ENCYCLOPEDIA OF Espionage, Intelligence, and Security Volume ...

Double Agentscharge is enabled to leak through the gas tube; the amountof charge lost is a measure of the amount of radiation thathas passed through the tube. A pen dosimeter can be readby its bearer at any time, and so gives a current reading ofexposure; however, pen dosimeters readings can be affectedby mechanical shock or vibration.A more modern dosimeter design is the thermoluminescentdosimeter (TLD). A TLD contains a tiny crystal oflithium fluoride (sometimes mounted in a finger-ring) thatundergoes cumulative structural changes as it is exposedto ionizing radiation. When heated, the crystal glows,giving off an amount of light that is proportional to itsradiation exposure. This light is observed by an electronicsensor in a readout unit and recorded digitally. This datacan be stored in a central database, a convenient feature ifan organization wishes to systematically monitor radiationexposure of a large body of personnel. Databasing ofTLD data has been used, for example, by Canada tomonitor the exposure of its troops to radiation from depleted-uraniummunitions used by NATO in Bosnia. TLDs,unlike film badges, can be re-used; however, they must beinserted in a reader that heats the crystal and records thelight emitted, a process that may take 20 to 30 seconds anderases the data in the crystal.An even more recent entry in the dosimeter field is theoptically stimulated luminescence dosimeter (OSLD). Inthis design, a thin film of crystalline aluminum oxideundergoes cumulative structural changes as it is exposedto ionizing radiation; when an exposure reading is desired,the crystal is exposed to green laser light. The amount ofblue light emitted by the film in response is proportional toits radiation exposure. Unlike a TLD, an OSLD can supplyan instant readout that can be repeated if necessary.Solid-state devices that measure radiation by detectingionization leakage current through a transistor devicealso exist. Radiation detectors and dosimeters based onsuch solid-state technology have been available since the1980s, but have not edged out other dosimeter technologiesin terms of cheapness, sensitivity, and accuracy.Dosimetry for laser light, radio waves, and ultrasound,which is often required in medical contexts, ismore difficult than dosimetry of ionizing radiation. Onemethod of measuring dose delivered to a volume of tissueis to measure the temperature increase of the tissue; themore increase, the more radio or sound energy has beenabsorbed. However, these techniques do not work fortissue embedded in living organisms (where temperaturemeasurement is difficult and where heat is rapidly conductedaway) or for whole-body exposure, as biologicallytolerable doses of laser, radio, and sound energy produceundetectably slight changes in body temperature. Absorptionby the body of radio waves is particularly differentfrom absorption of ionizing radiation; the body acts asa complex antenna whose performance is strongly affectedby its posture and orientation and by nearby objects.Dosimetry for radio and ultrasound therefore reliesheavily on computational models rather than on directmeasurements.❚ FURTHER READING:ELECTRONIC:”Measuring Occupational Exposures.“ Health Physics Society. (April 17, 2003).”Using and Wearing Radiation Dosimeters.“ PrincetonUniversity: Environmental Health and Safety. (April 17, 2003).SEE ALSORadiation, Biological DamageRadioactive Waste StorageRadiological Emergency Response Plan, United StatesFederalDouble AgentsA double agent is person who conducts espionage fortwo, usually antagonistic, countries. Double agents allowintelligence services to gather information by infiltratingenemy organizations under cover. An organization usuallyrecruits double agents from the ranks of a rival intelligenceservice, and then ”turns“ them, using them as spiesfor their own purposes.The use of double agents in intelligence tradecraftand strategy is one of the oldest practices in the art ofespionage. Spies and double agents appear in literatureand written histories from the ancient civilizations of Egypt,China, India, Greece, and Rome. The rise of great civilizationsand militaries prompted the need for intelligencegathering through infiltration of enemy organizations.In the modern era, double agents gained notoriety ina variety of espionage scandals. While some double agentsworked in accordance with their ideals, others were paidhandsomely with money or political favor for betrayingsecrets. During the Cold War between the United Statesand the Soviet Union, exposure of double agents becamea key part of counterintelligence operations. Double agentscompromised intelligence, military, industrial, and governmentstrongholds in both nations, sometimes withdevastating consequences. Since the fall of the SovietUnion, and the dissolution of its KGB intelligence agency,access to formerly secret archives and testimony of formeragents has exposed several double agents, and theextent of their decades-long espionage operations. In theUnited States, double agents working for the Soviet Union(and later for Russia), such as Aldrich Ames and RobertHanssen were discovered, brought to trial, and sentencedto life in prison.During the Cold War, and the decade after its end,double agents were popularly associated with intrigue,360 Encyclopedia of Espionage, Intelligence, and Security