Nuclear Structure and Nuclear Astrophysics

该研究项目由圣母大学核科学实验室（NSL）负责，涉及核天体物理学、核结构物理学和核物理应用领域的关键问题。低能核反应测量将在NSL加速器上进行，使用伽马和粒子探测技术来确定反应截面和反应速率，从而确定核合成和静止和爆炸恒星燃烧过程的时间尺度。低能稳定光束测量恒星反应的截面在亚纳米范围内，主要受宇宙辐射和自然背景辐射的限制。对恒星爆炸过程的研究依赖于强烈的放射性光束，这些光束将由巴黎圣母院双太阳设施或美国或欧洲的其他稀有同位素加速器提供。新的实验方法和技术将利用新的圣乔治反冲分离器，与目前正在安装的新的低能重离子加速器相结合。核结构程序解决了核中奇异的旋转和振动激发模式的问题，这将有助于更好地理解核物质的基本特征，并研究预测核少体系统的量子现象的新模式。这个项目还包含了对许多天体物理现象至关重要的测量，比如核物质的不可压缩性，这对我们对中子星的理解很重要；原子核的质量测量对于各种恒星的过程，特别是对于理解重核的形成非常重要。该项目的目标是研究控制大质量恒星中时间尺度、演化和元素形成的核反应。还将研究驱动恒星爆炸的反应，如形成从铁到铅的重元素的新星和超新星。这些研究将与恒星环境的计算机模拟相结合，研究这些反应对第一代和下一代恒星中观测到的元素丰度的影响。所有这些结果将有助于我们更好地了解元素的起源以及与之相关的宇宙化学历史。对于天文学家来说，这些结果将导致新的观测特征的识别，例如从恒星核心发射的中微子，超新星爆炸中产生的长寿命放射性同位素，或者从爆炸的中子星外壳发射的引力波。该项目涉及大量的研究生和本科生，为美国国家实验室、大学、医疗机构和行业的核物理、核医学、核能、辐射安全和国家安全方面的职业生涯提供了独特的实践培训机会。

This research program at the Nuclear Science Laboratory (NSL) of the University of Notre Dame addresses critical questions in nuclear astrophysics, nuclear structure physics, and nuclear physics applications. Low energy nuclear reaction measurements will be performed at the NSL accelerators using gamma and particle detection techniques to determine the reaction cross sections and reaction rates that determine the nucleosynthesis and timescales of quiescent and explosive stellar burning processes. The measurement of stellar reactions with low energy stable beams have cross section in the sub-nanobarn range and are mainly handicapped by cosmic and natural background radiation. The study of nuclear processes in stellar explosions relies on intense radioactive beams which will be provided by the Notre Dame TwinSol facility or other rare isotope accelerators in the US or Europe. New experimental methods and techniques will be developed by utilizing the new St George recoil separator, in connection with a new low-energy heavy ion accelerator, which is presently being installed. The nuclear structure program addresses the question of exotic rotational and vibrational excitation modes in nuclei which will help to better understand the fundamental characteristics of nuclear matter and investigate new modes of quantum phenomena predicted for nuclear few body systems. This program also incorporates measurements critical to many astrophysical phenomena, such as incompressibility of nuclear matter, which is important for our understanding of neutron stars; and mass measurements of nuclei important for various stellar processes and, especially, for understanding of the formation of heavy nuclei.The goal of the program is to investigate nuclear reactions which control the timescales, evolution, and the formation of elements in massive stars. Also studied will be reactions that drive stellar explosions such as novae and supernovae building the heavy elements from iron to lead. These studies will be coupled with computer simulations of the stellar environment to study the impact of these reactions on the observed elemental abundances in first generation and later generation stars. All these results will lead to a better understanding of the origin of the elements and the associated chemical history of our universe. For the astronomer, these results will lead to the identification of new observational signatures, such as neutrinos emitted from the core of stars, long-lived radioactive isotopes produced in supernova explosions, or gravitational waves emitted from the crust of exploding neutron stars. The program involves a large number of graduate and undergraduate students and provides a unique hands-on training opportunity for a career in nuclear physics, nuclear medicine, nuclear energy, radiation safety, and national security at US national laboratories, universities, medical facilities, and industries.