中国先进研究堆高分辨中子成像技术研究

Research in High-resolution Neutron Imaging at China Advanced Research Reactor

  • 摘要: 中国先进研究堆热中子成像装置近年已完成建设并投入使用,探测器空间分辨率已达到亚毫米级,在航空航天、文物考古、氢含量表征等领域已有广泛的应用,但当前探测器分辨率仍无法满足一些高精度的测试需求。根据锆合金氢含量、文物制作工艺等领域的相关测试需求,本文搭建了一套基于中国先进研究堆热中子成像装置的高空间分辨中子成像探测器,介绍了搭建过程中光路系统设计、转换屏选择和相机的选择。通过相关模拟计算,搭建探测器光路系统,并对探测器整体进行调试。在中国先进研究堆热中子成像装置上完成了探测器系统的相关带束调试,并对注射器针管样品进行了测试。测试结果表明,探测器空间分辨率达到11.3 μm,实际可利用的视场大小达到23.6 mm×28 mm,实现了10 μm级空间分辨率。

     

    Abstract: Neutron imaging is a transmission imaging method, which has a wide range of applications in the fields of non-destructive testing of internal defects in materials, the distribution of light elements in samples, and the detection of radioactive samples due to the advantages of neutrons with deep penetration, ability to distinguish isotopes, and sensitivity to light elements. With the continuous development of various application fields, the requirements for the spatial resolution of neutron imaging are getting higher and higher, and improving the spatial resolution of neutron imaging and continuously approaching the micron level has become a key research direction in the field of neutron imaging. At present, the international advanced neutron imaging device has been able to complete the high-resolution neutron imaging test with spatial resolution at the micron level, and the domestic research in this field has also made some progress with the completion of the three major neutron sources, and is gradually approaching the international advanced level. The thermal neutron imaging device and the cold neutron imaging device of the China Advanced Research Reactor have been completed and put into use in recent years, and the maximum neutron flux density at the sample of the device can reach 4×109 cm−2·s−1, the optical path system has been greatly improved compared with the original neutron imaging device, and the spatial resolution of the detector has reached the sub-millimeter level, which has been widely used in aerospace, cultural relics and archaeology, hydrogen content characterization and other fields. The main factors affecting the spatial resolution of neutron imaging in neutron imaging devices are neutron sources, neutron optical path systems and neutron imaging detectors. In this study, based on the relevant test requirements in the fields of zirconium alloy hydrogen content and cultural relics production technology, the influencing factors of neutron imaging spatial resolution were studied, and a set of high-spatially resolved neutron imaging detectors based on the thermal neutron imaging device of China Advanced Research Reactor was built. At the same time, the spatial resolution of the detector was calculated theoretically, and the detector was debugged as a whole. Finally, the relevant band bundle commissioning of the detector system was completed on the thermal neutron imaging facility of China Advanced Research Reactor, and the syringe needle samples were tested. The test results show that the spatial resolution of the detector reaches 11.3 μm, and the actual available field of view size reaches 23.6 mm×28 mm, achieving a spatial resolution of 10 μm.

     

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