Precision measurements in one- and two- electron atoms for determinations of fundamental constants and tests of symmetries

一电子和二电子原子的精密测量，用于确定基本常数和测试对称性

• 批准号: 121521-2013
• 负责人: Hessels, Eric
• 金额: $ 4.37万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633145
• 关键词: Precision; measurements; two; electron; atoms

Measurement of the Lamb shift in atomic hydrogen to determine the charge radius of the proton:We will measure the 2S-to-2P intervals in atomic hydrogen to an accuracy of 2 kHz using the Ramsey technique of separated oscillatory fields (SOF), improving on the 1980 measurement of Lundeen and Pipkin. Our measurements, along with existing highly-precise QED theory, will each lead to a 0.6% determination of the proton charge radius, shedding light on the 4.3% (7 sigma) discrepancy between a proton radius obtained using muonic hydrogen and one from hydrogen spectroscopy and electron-proton scattering.Measurement of the fine-structure of atomic helium to determine the fine-structure constant:We have performed subnatural linewidth microwave measurements of the n=2 triplet P fine structure of helium using SOF (PRA 79, 060503). We have now devised a detection scheme that involves direct detection of the n=2 triplet P atoms by resonant transfer of these atoms to a previously emptied metastable n=2 triplet S sublevel, which allows for higher detection efficiency and lower background, and which removes the largest systematic effect in our measurement. We expect to improve our 350-Hz accuracy to better than 30 Hz, which will provide an important test of QED and lead to a 0.5 part-per-billion determination of the fine-structure constant. Additionally, we have identified a previously overlooked systematic effect due to quantum mechanical interference from distant neighboring resonances that is important for measurements of these intervals and for a large range of other precision measurements.Precise spectroscopy of trapped antihydrogen: a test of CPT symmetry and of antimatter physics:Our group at York continues an active participation in the ATRAP (a collaboration between Harvard, Mainz, Julich and York led by G. Gabrielse). ATRAP has now been successful in 2 of its 3 goals: production of cold antihydrogen (PRL 89, 213401) and trapping of these atoms in a Ioffe trap (PRL 108, 113002). The third goal of performing precise spectroscopy on these atoms remains.

测量原子氢中的兰姆位移以确定质子的电荷半径：我们将使用分离振荡场 (SOF) 的 Ramsey 技术以 2 kHz 的精度测量原子氢中的 2S 到 2P 间隔，改进了Lundeen 和 Pipkin 1980 年的测量。我们的测量以及现有的高精度 QED 理论将分别确定 0.6% 的质子电荷半径，揭示使用 μ 子氢获得的质子半径与氢光谱获得的质子半径之间 4.3% (7 sigma) 的差异测量原子氦的精细结构以确定精细结构常数：我们对 n=2 三重态 P 精细结构进行了次自然线宽微波测量使用 SOF 氦气 (PRA 79, 060503)。我们现在设计了一种检测方案，涉及通过将这些原子共振转移到先前清空的亚稳态n=2三重态S子能级来直接检测n=2三重态P原子，这允许更高的检测效率和更低的背景，并且消除了我们测量中最大的系统效应。我们期望将 350 Hz 的精度提高到 30 Hz 以上，这将为 QED 提供重要的测试，并导致精细结构常数的确定达到十亿分之 0.5。此外，我们还发现了一种先前被忽视的系统效应，该效应是由于来自遥远相邻共振的量子力学干扰而产生的，这对于这些间隔的测量和大范围的其他精密测量非常重要。捕获反氢的精确光谱：CPT 对称性和反物质物理学：我们约克的团队继续积极参与 ATRAP（由 G. Gabrielse 领导的哈佛、美因茨、尤利希和约克之间的合作项目）。 ATRAP 现已成功实现其 3 个目标中的 2 个：冷反氢的生产（PRL 89, 213401）以及将这些原子捕获在 Ioffe 陷阱中（PRL 108, 113002）。对这些原子进行精确光谱分析的第三个目标仍然存在。