一、前言利用X射线检测金属容器中的炸药、油、纸和塑料等含氢材料将会存在一定的困难,但是由于氢具有非常高的几乎比普通材料高出100倍的热中子俘获截面,所以利用热中子射线照相进行检测就非常容易。热中子在室温20℃状态下,具有约为0.025eV的Maxwell能量分布,且在中子射线照相中通常可采用核反应堆产生热中子。另外还可以采用锎252(Cf~(252))中子源自发地发射快中子,并进行调制成为热中子,Cf~(252)的半衰期为2.65年。由于枪炮中的炸药在检查中将会爆炸, I. INTRODUCTION The use of X-rays to detect hydrogen-containing materials such as explosives, oils, paper and plastics in metal containers presents some difficulties, but since hydrogen has a very high thermal neutron capture cross section that is almost 100 times higher than common materials , So using thermal neutron radiography for detection is very easy. The thermal neutrons have a Maxwell energy distribution of about 0.025 eV at room temperature of 20 ° C, and thermal neutrons can usually be generated using nuclear reactors in neutron radiography. In addition, you can also use 锎 252 (Cf ~ (252)) neutron source spontaneous emission of fast neutrons, and modulated into thermal neutrons, Cf ~ (252) half-life of 2.65 years. As the explosives in the guns will explode during the inspection,