First uncertainty evaluation of the cesium fountain primary frequency standard NMIJ-F2
First uncertainty evaluation of the cesium fountain primary frequency standard NMIJ-F2
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DOI：
10.1088/1681-7575/ac5e7b
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发表时间：
2022-03
期刊：
影响因子：
2.4
通讯作者：
A. Takamizawa;S. Yanagimachi;K. Hagimoto
中科院分区：
文献类型：
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作者：
A. Takamizawa;S. Yanagimachi;K. Hagimoto
本文报道了日本国家计量研究所第二原子喷泉主频率标准NMIJ-F2的首次不确定度评定。为了提高频率稳定性，我们使用高功率冷却激光束用于蒸汽加载光学糖蜜和光泵入塞曼亚能级m F = 0，将检测到的原子数量增加到9 × 105个。我们还采用了超稳定的低温蓝宝石振荡器作为本振，以防止由于迪克效应而导致频率稳定性下降。通过原子密度交替校正碰撞频移后，频率稳定性达到2.5 × 10−13(τ/s)−1/2。测量20天后，其值为1.9 × 10−16。B型不确定度通常为4.7 × 10−16；贡献最大的是分布腔相移，其次是微波漏移。在长期比较中，发现NMIJ-F2的频率在不确定度范围内与其他主次频率标准的频率一致。
We report the first uncertainty evaluation of NMIJ-F2, the second atomic fountain primary frequency standard at the National Metrology Institute of Japan. To improve the frequency stability, we increase the number of detected atoms to 9 × 105 using high-power cooling laser beams for vapor-loaded optical molasses and optical pumping into the Zeeman sublevel m F = 0. We also employ an ultra-stable cryogenic sapphire oscillator as a local oscillator to prevent the degradation of frequency stability due to the Dick effect. After correcting the collisional frequency shift by alternating atom densities, the frequency stability typically reaches 2.5 × 10−13(τ/s)−1/2. Its value is 1.9 × 10−16 after 20 days of measurement. Type B uncertainty is typically evaluated at 4.7 × 10−16; the largest contribution is from a distributed cavity phase shift, followed by a microwave leakage shift. In long-term comparison, the frequency of NMIJ-F2 is found to be consistent with that of the other primary and secondary frequency standards within the uncertainty.