CAREER: High Precision Spectroscopy of the Beryllium Isotope Chain

这个项目的目的是促进对原子内部工作原理的理解。具体来说，这个项目研究了组成铍原子（元素周期表上的第四个元素）的所有成分是如何聚集在一起赋予铍原子和核性质的。我们对原子系统的认识是由实验和理论结果驱动的。较轻的元素（氢、氦和锂）在实验和理论上都得到了广泛的研究。由于铍比这三种较轻的元素有更多的亚原子粒子，所以它的模型更加复杂和困难。随着原子建模的计算变得越来越复杂，提供实验结果来检查这些计算并确定哪些理论模型正确地描述了这个多电子系统变得至关重要。目前对铍的最精确的实验测量比对三种较轻的元素的测量要精确10000倍。这个项目将大大改进这些实验测量，以验证基本的原子和核理论，并提供有关原子的核和电子结构的信息。了解铍是发展多电子理论的重要基石，该理论成功地描述了更大、更重的原子，这些原子构成了元素周期表的大部分，是我们每天生活和工作的材料的重要组成部分。将对中性铍同位素链进行高精度光谱分析，显著提高几个关键能级的实验精度。结果将描述各种理论模型，测试量子电动力学，并帮助确定铍的核电荷半径。光谱学将在单重态（2s2p、2s3d和2snp里德堡态）和三重态（2s2p、2s3s、2s4s和2snp里德堡态）以及电离阈值上进行。1200摄氏度的烤箱会产生一束中性原子铍。横向光谱将使用多种激光源对原子束进行，包括四倍频钛蓝宝石激光器和外腔二极管激光器。光子能量校准由校准的超低膨胀腔提供，原子-光相互作用通过吸收、荧光或离子检测来检测，这取决于所研究的状态。

The aim of this project is to advance the understanding of the inner workings of the atom. Specifically, this project investigates how all the components that make up the beryllium atom, the fourth element on the periodic table, come together to give beryllium its atomic and nuclear properties. Our knowledge of atomic systems is driven by both experimental and theoretical results. The lighter elements (hydrogen, helium, and lithium) have been extensively studied both experimentally and theoretically. Because beryllium has more subatomic particles compared to the three lighter elements, it is more complex and difficult to model. As the computations involved in modeling this atom grow more complex, it becomes essential to provide experimental results to both check those calculations and determine which theoretical models correctly describe this multi-electron system. The most precise experimental measurements currently available for beryllium are up to 10,000 times less precise than those for the three lighter elements. This project will greatly improve upon these experimental measurements in order to validate fundamental atomic and nuclear theories as well as provide information about the nuclear and electronic structure of the atom. Understanding beryllium is an important stepping stone to developing a multi-electron theory that successfully describes larger and heavier atoms, which make up the bulk of the periodic table of the elements and are essential components of the materials that we live and work with every day. High precision spectroscopy will be performed on the neutral beryllium isotope chain to significantly improve the experimental accuracy of several key energy levels. The results will delineate various theoretical models, test quantum electrodynamics, and help determine the nuclear charge radius of beryllium. Spectroscopy will be performed on both singlet states (2s2p, 2s3d, and 2snp Rydberg states) and triplet states (2s2p, 2s3s, 2s4s, and 2snp Rydberg states) as well as the ionization threshold. An oven operating at 1200 degrees Celsius will produce a beam of neutral atomic beryllium. Transverse spectroscopy will be performed on this atomic beam using a variety of laser sources including a frequency quadrupled Ti-Sapphire laser and external cavity diode lasers. Photon energy calibration is provided by a calibrated ultra low expansion cavity and the atom-light interaction is detected by absorption, fluorescence, or ion detection depending on the state being studied.