Operation of NIM5 fountain with 1.5x10-15 uncertainty and design of new NIM6 in NIM

被引：4

作者：

Fang, F. ^{[1
]}

Liu, N. ^{[1
]}

Liu, K. ^{[1
]}

Chen, W. ^{[1
]}

Suo, R. ^{[1
]}

Li, Tianchu ^{[1
]}

机构：

[1] Natl Inst Metrol, Div Time & Frequency, Beijing, Peoples R China

来源：

8TH SYMPOSIUM ON FREQUENCY STANDARDS AND METROLOGY 2015 | 2016年 / 723卷

关键词：

1ST ACCURACY EVALUATION; CLOCK;

D O I：

10.1088/1742-6596/723/1/012009

中图分类号：

TH7 [仪器、仪表];

学科分类号：

0804 ; 080401 ; 081102 ;

摘要：

The cesium fountain primary frequency standard NIM5 started to operate since 2008 and started to report to BIPM since 2014. The major constrains of NIM5 is a relatively large background signal at the detection and microwave leakages due to the Ramsey cavity. A new fountain clock NIM6 is under construction. Besides some improvements on the vacuum system, a new Ramsey cavity and a microwave synthesizer are made to reduce the Type B uncertainty. Another feature of NIM6 is collecting atoms from a MOT loading optical molasses to get more atoms with a more uniform density distribution. With a new frequency synthesizer based on cryogenic sapphire oscillator (CSO), NIM6 is aiming to reach the quantum projection noise, thus leading to a reduced Type A uncertainty compared with NIM5.

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