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

测量氢原子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）的拉姆齐技术测量氢原子的2s到2p间隔，精度达到2khz，改进了1980年伦迪恩和皮普金的测量。我们的测量，加上现有的高精度QED理论，每个都将导致质子电荷半径的0.6%的测定，揭示了使用介子氢和氢光谱学和电子-质子散射获得的质子半径之间4.3%（7西格玛）的差异。测量原子氦的精细结构以确定精细结构常数：我们使用sofs （PRA 79, 060503）对氦的n=2三重态P精细结构进行了亚自然线宽微波测量。我们现在设计了一种检测方案，通过将n=2三重态P原子共振转移到先前空化的亚稳态n=2三重态S亚能级，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。我们希望将350赫兹的精度提高到30赫兹以上，这将为QED提供一个重要的测试，并导致精细结构常数的十亿分之一的确定。此外，我们已经确定了以前被忽视的系统效应，这是由于来自遥远邻近共振的量子力学干扰，这对于这些间隔的测量和大范围的其他精确测量很重要。捕获反氢的精确光谱学：CPT对称和反物质物理的测试：我们在约克的小组继续积极参与ATRAP（哈佛大学、美因茨、Julich和约克大学由G. Gabrielse领导的合作项目）。ATRAP目前已经成功实现了3个目标中的2个：产生冷反氢（PRL 89, 213401）和在Ioffe陷阱中捕获这些原子（PRL 108, 113002）。第三个目标是对这些原子进行精确的光谱学分析。

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.