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Measuring transverse relaxation time of Xenon Atoms Based on Single Beam of Laser in Nuclear Magnetic Resonance Gyroscope

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Journal of Shanghai Jiaotong university(Science) 2023年第5期28卷 569-576页

作者：钟国宸刘华郭阳李绍良赵万良成宇翔 School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Aerospace Control Technology Institute Shanghai Academy of Spaceflight TechnologyShanghai 201109China

Nuclear magnetic resonance gyroscope (NMRG) has the characteristics of high precision and miniaturization, and is one of the main applications of quantum technology in the field of navigation. The transverse relaxation time (T_(2)) of the xenon nuclear spin in the atomic cell of the NMRG directly affects the angular random walk of the gyro. Accurate and rapid measurement of T_(2) is conducive to further improvement of gyroscope. At present, for the measurement of T_(2), the schemes of two orthogonal lasers for pumping and detecting are usually used. By applying two fast-switching orthogonal static magnetic fields and a single beam of circularly polarized laser with corresponding wavelength to pump the atomic cell, the xenon nuclear macroscopic magnetic moment Larmor precession is generated. The cesium atoms parametric magnetometer in cell is formed to detect the free induction decay signal generated by nuclear spin precession of xenon atoms. The measurement of T_(2) by a single laser simplifies the measurement equipment compared with traditional method with two lasers. The experimental results show that the T_(2) of xenon atoms is more than 10 s, and the effects of temperature are studied, which lay the foundation for the subsequent improvement of gyro performance.

关键词： nuclear magnetic resonance gyroscope(NMRG) transverse relaxation time magnetometer free-induction decay

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Zeeman decoherence effect of trapped ^(199)Hg^(+) ion Ramsey spectra

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Chinese Physics B 2024年第11期33卷 272-277页

作者： Ge Liu Hao Liu Yihe Chen Jian Wang Shuhong Huang Chengbin Li Lei She Key Laboratory of Atomic Frequency Standards (KLAFS) Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

In the ^(199)Hg^(+) ion microwave clock,the Zeeman decoherence effect caused by the overlapping of Zeeman sidebands and the radial secular motion sidebands will decrease the contrast of the Ramsey fringe,thus reducing the signal-to-noise ratio of the *** this paper,the Zeeman decoherence effect is analyzed theoretically and investigated experimentally.A simplified model is built to describe the Ramsey spectral probability,in which the transverse relaxation time T2 is introduced to characterize the influence of the Zeeman decoherence effect *** experiments were carried out on a linear quadrupole trap ^(199)Hg^(+) ion *** results show that the probability model matches well with the experimental data,and the magnetic field value should be more than 150 mGs(1 Gs=10^(-4) T)to avoid the Zeeman decoherence effect.

关键词： ^(199)Hg^(+)ion microwave clock Zeeman decoherence transverse relaxation time

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Classification of different walnut varieties using low-field nuclear magnetic resonance technology and cluster analysis

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International Journal of Agricultural and Biological Engineering 2019年第6期12卷 116-121页

作者： Ping Song He Gao Baojun Zhao Aiguo Zhang Feng Liu College of Information and Electrical Engineering Shenyang Agricultural UniversityShenyang 110866China Service Center of Liaoning Forestry Development Shenyang 110036China Liaoning Institute of Economic Forestry Dalian 116031China

To classify different walnut varieties based on water and oil content of walnut,and determine their storage conditions,the low-field nuclear magnetic resonance(LFNMR)technology was used to obtain the NMR transverse relaxation time(T 2)of the samples based on the physical and chemical indicators of the walnut *** relationship between the relaxation time and phase state of the internal material of the sample was investigated,and the characteristic parameters of the NMR spectrum signals were statistically analyzed using cluster analysis to determine the different walnut varieties,and three different components,as well as their contents,were detected by a LFNMR spectrometer:firmly bound water,weakly bound water,and weakly bound *** results indicated that the oil peak was dominant in the overall signal intensity compared to the water peaks,in which the firmly bound water phase contributed more to the overall water signal between the water *** the analytic hierarchy process of cluster analysis,21 walnut samples were classified into three different classes,based on the characteristic parameters of the water-content and oil-content spectrum *** first class contains four walnut varieties characterized by least water and highest oil contents;the third class contains two walnut varieties,with the highest water content and least oil content;whereas,the second class contains 15 walnut varieties,with both water and oil contents at medium *** results showed that LFNMR led to a rapid detection of moisture and oil contents in walnuts,while cluster analysis classified different walnuts varieties based on these *** study also provided the basis for optimizing the storage methods and storage conditions of walnuts.

关键词： low-field nuclear magnetic resonance technology transverse relaxation time walnut cluster analysis decay curves

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Detection of rice seed vigor by low-field nuclear magnetic resonance

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International Journal of Agricultural and Biological Engineering 2018年第6期11卷 195-200页

作者： Ping Song Peng Song Hongwei Yang Tao Yang Jing Xu Kaitian Wang College of Information and Electrical Engineering Shenyang Agricultural UniversityShenyang 110866China Beijing Research Center for Information Technology in Agriculture Beijing 10097China National Research Center of Intelligent Equipment for Agriculture Beijing 10097China

A new method to predict the seed vigor of rice was developed to control adulteration during the seed trading process and to address the deficiencies of traditional manual detection ***-field nuclear magnetic resonance(LF-NMR)technique was used to detect the vigor of rice *** varieties(Beijing-1,Qianchonglang-2,Yanfeng-47 and Shennong-265)of rice seeds from the Rice Research Institute of Shenyang Agricultural University were chosen for the *** transverse relaxation time T_(2),T_(21) and T_(22) were observed in the *** peak start time of free water(transverse relaxation time T_(22)),signal amplitude of bound water(transverse relaxation time T_(21)),and moisture content decreased with the decrease in the vigor of the *** were no obvious trends observed for the top of the peak and the end point of the transverse relaxation time T_(22).In addition,the start,top,and end time of the peak(transverse relaxation time T_(21)),and the signal amplitude of bound water showed no consistent *** results indicated that LF-NMR could be used as a method to distinguish the vigor of rice seeds *** study provided theoretical basis and technical support for the rapid detection of rice seed vigor.

关键词： nondestructive detection nuclear magnetic resonance transverse relaxation time signal amplitude rice seeds vigor

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