RUI: Laser Probing of Proton-Rich Rare Isotopes

该奖项邀请南达科他州苏福尔斯奥古斯塔纳大学的本科生和教职员工参与实验核物理研究。这项研究将在奥古斯塔纳以及密歇根州立大学的国家超导回旋实验室(NSCL)和稀有同位素束设施(FRIB)进行。将在NSCL/FRIB对稀有同位素进行激光光谱分析，以阐明具有极端质子与中子比率的核素形状和大小的系统变化。这些数据将为核理论提供重要的输入，这些理论被用来理解在稳定边缘将原子核捆绑在一起的基本力。此外，该奖项主要授予一所本科院校，为处于核科学前沿的学生提供独特的教育体验。由该奖项资助的尖端研究和仪器设备将延续奥古斯塔纳大学吸引和激励学生的传统，在一个传统上缺乏重要研究基础设施的地理区域，这是一个特别重要的成果。学生通过精密测量(如光谱学)获得的技能对STEM劳动力非常重要，而STEM劳动力反过来又是繁荣和创新的国民经济的关键组成部分。共线激光光谱学将用于研究富质子稀有同位素的电磁矩和电荷半径。此外，将在NSCL/FRIB的现有光束冷却和激光光谱分析(BECOLA)设施中安装一个高精度和高精度激光频率确定系统。改进后的激光系统将能够研究核结构效应，如轻质量核中壳层关闭和核配对的位置。将对稀有同位素进行共线激光光谱分析，根据原子超精细结构和同位素位移推算出缺中子核的核电荷半径、电磁矩和核自旋。对质子滴线附近富质子40，41Sc的研究将揭示Sc同位素的电荷半径是否在N=20壳层闭合时保持减小的趋势。这些测量对于从整体和微观上理解电荷半径在N=20壳层闭合时作为Ca同位素周围质子数函数的反常行为的机制是重要的。这些数据也将是对一个成功的密度泛函理论模型的关键检验，该模型使用了一个新的Fayans能量密度泛函来描述钙链。饱和吸收光谱仪将提供一种方法来确定探测激光频率，其精度优于1 MHz，比目前使用现有波长计可实现的精度高10倍。更高的精度将把推断的同位素漂移的系统误差从几个百分点减少到远低于1%。该项目由实验核物理计划和既定的刺激竞争研究计划(EPSCoR)联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award engages undergraduate students and faculty at Augustana University in Sioux Falls, South Dakota in experimental nuclear physics research. The research will be carried out at Augustana as well as the National Superconducting Cyclotron Laboratory (NSCL) and Facility for Rare Isotope Beams (FRIB) at Michigan State University. Laser spectroscopy will be performed on rare isotopes at NSCL/FRIB to elucidate systematic changes in the shape and size of nuclides with extreme proton-to-neutron ratios. The data will provide vital input to nuclear theories that are used to understand the fundamental forces that bind nuclei together at the edges of stability. Additionally this award, to a primarily undergraduate institution, provides a unique educational experience for students at the forefront of nuclear science. The cutting-edge research and instrumentation that will be funded by this award will continue a tradition at Augustana University to attract and inspire students, an especially important outcome in a geographical area that has traditionally lacked significant research infrastructure. The skills students will gain with precision measurements, such as spectroscopy, are important for the STEM workforce, which is, in turn, a key component of a prosperous and innovative national economy. Collinear laser spectroscopy will be used to study electromagnetic moments and charge radii of proton-rich rare isotopes. Additionally, a high accuracy and high precision laser frequency determination system will be installed at the existing BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/FRIB. The improved laser system will enable studies of nuclear structure effects such as the location of shell closures and nuclear pairing in light mass nuclei. Collinear laser spectroscopy will be performed on rare isotopes, and nuclear charge radii, electromagnetic moments, and nuclear spin of neutron-deficient nuclei will be deduced from atomic hyperfine structure and isotope shifts. Studies of proton-rich 40,41Sc in the vicinity of the proton drip line will reveal if the charge radii of Sc isotopes keeps the decreasing trend across the N = 20 shell closure. These measurements are important for the global and microscopic understanding of the mechanism for the abnormal behavior of charge radii as a function of the proton number around Ca isotopes at the N = 20 shell closure. These data will also be a critical test of a successful Density Functional Theory model using a novel Fayans energy density functional for the Ca chain. The saturated absorption spectrometer will provide a means to determine the probe laser frequency to better than 1 MHz, 10 times more precise than currently achievable using the existing wavelength meter. The greater precision will reduce the systematic errors in the deduced isotope shifts from several percent to much less than one percent.This project is jointly funded by the Experimental Nuclear Physics Program and the Established Program to Stimulate Competitive Research (EPSCoR).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.