Bragg diffraction technique for the concentration of hard x-rays for space astronomy.

Results of an investigation that was devoted to determining whether the Bragg diffraction technique can be used for the concentration of hard x rays (> 10 keV) are reported. Our final goal was to develop a hard x-ray concentrator for space astronomy. General formulas for the reflecting power of the mirrors are given, and criteria for optimizing the integrated reflectivity are derived. An application of these optimization criteria is presented to evaluate the performances that can be expected of a particular configuration of the Bragg concentrator for space astronomy.