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ИСТИНА ПсковГУ |
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The method applying LiF fluorescent media as a detector to perform a high-resolution single-shot in situ imaging of near- and far-field intensity distribution in ultra-intense X-ray beams is introduced. Recent achievements in characterization and control of various free electron laser (FEL) sources, as well the calibration data for LiF detectors for particular photon energy range, are given. Experiments proved spatial resolution to be of ~ 700 nm for soft X-ray range, and of ~ 1.0 µm for 10 keV X-ray beam. Theoretical estimates on photoelectron cloud formation revealed fundamental limit on spatial resolution capability of the method. High sensitivity and uniquely large dynamic range exceeding 106 of LiF crystal detector allowed measurements on the intensity distribution of hard X-ray SACLA XFEL beam at distances as far from the focal plane, as near the best focus. In situ 3D visualization of SACLA XFEL focused beam profile along the propagation direction is realized, including propagation inside photoluminescence solid matter. Considering the diffraction patterns from test objects, spectral and coherent properties of X-ray beams were revealed. Also, the method was applied to control XFEL beam profile in pump-probe experiment and in consequent optimization of X-ray beam line configuration and the positioning of probed samples.