gamma ray

American  

noun

Physics.

1. a photon of penetrating electromagnetic radiation gamma radiation emitted from an atomic nucleus.

2. a photon emitted by an electron as a result of internal conversion.

3. electromagnetic radiation with wavelengths shorter than approximately one tenth of a nanometer.

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gamma ray Scientific  

1. 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.

2. See more at radioactive decay

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Etymology

Origin of gamma ray

First recorded in 1900–05

Example Sentences

Using rare isotope beams at Michigan State University and highly sensitive gamma ray detectors, the team measured the lifetimes of excited nuclear states with precision on the scale of picoseconds.

From Science Daily • Mar. 8, 2026

Further support could come from finding the same gamma ray signature in other regions rich in dark matter.

From Science Daily • Nov. 29, 2025

Totani explains that the gamma ray pattern cannot be easily matched to other known sources or more common astrophysical processes.

From Science Daily • Nov. 29, 2025

"It could be that these gamma ray bursts and supernova explosions are not necessarily directly linked to each other and they could be separate processes going on," he told BBC News.

From BBC • Apr. 12, 2024

I would very much like this to be the case but I have to recognize that there are other possible explanations for the gamma ray bursts, such as colliding neutron stars.

From "A Brief History of Time: And Other Essays" by Stephen Hawking