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

测量原子氢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技术测量原子氢中的2S到2P间隔，精度为2 kHz，改进了1980年伦丁和皮普金的测量。我们的测量，加上现有的高精度QED理论，每一个都将导致0.6%的质子电荷半径的确定，揭示了使用介子氢获得的质子半径与通过氢光谱和电子-质子散射获得的质子半径之间4.3%(7sigma)的差异。 测量氦原子的精细结构以确定精细结构常数： 我们用SOF(PRA79,060503)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探测方案，它包括通过将n=2三重态P原子共振转移到先前被清空的n=2三重态S子能级来直接探测这些原子，这允许更高的探测效率和更低的本底，并且消除了我们测量中最大的系统影响。我们希望将我们的350赫兹精度提高到30赫兹以上，这将为QED提供一项重要的测试，并导致对精细结构常数的十亿分之零点五的测定。此外，我们还发现了一个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其他大范围的精确测量是重要的。 捕获反氢的精确光谱：CPT对称性和反物质物理的测试： 我们在约克的团队继续积极参与ATRAP(哈佛、美因茨、朱利奇和约克之间的合作，由G.加布里埃尔斯领导)。ATRAP的三个目标中的两个现在已经成功：生产冷反氢(PRL89,213401)和在IOFFE陷阱中捕获这些原子(PRL108,113002)。对这些原子进行精确光谱分析的第三个目标仍然存在。

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.