Preventions Efforts — The Role of Sensors

government is also focused on the risk posed by attacks on industrial chemical facilities [53]. According to Massachusetts s representative, Edward Markey, Chemical facilities are at the top of the terrorists target list [14]. However, because attacks on these facilities are more likely to result in a known release of a defined chemical entity, sensors are less important than situations where either the chemical release goes undetected or where an unknown substance is released. 

Common radioactive material in use today includes the alpha emitters Americium-241 and Plutonim-238 the beta emitters Phosporus-32 and Strontium-90 and the gamma emitters Cesium-137, Cobalt-60, and Iridium-192 [44], These materials are commonly used in smoke detectors, oil exploration, industrial gauges, food and mail irradiation, cancer therapy, industrial radiography, and in research laboratories. 

Nuclear Materials. The United States has deployed sensors both nationwide and overseas for the detection of nuclear materials. Although the presence of highly enriched uranium (an indication of a functional or potential nuclear weapon) would present the greatest threat, currently deployed sensors are unable to detect this material because of its low radioactivity. The Department of Homeland Security alone spent more 

Recognizing that nuclear materials are widely available and the terrorists interests in radiological and nuclear devices, the United States Congress appropriated 300 million to the Department of Homeland Security to install radiation detectors at U.S. borders. Through 2005, DHS had installed 470 radiation portal monitors throughout the country including mail facilities and land and sea entries into the United States. The U.S. has also supported the installation of detectors at the borders of the states of the former Soviet Union through its Departments of State, 

Chemical. Exquisitely sensitive chemical agent sensors are available, but work best under laboratory conditions. Environmental chemical sensors suffer many of the same issues as biological detectors. They lack sensitivity, are not sufficiently mobile or flexible, and require trained users. Several types of chemical detectors are in use and are mentioned above. 

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