Special Nuclear Material (SNM) Detection

The challenge of highly specific long-range detection of special nuclear materials (SNM) requires the development of alternative technologies to those typically deployed in the nuclear radiation detection field. We propose to quantify the feasibility of one such alternative during the Phase I research. Specifically, in order to detect SNM with greater than 95 % probability and to control the false positive rate (Pf < 0.01 %), we will design a radar system based on the cm-wave electromagnetic radiation. We will concentrate our efforts on an indirect measure of the presence of the radioactive materials; namely, on the secondary ionization that surrounds the package, most notably in the air. In order to minimize the power requirements of the system, our calculations indicate that one should employ a synchronous microwave pulse (among other potential solutions) to stimulate the electron concentration in ionization region surrounding the SNM. Since the method is relatively untested for the particular ionizing radiation source targeted, the work will focus on accurately simulating: (a) the impact of SNM on its surrounding environment, focusing on the induced ionization due to neutron and gamma-ray interactions in the surrounding air, (b) the impact that the resulting ionization has on propagating electromagnetic waves, and (c) the optimal means to identify the particular isotopic composition of the package from the back-scattered radar pulse. These simulated results will then be used to assess the performance of the system in terms of the detection power and specificity of the system response.