| 1. |
- Sanchez-Gonzalez, A., et al.
(författare)
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Accurate prediction of X-ray pulse properties from a free-electron laser using machine learning
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Free-electron lasers providing ultra-short high-brightness pulses of X-ray radiation have great potential for a wide impact on science, and are a critical element for unravelling the structural dynamics of matter. To fully harness this potential, we must accurately know the X-ray properties: intensity, spectrum and temporal profile. Owing to the inherent fluctuations in free-electron lasers, this mandates a full characterization of the properties for each and every pulse. While diagnostics of these properties exist, they are often invasive and many cannot operate at a high-repetition rate. Here, we present a technique for circumventing this limitation. Employing a machine learning strategy, we can accurately predict X-ray properties for every shot using only parameters that are easily recorded at high-repetition rate, by training a model on a small set of fully diagnosed pulses. This opens the door to fully realizing the promise of next-generation high-repetition rate X-ray lasers.
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| 2. |
- Soderstrom, J, et al.
(författare)
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X-ray-emission-threshold-electron coincidence spectroscopy
- 2004
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 141:2-3, s. 161-170
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Tidskriftsartikel (refereegranskat)abstract
- Using a penetration-field threshold photoelectron (TPE) analyzer and efficient photon detectors X-ray-emission-threshold-electron coincidence (XETECO) spectroscopy has been developed to a point where peak shape analysis becomes meaningful. The spectra can, on the present level of accuracy, be interpreted as conventional TPE spectra free from post collision interaction effects. For the neon atom and the nitrogen molecule we find a detailed correspondence with state-of-the-art photoemission spectra, both regarding peak positions, line shapes, and relative intensities. Intensity redistribution due to fast core vacancy rearrangement processes in systems with close-lying core levels, like O-2, N2O, and NO is briefly discussed. It is demonstrated that even the complex threshold behavior at the F K threshold in SF6 leads to a well-defined XETECO peak, directly corresponding to classical photoemission results. (C) 2004 Elsevier B.V. All rights reserved.
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| 3. |
- Gorczyca, TW, et al.
(författare)
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Radiative and relativistic effects in the decay of highly excited states in helium
- 2000
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Ingår i: PHYSICAL REVIEW LETTERS. - : AMERICAN PHYSICAL SOC. - 0031-9007. ; 85:6, s. 1202-1205
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Tidskriftsartikel (refereegranskat)abstract
- A recent experimental study [J.-E. Rubensson et al., Phys. Rev. Lett. 83, 947 (1999)] measured a significant fluorescence yield of the He(2lnl') photoexcited resonances, showing major qualitative differences from nonrelativistic predictions. We present a
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| 4. |
- John Mukkattukavil, D., et al.
(författare)
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Resonant inelastic soft x-ray scattering on LaPt 2 Si 2
- 2022
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Ingår i: Journal of physics. Condensed matter : an Institute of Physics journal. - 1361-648X .- 0953-8984. ; 34:32
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption and resonant inelastic x-ray scattering spectra of LaPt2Si2single crystal at the Si 2pand La 4dedges are presented. The data are interpreted in terms of density functional theory, showing that the Si spectra can be described in terms of Sisanddlocal partial density of states (LPDOS), and the La spectra are due to quasi-atomic local 4fexcitations. Calculations show that Ptd-LPDOS dominates the occupied states, and a sharp localized Lafstate is found in the unoccupied states, in line with the observations.
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| 5. |
- Mukkattukavil, Deepak John, 1993-, et al.
(författare)
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Resonant inelastic soft x-ray scattering on LaPt2Si2
- 2022
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 34:32
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption and resonant inelastic x-ray scattering spectra of LaPt2Si2 single crystal at the Si 2p and La 4d edges are presented. The data are interpreted in terms of density functional theory, showing that the Si spectra can be described in terms of Si s and d local partial density of states (LPDOS), and the La spectra are due to quasi-atomic local 4f excitations. Calculations show that Pt d-LPDOS dominates the occupied states, and a sharp localized La f state is found in the unoccupied states, in line with the observations.
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