Cross sections of some efficient slow-neutron reflectors

The proposal seeks to investigate the reflection capacity of two systems that are candidates for use in the design of cold neutron sources. These are carbon nanodiamonds and magnesium hydride. The first shows a strong Small Angle Neutron Scattering component in its cross section, while the second has scattering distributions closer to the isotropy. The comparison between forward and backward scattering signals will serve to evaluate such properties. In addition, the transmission measured with the new 2D transmission detector will serve to confirm the presence of the SANS signal in the nanodiamond powder in contrast to the magnesium hydride. The DINS spectra will be used to analyze the effective temperatures of the atoms, a quantity that will be used in the formulation of the dynamic models of both systems, necessary to model the materials to perform Monte Carlo simulations.

本提案旨在研究两种冷中子源设计候选系统的反射能力，即碳纳米金刚石与氢化镁。前者的截面中存在显著的小角中子散射（Small Angle Neutron Scattering, SANS）分量，而后者的散射分布更接近各向同性。通过对比前向与后向散射信号，可对上述特性进行评估。此外，利用新型二维透射探测器测得的透射率，能够确认纳米金刚石粉末中存在SANS信号，而氢化镁则无此现象。DINS谱将用于分析原子的有效温度，该物理量将被纳入两种系统的动力学模型构建中，为材料的蒙特卡洛模拟提供必要基础。