Penetrating very short-wavelength electromagnetic radiation, similar to an X-ray but of higher energy, that is emitted spontaneously by some radioactive substances (see gamma decay; radioactivity). Gamma radiation also originates in the decay of certain subatomic particles and in particle-antiparticle annihilation (see also antimatter). Gamma rays can initiate nuclear fission, can be absorbed by ejection of an electron (see photoelectric effect), and can be scattered by free electrons (see Compton effect).
This entry comes from Encyclopædia Britannica Concise.For the full entry on gamma ray, visit Britannica.com.
What made you look up gamma ray? Please tell us what you were reading, watching or discussing that led you here.
Take Our 10-Question Quiz
The commonly misspelled words quiz
A quick quiz about stuff worth knowing
How strong is your vocabulary?
The Vocab Quiz Game for iPhone & iPad
"Incredibly fun and addictive. And informative!" User Review, iTunes