On radiation by relativistic electrons and positrons channeled in crystals

In this work the radiation processes by relativistic electrons and positrons in crystals have been considered. Based on the terminology of coherent radiation length, the influence of target structure periodicity on radiation features is revealed. The unified theory of electromagnetic radiation by relativistic channeled electrons has been developed. It is shown that, depending on the angles of orientation between projectile and crystallographic row (plane), various types of scattering play an essential role for different ranges of emitted frequencies. A general expression for the probability of bremsstrahlung is reduced taking into account the main factors of scattering under the channeling conditions. The analysis of various mechanisms of radiation and scattering together with their contributions to the radiation spectrum is presented. It is shown that the total spectrum of electromagnetic radiation at channeling is formed by both incoherent bremsstrahlung and channeling radiation.