冷中子非弹性散射谱仪能量分辨率的模拟研究

能量分辨率是中子散射谱仪设计中需重点模拟计算的一项指标。本文阐述了基于反应堆中子源的两种冷中子非弹性散射谱仪——三轴谱仪和广谱谱仪的基本测量原理,利用MCSTAS软件分别建立两种谱仪的中子束追踪模型,完成了不同中子入射能量和出射能量下的谱仪整体能量分辨率的定量模拟计算。通过对比发现,广谱谱仪由于其测量原理即特殊的变异散射平面的限制,较三轴谱仪具有低的能量分辨率,但这种特殊的变异散射平面的中子散射轨迹却可优化广谱谱仪的分析器和探测器空间布局。通过分析模拟计算结果给出了适用于提高广谱谱仪能量分辨率的中子准直器类型。

Simulation Study on Energy Resolution of Cold Neutron Inelastic Scattering Spectrometer

The energy resolution is an important index for simulation and calculation in the design of neutron spectrometers. In this paper, the working principles of neutron triple axis spectrometer and neutron multi-channel spectrometer were illustrated. With MCSTAS software, the neutron tracing models of the two spectrometers were built, and the quantitative calculations of the energy resolution in different neutron incident and final energy were completed based on the simulation results. The multi-channel spectrometer has relatively low energy resolution comparing with triple-axis spectrometer because of the variation of scattering plane. However, the variation of scattering plane could optimize the special arrangement of analyzers and detectors in multi-channel system. Through analyzing the simulation results, the appropriate collimator types were given in order to improve the energy resolution of multi-channel spectrometer.