New technologies identify explosives with nuclear fingerprintBy Peter A. Buxbaum, AJOTA Massachusetts company, backed by funding from the Department of Homeland Security, is developing what it calls the next generation of explosive detection systems for cargo security. What differentiates this new system from its predecessors, according to Passport Systems, based in Acton, is that it can provide users with an atomic fingerprint of container contents, instead of a mere image. The system makes use of nuclear resonance fluorescence imaging (NRFI), a technology invented by MIT professor William Bertozzi in the 1990s in the aftermath of the Lockerbie terrorist plane bombing. Passport Systems was formed in 2002 to adapt NRFI to cargo security. The system works by bombarding containers with a stream of photons designed to excite nuclear particles. The energy emitted by the nuclear particles during the process of returning from an excited to a normal state results in a unique energy spectrum which is read by the system. This is by no means DHS’s first foray into the area of cargo security. The agency has aided in the development, testing, and deployment of a number of different explosive detection systems, some of which make claims similar to Passport’s. “What makes this so exciting, versus the research that has been done in the past with x-ray machines, is that we are able to get better penetration into dense and big cargoes to find out what is inside,” said Bob Ledoux, Passport System’s CEO. “The second generation of x-ray detection systems now being deployed uses high energy x-rays to get more penetration. But the main drawback to the older systems is that an operator has to interpret the image generated by the x-ray.” Terrorists attempting to smuggle radiological material into the United Stated will shield it behind material that x-rays won’t be able to penetrate, according to Ledoux. An operator viewing a large dark image on an x-ray picture will likely flag the container for manual inspection, a process that will yield too many false positives and which can slow down the flow of commerce. “No one wants that,” said Ledoux. “Port authorities, users, shippers, and the government all say they will deploy second generation systems, but our technology will be the next step beyond that. Our system can detect what kind of material is behind the shield. If it is a potential weapon of mass destruction, we can also tell what it is. You don’t want some unskilled person opening the container when you should be evacuating the port and sending in a SWAT team.” The Passport system is not the first innovative cargo security system with which the Department of Homeland Security has been involved. In 2004, the Transportation Security Administration broke ground on a facility in Ysleta, Texas, the sixth largest truck border crossing between the United States and Mexico, which deployed a Pulsed Fast Neutron Analysis (PFNA) system. The facility, which became operational in April 2005, cost TSA, along with the Department of Defense, the Bureau of Customs and Border Protection, and the General Services Administration $13.5 million “The PFNA system is being installed at Ysleta to undergo an operational test and evaluation,” said Susan Hallowell, director of the Transportation Security Administration’s laboratory in Atlantic City, NJ. “This program will measure the detection capability, false alarm rate, and inspection throughput of the PFNA system.” PFNA technology, developed during the 1980s and 1990s with help of Defense Advanced Research Projects Agency funding, inspects containers using neutrons to distinguish one type of material from another by comparing inspection results to a programmed data base of signatures of explosives, chemical and nerve agents, radioactive materials, and other contraband. The system creates an image indicating where the potential explosive or chemical agent is located. The TSA is planning to deploy PFNA systems at Houston’s George Bush Intercontinenta