Coherent radiation at regular and chaotic motion of relativistic electrons and positrons in the periodic field of the atomic chain of a crystal

It is shown that taking into account the actual dynamics of relativistic electrons and positrons moving inside a crystal at a small angle to one of its axes results in a considerable distortion of spectrum and polarization characteristics of the coherent radiation, obtained on the base of traditional Born theory of coherent radiation. In this case not only the radiation intensity undergo changes, but also the interference pattern of the radiation process does. This effect is caused by the existence of different particle motion regimes in a periodical field of crystal atomic strings (regular and chaotic ones) and depends essentially on the particle charge sign