Methods of synchrotron radiation monochromatization (research review)

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 3 2024 field. The beam leaving the linear accelerator is directed to the booster (3), where electrons are accelerated to relativistic velocities. Then the beam passes to the storage ring, the main elements of which are bending magnets (4), which form a closed trajectory of electron motion, radio-frequency resonators (5), which replenish the beam energy that is spent when emitting SR, and insertion devices (6). The bending magnets and insertion devices are used to generate synchrotron radiation, which is directed to the beamline (7) and, after passing through the optical hutch (9), enters the experimental hutch of the station (10) with the analyzed object inside it. Synchrotron radiation is magnetically induced electromagnetic radiation emitted by relativistic charged particles (traveling at a radiation velocity close to the speed of light), which are forced by a constant magnetic field to move in circular orbits. Devices generating synchrotron radiation can be bending magnets, wigglers, or undulators. The magnetic field of these devices, due to the Lorentz force, leads (1) to a change in the trajectory of electrons and (2) to the formation of synchrotron radiation. The synchrotron radiation directed tangentially to the storage ring enters the beamline, moving along which it is brought to the specimen located in the experimental hutch (10). The optical circuitry of the station includes many devices performing various functions. These include optical elements that change the geometric parameters of the beam (slits, collimating and focusing lenses, X-ray mirrors, etc.), filters, and windows that separate vacuum volumes. The optical scheme should also include beam monitoring elements, which can be divided into two groups. The first group includes detectors that determine the beam position, and the second group includes detectors that record the intensity and spectral composition of the radiation. The field of applying synchrotron radiation is large and for this reason the methods of experiments may differ significantly. The necessity of solving different kinds of problems leads to the development of beamlines that differ in the set of their elements. Monochromators are one of the key elements of beamlines, which are spectral optical-mechanical devices that allow separating narrow bands of radiation from a wide range of wavelengths. Themonochromatorsusedat SRS includeunits that are identical inpurpose.However, themonochromators differ from each other structurally. Technical features of the monochromators are determined not only by the tasks solved at the beamlines, but also by the magnitude of the incoming heat flux, the cooling system of crystals, and the accuracy of their adjustment. Elementary information on X-ray diffraction In 1985, Wilhelm Conrad Röntgen, conducting experiments with the Crookes tube, discovered a previously unknown radiation, which he called X-rays. Fig. 2 shows a scale of wavelengths and frequencies of electromagnetic radiation, and highlights the conditional range corresponding to X-ray radiation, Fig. 1. A conceptual sketch of the SRS. Taken from [3]

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