X-ray spectrum determination from the angular dispersion of radiation in a diamond prism

The X-ray spectrum of hard polychromatic radiation with energies of up to $40$ keV was obtained from the angular dispersion of the radiation beam in a diamond prism. In contrast to the classical optical scheme, the beam to be analyzed is passed through the entrance face of the prism without refraction and is directed onto the exit face at a glancing angle $\sim(2\delta)^{1/2}$, where $\delta$ is the real part of the decrement of the refractive index for the short-wavelength edge of the spectrum. The spectrum distortions caused by the intersection of the reciprocal lattice points by the Ewald sphere at a fixed number of wavelengths $\lambda$ are minimized by the use of the angular divergence of the beam of $\sim10'$ in the plane perpendicular to the refraction plane. In the energy range of 8-9 keV, an energy resolution of less than 100 eV was obtained, which exceeds the corresponding parameter for cooled semiconductor detectors. The measuring scheme suggested makes it possible to solve the problem of the analysis of spectra of directional X-ray beams when studying fast nonstationary generation processes.