ARI-MA: Nuclear Materials Detection via Time-Encoded Differential Absorption and/or Differential Fluorescence

该奖项的研究目的是演示和评估差分吸收和差分荧光在探测恐怖分子隐藏在集装箱、公路车辆、飞机和船舶中的裂变核材料方面的应用。长期以来，微分吸收和荧光一直有效地用于光学和x射线波长，以识别由于嵌入感兴趣的结构的材料具有较高的吸收或荧光水平而无法检测到的材料和结构。但是，以前没有实际的手段可以将这项技术扩展到区分特殊核材料和非核材料所需的高光子能量，以及恐怖分子用来隐藏所关注的特殊核材料的运输的辐射屏蔽。在这个奖项中，我们将研究反向康普顿散射的使用，利用一系列不同波长的光脉冲来产生一系列匹配的、不同能量的强的、准正的伽马射线脉冲，通过检测这些脉冲的时间窗来确定这些脉冲通过的材料的吸收或荧光的能量依赖性。通过这些强大但简单的手段，可以识别特殊核材料的存在。即使浓度很低？通过其独特的能量依赖性的吸收和/或荧光。如果成功，这项研究将(1)验证一种新的具有成本效益的方法来检测这些核材料，(2)提供所需的学生和博士后培训，以帮助建立实施这些技术所需的人力基础，(3)促进这些技术和相关技术在科学，医学和工业中的平行应用的更广泛发展。

The research objective of this award is to demonstrate and evaluate the use of differential absorption and differential fluorescence for the detection of fissionable nuclear materials concealed by terrorists in shipping containers, road vehicles, aircraft and ships. Differential absorption and fluorescence have long been used effectively at optical and x-ray wavelengths to identify materials and structures that would otherwise be undetectable due to the higher levels of absorption or fluorescence by the materials in which the structures of interest are embedded. But there has previously been no practical means available to extend this technique to the high photon energies needed to distinguish special nuclear materials from the non-nuclear materials and radiation shielding relied on by terrorists to conceal the shipment of the special nuclear materials of concern. In this award we will investigate the use of inverse Compton scattering employing a sequence of optical pulses of varying wavelengths to generate a matching sequence of intense, collimated gamma ray pulses of differing energies identifiable by the time windows in which these pulses are detected to determine the energy dependence of the absorption or fluorescence of the materials through which these pulses pass. By these powerful but simplified means, the presence of special nuclear materials can be identified ? even at low concentrations ? by the unique energy-dependence of their absorption and/or fluorescence. If successful, this research will (1) validate a new cost-effective means for detection of these nuclear materials, (2) provide the student and postdoctoral training needed to help establish the manpower base needed to implement these techniques, and (3) contribute to the broader development of these and related techniques to the parallel applications in science, medicine and industry.