用于中子小角散射的中子反射镜聚焦性能评价  

Focusing performance evaluation of ellipsoidal neutron-focusing mirror for small-angle neutron scattering

作　　者：郭江 李琳光 GUO Jiang;LI Lin-guang(School of Mechanical Engineering,Dalian University of Technology,Dalian 116023,China;Ningbo Institute of Dalian University of Technology,Ningbo 315000,China)

机构地区：[1]大连理工大学机械工程学院,辽宁大连116023 [2]大连理工大学宁波研究院,浙江宁波315000

出　　处：《光学精密工程》2021年第9期2075-2082,共8页Optics and Precision Engineering

基　　金：辽宁省“兴辽英才计划”资助项目(No.XLYC1807230);宁波市“3315系列计划”资助项目(No.2020A-12-G)。

摘　　要：中子因具有极强的穿透力被广泛应用于材料与生物试样微观结构检测,但由于中子束强度显著弱于X射线,通常采用聚焦的方式来实现对中子束的有效利用。针对前期基于高性能制造思想研发的金属材质部分回转椭球中子反射镜进行了聚焦和中子小角散射实验测试。结果表明,聚焦中子束的最大强度能够达到漫散射强度的103,实现了与前端针孔尺寸几乎相等的圆形焦斑。通过远离最佳焦平面的聚焦实验,获得了不同镜心到探测器距离的束流剖面,该束流剖面的半峰全宽与基于几何光学的理论计算值吻合良好,分析了直射中子束和反射中子束的波长分布,中子的反射率达到了60%,峰值强度超过了1 000个计数/像素(0.1 mm×0.1 mm)。以介孔二氧化硅(MCM-41)为标样,获得了中子小角散射的初步结果。结果表明,该中子反射镜具有良好的聚焦性能,能够应用于中子小角散射。Neutrons are widely used in the microstructure inspection of materials and biological samples owing to their strong penetrating power.However,the intensity of the neutron beam is weaker than that of X-rays.A neutron-focusing mirror is usually employed to efficiently utilize a neutron beam.In this study,an ellipsoidal neutron-focusing mirror using a metal substrate was developed based on the high-per⁃formance manufacturing concept.Experiments on the focusing and small-angle neutron scattering(SANS)of the mirror were conducted.The results show that the maximum intensity of the focused neu⁃tron beam is 103 of the diffuse scattering intensities.A circular focusing spot with a size almost equivalent to that of one of the upstream pinholes was created.The experiment of focus was conducted away from the best focal plane.The beam profiles at several mirror-center-to-detector distances were obtained and the FWHM values of the beam profiles were in good agreement with the theoretical estimations based on the geometric optics.The wavelength distributions,such as the direct beam and the reflected beam were ana⁃lyzed.The reflectivity of the neutron focusing mirror reaches 60%,and the peak intensity exceeded 1000 counts/pixel(0.1 mm×0.1 mm).Moreover,a preliminary result for SANS using a standard sample made of porous silica(MCM-41)was reported.Studies have shown that the ellipsoidal neutron-focusing mirror has satisfactory focusing performance,which is sufficient for small-angle neutron scattering re⁃search.

关 键 词：中子光学 焦点 反射率 漫散射 中子小角散射 

分 类 号：O571.56[理学—粒子物理与原子核物理] TB851.9[理学—物理]