On a blustery winter day last December, a car carrying radioactive material approached one of the Port Authority of New York and New Jersey’s major transportation hubs. As the car got closer, an alarm flashed and sounded on a large monitor in the police operations center, identifying on a digital map the exact location of the vehicle and the specific radioactive isotope radiating from the car – Cesium-137. Within minutes, officers in the Port Authority Police Department – equipped with vehicle-mounted and pocket-sized radiation sensors displaying the same real-time digital map – tracked the vehicle and apprehended the suspects in a parking lot. Thankfully, the potential terrorists and radiation-emitting isotope were not a threat, as the scenario was only a drill.
The December exercise marked the capstone for DARPA’s SIGMA program, culminating a five-year effort to develop and deploy an automated, high-performance, networked radiation detection capability for counterterrorism and continuous city-to-region scale radiological and nuclear threat monitoring. The transition of the radiation-detection system took place prior to the coronavirus disease (COVID-19) pandemic. In the eight months since the SIGMA transition, DARPA has been developing and testing additional sensors under its SIGMA+ effort to detect chemical, biological and explosive threats as well.
“We want to thank the Port Authority for their outstanding support throughout the SIGMA program and their continued support as we test SIGMA+ sensors,” said Mark Wrobel, DARPA program manager in the Defense Sciences Office. “Being able to test and refine the system in the country’s largest metropolitan region was invaluable in taking SIGMA from a research project to an operationally deployed system in just five years.”
SIGMA adds an additional layer of radiation-detection capability for the Port Authority.
“New York City and Northern New Jersey have some of the nation’s most critical transportation infrastructure – heavily trafficked tunnels, bridges, airports, train and bus stations, and ferry terminals,” said Dave Warrington, senior manager for strategic preparedness in the Port Authority’s Office of Emergency Management. “This unique partnership with DARPA was mutually beneficial – DARPA had access to our transportation nodes to collect real background radiological data for developing the system, and the Port Authority now has a network of high-performance stationary, vehicle-mounted, and wearable sensors providing enhanced, 24-hour nuclear and radiological threat detection.”
Port Authority Police Department (PAPD) officers commented on the capabilities and improved detection sensitivity SIGMA provides, significantly reducing false-positives.
“Our legacy radiation-detection system takes a lot more time to identify if a radioactive hit is a threat or a non-threatening source, such as construction-site materials,” said Lt. Rich Munnelly, emergency management liaison officer at PAPD headquarters. “SIGMA enables much faster reaction time, since you don’t need to wait for additional equipment to be brought in to evaluate the radioactive material. With SIGMA, the first responder knows immediately via handheld display what the radioactive isotope is and can quickly determine if it’s a threat or not.”
Munnelly noted how user friendly the system is. SIGMA uses an app-like Android interface that is easy to train new officers on. He also highlighted how the network allows officials up the chain of command to follow alerts and track potential threats in real-time along with first responders, significantly streamlining the coordination process across various levels of command and with federal agencies in the case of a radiological event.
“The system automatically sends officers alert notifications and texts, which is key,” Munnelly said. “Everyone gets all the information at the same time, and because the various sensors are networked it allows for remote monitoring and standoff detection, increasing safety for our officers and the public.”
Another benefit of the SIGMA sensors is their reduced size, weight, and power – from the portable sensors first responders wear on their vest to the more powerful sensors carried in police vehicles, to the stationary sensors at key transportation nodes. For example, legacy vehicle-borne sensor packages take up the whole vehicle, Warrington said, whereas SIGMA’s vehicle-mounted detectors require significantly less space, allowing vehicles to perform their primary function and have room for additional gear.
Most importantly, SIGMA runs continuously, analyzing background radiological conditions daily to constantly refine threat-detection algorithms.
“It’s not a closed-end system,” Munnelly said. “Software refreshes are pushed out regularly, updating isotope profiles to improve detection of known threats and to account for potential new ones.”
The use of this constantly collected background data also supports reduction in false and nuisance alarm rates, a major operational burden with legacy systems.
The DARPA performers who developed the SIGMA radiation detectors and network are Physical Sciences Inc., Kromek Ltd., Silverside Detectors, and Two Six Labs.