# Gamma Ray

A gamma ray, also known as gamma radiation (symbol γ), is a penetrating form of electromagnetic radiation arising from high-energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. Lower energy gamma radiation overlaps the upper end of X-ray radiation; they are distinguished by their different origins. gamma ray photons have photon energy at the lower end from 10keV to 10,000 keV; ultra-high-energy gamma rays have energies over 1011 keV. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium.