Compton effect - definition - quantum physics, particle physics, special relativity

Definition: The elastic scattering of photons by electrons. If λ_s and λ_i are respectively the wavelengths associated with scattered and incident photons, the Compton shift is given by λ_s-λ_i = λ₀(1-cos θ) where θ is the angle between the directions of the incident and scattered photons and λ₀ is the Compton wavelength (λ₀=0.00243 nm) of the electron. The effect is only significant for incident X-ray and γ-ray photons.