基于核共振吸收法开展爆炸物检测的原理验证研究

Proof-of-principle Study of Explosive Detection Based on Nuclear Resonance Absorption

集装箱爆炸物检测是当代全球运输安全领域的重要问题之一,由于运输环境的复杂性,检测和识别过程存在很多困难。特征γ射线共振吸收法被视为最有应用前景的探测方法之一,但目前相关研究的报导较少。以炸药为代表的爆炸物的含N成分浓度通常远高于其他普通材料,因此可通过^(14)N(γ,p)^(13)C反应对9.17 MeV特征γ射线共振吸收测量实现爆炸物的探测。本工作基于北京师范大学2×1.7 MV串列加速器,利用^(13)C(p,γ)^(14)N反应产生的9.17 MeVγ射线,开展了含N化合物三聚氰胺的共振吸收实验研究,并与常规石墨材料进行了比对,得到了含N化合物检测的灵敏度曲线。实验结果表明:该方法可明显观测到^(14)N特征γ射线的共振吸收现象,从而可有效应用于含N爆炸物的检测,为进一步开展含N液闪探测器的研制奠定了技术基础。

With the increasing of trade globalization,the amount of cargo container transportation between countries grows higher and higher.Handling the threat of explosive materials concealed in cargos is a prickly subject,since the conventional explosives are relatively easy to obtain and may cause massive harm to people and property.For this reason,a quick and accurate method of finding hidden explosives is a high priority in national security.Several methods have been used to detected explosives,such as X-ray screening,neutron interrogation,etc.However,these explosives interrogation methods all have drawbacks that limit their effectiveness.Detection of explosives based on nuclear resonance absorption of gamma rays in^(14)N,which was proposed in 1991,is a promising method.Because most of the explosives have higher nitrogen density than other common materials,it can be exploited as a means of distinguishing them from a host of other commonly transported materials.It is known that the materials with largely concentrated nitrogen can resonantly absorb theγ-ray with the energy of 9.17 MeV.In this work,a proof-of-principle experiment on the 2×1.7 MV Tandem Accelerator at Beijing Normal University was performed.The 9.17 MeVγ-ray was produced by the^(13)C(p,γ)^(14)N resonant reaction at the beam energy of 1.75 MeV.Different lengths of boxed melamine at the direction of 9.17 MeVγ-ray emitted were used as absorbers to study the absorption effect of highly concentrated nitrogen materials.As a comparison,a graphite rod was also used in the experiment for the study of absorption effect of nonconcentrated nitrogen materials.It is verified that the longer of the melamine absorber,the more distinctive absorption effect are observed.A lower detection limit of 23 g/cm^(2) concentrated nitrogen was also obtained in the experiment.This work lays the foundations of the establishment of the detection method for explosive materials concealed in cargo containers.