PM: Atomic Physics Investigations of Rare Earth Elements: A Prologue to New Physics Beyond the Standard Model

该奖项支持铈（Ce）和铽（Tb）作为下一代光学原子钟和激光冷却的潜在候选者的研究。原子钟在20世纪的科学和技术进步中发挥了重要作用，导致了全球定位、先进通信和基本粒子物理学测试等创新。下一代光学原子钟将扩展这些系统的功能，并将实现定时应用的复兴，例如增强数据路由和通信的安全性，先进的地球和空间时间导航，地球物理测量，测试爱因斯坦的广义相对论，以及搜索宇宙基本常数的变化。激光冷却是一种利用光的机械作用来降低气体中原子速度的技术。使用激光冷却原子开辟了物理学的新领域，从物质新状态的形成到新兴量子技术的实现。该项目的目标是将激光冷却扩展到所提出的原子物种，以提供额外的实验发现平台，以促进新的科学探索，解决与暗物质搜索和宇宙组成相关的基本物理问题。更具体地说，该项目将研究原子物理特性，并实施Ce和Tb的激光冷却，以实现其作为下一代时间/频率标准和具有独特性能和动力学的超冷集成的潜在用途。该项目将涉及少数民族研究生、本科生和高中生，他们将通过阿拉巴马大学伯明翰分校现有的项目参与Simien光谱和激光冷却小组的研究项目。额外的推广活动将旨在通过在该地区当地学校进行物理和化学演示，让K-12学生对科学和工程感兴趣。该项目是一个实验研究项目，旨在研究光谱、激光冷却和原子铈和铽的碰撞特性，因为它与光学时钟、标准模型之外的新物理搜索的基本常数变化以及偶极量子气体有关。这些原子具有奇异的电子构型和大的基态磁矩，这使得它们具有对精细结构常数α变化敏感的淹没壳光学时钟跃迁，以及奇异的量子气相，其现象以偶极子-偶极子相互作用为主。特别是，光谱研究将包括测量超精细结构、同位素位移、强电偶极子和自旋禁止跃迁的辐射寿命。本研究的目的是确定Ce和Tb的超精细常数、同位素位移、自然线宽和寿命。超细常数定义了超细峰的顺序以及对磁偶极子和电四极子相互作用的能量转移的贡献。同位素位移是由于原子核的质量和体积的不同而引起的跃迁能量的小偏差。自然线宽和寿命与转换速率有关。这些光谱性质的测定是实现激光冷却和捕获铈和铽的必要条件。此外，Ce和Tb将被激光冷却，作为进行精确测量和研究原子偶极物理的第一步。此外，碰撞淬火截面的测量、压力展宽和频移将发生在原子蒸汽电池内部。这些数量将表征碰撞灵敏度，并深入了解电子筛选和所提出的Ce和Tb激光冷却和光时钟跃迁的构型相互作用的联合作用。这项研究将有助于确定碰撞对铈或铽作为频率标准精度的影响。该项目由原子、分子和光学实验物理计划、刺激竞争性研究的既定计划（EPSCoR）、实验粒子物理计划和实验核物理计划资助。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。

This award supports the investigation of cerium (Ce) and terbium (Tb) as prospective candidates for next generation optical atomic clocks and laser cooling. Atomic clocks have been instrumental in the advancement of science and technology in the twentieth century, leading to innovations such as global positioning, advance communications, and tests of fundamental particle physics. A next generation optical atomic clock would extend the capabilities of these systems and will enable a renaissance of timing applications such as enhanced security for data routing and communications, advanced earth and space time-based navigation, geophysical surveying, testing Einstein's Theory of General Relativity, and searches for variations in the fundamental constants of the universe. Laser cooling is a technique that utilizes the mechanical action of light to reduce the velocity of an atom in a gas. The use of lasers to cool atoms opened up new frontiers in physics ranging from the formation of new states of matter to enabling emerging quantum technologies. The goal of this project is the extension of laser cooling to the proposed atomic species to enable additional experimental discovery platforms to facilitate new scientific explorations to address fundamental physics questions related to dark matter searches and the composition of the universe. More specifically, this project will investigate the atomic physics properties and implement laser cooling of Ce and Tb for their potential uses as next generation time/frequency standards and as ultracold ensembles with unique properties and dynamics. The project will involve minority graduate, undergraduate, and high school students via existing University of Alabama-Birmingham programs to participate in research projects in the Simien Spectroscopy and Laser Cooling group. Additional outreach activities will aim to get K-12 students interested in science and engineering by performing physics and chemistry demonstrations at local schools in the region.This project is an experimental research program directed towards investigating spectroscopic, laser cooling, and collisional properties of atomic cerium and terbium as it relates to optical clocks, variation in fundamental constants for new physics searches beyond the Standard Model, and dipolar quantum gases. These atoms have exotic electronic configurations and large ground state magnetic moments that allows them to have submerged shell optical clock transitions that are sensitive to variations in the fine structure constant alpha, and exotic quantum gas phases with phenomenon dominated by dipole-dipole interactions. In particular, the spectroscopic studies will involve measurements of the hyperfine structure, isotope shifts, and radiative lifetimes of strong electric dipole and spin-forbidden transitions. The objective of this study is to determine Ce and Tb hyperfine constants, isotope shifts, and natural linewidths and lifetimes. The hyperfine constants define the ordering of the hyperfine peaks and contributions to the energy shifts from the magnetic dipole and electric quadrupole interactions. The isotope shifts are small deviations in the transition energies due to differences between masses and the volumes of the nuclei. The natural linewidths and lifetimes are associated with transition rates. The determination of these spectroscopic properties are necessary for implementing laser cooling and trapping of cerium and terbium. Furthermore, Ce and Tb will be laser cooled as a first step towards performing precision measurements and studying atomic dipolar physics. In addition, measurements of collision quenching cross sections, pressure broadening, and frequency shifts will occur inside an atomic vapor cell. These quantities will characterize the collision sensitivity and give insight into the combined action of electron screening and configurational interactions of the proposed Ce and Tb laser cooling and optical clock transitions. This study will help determine the effect of collisions on the accuracy of cerium or terbium as a frequency standard. This project is funded by the Atomic, Molecular and Optical Experimental Physics program, the Established Program to Stimulate Competitive Research (EPSCoR), the Experimental Particle Physics program, and the Experimental Nuclear Physics Program.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.