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To fight the drive-by dirty bomb

Developing advanced radiation sensors for highway tolling systems

Engineers monitor vehicles driving through a RAIN portal test track in Massachusetts.

A windowless van speeds along the turnpike. It carries a dirty bomb.

Law enforcement agencies must stop that van before it reaches a major city.

First they have to find it. Together, Raytheon and research firm Physical Sciences Inc. have formed one of three industry teams that will demonstrate advanced technologies for a nationwide project called the Radiation Awareness and Interdiction Network, or RAIN. The vision is to develop a network of sensors, communications systems and analytical tools that will work together to detect, identify and attribute vehicle-borne threats before they reach a protected region or site.

“In the past, detection systems were slow and relatively simple,” said Rich Moro, program manager for Raytheon’s RAIN offering. “They could not distinguish between types of radiation, so even legitimate cargo triggered a large number of nuisance alarms.”

The issue is normally occurring radioactive material, or NORM, a buzzword in detection circles. NORM shipments might be anything from radioactive isotopes in medical materials to a truckload of bananas, which naturally contain the radioactive isotope potassium-40. Or it could be any number of other, innocuous materials.

“One study found a third of nuisance alarms at some border crossings were caused by shipments of kitty litter,” said Dr. Erik Johnson, a Raytheon nuclear engineer and deputy program manager.

Clearing such alarms is expensive, occupying law enforcement personnel and causing delays for commercial traffic.

“Over time, the sensors got more capable,” said Moro. “But you still needed trucks to drive one at a time slowly through relatively expensive, single-mission screening portals. This is why the portals are deployed at natural choke points like a seaport, because they [would] add to traffic bottlenecks."

Fast forward to the present, and the government’s advanced technology demonstration program. In a two-mile strip of roadway at the Virginia Tech Smart Highway Facility, cars and trucks maneuver past checkpoints where researchers measure the performance of different RAIN concepts.

Systems engineers and nuclear detection experts from the Raytheon/ PSI team designed a two-part solution. First, they needed to detect and analyze potential radiation in the fraction of a second it takes for traffic to drive past the sensor. 

The team used PSI’s gamma detector technology, which combines off-the-shelf components with a proprietary algorithm called Poisson Clutter Split, or PCS. True to its name, this unique algorithm processes energy spectra and suppresses clutter — reducing noise levels in the radiation it reads.

As a result, the PCS-enabled radiation monitor, or PERM, detects and measures even small amounts of the target radiation, minimizes false alarms and accurately identifies threat signals from fast-moving vehicles. 

Second, the team addressed the economics of implementing the overall system. They installed the PERM radiation detectors as an upgrade to the Raytheon-built, all-electronic tolling systems now in use on roadways from Florida to Israel. 

The detectors become part of the elevated, drive-through gantries that have replaced toll booths on major highways around the world. The same vehicle timing and identification data that's used for accurate tolling can help with threat detection, discrimination and vehicle attribution.

“From the beginning, we took a practical approach to technology and ease of deployment by integrating with the existing tolling system and business practices,” said Moro.

The best part: RAIN builds on proven technology.

“This is another evolutionary step that transforms Raytheon’s all-electronic tolling systems into a multi-mission national security platform,” said Dr. Waseem Naqvi, technology director for Raytheon’s highway transportation solutions.

RAIN would be especially valuable to the federal, state and local authorities that protect interstate shipments, said Moro: "Law enforcement can monitor multiple lanes of traffic for radioactive materials moving at highway speeds, using a system that's already linked with the operations of other public safety agencies.”

This work has been supported by the U.S. Department of Homeland Security, Domestic Nuclear Detection Office, under competitively awarded contract HSHQDC-14-C-B0050. This support does not constitute an express or implied endorsement on the part of the government.

Last Updated: 05/25/2017

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