Diffraction x-ray radiation from a relativistic oscillator in a crystal

Diffraction of x-rays in radiation from a relativistic oscillator formed by an external ultrasonic (laser) wave in a crystal is considered. Ultrasonic (laser) excitation, in the general case, leads not only to the formation of a transverse oscillator but also to the formation of a set of lattices by which the emitted photons are diffracted. It is shown that, in the particular case of a transverse ultrasonic wave excitation at τ · b << 1, we can neglect the ultrasonic wave influence on diffraction process. Just this situation is considered in detail in the present paper. The expressions for the angular and spectral distributions of considered radiation are derived. It is shown that the radiation spectrum, in this case, is more complicated than that of ordinary channelling radiation and its intensity in the vicinity of the Bragg frequency can be even higher than the intensity of the latter. (author)