Nov 9 2006
In an exciting development in neutron science, the Spallation Neutron Source (SNS) project is a partnership of six US DOE National Laboratories to design and construct the most powerful spallation source in the world for neutron-scattering R&D. Instruments being built at the SNS include neutron spectrometers and diffractometers, used to determine the positions, or arrangements, of atoms in crystals, ceramics, superconductors and proteins. Novel neutron diffractometers and detectors at the Oak Ridge National Laboratory will be using neutron scintillators, developed in conjunction withApplied Scintillation Technologies (AST)。
AST has received two major orders for this project. The first is the supply of glass scintillator plates for use on an Anger camera. The scintillators are 158 mm square and 2 mm thick and are used in a 4 x 4 array. Each plate is coupled to a photomultiplier tube to give area position-sensitive neutron detection. The scintillator material has a fast decay time (80-90 ns) and offers excellent discrimination between neutrons and gamma rays. The plates are robust and extremely stable over time.
第二个阶是用于新型中子检测筛选，用于用于Vulcan和Powgen3衍射仪的交叉纤维中子检测器。对于广泛的结构研究，Powgen3将是极其灵活且通用的通用衍射仪。Vulcan是一种工程衍射仪，将用于变形和残留应力相关研究。其他用途包括化学，微结构和纹理的空间映射。
The crossed-fibre detector combines the AST neutron detection screen with a network of overlaid, wavelength shifting optical fibres, which are coupled to photomultiplier tubes. The screen itself has a blend of 6Li compounds and phosphors with an increased 6Li loading per unit area, which gives up to 20% increase in neutron capture compared to previous formulations. Each detector module utilizes 32 of these screens, tiled together in a 4 x 8 array.
屏幕设计使光纤具有最佳接触区域。与屏幕的中子相互作用在450 nm处产生闪烁。450 nm光子被波长转移纤维吸收，并转换为520 nm光子，从纤维的末端传播。光电倍增管提供了相互计数和位置编码，以允许2D检测中子事件。