Project of a two-mirror monochromator for the photon energy range 8–36 keV for the “SKIF” synchrotron

A project of an X-ray monochromator for the "SKIF" synchrotron based on two flat mirrors with multilayer reflective coatings is reported. The concept of the monochromator is based on the absence of precision mechanical systems and feedthroughs in vacuum, which significantly reduces mirror surface contamination and increases scanning accuracy. In addition, the overall structure of the device is greatly simplified in this way, which in turn leads to a significant reduction in the total cost and labor for manufacturing. The grazing angle of incidence of radiation on the mirrors in the process of scanning by photon energy varies within 0.5–1.3$^\circ$. The length of the mirrors is 120 mm, the assumed size of the input beam is 1 $\times$ 1 mm$^2$. A wide operating energy range, 8-36 keV, is achieved through the use of 3 strip-mirrors with coatings of different chemical composition, namely: Mo/B4C, W/B4C and Cr/Be. The article presents the X-ray optical scheme, the expected reflection coefficients and spectral selectivity of the monochromator, the results of the calculation of thermally induced surface deformations and the corresponding slope errors of the first mirror.