Type of radioactivity in the most common form of which an unstable atomic nucleus dissipates energy by gamma emission, producing gamma rays. Gamma decay also includes two other processes, internal conversion and internal pair production. In internal conversion, excess energy in a nucleus is transferred to one of its own orbiting electrons and the electron is ejected from the atom. In internal pair production, excess energy is converted into an electron and a positron, which are emitted together. Typical half-lives (see half-life) for gamma emission range from about 109 to 1014 second.
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