Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 7: Modeling and Data Analysis
DY 7.3: Vortrag
Montag, 12. März 2018, 10:30–10:45, BH-N 128
Temporal and spatial characteristics of electron cascades triggered by X-ray photons in LiF — •Vladimir Lipp1, Nikita Medvedev2, and Beata Ziaja1,3 — 1CFEL at DESY, Hamburg, Germany — 2Institute of Physics and Institute of Plasma Physics, Academy of Science of Czech Republic, Prague, Czechia — 3Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
Low-fluence X-ray irradiation of alkali halides may cause long-living lattice defects called color centers. It is assumed that their spatial distribution reflects the X-ray beam shape and, therefore, may serve as an efficient diagnostic tool for the spatial pulse profile [1]. The color centers may be created via exciton decay mechanism; excitons are created when self-trapped valence holes catch free electrons, both produced by an intense X-ray pulse. However, X-ray-induced energetic photoelectrons trigger secondary electron cascades, which may strongly influence the final distribution of the valence holes before their self-trapping, and thereby of the color centers. Our in-house classical Monte-Carlo simulation tool XCascade-3D [2] follows the electron cascades in time and space. It provides distributions of the electrons and holes in various X-ray-irradiated materials, including alkali halides. For the study case of LiF, we present the corresponding calculations which enable to establish a connection between the experimentally measured distribution of the X-ray-induced color centers in LiF and the spatial shape of the X-ray beam -- with potential experimental applications. References: [1] Pikuz, Faenov, Matsuoka et al., Scientific Reports 5, 17713 (2015). [2] Lipp, Medvedev, Ziaja, Proc. SPIE 10236, 102360H (2017).