Synchrotron Radiation
Relativistic electrons bending in B-field emit a tight forward cone of X-rays
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Critical energy E_c (keV)
Synchrotron Radiation: A relativistic electron (Lorentz factor γ = E/m_e c²) bending in a magnetic field radiates in a narrow forward cone of half-angle 1/γ. The critical photon energy E_c = (3/2)ℏcγ³/ρ ∝ γ²B, concentrating power in the X-ray range for GeV electrons. The radiation is horizontally polarized in the bend plane and covers a broad spectrum from IR to hard X-rays. Synchrotrons like ALS, APS, ESRF produce the brightest X-ray beams on Earth.