Walk-Through Explosives Detection Portal

Screening people for explosives, especially at airports, is a high priority problem needing a technological solution. The goal of this project is fielding an affordable system which can screen hundreds of passengers per hour for common high explosives (dynamite, TNT, C-4, Semtex, Detasheet) in a noninvasive way. A prototype of such an explosives detection portal has been constructed at Sandia National Laboratories, with an estimated cost below $150,000. While a person stands in the portal for several seconds, an overhead fan blows air over the body and any explosive vapors or dislodged particles are collected in vents at the feet. Explosives are separated from the air flow in a preconcentrator and subsequently directed into an ion mobility spectrometer (IMS) for detection. This detector determines which explosives are present and in what amounts. Total time for screening each passenger is twelve seconds (300 per hour). Testing was conducted at Sandia for explosive vapor and particulate contamination which would accompany a terrorist with a bomb. Vapor tests, where a standard mass of explosive vapor is injected into the portal, show that the system has a linear mass response range which spans more that two orders of magnitude. That linear relationship provides the calibration necessary to quantify explosives particles collected during more realistic particulate tests. Subfingerprint amounts of explosive contamination on clothing are detectable. Field testing at the Albuquerque International Sunport will begin during the summer of 1997.