The neutron flux of compact neutron sources is low, making it difficult to measure scattered neutrons with a typical small-angle neutron scattering (SANS) geometry. A SANS geometry with ring-shaped collimation (r-SANS) was thus developed to enable experiments to be conducted using low-flux neutron source facilities. In this geometry, circumferentially collimated beams hit a sample. The scattered neutron flux is high on the ring center axis because scattered neutrons with each nominal scattering angle are superimposed on each point of the ring center axis. A ³He point detector – which has higher neutron counting efficiency compared with that of a typical scintillation detector and can also properly distinguish neutron from gamma events – is set on the ring center axis. These features make high signal-to-noise ratio experiments possible. Monte Carlo (MC) simulation studies were conducted to evaluate the characteristics of the r-SANS geometry. The results show that oblique incident neutrons, which cause cross-talk, asymmetrically smear the scattering intensity, and increase the incident neutrons. To study the feasibility of the r-SANS geometry, it was tested at the Kyoto University Accelerator-driven Neutron Source (KUANS), which is one of the most compact and has one of the lowest neutron fluxes among available neutron beam facilities. Two types of porous silica gels, HC-N and C-500HG, were examined. As reference, the same samples were analyzed using a small-angle X-ray scattering (SAXS) spectrometer under a typical pinhole geometry. To consider the smearing effect of the r-SANS geometry, MC simulations with SAXS experimental results were conducted. The simulated results agree with the r-SANS experimental results. In addition, to show the consistency of the scattering model parameters determined via r-SANS with those via SAXS, a parameter survey was performed, revealing reasonable agreement between the results.

紧凑中子源的中子通量很低，因此很难测量具有典型小角中子散射（SANS）几何形状的散射中子。因此，开发了具有环形准直（S-SANS）的SANS几何形状，以使能够使用低通量中子源设备进行实验。在这种几何形状中，沿圆周方向准直的光束撞击样品。散射中子通量在环中心轴上较高，因为具有每个标称散射角的散射中子叠加在环中心轴的每个点上。A ³他点探测器设置在环中心轴上，该探测器比典型的闪烁探测器具有更高的中子计数效率，并且还可以正确地区分中子和伽马事件。这些功能使高信噪比实验成为可能。进行了蒙特卡洛（MC）仿真研究，以评估r-SANS几何形状的特征。结果表明，倾斜的入射中子引起串扰，不均匀地涂抹了散射强度，并增加了入射中子。为了研究r-SANS几何的可行性，它在京都大学加速器驱动的中子源（KUANS）上进行了测试，这是现有中子束设施中最紧凑的之一，中子通量最低的之一。检查了两种类型的多孔硅胶HC-N和C-500HG。作为参考，在典型的针孔几何结构下，使用小角度X射线散射（SAXS）光谱仪分析了相同的样品。为了考虑r-SANS几何形状的拖尾效应，使用SAXS实验结果进行了MC模拟。仿真结果与r-SANS实验结果吻合。此外，为了显示通过r-SANS确定的散射模型参数与通过SAXS确定的散射模型参数的一致性，进行了参数调查，揭示了结果之间的合理一致性。