Inverse Compton Scattering of Photons and Equivalent Photons on Channeled Particles

The Compton scattering effect of electromagnetic waves (photons) on free electrons has been known since the beginning of the twentieth century. A photon moving toward a fast electron can be scattered in the opposite direction, significantly increasing its energy because of the loss of it by the electron. When the scattering electron is not free, but moves in a single crystal in the channeling mode, periodic harmonics of the potential of atomic planes or axes along which the channeled electron moves can serve as the scattered photon. In the so-called accompanying reference system moving at the velocity equal to the longitudinal component of the channeled particle velocity, these harmonics can be considered as electromagnetic waves (equivalent photons) interacting with the electron making finite orbital or oscillatory motion in the averaged potential of the atomic axis or plane. The result of equivalent photon backscattering is a real photon, observable as a high-energy photon in the laboratory system. Because of the discreteness of the transverse motion energy spectrum of the channeled electron, the emitted photon spectrum will also be discrete. This work continues a series of our previous studies [3-5] of effects associated with electromagnetic processes during the passage of fast charged particles through crystal structures within a mixed quantum-classical approach. The backscattering kinematics of photons and equivalent photons by the ultrarelativistic electrons has been analyzed in detail in the general case and in the channeling mode. The characteristic frequencies have been calculated and the intensity of the resulting radiation has been estimated.