α粒子散射对爆炸物检测时间分辨的影响
Influence of scattering α particle on time spectra in explosive detection
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摘要: 对爆炸物检测中伴随α粒子技术的时间谱进行了研究，建立了一套基于伴随α粒子技术的时间谱测量装置，分析了影响时间谱分辨的若干因素。采用60 μm厚的铜箔设计了一个锥形准直筒对散射的α粒子进行屏蔽，以500 g尿素为样品测量了α-γ符合时间谱。结果表明，α粒子在靶室内壁的散射是影响时间谱分辨的重要因素，锥形准直筒抑制了与α散射相关中子产生的γ射线，提高了α-γ符合时间谱的分辨。在有无锥形准直筒的条件下，符合时间谱特征瞬发峰γ的半高宽分辨力分别为1.8 ns和6.4 ns。分辨力高的时间谱可用于获取爆炸物样品的特征瞬发γ能谱。Abstract: The resolution of time spectrum is an important factor to obtain the excellent prompt gamma spectrum in the explosive detection. In this paper, we consider the scattering of α particle in the D-T reaction chamber wall is the main reason to the resolution of time spectrum. A measured device of time spectra based on associated α particle technique was built. A cone-shaped α particle collimator was designed to restrain the gamma induced by the neutron which is correlated to the scattering α particle. Thus, the resolution of the time spectrum was improved. Measurements show that with and without the collimator, the resolutions of the time spectrum are 1.8 ns and 6.4 ns, respectively.
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