【摘要】 中子成像是一种重要的无损检测方法，快中子（MeV级能量）成像技术，能够在中大型样品的轻材料缺陷检测发挥其独特优势。经过理论分析和蒙特卡罗模拟设计，采用过滤结构将绵阳研究堆热中子束线的裂变中子份额大大提高，在等效准直比约260情况下，成像位置的裂变中子注量率可以达到3×10⁵ cm^-2·s^-1。采用快中子荧光屏作为探测器，通过研发的大视场成像装置，形成了一套直接视场可达400 mm×400 mm，分辨率优于0.5 mm的裂变中子成像系统。利用超视场成像技术，该系统还能够检测横向尺寸不超过600 mm的大型样品。更多还原

【Abstract】 [Background] Neutron radiography（NR） is an important nondestructive testing method. NR is particularly useful for detection of light materials in medium and large heavy samples. Especially, the fast neutrons can penetrate the heavy materials and reveal the structure of the light materials. Compared to accelerator neutron sources, the fission neutrons elicited from a reactor are stable and of high quality. The fission neutron imaging is a useful complementary testing technology, especially for industrial applications that require high throughput and largescale testing. [Purpose] This study aims to investigate the super field of view neutron imaging by fission neutrons elicited from research reactor. [Methods] Based on theoretical analysis and Monte-Carlo simulation, one filter combination was employed to improve the proportion of fission neutrons in the thermal neutron beamline at China Mianyang Research Reactor（CMRR）. A fission neutron imaging system was constructed by employing a large field fast neutron fluorescent screen, short focus distance lens, and scientific charge coupled device（CCD） camera. Finally,some samples were tested using fission neutron tomography. [Results] The fission neutron flux reaches up to 3×10⁵ cm^-2·s^-1 when the L/D ratio is about 260. The field of view of NR is up to 400 mm×400 mm with resolution was better than 0.5 mm. Using super field of view method, samples less than 600 mm can be tested with this new system. [Conclusions] Combination of theoretical calculation and experimental methods, fission neutron imaging can be improved to overcome some of the limitations of traditional neutron radiography techniques, and meet the needs of large sample detection in the future.更多还原