Detection Systems for Dirty Bombs

Anti-terrorism efforts are getting a boost from the Princeton Plasma Physics Laboratory (PPPL). A PPPL team has developed a Miniature Integrated Nuclear Detection System, called MINDS, which can be used to scan moving vehicles, luggage, cargo vessels, and the like for specific nuclear signatures associated with materials employed in radiological weapons. MINDS could be employed at workplace entrances, post offices, tollbooths, airports, commercial shipping ports, as well as in police cruisers, to detect the transportation of unauthorized nuclear materials.

A cost-effective compact system which combines many off-the-shelf components with specific nuclear detection software, MINDS is capable of detecting X-rays, soft gammas, gammas, and neutrons. Radionuclides can be recognized and differentiated from one another since each has a distinctive energy signature or fingerprint. The system compares the energy spectrum of the detected radionuclide with the spectra of particular radiological materials that might be used in weapons.

MINDS can detect one-billionth of the material deemed plausible to create a radiological dispersion device — a “dirty bomb.” The system can be deployed in a variety of applications, because it is capable of differentiating among naturally occurring radioactive elements, authorized medical and acceptable industrial nuclear substances, and threat materials. By identifying the specific radioactive material present, MINDS eliminates the “car alarm” syndrome, where the operator is accustomed to so many false alarms that future warnings could be ignored. MINDS can be configured to “filter out” natural radiation, or any acceptable radiation in the background environment. It is sophisticated to the degree that it will identify radioactive materials even when they are intentionally concealed or masked. As MINDS scans a target, in approximately one second the system senses, identifies, and transmits the presence of radioactive materials at levels slightly above background. Also, MINDS itself does not emit radiation and thus does not require active cooling as other technologies do. In addition, it can be fitted with up to three different radiation detectors, or heads, to cover a whole gamut of nuclear radiation. The detector heads can include, for example, a boron trifluoride or helium tube to detect neutrons; a PIN diode or a cadmium zinc telluride detector to detect X-rays and low-energy gamma rays; and a sodium iodide crystal to detect higher energy gamma rays.

MINDS deployed at a guard station