Klein–Nishina formula

The Klein–Nishina formula gives the differential cross section of photons scattered from a single free electron in lowest order of quantum electrodynamics. At low frequencies (e.g., visible light) this yields Thomson scattering; at higher frequencies (e.g., x-rays and gamma-rays) this yields Compton scattering. For an incident unpolarized photon of energy , the differential cross section is: Note that this result may also be expressed in terms of theclassical electron radius : Note that if , and the Klein–Nishina formula reduces to the classical Thomson expression.

Klein–Nishina formula

The Klein–Nishina formula gives the differential cross section of photons scattered from a single free electron in lowest order of quantum electrodynamics. At low frequencies (e.g., visible light) this yields Thomson scattering; at higher frequencies (e.g., x-rays and gamma-rays) this yields Compton scattering. For an incident unpolarized photon of energy , the differential cross section is: Note that this result may also be expressed in terms of theclassical electron radius : Note that if , and the Klein–Nishina formula reduces to the classical Thomson expression.