Rare Isotope Reaction Studies for Nuclear Structure and Astrophysics

该奖项将支持首席研究员和她的早期职业科学家团队，以促进我们对原子核结构的理解，以及它们在爆炸恒星中的反应和合成。 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，PI将领导使用稀有同位素束的实验，集中在富含中子的核上。 该研究计划将使用美国最先进的仪器和加速器设施，该项目还将有助于提高核科学工作人员的多样性。 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在高等教育和国家实验室和工业中的基础和应用研究做好准备。轻离子转移反应将研究与束的稀有同位素的能量附近的库仑势垒和约45兆电子伏每个核子。研究将集中在N=50中子壳层闭合附近的富中子核和轻核，这对理解恒星核的合成及其爆炸很重要。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，首先是ReA束能力，并从2022年开始使用稀有同位素束设施（FRIB）。其他实验将在阿贡国家实验室的ATLAS加速器设施进行。 在FRIB的重点是约束的形状的潜力，结合中子在一个富中子的核，因此，提取光谱强度和直接中子俘获率与理论模型参数的依赖性降低。与氘靶的中子转移反应已被验证为中子俘获的替代品时，反应产物测量符合γ射线。 因此，带电粒子和符合伽马辐射将测量与伽马阵列ORRUBA：双探测器的实验结构研究（GODDESS），其中橡树岭罗格斯大学桶阵列（ORRUBA）耦合到大，高度分段阵列的高纯度锗伽马射线探测器。研究结果将与核结构和远离稳定性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，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

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.