Collaborative Research: RUI: Study of Neutron-Rich Nuclei and Neutron Detector Response

该奖项将促进对富中子原子核性质的理解，并将本科生的参与作为不可或缺的组成部分。实验将在密歇根州立大学（MSU）的稀有同位素束设施（FRIB）进行，使用模块化中子阵列（莫纳）和大面积多机构闪烁体阵列（丽莎），这两种阵列都是由来自莫纳合作的几个机构的本科生建造和测试的。PI与他们的本科生团队和其他合作成员一起，沿着将研究轻富中子核在其稳定性极限附近的结构，这将为当前的核结构理论模型提供测试。 这些弱结合或未结合的核与它们的稳定对应物相比表现出不同的结构。它们是由加速的核束与稳定的靶碰撞产生的。 为了测试和提高计算机模拟的准确性，这对分析数据和从实验数据中提取物理结果至关重要，PI还在洛斯阿拉莫斯国家实验室的洛斯阿拉莫斯中子科学中心（LANSCE）进行实验。这些实验将直接观察16个莫纳探测器中的中子散射，作为模拟的测试。 该合作有一个长期的传统，涉及本科生参与其研究活动的核心。该研究项目为本科生提供前沿研究机会，帮助培养下一代科学家。PI及其本科生将参与使用模块化中子阵列（莫纳）的两项FRIB实验，分析最近和未来的数据，并为改进数据分析中使用的Monte Carlo模拟做出贡献。FRIB批准的两个莫纳实验将研究富中子核（特别是30 F和53 Ca）中的中子未束缚态。第一个实验的目标是首次测量30 F基态，这将提供有关氟同位素结构变化的细节。第二个实验的目的是通过测量53 Ca中的未束缚激发态来更好地理解N = 32的亚壳层闭合。这两个实验都为检验现代核结构模型提供了相关数据。 PI还寻求改进这些塑料衰减器中中子相互作用的计算机建模，这对于提高FRIB实验的探测器分辨率和数据过滤至关重要。 他们将在LANSCE进行第三次核散射实验，使用金刚石探测器作为活动靶，并与16个莫纳探测器配合使用。 在LANSCE的PI以前的两个实验暴露了当前模拟包的一些缺点。金刚石探测器仅由C原子核组成，可以聚焦于在塑料散射器中引起暗散射的中子-碳相互作用，从而降低阵列中的位置分辨率。该奖项反映了NSF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。

This award will advance understanding of the nature of neutron-rich atomic nuclei, with undergraduate student participation as an integral component. Experiments will be conducted at the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) using the Modular Neutron Array (MoNA) and the Large-area multi-Institutional Scintillator Array (LISA), both constructed and tested by undergraduate students from several institutions in the MoNA collaboration. The PIs, along with their team of undergraduate students and other collaboration members, will investigate the structure of light neutron-rich nuclei near the limits of their stability, which will provide tests for current theoretical models of nuclear structure. These weakly-bound or unbound nuclei exhibit different structures compared with their stable counterparts. They are produced by collisions of an accelerated beam of nuclei with a stable target. In order to test and improve upon the accuracy of computer simulation, critical for analysis of data and extraction of physics results from experimental data, the PIs also conduct experiments at the Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory. These experiments will directly observe neutron scattering in 16 MoNA detectors as a test of the simulation. The collaboration has a long-standing tradition of involving undergraduate student participation at the heart of its research activities. This research program provides cutting-edge research opportunities for undergraduate students, helping to train the next generation of scientists.The PIs and their undergraduate students will participate in two FRIB experiments using the Modular Neutron Array (MoNA), analyze recent and future data, and contribute to the improvement of Monte Carlo simulation used in data analysis. The two approved MoNA experiments at FRIB will study neutron-unbound states in neutron-rich nuclei (specifically 30F and 53Ca). The goal of the first experiment is to measure the 30F ground state for the first time, which will provide details on the structural changes in the fluorine isotopes. The goal of the second experiment is to better understand the N = 32 subshell closure by measuring unbound excited states in 53Ca. Both experiments provide data relevant for testing modern nuclear structure models. The PIs also seek to improve the computer modeling of neutron interactions in these plastic scintillators, critical for improving detector resolution and filtering of data for FRIB experiments. They will conduct a third approved neutron-scattering experiment at LANSCE using a diamond detector as active target in conjunction with 16 MoNA detectors. Two previous experiments by the PIs at LANSCE exposed some shortcomings of current simulation packages. The diamond detector, which consists only of C nuclei, allows for a focus on the neutron-carbon interactions that cause dark scattering in the plastic scintillators, which decrease position resolution in the array.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.