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~4He原子2~3S_1→2~3P_(0,1,2)跃迁的精细结构分裂,目前在理论和实验上都能够达到10~(-8)水平的精度,并可被应用于测定精细结构常数α,和对量子电动力学进行检验.该方面实验研究的关键,是需要提高测量信噪比,并消除各种可能的系统偏差,将这一精细结构分裂测量到亚kHz水平.在设计的这套实验方案中,首次结合激光冷却原子技术,通过激光横向冷却来提高亚稳态氦原子束的束流强度,并对三态亚稳态氦原子进行偏折,将其从原子束中分离,从而大幅降低测量背景,并利用频率锁定激光器的边带扫描的方式来进行光谱测量,以使得扫描测量中保持足够的频率精度.在目前基本搭建成的实验装置上,实验方法的可行性已经获得验证,分析表明有望实现亚千赫兹水平的测量准确度.
~ 4He atom 2 ~ 3S_1 → 2 ~ 3P_ (0,1,2) transition fine structure splitting, at present both in theory and experiment to achieve the level of 10 ~ (-8) accuracy, and can be used to determine the fine structure Constant α, and the test of quantum electrodynamics.The key to the experimental research in this aspect is to improve the measured signal-to-noise ratio and eliminate all possible system deviations, and to measure the sub-kHz level of this fine structure. In this experimental scheme, the laser cooling atomic technique is first used to increase the beam intensity of the metastable helium atomic beam by laser lateral cooling and to deflect the tristable metastable helium atoms to separate them from the atomic beam , Thus greatly reducing the measurement background, and the use of frequency-locked laser side-scan mode to carry out spectral measurements to make scanning measurements to maintain sufficient frequency accuracy in the basic structure of the experimental device at present, the feasibility of experimental methods have been Verified, the analysis shows promise of measurement accuracy at sub-kilohertz levels.