NIST-Time and Frequency Division, 325 Broadway Div 688 Boulder, Colorado 80305, USA.
INRIM, Str della Cacce, 91 10135 Torino, Italy.
Phys Rev Lett. 2014 Feb 7;112(5):050801. doi: 10.1103/PhysRevLett.112.050801.
We report a high-accuracy direct measurement of the blackbody radiation shift of the 133Cs ground-state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the International System of Units (SI) second. Uncertainty in the blackbody radiation frequency shift correction has led to its being the focus of intense theoretical effort by a variety of research groups. Our experimental measurement of the shift used three primary frequency standards operating at different temperatures. We achieved an uncertainty a factor of five smaller than the previous best direct measurement. These results tend to validate the claimed accuracy of the recently calculated values.
我们报告了对 133Cs 基态超精细跃迁的黑体辐射位移的高精度直接测量。该频率位移是实现国际单位制（SI）秒当前定义时遇到的最大系统频率偏差之一。黑体辐射频率位移修正的不确定性导致各种研究小组进行了大量的理论研究。我们对位移的实验测量使用了在不同温度下运行的三个主要频率标准。我们实现了比以前的最佳直接测量小五倍的不确定度。这些结果倾向于验证最近计算值的声称精度。
