Tests of fundamental physics using precision measurements of simple atomic systems

拟议的研究涉及几个不同的领域，每个领域都有非常不同的方法和目标。所有领域都备受瞩目，Hessels博士被国际原子物理界认为是这些领域的领导者：*1.兰姆位移和质子电荷半径*使用微波和Hessels博士团队开发的新的频偏分离振荡场(FOSOF)技术测量原子氢n=2兰姆位移。当测量完成后，它将以比现有所有其他氢测量总和更高的精度来确定质子的电荷半径。这一结果将有助于解决(或加强)目前不同的装药半径测定之间的几个标准差。这种差异被社会各界称为质子半径之谜，在过去的7年里一直是数百篇论文的主题。*2.氦的精细结构和精细结构常数*新的超精密微波FOSOF测量氦的n=2三重态P精细结构正在完成，这将是所有氦精细结构中最精确的测量。它们将形成一种新的量子电动力学精确测试，并将使精密测量社区更接近于高精度地确定精细结构常数(决定所有电磁相互作用强度的自然基本常数)。精细结构常数的测定与电子g因子的测定之间的比较形成了对物理学理论(包括暗物质或标准模型以外的其他物理可能的影响)的强有力的测试。*3.反物质原子的捕获、激光冷却和精确光谱*Hessels博士和ATRAP的合作伙伴正在为一项实验做准备，在该实验中，被捕获的反氢原子将与激光相互作用。激光将被用来减慢反物质原子的运动，这种减速是朝着这些反原子的精确光谱迈出的重要的下一步。氢和反氢光谱的比较将检验CPT以及物质和反物质之间的对称性。成功的激光冷却和激光冷却反物质的光谱将极大地推进反物质研究领域。*4.其他工作*此外，Hessels博士正在与ATRAP合作，对反质子磁矩进行更精确的测量，与HorBatsch博士(York)合作计算量子干涉对精确测量的影响，与Storry博士(York)合作，对正电子进行精确光谱研究，并生产新的正电子原子(由负氢离子和正电子组成)，他正在与多伦多大学的武塔博士合作，研究一种测量电子电偶极矩的新想法。

The proposed research involves several separate areas, each with very different methodologies and objectives. All areas are high-profile, and Dr. Hessels is considered by the international atomic physics community to be a leader in these areas:***1. Lamb shift and the proton charge radius ***The atomic hydrogen n=2 Lamb shift is being measured using microwaves and the new Frequency-Offset Separated-Oscillatory-Fields (FOSOF) technique developed in Dr. Hessels' group. When the measurement is completed, it will determine the charge radius of the proton at a higher precision than can be achieved from all other existing hydrogen measurements combined. This result will help to resolve (or enhance) the current several-standard-deviation discrepancy between different determinations of the charge radius. This discrepancy is referred to by the community as the proton radius puzzle, and has been the topic of hundreds of papers in the past 7 years.***2. Helium fine structure and the fine-structure constant ***New ultraprecise microwave FOSOF measurements of the n=2 triplet P fine structure of helium are being completed, and will be the most precise measurements of any helium fine structure. They will form a new precise test of quantum electrodynamics and will also move the precision measurements community closer to a high-precision determination of the fine-structure constant (the fundamental constant of nature that determines the strength of all electromagnetic interactions). A comparison between this determination of the fine-structure constant and a determination from the electron g-factor forms a strong test of the theories of physics (including possible effects of dark matter or other physics beyond the Standard Model). ***3. Trapping, laser-cooling and precise spectroscopy of antimatter atoms ***Dr. Hessels and the ATRAP collaboration are preparing for an experiment in which trapped antihydrogen atoms will interact with laser light. The laser light will be used to slow the motion of the antimatter atoms, and this slowing is the next major step towards precision spectroscopy of these anti-atoms. A comparison between hydrogen and antihydrogen spectroscopy will test CPT and the symmetry between matter and antimatter. Successful laser cooling and spectroscopy of laser-cooled antimatter will greatly advance the field of antimatter research.***4. Other work***Additionally, Dr. Hessels is working with the ATRAP collaboration on a more precise measurement of the antiproton magnetic moment, is collaborating with Dr. Horbatsch (York) on calculations of the effect of quantum interference on precision measurements, is collaborating with Dr. Storry (York) on precision spectroscopy of positronium and on the production of a new positronic atom (composed of a negative hydrogen ion and a positron), and is collaborating with Dr. Vutha (U. Toronto) on a new idea for measuring the electric dipole moment of the electron.**