Evaluation of second-order Zeeman frequency shift in NTSC-F2  

作　　者：Jun-Ru Shi Xin-Liang Wang Yang Bai Fan Yang Yong Guan Dan-Dan Liu Jun Ruan Shou-Gang Zhang 施俊如;王心亮;白杨;杨帆;管勇;刘丹丹;阮军;张首刚(National Time Service Center,Chinese Academy of Sciences,Xi'an 710600,China;Key Laboratory of Time and Frequency Primary Standards,Chinese Academy of Sciences,Xi'an 710600,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]National Time Service Center,Chinese Academy of Sciences,Xi'an 710600,China [2]Key Laboratory of Time and Frequency Primary Standards,Chinese Academy of Sciences,Xi'an 710600,China [3]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Chinese Physics B》2021年第7期163-170,共8页中国物理B（英文版）

基　　金：the National Key R&D Program of China(Grant No.2016YFF0200202);the Maintenance and Reformation Program for the Major Science and Technology Fundamental Devices of the Chinese Academy of Sciences(Grant No.DSS-WXGZ-2020-0005);the Foundation for Western Young Scholars,China(Grant No.XAB2018A06)。

摘　　要：Caesium atomic fountain clock is a primary frequency standard,which realizes the duration of second.Its performance is mostly dominated by the frequency accuracy,and the C-field induced second-order Zeeman frequency shift is the major effect,which limits the accuracy improvement.By applying a high-precision current supply and high-performance magnetic shieldings,the C-field stability has been improved significantly.In order to achieve a uniform C-field,this paper proposes a doubly wound C-field solenoid,which compensates the radial magnetic field along the atomic flight region generated by the lead-out single wire and improves the accuracy evaluation of second-order Zeeman frequency shift.Based on the stable and uniform C-field,we launch the selected atoms to different heights and record the magnetically sensitive Ramsey transition|F=3,mF=-1→|F=4,mF=-1 central frequency,obtaining this frequency shift as 131.03×10^(-15)and constructing the C-field profile(σ=0.15 n T).Meanwhile,during normal operation,we lock NTSC-F2 to the central frequency of the magnetically sensitive Ramsey transition|F=3,mF=-1→|F=4,mF=-1 fringe for ten consecutive days and record this frequency fluctuation in time domain.The first evaluation of second-order Zeeman frequency shift uncertainty is 0.10×10^(-15).The total deviation of the frequency fluctuation on the clock transition induced by the C-field instability is less than 2.6×10^(-17).Compared with NTSC-F1,NTSC-F2,there appears a significant improvement.

关 键 词：caesium atomic fountain clock second-order Zeeman frequency shift C-field magnetic shielding 

分 类 号：TM935.115[电气工程—电力电子与电力传动]