gamma ray
Americannoun
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a photon of penetrating electromagnetic radiation gamma radiation emitted from an atomic nucleus.
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a photon emitted by an electron as a result of internal conversion.
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electromagnetic radiation with wavelengths shorter than approximately one tenth of a nanometer.
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A stream of high-energy electromagnetic radiation given off by an atomic nucleus undergoing radioactive decay. Because the wavelengths of gamma rays are shorter than those of x-rays, gamma rays have greater energy and penetrating power than x-rays. Gamma rays are emitted by pulsars, quasars, and radio galaxies but cannot penetrate the Earth's atmosphere.
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See more at radioactive decay
Etymology
Origin of gamma ray
First recorded in 1900–05
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The team also tested whether the proposed blazar population would produce too many gamma rays compared with the known extragalactic gamma ray background measured by Fermi.
From Science Daily • May 24, 2026
It then releases a gamma ray to reach a stable state.
From Science Daily • Apr. 14, 2026
The estimated frequency of these annihilation events based on the observed gamma ray intensity also fits within expected theoretical ranges.
From Science Daily • Nov. 29, 2025
A gamma ray detector on a device developed by a Cornish company is being used to assess soil quality.
From BBC • Nov. 26, 2024
And to observe these few coming from the distance of Pluto would require a larger gamma ray detector than any that have been constructed so far.
From "A Brief History of Time: And Other Essays" by Stephen Hawking
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
