常波长超小角中子散射谱仪设计

The design of a constant wavelength ultra small angle neutron scattering spectrometer

为探索常波长模式的超小角中子散射(USANS)谱仪技术,在广泛调研的基础上对USANS谱仪作原理设计,用Simres、NOP程序以及解析方法,进行了单色器/分析器的切槽单晶设计,谱仪前置单色器设计,并计算了谱仪最小Q分辨。结果表明,达尔文平台宽度影响谱仪的最小Q分辨,设计选取的Si单晶几个晶面的角度分辨足可使USANS系统的最小Q分辨达10^(-5)量级,在单色化的中子导管后端,USANS谱仪使用垂直聚焦单色器并不明显增加样品台注量率,为简化单色器结构及其加工,建议对单色化中子后端的USANS谱仪采用非聚焦前置单色器。

In order to carry out the research of constant wavelength ultra small angle neutron scattering spectrometer （USANS）, the design principle is studied in this paper base on relevant information from international laboratories. The main components are designed and calculated by using the Simres and N0P codes, and analytic method. The channel-cut crystal for monochromator and analyzer, and the pre-monochromator are desiged, and minimum Q of spectrometer is calculated. The results indicate that width of Darwin plat affects the minimum Q of spectrometer, the angle resolution of reflectivity planes selected in the design can ensure a Q resolution in 10-5 order. After the monochromatic neutron guide, a vertical focus monochromator does not seem to increase neutron flux at the sample stage, to simplify the monochromator structure and its manufacturing process, we propose to use un-focus pre-monochromator after the monochromatic neutron guide.