Large-Array Special Nuclear Material Sensing With Tensioned Metastable Fluid Detectors

Combatting nuclear terrorism is a 21st century grand challenge (US-NAE report-2008). This paper discusses how tensioned metastable fluid detector (TMFD) radiation sensors in large-array format attain and exceed the global challenge efficiency metric announced by the U.S. Department of Defense for detection of neutron emissions from special nuclear materials such as Plutonium. The challenge calls for detector array area $(A-cm^{2})$ times nuclear fission spectrum neutron detection fractional efficiency ( ${\epsilon }$ ) to exceed 1000; furthermore, using detectors in array form with linear dimension to not exceed 1 m based on use of He-3 based sensors—considered the industry “gold” standard. Based on experimentally validated efficiency of TMFD sensors, this paper presents evidence that an array of TMFDs (using either isopentane or trimethyl borate as sensing fluids) when optimally placed in array form can enable $\text{A}\times {\epsilon }$ ~ 2000—therefore, exceeding the challenge goal by over 100%. Additional advancements are reported on TMFD sensor characterizations for instrinsic efficiency of neutron detection (~80%) and spectroscopic alpha radiation emitter Pu/U isotopic detection (~99%) at $\times 100$ lower levels versus state-of-the-art spectrometers; comparisons versus conventional sensors are also presented—evidence is provided for $\times 75$ higher detection efficiency compared with the moderated BF 3 industry standard and toward $\times 25$ to $\times 800$ versus NE-213 fast neutron detector standard.