极化中子照相磁场量化技术方案比较与分析

极化中子照相技术通过分析极化中子束的自旋相移对样品磁场进行成像,目前已发展出多种成像技术方案,其中能量选择法和自旋回波法极化中子成像技术从不同的原理出发,解决了极化中子照相中磁场量化的周期解问题,同时避免装置极化效率等参数的影响,可以实现较高的量化精度.本文对两种极化中子照相技术方案进行研究,通过对单色器能量分辨率和装置极化效率等关键参数的分析和模拟,确定在研究堆上开展相关实验的可行性,并初步明确其量化能力和适用范围.相关结果可为极化中子照相的实验数据处理技术研究及装置设计提供参考.

Comparison of two approaches to magnetic field quantification by polarized neutron images

Polarized neutron radiography allows the direct and real-space visualization of magnetic field distribution by detecting the polarization change in the transmitted beam. Two approaches to magnetic field quantification by means of polarized neutron images are studied. They are energy-selective method and spin-echo method. Both approaches need no corrections of parameters, such as polarization efficiency, and can quantify magnetic field integral without periodic uncertainty. The quantification ability, applicability and feasibility of two approaches at research reactor neutron source are verified by numerical simulation with key parameters such as monochromator resolution and polarization efficiency. The results will be helpful to process image data and designing instruments.
Keywords： polarized neutron radiography magnetic field quantification energy-selective method spin-echo