- type of radioactivity in which an unstable atomic nucleus dissipates energy by gamma emission, producing gamma rays.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- A radioactive process in which an atomic nucleus loses energy by emitting a gamma ray (a stream of high-energy photons). When an element undergoes gamma decay its atomic number and mass number do not change.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.