Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio
Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio
复制标题
DOI：
10.1126/science.aaf6702
复制
发表时间：
2016-11-04
期刊：
影响因子：
56.9
通讯作者：
Venturelli, Luca
中科院分区：
文献类型：
--
作者：
Hori, Masaki;Aghai-Khozani, Hossein;Venturelli, Luca
电荷、宇称和时间反演 (CPT) 对称性意味着粒子及其反粒子具有相同的质量。反质子与电子的质量比 M-(p) 与 bar/m(e) 的比值可以根据反质子氦的单光子跃迁频率精确确定。我们使用激光光谱测量了 13 个这样的频率，分数精度为 2.5 x 10(-9) 至 16 x 10(-9)。通过在低温低压氦气中使用缓冲气体冷却，约 2 x 10(9) 反质子氦原子被冷却至 1.5 至 1.7 开尔文之间的温度；狭窄的热分布导致观察到小热多普勒宽度的尖锐谱线。与以往的单光子实验相比，实验频率与三体量子电动力学计算结果的偏差减少了1.4至10倍。由此，M-(p) 比 bar/m(e) 确定为 1836.1526734(15)，这与最近在 8 x 10(-10) 范围内的质子到电子实验值一致。
Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio M-(p) over bar/m(e) can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 x 10(-9) to 16 x 10(-9). About 2 x 10(9) antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, M-(p) over bar/m(e) was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 x 10(-10).