RUI: Experimental Research in Nuclear Astrophysics and Nuclear Structure

几十年来，人们已经了解了恒星核反应如何产生元素的大致情况，但这一过程的许多重要细节仍有待发现。该奖项支持PI和印第安纳大学南本德分校（IUSB）的本科生参与一系列实验，研究涉及氦核与另一个更重的核融合的核反应，这对于全面了解恒星演化的氦燃烧阶段非常重要。实验利用圣乔治反冲质量分离器，这是圣母大学核科学实验室最近委托的一种设备，可以在非常低的能量下测量这些反应的速率，接近恒星内部反应发生的能量。IUSB学生将参与这些实验数据的收集和离线分析；特别是，通过对这种新实验装置的分析技术的发展做出贡献。该奖项还支持IUSB小组继续参与在国家超导回旋加速器实验室（NSCL）和密歇根州立大学稀有同位素束设施（FRIB）使用MoNA-LISA中子探测器研究稀有同位素结构的实验。圣乔治的探测系统利用飞行时间和能量的测量来区分α捕获反应产物和基于质量的残余光束粒子（又名背景）。IUSB小组将开发将粒子探测器归一化到圣乔治综合束流的技术，参与数据收集和在线分析，并参与收集数据的离线分析和解释。工作将从一个试运行实验开始，该实验将是对14N(α, γ)18F反应的研究。这个反应是生产Ne-22的第一步，Ne-22是s过程的中子源，通过22Ne(α,n)25Mg的反应。圣乔治非常适合，因为它的大角度和能量接受度，将α捕获反应的截面测量扩展到新的能量范围，并减少关键恒星反应速率的不确定性。该奖项还支持利用国家超导回旋加速器实验室的MoNA-LISA中子探测器阵列对中子滴线附近原子核结构的研究。IUSB是MoNA合作的成员机构，PI和IUSB的学生将在国家科学实验室参与MoNA实验期间的数据收集和共享数据分析，这是MoNA合作的一个标志。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

The broad picture of how elements are produced by nuclear reactions in stars has been known for decades, but many important details of this process remain to be discovered. This award supports the participation of the PI and undergraduate students at Indiana University South Bend (IUSB) in a series of experiments to study nuclear reactions involving the fusion of a helium nucleus with another, heavier nucleus, which are important for a complete understanding of the helium-burning phase of stellar evolution. The experiments utilize the St. George recoil mass separator, a device recently commissioned at the University of Notre Dame's Nuclear Science Laboratory that allows measurements of the rates of these reactions at very low energies, close to the energies at which the reactions occur inside stars. IUSB students will participate in the collection and offline analysis of data from these experiments; in particular, by contributing to the development of analysis techniques that are specific to this new experimental device. The award also supports the continuing participation of the IUSB group in experiments using the MoNA-LISA neutron detectors for studies of the structure of rare isotopes at the National Superconducting Cyclotron Laboratory (NSCL) and the Facility for Rare Isotope Beams (FRIB) at Michigan State University.The detection system for St. George utilizes measurements of time-of-flight and energy to distinguish between alpha-capture reaction products and residual beam particles (aka background) on the basis of mass. The IUSB group will develop techniques to normalize particle detectors to the integrated beam flux in St. George, participate in data collection and online analysis during, and participate in offline analysis and interpretation of collected data. Work will begin with a commissioning experiment which will be a study of the 14N(alpha,gamma)18F reaction. This reaction is the first step toward the production of Ne-22, which is a neutron source for the s-process via the via the reaction 22Ne(alpha,n)25Mg. St. George is well suited, because of its large angular and energy acceptances, to extend cross section measurements for alpha-capture reactions into new energy ranges and reduce uncertainties in key stellar reaction rates. The award also supports research on the structure of nuclei near the neutron dripline, utilizing the MoNA-LISA neutron detector array at the National Superconducting Cyclotron Laboratory. IUSB is a member institution of the MoNA Collaboration, and the PI and IUSB students will participate in data collection during MoNA experiments at the NSCL and in the shared data analysis that is a hallmark of the MoNA Collaboration.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.