The increase in wavelength and change in direction of an X-ray or gamma-ray photon when it collides with a charged particle, usually an electron. It is also known as Compton scattering and named after the American physicist Arthur Holly Compton (1892-1962). The opposite effect, in which a photon gains energy (and therefore decreases in wavelength) from a fast-moving electron, is known as the inverse Compton effect.
