SGER: IMR: Development of Efficient Thermal Neutron Position Sensitive Detectors

本课题组计划研制一种新型的基于掺硼钆微通道板（MCP）的冷热中子计数探测器。新型中子成像探测器将针对热中子成像进行优化，具有高探测效率（高达50%），对于冷中子甚至更高，每个探测到的中子的空间（~55 µm）和时间分辨率为~1 ms（或门控探测，门控精度1 µs）。具有Medipix读出的探测器的计数率可以高达100 MHz，有效面积可扩展到28 x（N*14）mm 2的矩形配置。该探测器的另一个吸引人的特点是它能够与外部触发器同步，允许用脉冲源进行能量选择性成像。中子成像设备将在中子束线上进行严格的测试，与我们来自Nova Scientific的同事合作。所提出的探测系统将极大地促进具有非常高的计数率、灵敏度和分辨率的热中子成像，大大提高现有实验的准确性（例如，用工程仪器Vulcan测量SNS残余应力分布，用高压仪器SNAP研究高压下的小样品，燃料电池研究），并且还可以利用现代中子源开辟无损检测的全新领域。中子是一种不带电荷的核粒子，它对研究原子结构的细节非常有用。它们特别有用，因为它们可以探测原子排列并研究重要的材料特性，如磁性和晶体中原子的振动特性。然而，探测中子一直是一个挑战。这项提案计划使用带有许多细孔的玻璃片作为中子探测器。中子穿过孔，在孔的边缘与玻璃相互作用，然后，由于玻璃的特殊性质（添加硼或钆），中子转化为光，然后可以检测到。孔的小尺寸允许非常高的精度定位每个中子的位置，从而可以构建图像。此外，这种探测器系统可以以与最好的中子源产生的中子相同的速率计数中子，从而允许充分利用这些新来源的实验。

Technical AbstractOur group plans to develop a novel type of thermal and cold neutron counting detector based on Boron and Gadolinium doped microchannel plates (MCPs). The new type of neutron imaging detectors will be optimized for imaging thermal neutrons with high detection efficiency (up to 50 %) and even higher for cold neutrons, spatial (~55 µm) and time resolution of ~1 ms (or gated detection with gate accuracy 1 µs) for each detected neutron. The counting rate of detector with Medipix readout can be as high as 100 MHz with active area scalable to rectangular configuration of 28 x (N*14) mm2. Another attractive feature of the detector will be its ability to be synchronized with the external trigger, allowing energy selective imaging with a pulsed source. The neutron imaging devices will be rigorously tested at a neutron beamline, in collaboration with our colleagues from Nova Scientific. The proposed detection system will greatly facilitate thermal neutron imaging with very high counting rates, sensitivity and resolution, substantially increasing the accuracy of existing experiments (e.g. SNS residual stress profile measurements with the engineering instrument Vulcan, studies of small samples under very high pressures with the high pressure instrument SNAP, fuel cell studies), and may additionally open up entirely new areas of non destructive testing with modern neutron sources. Non-technical AbstractNeutrons are nuclear particles with no electronic charge which are very useful for studying the details of structure at the atomic level. They are particularly useful because they can probe atomic arrangements and study important materials properties such as magnetism and the vibrational properties of atoms in a crystal. However, detecting neutrons has always been a challenge. This proposal plans to use pieces of glass with many fine holes as a neutron detector. The neutrons pass through the holes, interact with the glass at the edge of the holes, and then, because of the special properties of the glass (addition of Boron or Gadolinium) the neutrons are converted to light, which can then be detected. The small size of the holes allows very high precision in locating the position of each neutron, so that images can be constructed. In addition, this detector system can count neutrons at the same rate that they are produced in the best neutron sources, allowing experiments that take full advantage of those new sources.