Rare Isotope Reaction Studies for Nuclear Structure and Astrophysics

核结构和天体物理学的稀有同位素反应研究

• 批准号: 2110985
• 负责人: Jolie Cizewski
• 金额: $ 44万
• 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: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110985&HistoricalAwards=false
• 关键词: Rare; Isotope; Reaction; Studies; Nuclear

This award will support the principal investigator and her group of early career scientists to advance our understanding of the structure of atomic nuclei as well as their reactions and synthesis in exploding stars. Nearly all elements heavier than iron are made in stars and stellar explosions through processes that involve the capture of neutrons. To learn more about those processes the PI will lead experiments using beams of rare isotopes, concentrating on neutron-rich nuclei. This research program will use state-of-the-art instruments and accelerator facilities in the U.S. The project will also serve to enhance the diversity of the nuclear science workforce. The participation of these early career scientists in forefront research and the development of scientific instruments will prepare them for careers in higher education and fundamental and applied research at national laboratories and in industry. Light-ion transfer reactions will be studied with beams of rare isotopes with energies near the Coulomb barrier and about 45-MeV per nucleon. Studies will concentrate on neutron-rich nuclei near the N=50 neutron shell closure and light nuclei important for understanding the synthesis of nuclei in stars and their explosions. These studies will be carried out with accelerated beams of rare isotopes at Michigan State University, first with the ReAccelerated (ReA) beam capability and starting in 2022 with the Facility for Rare Isotopes Beams (FRIB). Additional experiments will be performed at the ATLAS accelerator facility at Argonne National Laboratory. At FRIB the focus is to constrain the shape of the potential that binds neutrons in a neutron-rich nucleus and, therefore, extract spectroscopic strengths and direct neutron capture rates with reduced dependence on theoretical model parameters. The neutron-transfer reaction with deuterated targets has been validated as a surrogate for neutron capture when reaction products are measured in coincidence with gamma rays. Therefore, both charged particles and coincident gamma radiation will be measured with Gamma-array ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS), where the Oak Ridge Rutgers University Barrel Array (ORRUBA) is coupled to large, highly segmented arrays of high-purity germanium gamma-ray detectors. The results will be compared with theoretical predictions of nuclear structure and reactions away from stability and disseminated as input into calculations of nucleosynthesis in stars and their explosions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项将支持首席研究员和她的早期职业科学家小组，以增进我们对原子核结构及其在爆炸恒星中的反应和合成的理解。 几乎所有比铁重的元素都是在恒星和恒星爆炸中通过捕获中子的过程产生的。 为了更多地了解这些过程，首席研究员将领导使用稀有同位素束进行实验，重点关注富中子原子核。 该研究计划将使用美国最先进的仪器和加速器设施。该项目还将有助于增强核科学劳动力的多样性。 这些早期职业科学家参与前沿研究和科学仪器的开发将为他们从事高等教育以及国家实验室和工业界的基础和应用研究做好准备。将使用稀有同位素束来研究轻离子转移反应，其能量接近库仑势垒且每个核子约为 45 MeV。研究将集中于 N=50 中子壳层闭合附近的富中子核和对于理解恒星中核的合成及其爆炸非常重要的轻核。这些研究将在密歇根州立大学使用稀有同位素加速束进行，首先使用再加速 (ReA) 束能力，并从 2022 年开始使用稀有同位素束 (FRIB) 设施。其他实验将在阿贡国家实验室的 ATLAS 加速器设施中进行。 FRIB 的重点是限制富中子核中结合中子的势的形状，从而提取光谱强度和直接中子捕获率，同时减少对理论模型参数的依赖。当与伽马射线同时测量反应产物时，使用氘化靶的中子转移反应已被验证为中子捕获的替代方法。 因此，带电粒子和重合伽马辐射都将使用伽马阵列 ORRUBA 进行测量：用于实验结构研究的双探测器 (GODDESS)，其中橡树岭罗格斯大学桶状阵列 (ORRUBA) 与大型、高度分段的高纯锗伽马射线探测器。结果将与核结构和远离稳定性的反应的理论预测进行比较，并作为恒星核合成及其爆炸计算的输入进行传播。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持以及更广泛的影响审查标准。