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Keeping Contraband on the Outside

NCJ Number
Date Published
July 2009
3 pages
This paper briefly describes seven types of electronic technologies available for correctional facilities to use at perimeter control points to detect any contraband on the person of staff, inmates, contractors, and visitors.
RF (radio frequency) metal detectors project low-frequency radio waves. As a person passes through the portal, a radio signal is received and interpreted by software in determining whether the person is carrying a metallic object. Millimeter wave detection devices consist of high frequency radio waves interpreted by software in determining whether a potentially prohibited object is on a person's body next to the skin. This technology detects all foreign substances on the human body, but it cannot detect objects within the body. Passive magnetic field metal detection senses and reports the earth's natural magnetic field within the space of an opening and then measures the same space when a human is standing in the portal space. Interpretive software shows on a monitor the location of any foreign objects on the person's body. It does not detect contraband located in body cavities. Electric field tomography projects weak electrical energy into a person's body. An interpretive software provides a graphic view as if the operator were looking through the person's body. This technology can detect all objects on and within a human body. Ion scan technology is typically used to detect drugs and explosives. It detects the ion profile within an air sample associated with a person's body, vehicle, or living space. Heartbeat detection uses geophone sensors combined with interpretive software to listen to vehicles parked in perimeter sally port enclosure for indications of a human heartbeat. Backscatter X-ray contraband detection uses high-energy, low-dose x-ray beams that pass over a human body. It does not penetrate the skin or detect objects inside body cavities.

Date Published: July 1, 2009