Showing 1–6 of 6 results for author: Leonau, A

Generation of high-fluence and high-intensity hard x-ray attosecond pulses at European XFEL

Authors: Ichiro Inoue, Ulrike Boesenberg, Rustam Rysov, Takahiro Sato, Ichika Harima, Chenzhi Xu, Jia Liu, Thomas M. Linker, Zain Abhari, Andrei Benediktovitch, Uwe Bergmann, Ye Chen, Lu Cao, Winfried Decking, Gianluca Geloni, Marc Guetg, Trey Guest, Aliaksei Halavanau, Jörg Hallmann, Takashi Kimura, Naresh Kujala, Aliaksandr Leonau, Shan Liu, Tianyun Long, Johannes Möller , et al. (19 additional authors not shown)

Abstract: By combining hard x-ray attosecond pulses from the European XFEL with total-reflection focusing x-ray optics, we generated nanofocused hard x-ray attosecond pulses with intensities and fluences comparable to the highest values attained in the hard x-ray regime. A peak intensity on the order of 10$^{20}$ W/cm$^2$ is confirmed through the observation of saturation in amplified spontaneous emission f… ▽ More By combining hard x-ray attosecond pulses from the European XFEL with total-reflection focusing x-ray optics, we generated nanofocused hard x-ray attosecond pulses with intensities and fluences comparable to the highest values attained in the hard x-ray regime. A peak intensity on the order of 10$^{20}$ W/cm$^2$ is confirmed through the observation of saturation in amplified spontaneous emission from copper atoms. These x-ray pulses enable new scientific opportunities, including the exploration of higher-order nonlinear light--matter interactions, damage-free structure determination, and coherent control of atoms and molecules. △ Less

Submitted 31 July, 2026; v1 submitted 29 July, 2026; originally announced July 2026.

X-ray resonance therapy with parametric X-ray radiation (PXR) for sulfur-containing tumor tissues

Authors: N. Q. San, O. D. Skoromnik, A. U. Leonau, V. Q. Nha, I. D. Feranchuk

Abstract: We investigate the possibility of usage of the parametric X-ray radiation (PXR) for the selective therapy of superficial sulfur-containing tumor tissues. In these tissues, the concentration of sulfur atoms is significantly higher than in healthy ones. Accordingly, the destruction of cancer cells is caused by the ionization of sulfur atoms. The selective nature of the therapy is determined by the n… ▽ More We investigate the possibility of usage of the parametric X-ray radiation (PXR) for the selective therapy of superficial sulfur-containing tumor tissues. In these tissues, the concentration of sulfur atoms is significantly higher than in healthy ones. Accordingly, the destruction of cancer cells is caused by the ionization of sulfur atoms. The selective nature of the therapy is determined by the narrow spectral-angular distribution of the PXR photon beam and the resonant absorption of radiation by sulfur atoms. This leads to a significant decrease in the total dose required to achieve the desired effects compared to irradiation with conventional X-ray tubes or electron accelerators. △ Less

Submitted 8 July, 2026; v1 submitted 3 October, 2025; originally announced October 2025.

A pipeline for Megahertz X-ray Photon Correlation Spectroscopy on soft matter samples at the MID instrument of European XFEL

Authors: Aliaksandr Leonau, Felix Brausse, James Wrigley, Mads B. Jakobsen, Amir Tosson, Michelle Dargasz, Nimmi Das Anthuparambil, Felix Lehmkühler, Anita Girelli, Maddalena Bin, Fivos Perakis, Sebastian Retzbach, Fajun Zhang, Frank Schreiber, Matheus Teodoro, Cammille Carinan, Robert Rosca, Fabio Dall Antonia, Wonhyuk Jo, Ulrike Boesenberg, Angel Rodriguez-Fernandez, Roman Shayduk, Jörg Hallmann, Alexey Zozulya, Jan-Etienne Pudell , et al. (5 additional authors not shown)

Abstract: In this paper we present the experimental protocol and data processing framework for Megahertz X-ray Photon Correlation Spectroscopy (MHz-XPCS) experiments on soft matter samples, implemented at the Materials Imaging and Dynamics (MID) instrument of the European X-ray Free-Electron Laser (EuXFEL). Due to the introduction of a standard configuration and the implementation of a highly automated data… ▽ More In this paper we present the experimental protocol and data processing framework for Megahertz X-ray Photon Correlation Spectroscopy (MHz-XPCS) experiments on soft matter samples, implemented at the Materials Imaging and Dynamics (MID) instrument of the European X-ray Free-Electron Laser (EuXFEL). Due to the introduction of a standard configuration and the implementation of a highly automated data processing pipeline, MHz-XPCS measurements can now be conducted and analyzed with minimal user intervention. A key challenge lies in managing the extremely large data volumes generated by the Adaptive Gain Integrating Pixel Detector (AGIPD) - often reaching several petabytes within a single experiment. We describe the technical implementation, discuss the hardware requirements related to effective parallel data processing, and propose strategies to enhance data quality, in particular related to data reduction strategies and an improvement of the signal-to-noise ratio. Finally, we address strategies for making the processed data FAIR (Findable, Accessible, Interoperable, Reusable), in alignment with the goals of the DAPHNE4NFDI project. △ Less

Submitted 10 June, 2025; originally announced June 2025.

Coherent X-rays reveal anomalous molecular diffusion and cage effects in crowded protein solutions

Authors: Anita Girelli, Maddalena Bin, Mariia Filianina, Michelle Dargasz, Nimmi Das Anthuparambil, Johannes Möller, Alexey Zozulya, Iason Andronis, Sonja Timmermann, Sharon Berkowicz, Sebastian Retzbach, Mario Reiser, Agha Mohammad Raza, Marvin Kowalski, Mohammad Sayed Akhundzadeh, Jenny Schrage, Chang Hee Woo, Maximilian D. Senft, Lara Franziska Reichart, Aliaksandr Leonau, Prince Prabhu Rajaiah, William Chèvremont, Tilo Seydel, Jörg Hallmann, Angel Rodriguez-Fernandez , et al. (16 additional authors not shown)

Abstract: Understanding protein motion within the cell is crucial for predicting reaction rates and macromolecular transport in the cytoplasm. A key question is how crowded environments affect protein dynamics through hydrodynamic and direct interactions at molecular length scales. Using megahertz X-ray Photon Correlation Spectroscopy (MHz-XPCS) at the European X-ray Free Electron Laser (EuXFEL), we investi… ▽ More Understanding protein motion within the cell is crucial for predicting reaction rates and macromolecular transport in the cytoplasm. A key question is how crowded environments affect protein dynamics through hydrodynamic and direct interactions at molecular length scales. Using megahertz X-ray Photon Correlation Spectroscopy (MHz-XPCS) at the European X-ray Free Electron Laser (EuXFEL), we investigate ferritin diffusion at microsecond time scales. Our results reveal anomalous diffusion, indicated by the non-exponential decay of the intensity autocorrelation function $g_2(q,t)$ at high concentrations. This behavior is consistent with the presence of cage-trapping in between the short- and long-time protein diffusion regimes. Modeling with the $δγ$-theory of hydrodynamically interacting colloidal spheres successfully reproduces the experimental data by including a scaling factor linked to the protein direct interactions. These findings offer new insights into the complex molecular motion in crowded protein solutions, with potential applications for optimizing ferritin-based drug delivery, where protein diffusion is the rate-limiting step. △ Less

Submitted 3 December, 2025; v1 submitted 11 October, 2024; originally announced October 2024.

Comments: This version of the article has been accepted for publication after peer review, but is not the Version of Record and does not reflect post-acceptance improvements or any corrections. The Version of Record is available online at: https://doi.org/10.1038/s41467-025-66972-6

Journal ref: Nature Communications volume 16, Article number: 10814 (2025)

Self amplification of channeling radiation at Bragg diffraction conditions

Authors: Stasis Chuchurka, Andrei Benediktovitch, Aliaksandr Leonau, Sergey Galyamin

Abstract: X-ray radiation of relativistic electrons passing through the crystal lattice (in case of channeling radiation) requires electrons with energies just from tens up to hundreds MeV, but has a drawback: low number of emitted X-ray quanta. However, the brightness of such a source could be potentially increased if the current density of the electron bunch is high enough to initiate the self amplified s… ▽ More X-ray radiation of relativistic electrons passing through the crystal lattice (in case of channeling radiation) requires electrons with energies just from tens up to hundreds MeV, but has a drawback: low number of emitted X-ray quanta. However, the brightness of such a source could be potentially increased if the current density of the electron bunch is high enough to initiate the self amplified spontaneous emission (SASE) process. The conditions at which this phenomenon could take place for the case of axial channeling are analyzed in the present paper within the first order perturbation theory. The transition from spontaneous to SASE regime is described, the requirements for bunch current parameters initiating SASE process are determined taking into account the periodic structure of the crystal medium. It is also shown that satisfying Bragg diffraction conditions could enhance self amplification. Numerical results for the case of axial channeling in Si, Ge and C crystals are presented as an example. △ Less

Submitted 19 February, 2019; originally announced February 2019.

Comments: 13 pages, 5 figures

Analytic model of a multi-electron atom

Authors: O. D. Skoromnik, I. D. Feranchuk, A. U. Leonau, C. H. Keitel

Abstract: A fully analytical approximation for the observable characteristics of many-electron atoms is developed via a complete and orthonormal hydrogen-like basis with a single-effective charge parameter for all electrons of a given atom. The basis completeness allows us to employ the secondary-quantized representation for the construction of regular perturbation theory, which includes in a natural way co… ▽ More A fully analytical approximation for the observable characteristics of many-electron atoms is developed via a complete and orthonormal hydrogen-like basis with a single-effective charge parameter for all electrons of a given atom. The basis completeness allows us to employ the secondary-quantized representation for the construction of regular perturbation theory, which includes in a natural way correlation effects, converges fast and enables an effective calculation of the subsequent corrections. The hydrogen-like basis set provides a possibility to perform all summations over intermediate states in closed form, including both the discrete and continuous spectra. This is achieved with the help of the decomposition of the multi-particle Green function in a convolution of single-electronic Coulomb Green functions. We demonstrate that our fully analytical zeroth-order approximation describes the whole spectrum of the system, provides accuracy, which is independent of the number of electrons and is important for applications where the Thomas-Fermi model is still utilized. In addition already in second-order perturbation theory our results become comparable with those via a multi-configuration Hartree-Fock approach. △ Less

Submitted 2 October, 2017; v1 submitted 17 January, 2017; originally announced January 2017.

Comments: 11 pages, 3 figures