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

该奖项的研究目标是展示和评价利用差分吸收和差分荧光探测恐怖分子隐藏在海运集装箱、公路车辆、飞机和船舶中的可裂变核材料。长期以来，差分吸收和荧光在光学和X射线波长下被有效地用于识别材料和结构，否则这些材料和结构将由于感兴趣的结构嵌入其中的材料的较高水平的吸收或荧光而不可检测。但是，以前没有任何实际手段可以将这一技术推广到区分特殊核材料与非核材料所需的高光子能量，以及恐怖分子用来掩盖所涉特殊核材料运输的辐射屏蔽。在这个奖项中，我们将研究使用逆康普顿散射采用一系列不同波长的光脉冲，以产生一个匹配的序列的强烈，准直伽马射线脉冲的不同能量可识别的时间窗口，这些脉冲被检测到，以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，可以确定特殊核材料的存在吗？即使在低浓度下？通过其吸收和/或荧光的独特能量依赖性。如果成功的话，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）提供必要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.