RUI: High-Precision Measurements and Tests of Fundamental Physics in Group III and IV Atoms

RUI：第三族和第四族原子基础物理的高精度测量和测试

• 批准号: 1912369
• 负责人: Protik Majumder
• 金额: $ 36.49万
• 依托单位: Williams College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1912369&HistoricalAwards=false
• 关键词: RUI; Precision; Measurements; Tests; Fundamental

This project supports the latest in a series of laser-based measurements of the electronic atomic structure of a set of particular heavy metal atoms, including thallium, indium, lead, and tin. The goal is to measure, with unprecedented precision, properties of these atoms by using lasers to cause electrons in the atom to "jump" from one quantum level to another. In a long-standing collaboration, the investigators will compare their high-precision measurements of atomic properties to the predictions by colleagues who perform complex theoretical calculations based on the quantum mechanical properties of these atoms. This interplay of experimental measurements and first-principles theoretical predictions reflects the process by which science should ideally progress: better experiments test current models and assess their accuracy while new theoretical techniques and predictions inform what additional experiments should be undertaken. The work in this atomic physics laboratory involves building and testing laser and optical systems, constructing and optimizing electronics and control systems, using computer-based methods to collect and then model and analyze large amounts of data. This work is located at an undergraduate liberal arts institution (Williams College) where students at all levels of their education become research partners, contribute to all aspects of the experimental work, collaborate on presentations at conferences and journal publications, and in many cases go on to graduate work in physics, engineering, and related fields. NSF funding also supports the hire of a postdoctoral research associate who will work closely with the Principal Investigator and undergraduates, receive important mentoring, and become involved in the department's educational life. The most recent NSF-funded postdoc will be departing the group this summer to begin a tenure-track faculty position at another nearby undergraduate institution, Connecticut College. Training of the next-generation of science and engineering students, as well as future faculty members and teachers, is thus a central aspect of the supported research project.This research program, located at an undergraduate institution, focuses on high-precision measurements of atomic structure in complex, multi-valence-electron systems using diode laser spectroscopy techniques. In addition to providing exacting tests of state-of-the-art ab initio atomic theory, these atomic systems play an important role in tests of fundamental physics, including searches for violations of discrete symmetries. These searches rely on accurate, independent atomic structure calculations, which are needed to distinguish the complicated (but "ordinary") quantum mechanical effects from the fundamental particle physics being tested. Recent work has focused on vapor-cell and atomic-beam-based spectroscopy of tri-valent indium and thallium where recent precise polarizability results have helped guide the latest theory work by distinguishing between two complementary approximation techniques. Current work focuses on transition amplitude measurements in four-valence lead, where new ab initio calculations have substantially improved calculational accuracy. This work utilizes a very-high-precision Faraday polarimetry technique to observe, for the first time, an electric quadrupole transition amplitude in the ground state configuration of lead. Given existing high-precision parity nonconservation measurements in lead and thallium, modest improvements in atomic theory precision can have significant impact on the quality of these atomic-physics-based tests of electroweak physics. In the course of this work, new techniques for laser stabilization, small-signal detection, and precision polarimetry will continue to be developed that have broad applicability. All of this work provides research-training opportunities for undergraduate students at every stage of their education, many of whom grow to become research partners, coauthor papers and conference presentations, and go on to attend highly selective Ph.D. programs in physics and related disciplines.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.

该项目支持一系列最新的基于激光的重金属原子的电子原子结构测量，包括铊、铟、铅和锡。目标是通过使用激光使原子中的电子从一个量子水平“跳跃”到另一个量子水平，以前所未有的精度测量这些原子的特性。在长期的合作中，研究人员将把他们对原子性质的高精度测量与同事们根据这些原子的量子力学性质进行复杂理论计算的预测进行比较。这种实验测量和第一原理理论预测的相互作用反映了科学应该理想地进步的过程：更好的实验测试当前模型并评估其准确性，而新的理论技术和预测则告知应该进行哪些额外的实验。这个原子物理实验室的工作包括建造和测试激光和光学系统，建造和优化电子和控制系统，使用基于计算机的方法收集，然后建模和分析大量数据。这项工作位于一个本科文科机构（威廉姆斯学院），在那里，各级教育的学生成为研究伙伴，为实验工作的各个方面做出贡献，在会议和期刊出版物上进行合作，并在许多情况下继续从事物理，工程和相关领域的研究生工作。美国国家科学基金会还支持聘请一名博士后研究助理，他将与首席研究员和本科生密切合作，接受重要的指导，并参与该系的教育生活。最近一名nsf资助的博士后将于今年夏天离开该小组，前往附近的另一所本科院校康涅狄格学院（Connecticut College）担任终身教职。因此，培养下一代理工科学生，以及未来的教职员工和教师，是受支持的研究项目的一个核心方面。该研究项目位于一所本科院校，主要研究使用二极管激光光谱技术对复杂多价电子系统中的原子结构进行高精度测量。除了为最先进的从头算原子理论提供严格的测试外，这些原子系统在基础物理学的测试中起着重要作用，包括寻找离散对称性的违反。这些搜索依赖于精确的、独立的原子结构计算，这是区分复杂（但“普通”）的量子力学效应和被测试的基本粒子物理学所必需的。最近的工作集中在三价铟和铊的气相电池和原子束光谱学上，其中最近精确的极化结果通过区分两种互补的近似技术帮助指导了最新的理论工作。目前的工作重点是四价铅的过渡幅度测量，其中新的从头计算大大提高了计算精度。这项工作利用非常高精度的法拉第偏振技术，首次观察到铅基态结构中的电四极跃迁幅度。考虑到铅和铊现有的高精度宇称不守恒测量，原子理论精度的适度改进可以对这些基于原子物理的电弱物理测试的质量产生重大影响。在这项工作的过程中，激光稳定、小信号检测和精密偏振测量等新技术将继续发展，具有广泛的适用性。所有这些工作都为本科学生在他们教育的每个阶段提供了研究训练的机会，他们中的许多人成长为研究伙伴，共同撰写论文和会议报告，并继续参加物理学和相关学科的高选择性博士课程。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。

项目成果

High-precision measurement and ab initio calculation of the (6s26p2) 3P0→3P2 electric-quadrupole-transition amplitude in Pb208

Pb208中(6s26p2)3P0～3P2电四极跃迁振幅的高精度测量和从头计算

• DOI: 10.1103/physreva.100.052506
• 发表时间: 2019
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Maser, Daniel L.;Hoenig, Eli;Wang, B.-Y.;Rupasinghe, P. M.;Porsev, S. G.;Safronova, M. S.;Majumder, P. K.
• 通讯作者: Majumder, P. K.