chapter  81
Radioactivity Detectors
Pages 27

Radioactivity was Ÿrst discovered by Henry Becquerel in 1896 when he noticed that photographic plates became fogged a£er exposure to uranium atoms. In addition to uranium nuclei, many other naturally occurring and man-made isotopes are known to be radioactive and decay by emitting uncharged particles (gamma rays and neutrons) and charged particles (alpha or beta particles) from their nuclei. Over the past few decades, there has been a growing need for monitoring, locating, and imaging radioactive sources in a wide variety of medical, environmental, industrial, space, scientiŸc, and national security applications. Many of the applications rely on the use of commercially available radiation detectors, whereas others require the development of new detectors to meet system requirements related to sensitivity, power, size, portability, ruggedness, maintenance, radiation hardness, and energy resolution.