Klein–Nishina formula

physics

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June 30, 2026

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The Klein–Nishina formula is a key equation in quantum electrodynamics (QED) that describes the scattering of photons by charged particles, primarily electrons. It specifically addresses the Compton effect, where photons lose energy and increase in wavelength after colliding with electrons.21

The formula, derived by Oskar Klein and Yoshio Nishina, details how the probability of scattering and the resulting change in photon wavelength depend on the photon's energy and the scattering angle. At low photon energies, scattering is nearly symmetrical. As energy increases, scattering becomes more directional, predominantly forward. This formula is crucial for understanding how intermediate and high-energy electromagnetic radiation interacts with matter, playing a significant role in energy transfer.2

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radiation
Cross section and Compton scattering
The Klein–Nishina formula shows almost symmetrical scattering for low-energy photons about 90° to the beam direction. As the photon energy increases, the scattering becomes predominantly peaked in the forward direction, and, for photons with energies that are greater than five times the rest energy of the…
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The Klein–Nishina formula shows almost symmetrical scattering for low-energy photons about 90° to the beam direction. As the photon energy increases, the scattering becomes predominantly peaked in the forward direction, and, for photons with energies that are greater than five times the rest energy of the…
Read More