Gamma ray

Article By:

Ramayya, Akunuri V. Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee.

Hwang, Jae-Kwang Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.279410

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• Gamma rays, published January 2014:Download PDF Get Adobe Acrobat Reader

The highest-energy form of electromagnetic radiation, or light. The energies of gamma rays range from a few kiloelectronvolts [(keV), where the prefix kilo (k) means 10³] to several hundreds of megaelectronvolts [(MeV), where the prefix mega (M) means 10⁶] and higher. Gamma rays have properties similar to that of "ordinary," visible light. Gamma rays are produced when atomic nuclei decay from a state of higher energy to a state of lower energy, in nuclear reactions, fission and fusion processes, and by various astrophysical phenomena (Fig. 1). Gamma rays are widely used in nuclear structure studies, nuclear medicine, and gamma-ray astronomy. Intense exposure to gamma (γ) radiation may cause injury and death or lead to cancer over the longer term. See also: Cancer; Electronvolt; Gamma-ray astronomy; Gamma-ray burst; Metric system; Nuclear fission; Nuclear fusion; Nuclear medicine; Nuclear reaction; Nuclear structure; Oncology

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