CAREER: Beams of Fast Exotic Nuclei and the Origin of Heavy Elements in Stars

职业：快速奇异核束和恒星中重元素的起源

• 批准号: 9875122
• 负责人: Thomas Glasmacher
• 金额: $ 25万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2005-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9875122&HistoricalAwards=false
• 关键词: CAREER; Beams; Fast; Exotic; Nuclei

9875122GlasmacherThis Faculty Early Career Development (CAREER) project, supported in the Nuclear Physics Program, focuses on research and education with particle beams of exotic nuclei. The research encompasses an experimental study of unstable nuclei with an extreme neutron-to-proton ratio. These exotic nuclei are close to the nuclear driplines, the locus in the chart of nuclides where the binding of nucleons ends. Even though nuclear shells are well established close to the valley of stability, theoretical models have predicted the possibility of a drastic change of conventional nuclear shell structure as the nuclear driplines are approached. Such a dramatic change in nuclear structure poses particular challenges for our understanding of the rapid neutron capture process in stars. This so-called r-process accounts for the generation of more than half of all elements heavier than iron in the universe. Since measurements of masses, half-lives, and deformations on the very neutron-rich nuclei in the r-process path are extremely scarce, theoretical models are currently used to calculate these properties. In the absence of experimental data on very neutron-rich nuclei the predictive power of currently used theoretical models is untested. To remedy this situation, the research proposed here will use different experimental techniques to measure basic properties of exotic nuclei, produced at the NSCL by fragmentation of beams of stable nuclei. Enhancing scientific literacy at all levels is the goal of the proposed educational activities. This effort will focus on three specific target groups: high-school students traditionally underrepresented in science, current pre-college science teachers, and undergraduate students (especially prospective teachers). An expansion of the NSCL summer outreach program ("Physics of Atomic Nuclei") is proposed. The purpose is to allow high-school students from groups traditionally underrepresented in science to experience the excitement and joy of science in an active research environment early enough in their careers that they can choose to pursue a career in science. At the same time middle and high-school science teachers are invited to the NSCL to get direct exposure to basic research and to learn how they can integrate basic research results into their classes. At Michigan State University, science education of undergraduate students in general and prospective teachers in particular, takes place in large lecture classes. Implementation of an active learning environment that makes use of modern technological teaching aides in such large lecture classes taught by the principal investigator is proposed. The format will shift from a traditional, teacher-centered classroom toward an interactive, student-centered forum where students can examine their own and new ideas, learning through conceptual understanding rather than listening alone. Segments in this interactive environment will highlight basic nuclear physics research at the NSCL and thus emphasize the relevance of introductory physics concepts through their connection to cutting-edge basic research.

9875122 numermacherThis教师早期职业发展（职业生涯）项目，在核物理计划的支持下，侧重于研究和教育与粒子束的异国情调的核。该研究包括对具有极端中子质子比的不稳定核的实验研究。 这些奇异的核靠近核滴线，在核素图中，核子结合结束的位置。 尽管核壳层在接近稳定谷的地方已经很好地建立起来，但理论模型已经预测，随着核滴线的接近，常规核壳层结构可能会发生急剧变化。 核结构的这种戏剧性变化对我们理解恒星中的快速中子捕获过程提出了特别的挑战。 这个所谓的r过程产生了宇宙中一半以上比铁重的元素。 由于测量的质量，半衰期和变形的非常丰富的中子核在r-过程的路径是非常稀缺的，理论模型目前被用来计算这些属性。 在非常丰富的中子核的实验数据的情况下，目前使用的理论模型的预测能力是未经检验的。 为了纠正这种情况，这里提出的研究将使用不同的实验技术来测量非稳定核的基本性质，这些非稳定核是在非稳定核实验室通过分裂稳定核束而产生的。 提高各级科学素养是拟议教育活动的目标。 这项工作将集中在三个特定的目标群体：高中学生传统上在科学，目前大学预科科学教师，和本科生（特别是未来的教师）代表不足。 建议扩大NSCL夏季外展计划（“原子核物理学”）。 其目的是让传统上在科学中代表性不足的群体的高中生在他们的职业生涯中尽早体验到科学在活跃的研究环境中的兴奋和喜悦，以便他们可以选择从事科学职业。 同时，邀请初中和高中科学教师到NSCL直接接触基础研究，并学习如何将基础研究成果融入课堂。 在密歇根州立大学，本科生的科学教育，特别是未来的教师，是在大型讲座班。 实施一个积极的学习环境，利用现代技术的教学辅助工具，在这样的大型讲座类教授的主要研究者提出。 形式将从传统的，以教师为中心的课堂转向互动的，以学生为中心的论坛，学生可以检查自己的和新的想法，通过概念理解而不是单独倾听来学习。 在这种互动环境中的部分将突出在NSCL的基础核物理研究，从而强调通过其连接到尖端的基础研究介绍物理概念的相关性。