The interaction of relativistic particles with strong crystalline fields

Crystals present a uniquely simple environment for the investigation of strong electromagnetic fields. When energetic charged particles are incident on crystals close to major crystallographic directions, their electromagnetic interactions depend crucially on the kinematic conditions. The coherence of the crystalline field can produce very strong electric fields in the rest frame of the particle, exceeding the so-called Schwinger field or quantum critical field. In that domain, the radiation emission takes a substantial part of the electron energy and the “formation zone” changes character. In this review the theory appropriate to the different kinematics domains is described, concentrating on the effects occurring at extreme fields. Properties discussed include strong field synchrotron radiation, channeling radiation, bremsstrahlung, and photon interactions. Applications are given to radiation sources, bending of particle beams, and sources of polarized GeV photons.