(FORTUNE Small Business) – Terrorists beware: Albuquerque-Based Applied Research Associates has invented a new, portable radiation detector that can alert authorities to even trace amounts of radiation used in small nuclear weapons and "dirty" bombs. Called MobileRad, the $130,000 device fits in the trunk of a police cruiser and is sensitive enough to pick out someone who has recently undergone radiation therapy, yet precise enough to allow police to distinguish that cancer patient from a would-be bomber, says ARA's Rollin Evans, a nuclear physicist, who along with principal scientist Randy Jones invented MobileRad. ARA, a privately held company, which last year posted revenues of $120 million, is pitching MobileRad to the U.S. Department of Defense, the New York City Police Department, and Los Angeles International Airport. --NINA SOVICH

SURVEILLANCE MobileRad fits in the back of a police cruiser and can detect radiation in cars traveling at speeds up to 60 mph. Using GPS technology, the car's location is determined, and the level of radiation is noted and sent to a command center. Housed in a tough plastic case, MobileRad can also be mounted at stationary high-risk areas such as office towers, highways, and bridges.

IDENTIFICATION From a separate case that contains a detector computer, experts download the suspect's location and the particular isotope spotted by the sensors. When radiation is detected, an icon on a location map will flash from green to red.

SEIZURE Having identified the type of radiation, its lethality, and the suspect's position, antiterrorism specialists can stop the vehicle to investigate its contents. The system boasts unprecedented radiation sensitivity and low false-alarm rates.