Compton Effect
The decrease in energy (increase in wavelength) of an X-ray or gamma-ray photon when scattered by a stationary electron.
Governing formula
Δλ = λ' - λ = (h / (m_e c)) (1 - cos θ)
SI unit
m or pm (Wavelength Increase)
In depth
Discovered by Arthur Compton in 1923, Compton scattering treats the photon-electron interaction as an elastic particle collision conserving energy and relativistic momentum, proving photons possess momentum p = h/λ.
Examples in the real world
Compton scattering of X-rays in radiation therapy and gamma-ray astronomy detectors.