Investigation of Monochromaticity of X-Rays in a Wide Energy Range

For quantitative assessment of X-ray absorption in the wavelength range from several angstroms to tenths of an angstrom (which approximately corresponds to energies from 5 to 50 keV) and energy calibration of X-ray detectors, a monochromatic radiation source is needed. In this paper, we report characteristics of an X-ray monochromator designed for operation in a wide energy range. The working principle of the instrument relies on X-ray diffraction. The diffracting element is a pyrolytic graphite crystal. Rotating it through a preset angle allows monochromatic radiation to be isolated from the bremsstrahlung of the X-ray tube. We demonstrate that, with this instrument, one can obtain a monochromatic X-ray beam in the energy range 15–100 keV with monochromaticity at a level from 1.5 to 9% (which meets requirements for detector energy calibration accuracy). In addition, we show that controlled monochromatic radiation can be generated using readily available laboratory components. The results of this study and the proposed approach can be used in nondestructive inspection, tomography, and other areas where spectrally selective X-ray analysis is needed.