型之间的平衡。 这种平衡作为激发能和角动量的函数而变化，并且在远离稳定谷的核中可能与观察到的接近稳定的核的行为完全不同。该建议的第二部分的重点是通过测量激发态的磁矩来解决单粒子配置与底层球形或变形核的相互作用。 逆运动学中的库仑激励技术已经很好地建立起来，并且已经在放射性束（RIBs）上进行了测试。然而，最近的高统计实验进行了比过去更重的核，更高的能量束，发现了几个问题，需要解决的方法之前，在新的RIB设施。 半魔锡-126将在HRIBF进行研究。 在ATLAS设施建立的一个新的研究计划将首先集中在钐-150和钆-152的低状态以及α转移反应的效率上。拟议活动的结构旨在对研究生和本科生以及博士后研究员的教育和培训产生尽可能大的影响。该项目还将通过包括女性或来自其他代表性不足背景的早期职业科学家来提高核科学工作人员的多样性。这些早期职业学者参与前沿研究将为他们在高等教育和基础及应用研究，国家实验室和行业的职业生涯做好准备。预期的核物理结果对天文学也很重要，有助于了解在宇宙中观测到的元素丰度;对凝聚态物理学也很重要，有助于了解瞬态超精细场的微观组成部分;对核能和国家安全也很重要，有助于了解裂变碎片的性质和反应。