出典:Wikipedia
出典:『Wikipedia』 (2011/06/30 00:31 UTC 版)
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays (especially in astronomy, by analogy with X-rays) and denoted as γ, is electromagnetic radiation of high frequency (very short wavelength). Gamma rays are produced by decay of high energy states in atomic nuclei (gamma decay) and also high energy sub-atomic particle interactions in natural processes and man-made mechanisms. These include electron-positron annihilation, neutral pion decay, fusion, fission, lightning strike and terrestrial gamma-ray flash, and many astronomical sources in which high-energy electrons are produced. These electrons then produce secondary gamma rays by bremsstrahlung inverse Compton scattering and synchrotron radiation.