Wang Xiaofei, Zhu Maohua, Xiao Kangda, Guo Jun, Wang Li
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences - Wuhan National Laboratory for Optoelectronics, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences - Wuhan National Laboratory for Optoelectronics, Wuhan 430071, China.
J Magn Reson. 2019 Oct;307:106580. doi: 10.1016/j.jmr.2019.106580. Epub 2019 Aug 19.
To measure the residual magnetic field, which is a kind of static magnetic fields in the magnetic shields, is a tough task in the design of the cylindrical magnetic shields. Here, we demonstrate a method to measure static weak magnetic fields based on low-field nuclear magnetic resonance (NMR), where the static magnetic field's strength can be obtained by measuring nuclear spin precession's frequency. Atomic magnetometers can be adopted to sense the nuclear spin precession, and the nuclear spin can be adopted to measure the static magnetic field through this indirect method to obtain the static magnetic field's strength. With this method, some adverse factors that can make atomic magnetometers yield fluctuations, such as fluctuations in the light intensity and misalignment of the pump and probe beams, can be avoid. We also measure the axial residual magnetic field in the magnetic shields, where the magnetic field's strength is about 235 pT in the direction along the pump beam. By monitoring NMR signals from protons and fluorine nuclei, we realize a nuclear-spin comagnetometer, which can be used to detect static weak magnetic fields. The possibility of using a miniaturized atomic magnetometer sensor (MAMS) for static field measurements is also discussed.
在圆柱形磁屏蔽设计中，测量作为磁屏蔽中一种静磁场的剩余磁场是一项艰巨的任务。在此，我们展示了一种基于低场核磁共振（NMR）测量静弱磁场的方法，其中静磁场强度可通过测量核自旋进动频率获得。可采用原子磁力计来感测核自旋进动，并且通过这种间接方法利用核自旋测量静磁场以获得静磁场强度。利用此方法，可避免一些会使原子磁力计产生波动的不利因素，如光强波动以及泵浦光和探测光的未对准。我们还测量了磁屏蔽中的轴向剩余磁场，在沿泵浦光方向磁场强度约为235 pT。通过监测来自质子和氟核的NMR信号，我们实现了一种可用于检测静弱磁场的核自旋共磁力计。还讨论了使用小型化原子磁力计传感器（MAMS）进行静磁场测量的可能性。
