Direct observation of anomalous Kossel lines

Anomalous Kossel lines corresponding to the yield of X rays from a germanium crystal under the conditions of strongly asymmetric diffraction have been observed in the simplest experimental scheme with the use of characteristic Mo K _α radiation and a germanium crystal analyzer. In agreement with the results of a previous theoretical analysis, such lines are narrow collimated beams of radiation in the form of a ridge in a narrow angular range near a given direction whose intensity is one or two orders of magnitude higher than the background with a divergence of about several seconds of arc in the diffraction plane and of about 10′ along the Kossel line. The possible applications of this effect, in particular, for solving the problems of X-ray holography, are discussed.