Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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42029 Publications
Multidimensional characterization of particle morphology and mineralogical composition using CT data and R-vine copulas
Furat, O.; Kirstein, T.; Leißner, T.; Bachmann, K.; Gutzmer, J.; Peuker, U. A.; Schmidt, V.
Abstract
Computed tomography (CT) can capture volumes large enough to measure a statistically meaningful number of micron-sized particles with a sufficiently good resolution to allow for the analysis of individual particles. However, the development of methods to efficiently investigate such image data and interpretably model the observed particle features is still an active field of research. When image data of particles exhibiting a wide range of shapes and sizes is considered, traditional image segmentation methods, such as the classic watershed algorithm, struggle to recognize particles with satisfying accuracy. Thus, more advanced methods of machine learning must be utilized for image segmentation to improve the validity of subsequent analyzes. Moreover, CT data does not include information about the mineralogical composition of particles and, therefore, additional SEM-EDS image data has to be acquired. In this paper, micro-CT image data of a particle system mostly consisting of zinnwaldite-quartz composites is considered. First, an image segmentation method is applied which uses deep convolutional neural networks, in particular an adaptation of the U-net architecture. This has the advantage of requiring less hand-labeling than other machine learning methods, while also being more flexible with the possibility of transfer learning. Then, fully parameterized models based on vine copulas are designed to determine multivariate probability distributions of descriptor vectors for the size, shape, texture and composition of particles -- allowing for the estimation and interpretable characterization of interdependencies between particle descriptors.
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Minerals Engineering 206(2024), 108520
Online First (2023) DOI: 10.1016/j.mineng.2023.108520
Cited 2 times in Scopus
Downloads
- Open Access Version from arxiv.org
- Secondary publication expected from 05.12.2024
Permalink: https://www.hzdr.de/publications/Publ-36337
Multivariate stochastic modeling of the influence of particle descriptors on flotation-based separation behavior
Wilhelm, T.; Sandbrink, J.; Furat, O.; Bachmann, K.; Rudolph, M.; Schmidt, V.
Abstract
Many separation processes are based on particle properties like wettability, composition, size and shape. Therefore, it is necessary to analyze the influence of different particle properties on the particle separation behavior. A common tool for classifying particle separation processes are Tromp functions. Recently, multivariate Tromp functions, computed by means of non-parametric kernel density estimation, have emerged which describe the separation behavior with respect to multidimensional particle properties. In this paper, an alternative flexible parametric modeling approach is proposed to model the separation behavior of particle systems with multivariate Tromp functions observed by mineral liberation analyzer (MLA) image measurements. However, different particle properties such as particle wettability cannot be observed in MLA data, although many separation processes such as flotation-based particle separation processes rely on differences in wettabilities. In order to analyze the influence of wettability on particle separation behavior, bivariate Tromp functions for area-equivalent diameter and aspect ratio of differently shaped glass particle systems with differently modified wettabilities are computed in a case study. Comparing the computed Tromp functions reveals
the influence of particle wettability on the separation behavior. In addition, we extend the parametric approach to model multivariate Tromp functions to handle separation processes when image measurements are not available for all separation streams.
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Lecture (Conference)
German probability and statistics days, 07.-10.03.2023, Essen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36336
Multivariate stochastic modeling of particle descriptors for studying the influence of wettability on flotation-based separation behavior
Wilhelm, T.; Sygusch, J.; Furat, O.; Bachmann, K.; Rudolph, M.; Schmidt, V.
Abstract
In the context of mineral processing, the separation of particles of some feed material into a valuable and a waste fraction is commonly achieved by processes like magnetic (1) or flotation separation (2). The outcome of such processes often depends on particle properties like wettability, but it can also depend on the composition, size and shape of particles. Therefore, with regard to the goal of optimizing separation processes, it is useful to analyze different particle descriptors when studying the influence of wettability on the particle separation behavior. A common tool for classifying particle separation processes are Tromp functions (3). Recently, multivariate Tromp functions, computed by means of non-parametric kernel density estimation, have emerged which characterize the separation behavior with respect to multidimensional vectors of particle descriptors (4). However, estimating multivariate probability densities of particle descriptors using methods of kernel density estimation requires a relatively large sample size (5). Therefore, we propose an alternative parametric approach based on copulas (6) in order to compute multivariate Tromp functions and, in this way, to characterize the separation behavior of particle systems, see Figure 1. Moreover, the parametric modeling approach is extended by an optimization routine to handle separation processes when measurements are not available for all separated fractions. A potential application of the optimization routine is to reduce the measurement effort in a series of separation experiments for a given feed material and various separated fractions. A simulation study has been performed in order to quantitatively compare the parametric with the non-parametric modeling approach. This comparison focuses especially on scenarios for which only a relatively small number of particles is observed in measurements. Such scenarios occur, for example, when image data of particle systems are considered, from which descriptors of individual particles can be determined, but
the number of observed particles tends to be smaller than the number of particles obtained with other measurement techniques. However, some particle properties like wettability cannot be directly deduced from image data, although many separation processes, such as flotation-based particle separation processes, rely on differences in wettabilities. Building on recent studies regarding flotation separation (2), bivariate Tromp functions for the area-equivalent diameter and aspect ratio of glass particles with differently modified wettabilities have been computed. Comparing the Tromp functions obtained in this way reveals the influence of particle wettability on the separation behavior.
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Poster
PARTEC 2023, 26.-28.09.2023, Nürnberg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36334
Quality Assessment of Cyclotron-produced 67Cu
Brühlmann, S. A.; Walther, M.; Kreller, M.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.
Abstract
This project aims to explore the cyclotron-based production of 67Cu through the 70Zn(p,α)67Cu reaction, in contrast to other possible routes (e.g. photonuclear reaction). The reaction features a low yield and the need of expensive target material, thus demanding a recycling strategy. Although by this reaction no carrier added 67Cu is produced, contamination with or co-production of stable copper (via 68Zn(p,α)65Cu) cannot be entirely excluded.
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Contribution to proceedings
Fourth international edition of the symposium on Technetium and Other Radiometals in Chemistry and Medicine (TERACHEM 2022), 14.-17.09.2022, Brixen, Italien
Permalink: https://www.hzdr.de/publications/Publ-36332
Antiferromagnetic spin chains: ground states and phase transitions in static magnetic field of arbitrary direction
Borysenko, Y.; Sheka, D.; Yershov, K.; Faßbender, J.; van den Brink, J.; Makarov, D.; Pylypovskyi, O.
Abstract
While easy axis antiferromagnets (AFMs) are robust against external magnetic fields of a moderate strength, spin reorientations in strong fields provide an insight into subtle properties of materials, which are usually hidden by the high symmetry of the ground state [1]. In absence of external magnetic fields, they reveal geometry-driven chiral and anisotropic responses supplemented by weak ferromagnetism [2]. Here, we address theoretically the effects of curvature in achiral anisotropic ring-shaped AFM spin chains exposed to strong magnetic fields using the methodology of curvilinear magnetism [3]. We identify the geometry-governed helimagnetic phase transition enabled in the spin-flop phase, separating locally homogeneous (vortex) and periodic (onion) AFM textures (Fig. 1). The curvature-induced Dzyaloshinskii–Moriya interaction results in the spin-flop transition being of the first- or second-order depending on the ring curvature. Spatial inhomogeneity of the Néel vector in the spin-flop phase generates the weakly ferromagnetic esponse in the plane perpendicular to the applied magnetic field, which is inherent to curved systems. In AFM spin chains possesing torsion, e.g. helices, these effects are enhanced by the inhomogeneity of local texture in the ground state. Our work provides further insights in the physics of curvilinear AFMs in static magnetic fields and guides prospective experimental studies of geometrical effects in the spin-chain nanomagnets.
Keywords: antiferromagnetism; curvilinear spin chains
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Lecture (Conference)
AIM 2023 Advances in Magnetics, 15.-18.01.2023, Moena, Italy, 15.-18.01.2023, Moena, Italy
Permalink: https://www.hzdr.de/publications/Publ-36331
A Contribution to a Better Understanding of Lithium-Ion Battery Recycling by Using Automated Mineralogy
Vanderbruggen, A.; Bachmann, K.; Rudolph, M.; Gutzmer, J.
Abstract
Recycling is a potential solution to narrow the gap between the supply and demand of battery materials such as Co, Ni, Mn and graphite. However, increasing the efficiency of the recycling of lithium ion batteries (LIB) remains a challenge. This paper evaluates the influence of the recycling routes on the liberation of LIB components and on the joint recovery of lithium metal oxides and spheroidized graphite particles using froth flotation. The products of the two different recycling routes – mechanical, and thermomechanical – were analyzed using a particle-based method, namely scanning electron microscopy (SEM)-based automated image analysis. The mechanical process enabled the delamination of active materials from the foils. However, binder preservation hinders active materials liberation as indicated by their aggregation. In contrast, the thermo-mechanical process showed a preferential liberation of individual anode active particle thus identified as an upstream route for flotation. However, this thermal treatment led to a lack of liberation of cathode material and to the oxidation of aluminium foil resulting in its distribution in all size fractions. Among the two, the thermo-mechanical black mass showed the highest flotation selectivity due to the removal of the binder thereby producing liberated active particles.
- World of Metallurgy - Erzmetall 75(2022)3, 144-152
Permalink: https://www.hzdr.de/publications/Publ-36330
Production of 67Cu at the TR-FLEX Cyclotron
Brühlmann, S. A.; Walther, M.; Kreller, M.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.
Abstract
For the cyclotron-based production of the theranostic radionuclide 67Cu through the 70Zn(p,α)67Cu reaction electroplated metallic Zn and ZnO powder targets are being studied. Highly enriched 70Zn targets were designed and optimized considering nuclear and thermal aspects.
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Contribution to proceedings
18th Workshop on Targetry and Target Chemistry, 21.-26.08.2022, Whistler, Canada
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36329
Synthesis of [18F]FMISO, a hypoxia-specific imaging probe for PET, an overview from a radiochemist’s perspective
Knieß, T.; Zessin, J.; Mäding, P.; Kuchar, M.; Kiß, O.; Kopka, K.
Abstract
[18F]Fluoromisonidazole ([18F]FMISO, 1H-1-(3-[18F]fluoro-2-hydroxypropyl)-2-nitroimidazole) is a commonly used radiotracer for imaging hypoxic conditions in cells. Since hypoxia is prevalent in solid tumors, [18F]FMISO is in clinical application for decades to explore oxygen demand in cancer cells and the resulting impact on radiotherapy and chemotherapy.
Since the introduction of [18F]FMISO as positron emission tomography (PET) imaging agent in 1986, a variety of radiosynthesis procedures for the production of this hypoxia tracer has been developed. This paper gives a brief overview on [18F]FMISO radiosyntheses published so far from its introduction until now. From a radiopharmaceutical chemist’s perspective, different precursors, radiolabeling approaches and purification methods are discussed as well as used automated radiosynthesizers, including cassette-based and microfluidic systems.
In a GMP compliant radiosynthesis using original cassettes for FASTlab we produced [18F]FMISO in 49% radiochemical yield within 48 min with radiochemical purities >99% and molar activities >500 GBq/µmol . In addition, we report an easy and efficient radiosynthesis of [18F]FMISO, based on in-house prepared FASTlab cassettes, providing the radiotracer for research and preclinical purposes in good radiochemical yields (39%), high radiochemical purities (>99%) and high molar activity (>500 GBq/µmol) in a well-priced option.
Keywords: [18F]FMISO; [18F]Fluoromisonidazole; automated radiosynthesis; FASTlab
Involved research facilities
- PET-Center
- ZRT
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EJNMMI Radiopharmacy and Chemistry 8(2023)1, 5
DOI: 10.1186/s41181-023-00190-7
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36328
Joint recovery of lithium metal oxides and graphite particles from spent lithium-ion batteries using froth flotation
Vanderbruggen, A.; Bachmann, K.; Olutogun, M.; Bresser, D.; Rudolph, M.; Serna, R.
Abstract
Recycling symposium This talk presents how we can separate the fine active particles (lithium metal oxides and graphite) from the black mass by using froth flotation. This research demonstrates that graphite can be recovered from spent lithium ion batteries and recycled into new anodes
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Lecture (Conference)
Advanced Automotive Battery Conference AABC 2022, 19.-22.06.2022, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36327
Cyclotron-based Production of 67Cu for Radionuclide Theranostics Via the 70Zn(p,α)67Cu Reaction
Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.
Abstract
Theranostic matched pairs of radionuclides have aroused interest during the last couple of years and in that sense copper is one element that has a lot to offer. While 61Cu and 64Cu are slowly being established as nuclides for diagnostic with PET, the availability of the therapeutic counterpart 67Cu plays a key role for further radiopharmaceutical development in the future. Up to date, the 67Cu shortage has not been solved, however, different production routes are being explored. This project aims at the production of no carrier added 67Cu with high radionuclidic purity with a medical 30 MeV compact cyclotron via the 70Zn(p,α)67Cu reaction.
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Pharmaceuticals 16(2023), 314
DOI: 10.3390/ph16020314
Cited 7 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36326
β Decay of 61V and its Role in Cooling Accreted Neutron Star Crusts
Ong, W.-J.; Brown, E. F.; Browne, J.; Ahn, S.; Childers, K.; Crider, B. P.; Dombos, A. C.; Gupta, S. S.; Hitt, G. W.; Langer, C.; Lewis, R.; Liddick, S. N.; Lyons, S.; Meisel, Z.; Möller, P.; Montes, F.; Naqvi, F.; Pereira, J.; Prokop, C.; Richman, D.; Schatz, H.; Schmidt, K.; Spyrou, A.
Abstract
The interpretation of observations of cooling neutron star crusts in quasipersistent x-ray transients is affected by predictions of the strength of neutrino cooling via crust Urca processes. The strength of crust Urca neutrino cooling depends sensitively on the electron-capture and β-decay ground-state-to-ground-state transition strengths of neutron-rich rare isotopes. Nuclei with a mass number of A=61 are predicted to be among the most abundant in accreted crusts, and the last remaining experimentally undetermined ground-state-to-ground-state transition strength was the β decay of 61V. This Letter reports the first experimental determination of this transition strength, a ground-state branching of 8.1+4.0−3.1%, corresponding to a log ft value of 5.5+0.2−0.2. This result was achieved through the measurement of the β-delayed γ rays using the total absorption spectrometer SuN and the measurement of the β-delayed neutron branch using the neutron long counter system NERO at the National Superconducting Cyclotron Laboratory at Michigan State University. This method helps to mitigate the impact of the pandemonium effect in extremely neutron-rich nuclei on experimental results. The result implies that A=61 nuclei do not provide the strongest cooling in accreted neutron star crusts as expected by some predictions, but that their cooling is still larger compared to most other mass numbers. Only nuclei with mass numbers 31, 33, and 55 are predicted to be cooling more strongly. However, the theoretical predictions for the transition strengths of these nuclei are not consistently accurate enough to draw conclusions on crust cooling. With the experimental approach developed in this work, all relevant transitions are within reach to be studied in the future.
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Physical Review Letters 125(2020)26, 262701
DOI: 10.1103/PhysRevLett.125.262701
Cited 8 times in Scopus
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36325
Establishing the ground-state spin of 71Kr
Waniganeththi, S.; Hoff, D. E. M.; Rogers, A. M.; Lister, C. J.; Bender, P. C.; Brandenburg, K.; Childers, K.; Clark, J. A.; Dombos, A. C.; Doucet, E. R.; Jin, S.; Lewis, R.; Liddick, S. N.; Meisel, Z.; Morse, C.; Schatz, H.; Schmidt, K.; Soltesz, D.; Subedi, S. K.
Abstract
Nuclei in the vicinity of the N=Z line provide many sensitive probes of isospin symmetry. One example concerns the character and sequence of low-lying states of the T=1/2 mirror pair 71Kr and 71Br which has been under debate for several decades. In this paper we report a new measurement of the absolute β-branching to ground and excited states which, taken with our precise lifetime of T1/2=94.9(4)ms, gives a superallowed ground state–to–ground state log(ft) value of 3.64(4). This is only consistent with both 71Br and 71Kr having the same spin and parity, Jπ=5/2−, as expected from mirror symmetry. The β-delayed proton emission to the first-excited state in 70Se was observed for the first time which also strongly supports this assignment.
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Physical Review C 106(2022)4, 044317
DOI: 10.1103/PhysRevC.106.044317
Cited 3 times in Scopus
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36324
Developing the 32S(p, d)31S*(p) reaction to probe the 30P(p, γ)31S reaction rate in classical novae
Burcher, S.; Chipps, K. A.; Hughes, R. O.; Reingold, C.; Sasstamoinen, A.; Harke, J. T.; Cooper, N.; Ahn, S.; Allmond, J. M.; Clark, H.; Cizewski, J. A.; Hall, M. R.; Hooker, J.; Jayatissa, H.; Jones, K. L.; Ota, S.; Pain, S. D.; Schmidt, K.; Simon, A.; Upadhyayula, S.
Abstract
Background: The 30 P(p, γ ) 31 S reaction rate is one of the largest remaining sources of uncertainty in the
final abundances of nuclei created in a classical nova involving a ONe white dwarf. The reaction rate directly
influences silicon isotopic ratios, which are used as identifiers of presolar grains with nova origins. In addition,
the uncertainty in the 30 P(p, γ ) 31 S reaction rate has been found to limit the use of nova nuclear thermometers
based on observations of elemental ratios in nova ejecta.
Purpose: Reduce uncertainties in the nuclear data for proton-unbound states in 31 S, which act as resonances
for the 30 P(p, γ ) 31 S reaction at classical nova temperatures, and develop a technique for high efficiency, high-
resolution reaction-decay coincidence measurements.
Methods: The 32 S(p, d ) 31 S reaction was used to populate the states of interest in 31 S. The experiment was
performed at the Texas A&M Cyclotron Institute using the LLNL Hyperion array for the detection of charged
particles and γ rays. A downstream silicon telescope was used to select reaction deuterons, and a single upstream
silicon detector was used to measure protons emitted in the decay of unbound 31 S levels.
Results: Several states in 31 S above the proton separation energy were observed to have been populated. Decay
protons from the resonant states in 31 S were identified as events in the upstream silicon detectors that came in
coincidence with deuterons in the downstream telescope. Protons emitted from these states were measured and
branching ratios extracted.
Conclusions: While no new reaction rate is derived, spin-parity assignments for several higher-lying proton
unbound states have been confirmed. Measured p0 branching ratios for these levels have been compared to
previous measurements with good agreement, and in some cases provided a reduction in uncertainty. The
previously identified T = 3/2 state may have been incorrectly assigned a large p0 branching ratio in a previous
measurement. The technique of measuring reaction-decay coincidences with a particle-gamma setup appears
promising.
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Physical Review C 105(2022)4, 045805
DOI: 10.1103/PhysRevC.105.045805
Cited 1 times in Scopus
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36323
Statistical characterization of the interfacial behavior captured by a novel image processing algorithm during the gas/liquid counter-current two-phase flow in a 1/3 scaled down of PWR hot leg
Astyanto, A. H.; Nugroho, A. N. A.; Indarto; Catrawedarma, I. G. N. B.; Lucas, D.; Deendarlianto
Abstract
This study addresses a statistical characterization of the interfacial behaviors during gas/liquid counter-current flow in a large scale of pressurized water reactor’s hot leg typical geometry on the basis of both time and frequency domain analyses. Here, the visualizations were captured by high-speed cameras. Furthermore, the image processing algorithm on the basis of pixel identification was developed to identify the time-series interfacial dynamics of the liquid holdup fluctuations, comprising the wave growth and its movement. The obtained data were further analyzed by using various advanced statistical tools comprising the probability density function, power spectral density function, and also discrete wavelet transform. Additionally, chaotic levels of the flow were obtained through the Kolmogorov-entropy analysis.
Particular results reveal that a typical mechanism of flooding begins with the appearance of a wavy interface which further develops into either a roll or large wave, and later blocks the entire cross-sectional area of the conduit around the bend region. This later stage indicates the inception of flooding which is characterized by the increase of the water level close to the bend region. Next, the higher the pressure of system, the higher the frequency occurrence of slugging, while the injected gas flow rate obtained a different trend. However, the Kolmogorov entropy enables to correlate the stabilizing effect due to the fluid resistance which corresponds to either the pressure of the system or the physical properties of the fluid. In addition, there were no significant differences between the flooding mechanisms for both the air/water and steam/water flows.
Keywords: Counter-Current Flow Limitation; stratified flow
Involved research facilities
- TOPFLOW Facility
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Nuclear Engineering and Design 404(2023), 112179
DOI: 10.1016/j.nucengdes.2023.112179
Cited 3 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36322
Matrix-Matched Reference Materials for the Analysis of Tungsten-Minerals for Trace Elements with Laser Ablation Inductively Coupled Plasma Mass Spectrometry
Abstract
Scheelite (CaWO4) and wolframite-group minerals (Fe,Mn)WO4 represent the economically most important W-ore minerals. In order to constrain the processes responsible for the formation and overprint of W-ores knowledge of trace element concentrations including Mo, Sr, As, Nb, Ta and REE are necessary. In some cases, these ores are also associated with Au-mineralization.
Accuracy of quantitative analysis with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is improved by the use of matrix matched reference materials (RMs). In addition to matrix effects, the analysis of W-minerals involves analytical challenges such as abundance sensitivity of W on Ta and Re and molecular interferences of W-oxides and -nitrides on Au.
A gem-quality scheelite (Scheelite S) from a late-stage alpine vein in the Felbertal tungsten mine, Austrian Alps, is free of Ta and Re and therefore provides the opportunity to determine correction factors for abundance sensitivity of W on Ta and Re. For an exemplary set of samples from the Felbertal tungsten mine, the uncorrected data yield fairly constant Re concentrations of ~5-6µg/g and 0.99-2.14 µg/g for Ta respectively. After correction for abundance sensitivity, Re is below the lower limit of quantification and Ta ranges from 0.07-1.09 µg/g.
For Au the uncorrected concentrations range from 0.14 to 0.38 µg/g. After the correction for molecular interferences by W-oxides and -nitrides the concentrations varied between 0 and 0.32 µg/g.
Preliminary data from wolframite-group minerals indicate similar effects of the abundance sensitivity of W on Ta and Re, as well as the molecular interferences of W-oxides an –nitrides on Au.
Our study demonstrates significantly improved analyses of some important trace elements in W-minerals when matrix-matched RMs are used for the correction of the abundance sensitivity and molecular interferences.
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Lecture (Conference)
Geoanalysis 2022, 06.-11.08.2022, Freiberg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36321
Atom Probe Tomography: Basics and applications on complex sulphides
Abstract
Atom Probe Tomography combines the three dimensional reconstruction of the lattice in real space with a time–of–flight mass spectrometer. The result is a tomographic image of the chemical composition of a solid sample making it a powerful technique to determine the chemical composition of nanostructures in 3-D with sub-nanoscale spatial resolution. It is a powerful technique to study processes on the near-atomic scale such as diffusion, exsolution, or the formation of nano-scale inclusions.
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Invited lecture (Conferences)
Vortragsreihe der Österreichischen Mineralogischen Gesellschaft, 17.03.2022, Universität Innsbruck, Österreich
Permalink: https://www.hzdr.de/publications/Publ-36320
Atom Probe Tomography: Basics and applications on complex sulphides
Abstract
Atom Probe Tomography combines the three dimensional reconstruction of the lattice in real space with a time–of–flight mass spectrometer. The result is a tomographic image of the chemical composition of a solid sample making it a powerful technique to determine the chemical composition of nanostructures in 3-D with sub-nanoscale spatial resolution. It is a powerful technique to study processes on the near-atomic scale such as diffusion, exsolution, or the formation of nano-scale inclusions.
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Invited lecture (Conferences)
Vortragsreihe der Österreichischen Mineralogischen Gesellschaft, 16.03.2022, Montanuniversität Leoben, Österreich
Permalink: https://www.hzdr.de/publications/Publ-36319
Atom Probe Tomography: Basics and applications on complex sulphides
Abstract
Atom Probe Tomography combines the three dimensional reconstruction of the lattice in real space with a time–of–flight mass spectrometer. The result is a tomographic image of the chemical composition of a solid sample making it a powerful technique to determine the chemical composition of nanostructures in 3-D with sub-nanoscale spatial resolution. It is a powerful technique to study processes on the near-atomic scale such as diffusion, exsolution, or the formation of nano-scale inclusions.
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Invited lecture (Conferences)
Vortragsreihe der Österreichischen Mineralogischen Gesellschaft, 14.03.2022, Universität Wien, Österreich
Permalink: https://www.hzdr.de/publications/Publ-36318
Helmholtz AI: Diversity in Teaching Machine Learning supports democratising AI
Cea, D.; Hoffmann, H.; Weiel, M.; Steinbach, P.; Kesselheim, S.
Abstract
“Democratising AI” – that is the motto for the Helmholtz AI consultants. With our scientific consulting, we enable Helmholtz researchers from all domains to leverage AI for their datasets by providing comprehensive support with AI methods, tools, and software engineering. And this does not only apply to scientists working on their own research projects. We also offer courses, workshops, lectures, and challenges on various AI-related topics. On our poster, you can find an overview of past teaching experiences from the different consultant teams. These include an in-depth introductory course to deep learning using the flipped classroom approach, advanced courses on AutoML and explainable AI with multiple hands-on sessions, data challenges introducing the learners to domain adaptation tasks and making them experiment and search for personal solutions to complex and current problems, and crash courses on AI for a broader and less technical audience.
You are curious to learn more? Then drop by our poster and let’s have a chat.
Keywords: machine learning; community; learning; diversity; inclusion
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Poster
TEACH2, 09.11.2022, zoom, Germany
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36317
Know your learners to adapt teaching early - a discussion of pre-workshop surveys
Abstract
During the process of composing teaching material and preparing for a lesson, an instructor typically bears in mind an expected composition of his/her audience with respect to prior knowledge, speed of learning, and expectations. In this discussion, we would like to present our approaches to assessing these 3 dimensions before a workshop starts in order to prepare the teacher for his/her students. We will share some typical questions we survey with and explain how it helps us to target our content better. Moreover, it can provide a solid baseline for teachers with respect to preparing group activities to foster a community of learners in the classroom. The largest part of the discussion will be devoted to an exchange of experiences by the participants on assessing learner communities before they meet in class and on how to improve for future workshops.
Keywords: machine learning; teaching; interactive
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Invited lecture (Conferences)
(Online presentation)
TEACH2, 09.11.2022, zoom, Germany
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36316
Spectroscopy of XFEL heated Cu and x-ray absorption in laser-produced Warm Dense Cu a pár dalších témat
Abstract
Warm Dense Matter (WDM) is a transitional state between solid and ideal plasmas. It can contain highly charged ions and moderate electron temperatures, while retaining rest of crystalline-like structure. In experimental conditions it can be typically created in a dynamical way by irradiation of solid targets with ultra-short pulse lasers. The x-ray spectroscopy of plasma is a great way of studying this transitional state of matter, by using either a broadband x-ray beam as a backlighter for absorption measurement, or self-emission to observe the radiation of various charge states of present ions.
In this talk I will present two different experiments studying warm dense Copper with their results and a minimum of underlying theory. In the first case, the matter is heated by direct irradiation by optical laser (Draco, Dresden), and probed variable delay later by a 'Laser wakefield accelerated' (LWFA) betatron beam. From the x-ray absorption techniques we can infer both the electron and ion temperatures, therefore observing the heating and melting of the material. In the second case, the matter is created ('pumped') and probed simultaneously by the same pulse of the X-ray Free Electron Laser (European XFEL, Hamburg). Moderately charged ions are created within the duration of the pulse (~30 fs) and their Kα emission is stimulated by the beam. The self-emission spectra in this well described environment serves as a road map of various atomic transitions and non-equilibrium atomic-physics effects of those ions.
Involved research facilities
- HIBEF
- Draco
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Invited lecture (Conferences)
15th Student Workshop - Winter school on Plasma Physics, 16.-20.01.2023, Marianska, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-36314
Neptunium(V) and uranium(VI) sorption onto the zircaloy corrosion product zirconia (ZrO₂)
Abstract
The interactions of long-lived radionuclides, such as uranium and the transuranium element
neptunium, with corroded phases in the near-field of a repository are crucial processes that
have to be taken into account in the safety assessment of a repository. Neptunium(V) and
uranium(VI) were chosen as representatives of pentavalent and hexavalent actinides,
respectively. Zirconia (ZrO₂) is the main corrosion product of the zircaloy cladding material of
spent nuclear fuel rods and constitutes as one of the first barriers encountered by mobilized
radionuclides. A comprehensive, multi-method approach was pursued to obtain a detailed
understanding of the Np(V)/U(VI) interactions at the zirconia-water interface. pH-dependent
batch sorption studies and isotherm experiments as well as spectroscopic techniques (EXAFS,
IR) were employed to gain information on the macroscopic and the molecular scale,
respectively. The derived information about Np(V)/U(VI) binding sites as well as number and
structure of the formed surface species were then used to constrain the parametrization of a
thermodynamic surface complexation model. The results of this work will contribute to more
reliable predictions about the environmental fate of Np(V)/U(VI) surrounding the near-field of
a repository.
Keywords: uranium(VI); neptunium(V); zirconia; ZrO₂; EXAFS; IR; sorption
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Lecture (others)
Presentation PhD topic, 09.11.2022, Veldhoven, Netherlands
Permalink: https://www.hzdr.de/publications/Publ-36313
Uptake of Np(V) and U(VI) by zirconia (ZrO₂): a batch, spectroscopy and modeling study
Abstract
The interactions of long-lived radionuclides, such as uranium and the transuranium element
neptunium, with corroded phases in the near-field of a repository are crucial processes that
have to be taken into account in the safety assessment of a repository. Neptunium(V) and
uranium(VI) were chosen as representatives of pentavalent and hexavalent actinides,
respectively. Zirconia (ZrO₂) is the main corrosion product of the zircaloy cladding material of
spent nuclear fuel rods and constitutes as one of the first barriers encountered by mobilized
radionuclides. A comprehensive, multi-method approach was pursued to obtain a detailed
understanding of the Np(V)/U(VI) interactions at the zirconia-water interface. pH-dependent
batch sorption studies and isotherm experiments as well as spectroscopic techniques (EXAFS,
IR) were employed to gain information on the macroscopic and the molecular scale,
respectively. The derived information about Np(V)/U(VI) binding sites as well as number and
structure of the formed surface species were then used to constrain the parametrization of a
thermodynamic surface complexation model. The results of this work will contribute to more
reliable predictions about the environmental fate of Np(V)/U(VI) surrounding the near-field of
a repository.
Keywords: uranium(VI); neptunium(V); zirconia; ZrO₂; EXAFS; IR; sorption
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Lecture (others)
Seminar für Kern- und Radiochemie, 30.01.2023, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36312
The solubility of oxygen in water and saline solutions
Bok, F.; Moog, H. C.; Brendler, V.
Abstract
Oxygen is one of the key reaction partners for many redox reactions also in the context of nuclear waste disposal. Its solubility influences radionuclides’ behavior, corrosion processes and even microbial activity. Therefore, a reliable calculation of the solubility of molecular oxygen in aqueous solutions is relevant for the safety assessment.
In the available geochemical speciation and reactive transport programs, these data are handled very differently. In some data files for such codes the hypothetical equilibrium between dissolved oxygen and water is used to balance redox reactions. Equilibrium constants are given in “temperature grids” for up to 573.15 K. In other cases, temperature functions for the solubility of gaseous oxygen in water are given, without any reference to a valid temperature range.
In some cases, these data were also used in the context of modeling equilibria in high-saline solutions using the Pitzer formalism. This raised the question about the experimental foundation of equilibrium constants given in such data files and their validity for the solubility of molecular oxygen in saline solutions.
For this article a thorough literature review was conducted with respect to the solubility of molecular oxygen in saline solutions. From these primary experimental data Pitzer coefficients were derived. An internally consistent set of thermodynamic data for dissolved oxygen is presented, along with statements about its validity in terms of temperature and, as far as Pitzer coefficients are concerned, of solution composition.
Keywords: Oxygen (O2) solubility; water; electrolyte solutions; Pitzer ion interaction approach; EH equation
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Frontiers in Nuclear Engineering 2(2023), 1158109
DOI: 10.3389/fnuen.2023.1158109
Permalink: https://www.hzdr.de/publications/Publ-36310
Application of Community Data to Surface Complexation Modeling Framework Development: Iron Oxide Protolysis
Han, S.-C.; Chang, E.; Bok, F.; Zechel, S.; Zavarin, M.
Abstract
This study presents a comprehensive community data-driven surface complexation modeling framework for simulating potentiometric titration of mineral surfaces. Compiled community data for ferrihydrite, goethite, hematite, and magnetite are fit to produce representative protolysis constants
that can reproduce potentiometric titration data collected from multiple literature sources. Using this framework, the impact of SCM type and surface site density (SSD) on the fit quality and protolysis constants can be readily evaluated. For example, the non-electrostatic model (NEM) yielded a poor
data fit compared to diffuse double layer model (DDLM) and constant capacitance models (CCM) due to the absence of known surface charge effects. Regardless of the choice of iron oxide mineral, pKa1 decreased with increasing SSD while the opposite tendency was observed for pKa2. This newly
developed framework demonstrates a method to reconcile community data-wide potentiometric titration data using FAIR data principles to produce mineral protolysis constants that improve robustness of surface complexation models for applications in metal sorption and reactive transport
modeling. The framework is readily expandable (as community data increase) and extensible (as the number of minerals increase). The framework provides a path forward for developing self-consistent, comprehensive, and updateable surface complexation databases for surface complexation and
reactive transport modeling.
Keywords: Sorption; Protolysis; Iron oxides; Radionuclide; Surface Complexation; Potentiometric Titration
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Journal of Colloid and Interface Science 648(2023), 1015-1024
DOI: 10.1016/j.jcis.2023.06.054
Cited 4 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36309
Introduction to kernel methods and Gaussian processes
Abstract
Introduction to kernel methods and Gaussian processes
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Lecture (others)
(Online presentation)
Institute Seminar, 08.11.2022, Görlitz, Germany
Permalink: https://www.hzdr.de/publications/Publ-36308
Radiative particle-in-cell simulations of the beam hosing instability -- an analysis by components
Lebedev, A.; Pausch, R.; Widera, R.; Bastrakov, S.; Bussmann, M.; Schramm, U.; Debus, A.
Abstract
We present first results and analyses of radiation spectra expected to be produced by highly relativistic particle beams propagating through a plasma medium experiencing the hosing instability. We determine these spectra in particle-in-cell simulations by in-situ computation of coherent and incoherent radiation based on Liénard-Wiechert potentials, emitted by all simulated particles (>10^9) of the beam and plasma for over 160 distinct detectors distributed across half a solid angle. Our code allows us to distinguish radiation emitted by plasma particles from that of the bunch, thereby enabling us to infer the origin of the spectral features.
In the simulation campaign, conducted at the JUWELS Booster cluster at JSC, we considered linear and non-linear regimes of the instability for highly relativistic electron beams of varying emittance impacting a homogeneous electron plasma.
We further show a preliminary analysis of the data relating observed characteristics of the spectra to the characteristics of the instability.
A goal of these studies is to open up new experimental avenues for better understanding the beam instability evolution by identifying quantitative radiation signatures of the instability that can be measured in experiments.
Keywords: Firehose Instability; PIConGPU; High-Performance Computing; Plasma-Wakefield Accelerators; Plasma Instabilities; Radiation Signatures
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Lecture (Conference)
(Online presentation)
DPG Spring Meeting of the Divisions Hadronic and Nucleonic Physics, Plasma Physics and the Working Group Accelerator Physics, 28.03.-1.04.2022, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36307
Radiative particle-in-cell simulations of the beam hosing instability
Lebedev, A.; Pausch, R.; Bastrakov, S.; Widera, R.; Bussmann, M.; Schramm, U.; Steiniger, K.; Debus, A.
Abstract
We present the results and analyses of radiation spectra expected to be
produced by highly relativistic particle beams propagating through a
plasma medium and experiencing the hosing instability.
Coherent and incoherent contributions to the spectra are determined
in-situ for all simulated particles (>10^9) of the particle cloud and
ambient plasma for a lage assembly of detectors.
With the help of our particle-in-cell code we are able to distinguish
radiation emitted by plasma particles from that of the bunch.
In the simulation campaign, conducted at the JUWELS Booster cluster at
JSC, we consider linear and non-linear regimes of the instability for
highly relativistic electron beams impacting a homogeneous electron plasma.
We show an updated analysis of the data relating observed
characteristics of the spectra to the features of the bunch and ambient
plasma, thereby identifying first features indicative of the hosing
instability in PWFA.
A goal of these studies is to open up new experimental avenues for
better understanding the beam instability evolution by identifying
quantitative radiation signatures of the instability that can be
measured in experiments.
Keywords: Firehose Instability; High-Performance Computing; PIConGPU; Plasma-Wakefield Accelerator
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Lecture (Conference)
8th Annual Matter and Technologies Student Retreat, 27.-28.09.2022, DESY Hamburg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36306
Precipitation stripping of nanometrical particles for the recovery of metal vanadates
Sánchez-Loredo, M. G.; Ebert, D.; Chekhonin, P.; Labrada Delgado, G. J.; Kelly, N.
Abstract
Transition metal vanadates have shown potential in applications as sensors, in photocatalysis, and recently, because of their high theoretical capacity, safety, easy preparation, and low cost, as electrode materials for primary and rechargeable batteries. Motivated by these relevant applications, much research work has been done on the synthesis and electrochemical studies of various 1D transition metal vanadates. Metal vanadates are normally synthesized by hydrothermal methods at high temperatures and pressures, making the synthesis expensive, and the control of the microstructure and composition difficult to achieve.
Vanadium can currently be found in the slag by-products of certain steel production processes, and the development of hydrometallurgical processes for the recovery and purification is relevant, mostly from alkaline media. Various methods are being investigated for separation of the metal value from alkaline leach feeds, including solvent extraction.
In case of the recovery of vanadium an interesting modification of the conventional solvent extraction process is the addition of a crystallization operation (precipitation stripping). In this work, the extraction was carried out using an Aliquat 336 solution in n-octanol/kerosene as extractant. Precipitation stripping was carried out using several metal salts dissolved in a concentrated chloride solution. For some experiments, polyvinylpyrrolidone was used as stabilizer in order to avoid agglomeration and to control growth. The structural characteristics of the crystallized products were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable vanadium compounds.
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Poster
Jahrestreffen der ProcessNet Fachgruppen Extraktion, Phytoextrakte und Membrantechnik, 23.-24.05.2022, Frankfurt, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36305
The Extraction of HREES and LREES with Primene JM-T in Sulphate Media
Bastürkcü, E.; Kelly, N.; Stelter, M.; Yüce, A. E.; Timur, S. İ.
Abstract
The number of studies on the separation process of rare earth elements (REEs) has been studied intensively because REEs are playing a very critical role of high-tech products. Due to the restriction of export from China which has a dominating position in terms of reserve and production of REEs, other countries have investigated potential reserves and production techniques of rare earths. In case of Turkiye a high potential REE deposit is located in Eskisehir-Beylikova. In the presented study, the separation of heavy rare earth elements (HREEs) from light rare earth elements (LREEs) from the model solution was studied with solvent extraction. The solution was produced based on dissolution of pre-concentrate of Eskisehir-Beylikova ore by water leaching after acid baking. Primene JM-T was selected as an extractant which has not been studied in the separation of HREEs and LREEs. The key parameters pH, extractant concentration and A/O ratio were optimized. The optimum conditions were determined to be 10% concentration of extractant, pH 1 and A:O ratio, 1:1. The extraction for LREEs was 75-80% while HREEs had lower extraction rates of only 45-70%.
Keywords: REE; PrimeneJM-T; solvent extraction; sulphate media
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Lecture (Conference)
International Mineral Processing Symposium, 15.-17.12.2022, Istanbul, Türkiye -
Contribution to proceedings
International Mineral Processing Symposium, 15.-17.12.2022, Istanbul, Türkiye
Permalink: https://www.hzdr.de/publications/Publ-36304
Precipitation stripping of V(V) as a novel approach for the preparation of transition metal vanadates
Kelly, N.; Ebert, D.; Möckel, R.; Labrada-Delgado, G. J.; Sánchez-Loredo, M. G.
Abstract
Transition metal vanadates, and particularly copper vanadates (CVO), have shown potential in applications as sensors, in photocatalysis, and recently, because of their high theoretical capacity, safety, easy preparation, and low cost, as electrode materials for primary and rechargeable lithium-ion batteries (LIBs). During discharge, the Cu2+ is reduced, and, more than one lithium ion per vanadium react, giving a high theoretical discharge capacity. Motivated by this relevant application, much research work has been done on the synthesis and electrochemical studies of various 1D transition metal vanadates. Among them, particularly Cu3V2O7(OH)2.2H2O has been studied as an electrode for primary lithium batteries with a high storage capacity. CVO and other metal vanadates are normally synthesized by hydrothermal methods at high temperatures and pressures, making the synthesis expensive, and the control of the microstructure and composition difficult to achieve.
An interesting modification of the conventional solvent extraction process is the addition of a crystallization operation, where low-solubility metal salts such as oxalates, oxides, or sulfides can be precipitated (precipitation stripping). In this work, copper vanadate nanoparticles have been synthesized by a simple synthetic route by solvent extraction and precipitation stripping. The extraction was carried out by ion exchange using a 20% (v/v) Aliquat 336 solution in n-octanol/kerosene as extractant, and an alkaline aqueous solution (0.1 M NaOH) prepared using vanadium pentoxide (V(V) concentration 2 g/L). Precipitation stripping was carried out using copper sulphate (0.01, 0.05 and 1 mol/L) dissolved in a concentrated chloride solution (4 mol/L). For some experiments, polyvinylpyrrolidone (PVP, Sigma Aldrich, ~44,000 g/mol) was used as stabilizer in order to avoid agglomeration and control growth. The prepared materials were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), and X-Ray Fluorescence (XRF). The obtained diffractograms could be indexed to the Cu3V2O7(OH)2.2H2O phase, space group: C2/m(12), JCPDS Card No. 46-1443, corresponding to volborthite, an uncommon secondary mineral formed in the oxidized zone of vanadium-bearing hydrothermal mineral deposits, monoclinic or pseudohexagonal and forms normally rosette-like aggregates of scaly crystals. The copper vanadate particles are nanometrical in size, with morphologies varying from nanowires to spherical particles (in presence of PVP)
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Lecture (Conference)
International solvent extraction conference (ISEC), 26.-30.09.2022, Göteborg, Sweden
Permalink: https://www.hzdr.de/publications/Publ-36303
Selektive Extraktion von Molybdän mit Cyanex 272 und Cyanex 600: Charakterisierung der organischen Phase zur optimierten Prozessführung
Helbig, T.; Tasker, P.; Kaden, P.; Foerstendorf, H.; Lehmann, F.; Kelly, N.
Abstract
Der steigende Bedarf an Metallen für moderne technische Anwendungen erfordert die Entwicklung und Optimierung von Verfahren zur Rückgewinnung und zum Recycling dieser wertvollen Metalle. Die Bedeutung hydrometallurgischer Verfahren, z. B. unter Einsatz der Flüssig-Flüssig-Extraktion, aus Rohstoffquellen mit niedrig konzentrierten Wertelementen nimmt dabei stetig zu. Sie ermöglichen eine effiziente Rückgewinnung von Metallen sowohl aus industriellen Abwässern oder aber auch aus festen Sekundärrohstoffen und tragen zudem zu einer Reduzierung der Umweltbelastung durch alte Haldenmaterialien bei. Ein typisches Beispiel für diese Materialien stellt der Theisenschlamm dar, welcher bis 1990 im Rahmen der Aufbereitung von Kupferschiefer im Schachtofen als Abfallprodukt (220000 t) anfiel. Dieser enthält neben Elementen wie Kupfer und Zink auch signifikante Mengen an anderen Wertmetallen (Molybdän, Rhenium, Cobalt). Die komplexe Zusammensetzung des Materials, die Anwesenheit von umweltrelevanten Störelementen und der hohe Anteil an organischen Verbindungen erfordert ein mehrstufiges Verfahren, um die Metalle aufzukonzentrieren und mit notwendiger chemischer Reinheit zu gewinnen.
Im vorliegenden Beitrag wird die selektive Extraktion von Molybdän aus sauren Lösungen unter Einsatz der kommerziellen Extraktionsmittel Cyanex 272 und Cyanex 600 betrachtet. Dabei werden die in der organischen Phase gebildeten Komplexe durch vielseitige moderne, analytische Methoden (NMR, FTIR, Raman, MS) charakterisiert und diskutiert. Ein besseres Verständnis für diese bisher unzureichend untersuchten Extraktionssysteme ist ebenso hinsichtlich des Auftretens dritter Phasen hilfreich. In Kombination mit den optimierten technischen Parametern zur selektiven Abtrennung und Anreicherung des Molybdäns erfolgt eine Übertragung in einen kontinuierlich geführten Prozess.
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Lecture (Conference)
Jahrestreffen der ProcessNet Fachgruppen Extraktion, Phytoextrakte und Membrantechnik, 23.-24.05.2022, Frankfurt, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36302
Synthetic few-cycle shadowgraphy diagnostics in particle-in-cell codes for characterizing laser-plasma accelerators
Abstract
This work describes the in-situ CTR plugin for the particle-in-cell code PIConGPU. The C++ -plugin calculates coherent transition radiation (CTR) from millions to billions of macro-particles in a PIConGPU plasma simulation. In order to avoid excessive disk output of many GB to TB of data, as well as and extensive post-processing runtimes on only few CPUs, the plugin was parallelized on GPUs and implemented in-situ as part of PIConGPU.
The physics of this plugins was successfully implemented, tested and verified to agree with an initial python implementation, which again was verified using analytical CTR theory, with an average error of less than 1 %. Additionally the plugin was benchmarked, resulting in typical time to solutions for complete transition radiation spectra on the scale of several minutes.
The CTR plugin was then used in several Laser-wakefield accelerator (LWFA) simulations, with self-injected and down-ramp injected electrons respectively. Mimicking the hypothetical placement of successive transition radiaton foils along the LWFA interaction length, the CTR plugin was used multiple times for observing how the electron bunch evolution leads to the characteristic features of transition radiation spectra.
This new tool is a synthetic diagnostic, which enables direct comparison of experi- mentally measured transition radiation data to simulations. In future experiments this can provide insight into LWFA longitudinal electron pulse profiles on the fs-scale, required for future compact LWFA-driven free-electron laser applications.
Keywords: Shadowgraphy; Synthetic Diagnostics; In-Situ Plugin; PIConGPU; Laser-Electron Acceleration
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Master thesis
TU Dresden, 2022
Mentor: U. Schramm
90 Seiten
DOI: 10.5281/zenodo.7755263
Permalink: https://www.hzdr.de/publications/Publ-36301
Synthetic shadowgrams of laser-plasma accelerators computed by a PIConGPU in-situ plugin
Carstens, F.-O.; Steiniger, K.; Pausch, R.; Chang, Y.-Y.; Schöbel, S.; Couperus Cabadağ, J. P.; Irman, A.; Lehmann, M.; Widera, R.; Bussmann, M.; Schramm, U.; Cowan, T.; Debus, A.
Abstract
Few-cycle shadowgraphy is a valuable diagnostic for laser-plasma accelerators to obtain insight into the µm- and fs-scale relativistic plasma dynamics. To enhance the understanding of experimental shadowgrams we developed a synthetic shadowgram diagnostic within the fully relativistic particle-in-cell code PIConGPU.
In an initial version of the synthetic shadowgraphy diagnostic, the probe laser is propagated through the plasma using PIConGPU, and then extracted and propagated onto a virtual CCD using a post-processing code based on Fourier optics. However, the latter step requires 3D-FFTs, which results in performance and scaling limitations in large-scale simulations. To circumvent this, we develop an in-situ plugin for PIConGPU, in which we extract the probe laser slice-wise to obtain the synthetic shadowgrams during the simulation without post-processing.
In this talk, we present the development of the PIConGPU plugin and show preliminary results of synthetic shadowgrams for laser and plasma wakefield accelerators.
Keywords: Shadowgraphy; Synthetic Diagnostics; PIConGPU; Laser-Electron Acceleration
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Lecture (Conference)
(Online presentation)
Virtuelle DPG-Frühjahrstagung, 28.03.-01.04.2022, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36299
Dissipation losses limiting first-order phase transition materials in cryogenic caloric cooling: A case study on all-d-metal Ni(-Co)-Mn-Ti Heusler alloys
Beckmann, B.; Koch, D.; Pfeuffer, L.; Gottschall, T.; Taubel, A.; Adabifiroozjaei, E.; Miroshkina, O. N.; Riegg, S.; Niehoff, T.; Kani, N. A.; Gruner, M. E.; Molina-Luna, L.; Skokov, K. P.; Gutfleisch, O.
Abstract
Ni-Mn-based Heusler alloys, in particular all-d-metal Ni(-Co)-Mn-Ti, are highly promising materials for energy-efficient solid-state refrigeration as large multicaloric effects can be achieved across their magnetostructural martensitic transformation. However, no comprehensive study on the crucially important transition entropy change Δs exists so far for Ni(-Co)-Mn-Ti. Here, we present a systematic study analyzing the composition and temperature dependence of Δst. Our results reveal a substantial structural entropy change contribution of approximately 65 J(kgK)-1, which is compensated at lower temperatures by an increasingly negative entropy change associated with the magnetic subsystem. This leads to compensation temperatures Tcomp of 75 K and 300 K in Ni35Co15Mn50-yTiy and Ni33Co17Mn50-yTiy, respectively, below which the martensitic transformations are arrested. In addition, we simultaneously measured the responses of the magnetic, structural and electronic subsystems to the temperature- and field-induced martensitic transformation near Tcomp, showing an abnormal increase of hysteresis and consequently dissipation energy at cryogenic temperatures. Simultaneous measurements of magnetization and adiabatic temperature change ΔTad in pulsed magnetic fields reveal a change in sign of ΔTad and a substantial positive and irreversible ΔTad up to 15 K at 15 K as a consequence of increased dissipation losses and decreased heat capacity. Most importantly, this phenomenon is universal, it applies to any first-order material with non-negligible hysteresis and any stimulus, effectively limiting the utilization of their caloric effects for gas liquefaction at cryogenic temperatures.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Acta Materialia 246(2023), 118695
DOI: 10.1016/j.actamat.2023.118695
arXiv: arXiv:2301.03934
Cited 13 times in Scopus
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36298
Bentonite and concrete: Efficient barrier materials for actinide retention under hyperalkaline conditions at increased ionic strengths and in presence of organics
Schmeide, K.; Philipp, T.; Huittinen, N. M.; Sieber, C.; Kretzschmar, J.
Abstract
The safe disposal of radioactive waste from operation and decommissioning of nuclear power plants in geological repositories requires the application of multiple barriers to isolate the waste from the biosphere. Bentonite and cementitious materials are foreseen as buffer and borehole sealing material or for stabilization purposes. Pore waters of the North German clay deposits are characterized by high ionic strengths up to 4 M [1,2]. The contact of such saline formation waters with concrete will result in an enhanced corrosion of concrete and to the evolution of highly alkaline cement pore waters (10 < pH < 13), which in turn, can react with the bentonite buffer as well as with the clay host rock, changing their retention potential towards radionuclides. Moreover, the role of organics (as admixtures in cement-based materials or waste constituents [3]) on actinide retention has to be studied.
The U(VI) retention on Ca-bentonite in mixed electrolyte solutions (‘diluted Gipshut solution’, I = 2.6 M) was found to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species [4]. By means of luminescence and X-ray absorption spectroscopy, the U(VI) speciation could be clarified. A substantial contribution of calcium (aluminum) silicate hydrates (C-(A-)S-H), formed as secondary phases in the presence of Ca due to partial dissolution of alumosilicates at hyperalkaline conditions, to the retention of anionic actinide species in clayey systems was shown [5]. Citrate and 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC) were found to reduce U(VI) retention only when present at high concentrations.
The U(VI) and Eu(III)/Cm(III) retention by C-A-S-H, formed due to Al-rich additives in cement formulations, was studied applying samples with Ca/Si molar ratios of 0.8, 1.2 and 1.6, representing different alteration stages of concrete, and with increasing Al/Si molar ratios of 0, 0.06 and 0.18 in each series. Furthermore, the impact of temperature (25°C, 100°C, 200°C) on both the C-A-S-H structure and the actinide retention mechanism was studied. Solid-state 27Al and 29Si NMR spectroscopy along with XRD revealed that enhanced temperatures increase the crystallinity of the material with the appearance of neoformed crystalline phases. Surface-sorbed, interlayer-sorbed or incorporated actinide species were detected by luminescence spectroscopy. Actinide mobilization due to high ionic strengths or presence of organics (gluconate, PBTC or nitrilotriacetate (NTA)) was very low [6,7].
The results show that both bentonite and cementitious material constitute an important retention barrier for actinides under hyperalkaline conditions at increased ionic strengths and in presence of organics.
Keywords: bentonite; cement; concrete; uranium; organics; ionic strength
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 36297) publication
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Contribution to proceedings
EGU General Assembly 2023, 23.-28.04.2023, Vienna, Austria -
Lecture (Conference)
EGU General Assembly 2023, 23.-28.04.2023, Vienna, Austria
Permalink: https://www.hzdr.de/publications/Publ-36297
From laser-plasma accelerator experiments to digital twins
Abstract
Building high-fidelity digital twins through start-to-end models to better understand and control advanced laser-plasma accelerators, as well as compact free-electron laser beamlines, requires direct comparison to experimental data. We highlight recent results in start-to-end simulations and developments with a focus on their connection to experiment, such as by synthetic diagnostics and experimental data reconstruction analyses.
Keywords: digital twins; machine learning; laser-plasma accelerators; free-electron laser
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Invited lecture (Conferences)
8. Annual MT meeting, 26.-27.9.2022, DESY, Hamburg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36296
PIConGPU: Getting Particle-in-cell Plasma Simulations Ready for Exascale
Debus, A.; Widera, R.; Lebedev, A.; Bastrakov, S.; Pausch, R.; Steiniger, K.; Pöschel, F.; Stephan, J.; Bussmann, M.
Abstract
No official abstract here. We present an overview talk on laser-particle acceleration research with the challenges of modeling laser-plasma interactions using PIConGPU on latest exascale machines (JUWELS BOOSTER, Perlmutter,Summit and early-access systems for Frontier).We show the softwarestack of the particle-in-cell code PIConGPU (alpaka,openPMD, ...) with an emphasis on performance-portability and I/O at exascale. Furthermore we showed in an example how detailed performance benchmarking and profiling (together with JSC) helped improving code performance.
Keywords: particle-in-cell code; PIConGPU
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Invited lecture (Conferences)
(Online presentation)
10 Year Anniversary Workshop of NVIDIA Application Lab at Jülich, 21.-22.6.2022, Jülich, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36295
Traveling-wave electron accelerators -- Getting PIConGPU simulations ready for exascale
Debus, A.; Chandrasekaran, S.; Steiniger, K.; Widera, R.; Bastrakov, S.; Meyer, F.; Pausch, R.; Garten, M.; Kluge, T.; Kelling, J.; Hernandez Arreguin, B.; Leinhauser, M.; Young, J.; Pöschel, F.; Hübl, A.; Rogers, D.; Juckeland, G.; Bussmann, M.
Abstract
Traveling-wave electron acceleration (TWEAC) is an advanced laser-plasma accelerators scheme, which is neither limited by dephasing, nor by pump depletion or diffraction. Such accelerators are scalable to energies beyond 10 GeV without the need for staging and are candidates for future compact electron-positron colliders.
TWEAC simulations to high energies require exascale compute resources. Within the early-access program (CAAR) for the upcoming exascale Frontier cluster at ORNL, we prepare PIConGPU, a 3D3V particle-in-cell code, for large-scale TWEAC simulations, including tuning and refining PIConGPU to run on the latest AMD GPUs. In this talk we present progress in TWEAC simulations and the technical advances in PIConGPU that enable running on Frontier.
Keywords: Traveling-wave electron acceleration; TWEAC; exascale; Laser-plasma accelerator; PIConGPU; particle-in-cell code
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Lecture (Conference)
(Online presentation)
Virtuelle DPG-Frühjahrstagung in "Mainz" 2022, 28.03.-01.04.2022, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36294
Ab initio modelling of magnetite surfaces for plutonium retention
Katheras, A. S.; Karalis, K.; Krack, M.; Scheinost, A.; Churakov, S. V.
Abstract
In many European countries (e.g., Switzerland, France, Sweden), thick steel casks are foreseen for the containment of high-level radioactive waste in deep geological repositories. In contact with pore-water, steel corrodes forming mixed iron oxides, mainly magnetite at the surface (Fe3O4). After tens of thousands of years, casks may breach allowing for leaching of the radionuclides by pore-water. Magnetite can retard dissolved radionuclides either by adsorption or structural incorporation [1,2]. But since these interaction mechanisms are poorly understood at the atomistic scale, our goal is to better understand them by using computer simulations alongside experiments [3].
In this computational study, we identified the dominant low-index surfaces of magnetite particles and their termination at the relevant conditions based on Kohn-Sham density functional theory (DFT). This was done using the open-source code CP2K. The DFT+U method was employed for the strongly correlated 3d and 5f electrons of Fe and Pu, respectively. After revising our model and determining the Hubbard U parameter [4], we examined the preferential magnetite crystal orientation plane (111) allowing for different surface terminations, water coverage and redox conditions. Comparing the surface energy, the most stable surface can be deduced and we found the most stable magnetite (111) surfaces under real repository conditions. Subsequently, we used ab initio molecular dynamics (MD) to simulate sorption structures on the expected magnetite (111) surfaces.
[1] T. Dumas et al. (2019). Plutonium Retention Mechanisms by Magnetite under Anoxic Conditions: Entrapment versus Sorption. ACS Earth & Space Chemistry, 2019, 3(10), 2197.
[2] R. Kirsch et al. (2011). Oxidation State and Local Structure of Plutonium Reacted with Magnetite, Mackinawite, and Chukanovite. Environmental Science & Technology, 2011, 45(17), 7267.
[3] E. Yalçintaş et al. (2016). Systematic XAS study on the reduction and uptake of Tc by magnetite and mackinawite. Dalton Transactions, 2016, 45(44), 17874.
[4] A. Kéri et al. (2017). Combines XAFS Spectroscopy and Ab Inito Study on the Characterization of Iron Incorporation in Motmorillonite. Environmental Science & Technology, 51(18), 10585.
Keywords: DFT; Magnetite; Pu
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 36293) publication
-
Lecture (Conference)
BMBF AcE Methods, 20.-22.03.2023, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-36293
Influence of Underlayer Quality and Sputter Gas Pressure on Structural and Magnetic Properties of Co/Pt Multilayers
Ehrler, R.; Uhlig, T.; Hellwig, O.
Abstract
Influence of Underlayer Quality and Sputter Gas Pressure on Structural and Magnetic Properties of Co/Pt Multilayers
-
Lecture (Conference)
AVS 68th International Symposium & Exhibition, 07.-11.11.2022, Pittsburgh, USA
Permalink: https://www.hzdr.de/publications/Publ-36292
Exploring Magnetic Reversal Behavior and Domain Structure in Perpendicular Anisotropy Layered Synthetic Antiferromagnets
Abstract
Exploring Magnetic Reversal Behavior and Domain Structure in Perpendicular Anisotropy Layered Synthetic Antiferromagnets
-
Lecture (Conference)
AVS 68th International Symposium & Exhibition, 07.-11.11.2022, Pittsburgh, USA
Permalink: https://www.hzdr.de/publications/Publ-36291
Designing Antiferromagnetic Domain Landscapes via Focused Ion Beam Irradiation
Samad, F.; Hlawacek, G.; Koch, L.; Hellwig, O.; Xu, X.
Abstract
Designing
Antiferromagnetic Domain Landscapes
via
Focussed Ion Beam Irradiation
-
Lecture (Conference)
AVS 68th International Symposium & Exhibition, 09.11.2022, Pittsburgh, USA
Permalink: https://www.hzdr.de/publications/Publ-36290
Plasma shutter for ion acceleration and spiral pulse generation
Matys, M.; Klimo, O.; Jirka, M.; Proska, J.; Kucharik, M.; Nikl, J.; Kecova, M.; Psikal, J.; Korn, G.; Mima, K.; Jeong, T. M.; Bulanov, S. V.
Abstract
The plasma shutter is a thin solid foil (or series of them) placed in front of the main target irradiated by high intense laser. It can mitigate the prepulse and also shape the main pulse, resulting in the generation of a steep-rising front and local intensity increase of the pulse. We study the application of the shutter for ion acceleration via 3D PIC simulations assuming Si₃N₄ plasma shutter, ultrathin silver target and a PW-class laser. The application of shutter results in increase of maximal ion energy for both linear and circular polarizations. It also significantly reduces the beam divergence for the linear polarization. In the case of circular polarization, the transmitted laser pulse obtains a spiral-like intensity profile. The structure is transferred into the electron density profile of the shutter and the main target behind it. The use of a double-shutter is studied via a combination of 2D PIC and hydrodynamic simulations assuming the laser pulse accompanied by a sub-ns prepulse. We present a prototype of the double-shutter and the design of the whole shutter-target setup. The generated steep-front has also positive effect on different scenario with low-Z double-layer targets. The 3D shutter simulation is also represented via an interactive Virtual Reality visualization.
-
Lecture (Conference)
Laser and Plasma Accelerators Workshop 2023, 06.-10.03.2023, Lagos, República Portuguesa
Permalink: https://www.hzdr.de/publications/Publ-36289
Positrons in Material Sciences: Intense Beams for Defect Characterizations and Porosimetry
Abstract
The Helmholtz-Center Dresden - Rossendorf operates a superconducting electron linear accelerator as a driver for secondary radiation sources, which include two IR-FEL, a broadband high-field THz radiation source, high-energy X-rays, neutrons and positrons. The accelerator runs in continuous-wave (CW) mode and in a 24/7 regime serving an international user community.
Electron-bremsstrahlung is being converted into an intense beam of positrons by means of pair production. After moderation to thermal energies, positrons are re-accelerated to form a mono-energetic positron beam with variable kinetic energies ranging from 0.5 to 18 keV for depth profiling of atomic defects and porosities on nm-scales in thin films. High timing resolutions ( < 100 ps) at high average rates (105 s-1) and adjustable beam repetition rates allow performing high-throughput experiments of positron annihilation lifetimes.
The accelerator-based positron source is complemented by a several radioisotope-driven setups for conventional annihilation lifetime measurements (defect characterizations) and Doppler-broadening spectroscopy, which is sensitive to the defect’s chemical surroundings.
In my presentation, I will highlight some of the unique features of the experimental facilities and I will show various experimental results obtained with positrons in defect characterizations of materials and porosimetry due to their sensitivity on open-volume defects ranging from sub-nm to µm scales.
Keywords: material sciences; positron; positron annihilation spectroscopy; positron lifetime spectroscopy
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- P-ELBE
- γ-ELBE DOI: 10.58065/24020
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 36287) publication
- DOI: 10.58065/24020 is cited by this (Id 36287) publication
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Invited lecture (Conferences)
Department seminar, 12.01.2023, Bowling Green, Ohio, USA -
Invited lecture (Conferences)
Materials Science Laboratory Seminar, 19.01.2023, Los Alamos, New Mexico, USA
Permalink: https://www.hzdr.de/publications/Publ-36287
Out-of-field measurements and simulations of a proton pencil beam in a wide range of dose rates using a Timepix3 detector: Dose rate, flux and LET
Oancea, C.; Granja, C.; Marek, L.; Jakubek, J.; Solc, J.; Bodenstein, E.; Gantz, S.; Pawelke, J.; Pivec, J.
Abstract
Stray radiation produced by ultra-high dose-rates (UHDR) proton pencil beams is characterized using ASIC-chip semiconductor pixel detectors. A proton pencil beam with an energy of 220 MeV was utilized to deliver dose rates (DR) ranging from conventional radiotherapy DRs up to 270 Gy/s. A MiniPIX Timepix3 detector equipped with a silicon sensor and integrated readout electronics was used. The chip-sensor assembly and chipboard on water-equivalent backing were detached and immersed in the water-phantom. The deposited energy, particle flux, DR, and the linear energy transfer (LET(Si)) spectra were measured in the silicon sensor at different positions both laterally, at different depths, and behind the Bragg peak. At low-intensity beams, the detector is operated in the event-by-event data-driven mode for high-resolution spectral tracking of individual particles. This technique provides precise energy loss response and LET(Si) spectra with radiation field composition resolving power. At higher beam intensities a rescaling of LET(Si) can be performed as the distribution of the LET (Si) spectra exhibits the same characteristics regardless of the delivered DR. The integrated deposited energy and the absorbed dose can be thus measured in a wide range. A linear response of measured absorbed dose was obtained by gradually increasing the delivered DR to reach UHDR beams. Particle tracking of scattered radiation in data-driven mode could be performed at DRs up to 0.27 Gy/s. In integrated mode, the saturation limits were not reached at the measured out-of-field locations up to the delivered DR of over 270 Gy/s. A good agreement was found between measured and simulated absorbed doses.
Keywords: Out-of-field proton therapy; Timepix3; Particle tracking; LET(Si) spectra; UHDpulse; Flash radiotherapy
Involved research facilities
- OncoRay
-
Physica Medica, European Journal of Medical Physics 106(2023), 102529
DOI: 10.1016/j.ejmp.2023.102529
Cited 11 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36286
Spectral-temporal Measurement Capabilities of Third-order Correlators
Bock, S.; Oksenhendler, T.; Püschel, T.; Gebhardt, R.; Helbig, U.; Pausch, R.; Ziegler, T.; Bernert, C.; Zeil, K.; Irman, A.; Toncian, T.; Kiriyama, H.; Nishiuchi, M.; Kon, A.; Schramm, U.
Abstract
We present a method extending scanning third-order correlator temporal pulse14
evolution measurement capabilities of high power short pulse lasers to spectral sensitivity within15
the spectral range exploited by typical chirped pulse amplification systems. Modelling of the16
spectral response achieved by angle tuning of the third harmonic generating crystal is applied17
and experimentally validated. Exemplary measurements of spectrally resolved pulse contrast of a18
Petawatt laser frontend illustrate the importance of full bandwidth coverage for the interpretation19
of relativistic laser target interaction in particular for the case of solid targets.
Involved research facilities
- Draco
-
Optics Express 31(2023)6, 9923-9934
DOI: 10.1364/opticaopen.21922056
Permalink: https://www.hzdr.de/publications/Publ-36285
Non-linearity induced contrast degradation in high-power lasers
Bock, S.; Oksenhendler, T.; Püschel, T.; Gebhardt, R.; Helbig, U.; Ziegler, T.; Zeil, K.; Pausch, R.; Toncian, T.; Nishiuchi, M.; Kiriyama, H.; Schramm, U.
Abstract
The characteristics of high power lasers applied for relativistic plasma experiments are a matter of constant research and improvement for supporting highest possible performance. Especially the temporal contrast is crucial, while different mechanisms can lead to its degradation. One prominent effect is the non-linear B-integral induced pulse coupling from a post pulse generating a pre-pulse, generally described by Didenko, et.al. [1]. Recent measurements showed a more complex behavior with delayed pre-pulse generation and complex temporal shapes [2]. We applied an improved SRSI-ETE [3] setup to measure the non-linear pulse coupling at the DRACO Petawatt facility [4], revealing the spectral-temporal structure of the generated pulses. To assist the understanding of the observed non-linear effects a model was developed [5], covering the principle B-integral induced pulse generation, as well as the generation of the additional pulse structures, by means of non-resonant and resonant non-linear optical effects. The performed study allows a full understanding of the non-linear processes generating the pre-pulse and subsequent structures.
Involved research facilities
- Draco
-
Lecture (Conference)
ICUIL 2022, 19.-23.09.2022, Jeju Island, Korea
Permalink: https://www.hzdr.de/publications/Publ-36284
High-content multi-spectral fluorescence microscopy sample preparation artefacts
Abstract
Sample preparation artefacts represent a significant source of errors in high-content screening datasets leading to misinterpretation of results in drug discovery. To address this we have created a multispectral high-content imaging dataset with typical sample preparation artefacts added to the samples. This dataset consists of high-content images of cultured HeLa ATCC cells in the presence of typical sample preparation artefacts. The aim of this dataset. HeLa cells imaged in this dataset were cultured in a black 96-well (rows A to H and columns 1 to 12) polystyrene imaging plate (Corning, Sigma).
To obtain a dataset similar to the experimental setup of a high-content image-based screening we have used a 96-well (rows A to H and columns 1 to 12) black polystyrene imaging plate (Corning, Sigma). HeLa cells were seeded a day prior to the experiment in 200 µL volume (per well) containing 250000 cells per mL in Dulbecco’s Modified Eagle’s Medium (Sigma) containing 10% fetal calf serum (Sigma) 4500 mg/L glucose (Sigma), sodium bicarbonate (Sigma), L-glutamine (Sigma), sodium pyruvate (Sigma), and non-essential amino acids (Sigma). To obtain a gradient of cell density, the cell suspension was stepwise diluted at 1:2 ratio during seeding (columns 2 to 12). The first column was reserved as no-cells control. Upon seeding, the HeLa cells were incubated overnight at 37° C in a 5% CO2 atmosphere with humidity control. The next day after seeding, cells were fixed with 4% paraformaldehyde (Sigma) solution prepared in phosphate buffer saline (PBS, Sigma). Upon fixation, HeLa cell nuclei were stained with Hoechst 33342 dye (Sigma) at 40 µg/mL concentration prepared in PBS. Row A was kept unstained as the control without Hoechst dye. Upon preparation of the bona fide artefact-free experimental plate, we have collected samples of dust across the approximately 100 m2 laboratory and prepared a suspension of these dust samples in PBS. Next, we added this suspension to rows A to G of the 96-well plate, leaving row H as an artefact-free control.
The dataset consists of images obtained with 4x and 10x objectives using fluorescence cube assemblies for DAPI, CFP, GFP, TRITC and Cy5 channels. For hardware reasons, images with the CFP filter cube were obtained separately from images with DAPI, CFP, GFP, TRITC and Cy5 filter cubes. Furthermore, CFP images (and in some cases DAPI images) were obtained with varying exposure times corresponding to “_w1”, “_w2” and so on filename suffixes. Images were obtained using ImageXpress Micro XL high-content microscope (Molecular Devices). Images are organised into the following folders:
-
4x-cfp
-
4x-dapi-gfp-tritc-cy5
-
10x-6cfp
-
10x-6dapi
-
10x-cfp
-
dapi-gfp-tritc-cy5
-
filters_spectra
Here, folders A and B correspond to 4x magnification and contain images obtained with the CFP (folder A) and the other filter cubes respectively (folder B). Each folder contains “TimePoint_1” subfolder containing the raw images. In the case of 4x images, each field of view (“site” designed with “_s1”, “_s2” etc. suffixes) corresponds to a nearly perfect quarter of a 96-well plate well. In addition to the raw images in the “TimePoint_1”, a subfolder “Stitched” contains images of the entire wells. In the case of folder B containing all other fluorescence channels, “_w1”, “_w2”, “_w3”, and “_w4” correspond to a single optimal exposure time of DAPI, GFP, TRITC and Cy5 filters respectively.
Similarly, folders C - F correspond to 10x magnification and contain images of multiple exposures of CFP and DAPI (folders C and D) and single exposures of CFP and other channels (folders E and F). In the case of CFP and DAPI multiple exposures folders, varying exposure times correspond to “_w1”, “_w2” etc. Finally, folder G contains metadata on filter cubes used in the dataset, including the emission and excitation filters spectra for each filter cube.
Keywords: fluorescence microscopy; high-content microscopy; sample preparation artefacts
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-01-16 Open access
DOI: 10.14278/rodare.1435
Versions: 10.14278/rodare.2442 | 1436
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36282
Catalytic Activity of Defect-Engineered Transition Metal Dichalcogenides Mapped with Atomic Scale Precision by Electrochemical Scanning Tunneling Microscopy
Lunardon, M.; Kosmala, T.; Ghorbani Asl, M.; Krasheninnikov, A.; Kolekar, S.; Durante, C.; Batzill, M.; Agnoli, S.; Granozzi, G.
Abstract
Unraveling structure–activity relationships is a key objective of catalysis. Unfortunately, the intrinsic complexity and structural heterogeneity of materials stand in the way of this goal, mainly because the activity measurements are area-averaged and therefore contain information coming from different surface sites. This limitation can be surpassed by the analysis of the noise in the current of electrochemical scanning tunneling microscopy (EC-STM). Herein, we apply this strategy to investigate the catalytic activity toward the hydrogen evolution reaction of monolayer films of MoSe₂. Thanks to atomically resolved potentiodynamic experiments, we can evaluate individually the catalytic activity of the MoSe₂ basal plane, selenium vacancies, and different point defects produced by the intersections of metallic twin boundaries. The activity trend deduced by EC-STM is independently confirmed by density functional theory calculations, which also indicate that, on the metallic twin boundary crossings, the hydrogen adsorption energy is almost thermoneutral. The micro- and macroscopic measurements are combined to extract the turnover frequency of different sites, obtaining for the most active ones a value of 30 s⁻¹ at −136 mV vs RHE.
Keywords: green hydrogen; two-dimensional materials; transition metal dichalcogenides; catalyst; hydrogen evolution reaction; defect; scanning tunneling microscopy
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36281) publication
-
ACS Energy Letters 8(2023), 972-980
DOI: 10.1021/acsenergylett.2c02599
Cited 15 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36281
Generalized Gelfand-Dikii equation for fermionic Schwinger pair production
Ahmadiniaz, N.; Pyo Kim, S.; Schubert, C.
Abstract
Generalized Gelfand-Dikii equation for fermionic Schwinger pair production
Keywords: Schwinger pair production; Gelfand-Dikii equation
-
Contribution to proceedings
29th annual International Laser Physics Workshop (LPHYS'21), 19.-23.07.2022, virtual, virtual
Journal of Physics: Conference Series 2249 (2022), 012020
DOI: 10.1088/1742-6596/2249/1/012020
arXiv: https://arxiv.org/pdf/2205.15945.pdf
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36280
Generalized Gelfand-Dikii equation and solitonic electric fields for fermionic Schwinger pair production
Ahmadiniaz, N.; Fedotov, A. M.; Gelfer, E. G.; Pyo Kim, S.; Schubert, C.
Abstract
Schwinger pair creation in a purely time-dependent electric field can be reduced to an effective quantum mechanical problem using a variety of formalisms. Here we develop an approach based on the Gelfand-Dikii equation for scalar QED, and extent it to spinor QED. We discuss some solvable special cases from this point of view. It was previously shown how to use the well-known solitonic solutions of the KdV equation to construct “solitonic” electric fields that do not create scalar pairs with an arbitrary fixed momentum. We show that this construction can be adapted to the fermionic case in two inequivalent ways, both leading to the vanishing of the pair-creation rate at certain values of the P ̈oschl-Teller like index of the associated Schr ̈odinger equation. Thus for any given momentum, we can construct electric fields that create scalar particles but not spinor particles, and also the other way round. Therefore, while often spin is even neglected in Schwingerpair creation, in such cases it becomes decisive.
Keywords: Schwinger mechanism; Pair production; Gelfand-Dikii equation
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Contribution to WWW
2205.159 [hep-th]: https://arxiv.org/pdf/2205.15946.pdf
arXiv: https://arxiv.org/pdf/2205.15946.pdf -
Physical Review D 108(2023)3, 036019
DOI: 10.1103/PhysRevD.108.036019
Cited 1 times in Scopus
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36279
Precision Storage Rings for Electric Dipole Moment Searches: A Tool En Route to Physics Beyond-the-Standard-Model
Ströher, H.; Schmidt, S. M.; Lenisa, P.; Pretz, J.
Abstract
Electric Dipole Moments (EDM) of particles (leptons, nucleons and light nuclei) are currently deemed one of the best indicators for new physics, i.e. phenomena, which lie outside the Stand-ard Model (SM) of elementary particle physics – so called physics “Beyond-the-Standard-Model” (BSM). Since EDMs of the SM are vanishingly small, a finite permanent EDM would indicate charge-parity symmetry (CP-) violation in addition to the well-known sources of the SM and could explain the baryon asymmetry of the Universe, while an oscillating EDM would hint at a possible Dark Matter (DM) field comprising axions or axion-like particles (ALPs). A new ap-proach exploiting polarized charged particles (proton, deuteron, 3He) in precision storage rings offers the prospect to push current experimental EDM upper limits significantly further includ-ing the possibility of an EDM discovery. In this paper, we describe the scientific background and the steps towards the realization of a precision storage ring, which will make such measure-ments possible.
Keywords: Baryon Asymmetry; Dark Matter; Electric Dipole Moments; Storage Rings; Polarized Beams
-
Particles 6(2023)1, 385-398
DOI: 10.3390/particles6010020
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36278
Summing Feynman diagrams in the worldline formalism
Ahmadiniaz, N.; Edwards, J. P.; Lopez-Arcos, C.; Lopez-Lopez, M. A.; Moctezuma Mata, C.; Nicasio, J.; Schubert, C.
Abstract
The worldline formalism shares with string theory the property that it allows one to write down master integrals that effectively combine the contributions of many Feynman diagrams. While at the one-loop level, these diagrams differ only by the position of the external legs along a fixed line or loop, at multiloop they generally involve different topologies. Here we summarize various efforts that have been made over the years to exploit this property in a computationally meaningful way. As a first example, we show how to generalize the Landau-Khalatnikov-Fradkin formula for the non-perturbative gauge transformation of the fermion propagator in QED to the general2𝑛- point case by pure manipulations at the path-integral level. At the parameter-integral level, we show how to integrate out individual photons in the low-energy expansion and then sketch a recently introduced general framework for the analytical evaluation of such worldline integrals involving a reduction to quantum mechanics on the circle and the relation between inverse derivatives and Bernoulli polynomials
Keywords: Woldline formalism; Feynman diagrams; QED
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Contribution to proceedings
Loops and Legs in Quantum Field Theory - LL2022, 25.-30.04.2022, Ettal, Germany
Proceedings of Science (LL2022), 052
DOI: 10.22323/1.416.0052
arXiv: https://arxiv.org/pdf/2208.06585.pdf
Permalink: https://www.hzdr.de/publications/Publ-36277
Spin-wave study of magnetic perpendicular surface anisotropy in single crystalline MgO/Fe/MgO films
Solano, J.; Gladii, O.; Kuntz, P.; Henry, Y.; Halley, D.; Bailleul, M.
Abstract
Broadband ferromagnetic resonance is measured in single crystalline Fe films of varying thickness sandwiched between
MgO layers. An exhaustive magnetic characterization of the films (exchange constant, cubic, uniaxial and surface
anisotropies) is enabled by the study of the uniform and the first perpendicular standing spin wave modes as a function of
applied magnetic field and film thickness. Additional measurements of nonreciprocal spin-wave propagation allow us to
separate each of the two interface contributions to the total surface anisotropy. The results are consistent with the model of a
quasi-bulk film interior and two magnetically different top and bottom interfaces, a difference ascribed to different oxidation
states
Keywords: Interface states; spin wave; Magnetic anisotropy; Broadband ferromagnetic resonance
-
Physical Review Materials 6(2022), 124409
DOI: 10.1103/PhysRevMaterials.6.124409
Cited 6 times in Scopus
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Permalink: https://www.hzdr.de/publications/Publ-36276
Coupled thermo-fluid-mechanical FEM simulations for thermoelastic harvesting of low-grade waste heat
Neumann, B.; Eckert, K.; Fähler, S.
Abstract
COMSOL-Multiphysics file for the FEM-Simulations of the paper. The attached version was used to generate plot data. The extracted plot data is attached as well.
Keywords: Energy; FEM; Thermoelastic Energy Harvesting; Simulation
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Reseach data in the HZDR data repository RODARE
Publication date: 2022-10-28 Open access
DOI: 10.14278/rodare.2089
Versions: 10.14278/rodare.2090
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36275
Field-assisted birefringent Compton scattering
Ahmadiniaz, N.; Cowan, T.; Ding, M.; Lopez Lopez, M. A.; Sauerbrey, R.; Shaisultanov, R.; Schützhold, R.
Abstract
Motivated by experimental initiatives such as the Helmholtz International Beamline for ExtremeFields (HIBEF), we study Compton scattering of x-rays at electrons in a strong external field (e.g., a strong optical laser) with special emphasis on the polarization-changing (i.e., birefringent) contribution on the amplitude level. Apart from being a potential background process for the planned vacuum birefringence experiments, this effect could be used for diagnostic purposes. Since the birefringent signal from free electrons (i.e., without the external field) vanishes in forward direction, the ratio of the birefringent and the normal (polarization conserving) contribution yields information about the field strength at the interaction point.
Keywords: Vacuum birefringent; Compton scattering; HIBEF
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Contribution to WWW
https://arxiv.org/pdf/2212.03350.pdf
arXiv: https://arxiv.org/pdf/2212.03350.pdf
Permalink: https://www.hzdr.de/publications/Publ-36274
Approaches to HERFD XANES calculations of U M4 edge
Amidani, L.; E. Silva, C. L.; Kvashnina, K.
Abstract
The M4 edge XANES of actindies acquired in the High-Energy-Resolution Fluorescence Detected (HERFD) mode is very powerful since it porbes directly the 5f manifold with sufficient resolution to resolve the relevant spectral features. Theoretical calculations of such spectra are then fundamental for a correct interpretation and to guide the insight into actinides electronic structure.
We recently explored the use of a DFT-based code for X-ray spectroscopies, i.e. FDMNES,1 to calculate the M4 edge HERFD XANES of U6+ systems.2 The DFT approach is suitable to calculate closed-shell systems and our results are in good agreement with the experimental data. Our findings reveal the high sensitivity of the M4 edge to the local environment of the An ion and the suitability of the DFT approach to reproduce closed-shell systems. In particular, we were able to reproduce the spectral variations observed in 4 different U6+ systems with a local geometry from uranate to uranyl. We are currently expanding our investigation to open-shell systems, in particular to U(III) halides. For this case we are using atomic multiplet theory3 and investigating how scaling of atomic parameters affects the spectra in order to reproduce the effects observed.
We will present the results from both approaches, discuss the assignment of spectral features as emerging from the analysis of the projected density of states (DOS), underline the critical points that suggest further developments in the calculation approach.
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Lecture (Conference)
2nd International Workshop on Theory Frontiers in Actinide Science: Chemistry & Materials, 26.02.-01.03.2023, Santa Fe, California, USA
Permalink: https://www.hzdr.de/publications/Publ-36272
Solid-Phase Parallel Synthesis of Dual Histone Deacetylase-Cyclooxygenase Inhibitors
Bachmann, L. M.; Hanl, M.; Feller, F.; Sinatra, L.; Schöler, A.; Pietzsch, J.; Laube, M.; Hansen, F. K.
Abstract
Multi-target drugs (MTDs) are emerging alternatives to combination therapies. Since both his-tone deacetylases (HDACs) and cyclooxygenase-2 (COX-2) are known to be overexpressed in several cancer types, we herein report the design, synthesis, and biological evaluation of a li-brary of dual HDAC-COX inhibitors. The designed compounds were synthesized via an efficient parallel synthesis approach using preloaded solid-phase resins. Biological in vitro assays demon-strated that several of the synthesized compounds possess pronounced inhibitory activities against HDAC and COX isoforms. The membrane permeability and inhibition of cellular HDAC activity of selected compounds were confirmed by whole-cell HDAC inhibition assays and western blot experiments. The most promising dual inhibitors C3 and C4 evoked antiprolifera-tive effects in the low micromolar concentration range and caused a significant increase in apoptotic cells. In contrast to previous reports, the simultaneous inhibition of HDAC and COX activity by dual HDAC-COX inhibitors or combination treatment with vorinostat and celecoxib did not result in additive or synergistic anticancer activities.
Keywords: COX; HDAC; multi-target drugs; cancer; solid-phase synthesis
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Molecules 28(2023), 1061
DOI: 10.3390/molecules28031061
Permalink: https://www.hzdr.de/publications/Publ-36271
Experimental investigations and qualification of innovative flow sensors in the 1000 K SOLTEC-2 sodium loop
Onea, A.; Krauter, N.; Hering, W.; Lenk, S.; Ruck, S.; Stieglitz, R.; Gerbeth, G.
Abstract
Liquid metals, such as sodium, have been already successfully used as heat transfer fluids (HTF) in concentrating solar power (CSP) plants up to ~550 °C. Even higher temperatures can be achieved and are envisioned for future CSP plants. The lack of measuring flow rate devices at high temperatures for liquid metals motivated this study. The present paper presents the experimental mock-up and the experimental results obtained with the SOLTEC-2 facility for two test flow sensors, one innovative eddy current flow sensor (ECFM) developed at HZDR, Germany and a built-in permanent magnet fly-wheel sensor for runs up to a sodium temperature of 700 °C. The signals of the sensors are compared also against the power level of the sodium pump.
Keywords: Sodium; Eddy Current Flow Sensor; Magnetic Fly-Wheel Flow Sensor; Experiment
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Contribution to proceedings
SOLARPACES 2022: 28th International Conference on Concentrating Solar Power and Chemical Energy Systems, 27.-30.09.2022, Albuquerque, USA
SolarPACES Conf Proc 1 (2022)
DOI: 10.52825/solarpaces.v1i.630
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Permalink: https://www.hzdr.de/publications/Publ-36270
Data publication: Core-shell structured MCM-48-type silica-polymer hybrid material synthesis and characterization
Yismaw, S.; Wenze, M.; Attallah, A. G.; Zaleski, R.; Matysik, J.; Poppitz, D.; Gläser, R.; Ebbinghaus, S. G.; Enke, D.
Abstract
In the current study, a core-shell structured material of MCM-48-type mesoporous silica nanoparticles (MSNs) and cross-linked poly(N-isopropylacrylamide) homopolymer and its copolymer with methacrylic acid was synthesized. The polymer was preferentially grafted on the outer surface of silane linker-functionalized MSNs based on free radical polymerization. The successful chemical grafting of the polymer on the silica surface was confrmed by FTIR, NMR, TG, and elemental analyses. The polymer contents of the hybrid particles vary from 18 to 40 % as determined by thermogravimetric and elemental analyses. The polymer content was tailored by varying diferent reaction parameters including monomer concentration, linker content/type, and reaction time. Well-defned uniform core-shell structured spherical particles with an average particle size of 367 ± 25 nm and shell thickness of 29 ± 8 nm were observed in TEM analysis. According to XRD and nitrogen physisorption studies, the ordered mesopore structure of the core MCM-48-type MSNs was maintained after an extended polymer grafting process and surface coverage with a high content of polymer. No signifcant pore blockage was observed in porosimetry analysis. More than 75% of specifc surface area, 68% of total pore volume, and the mean mesopore diameter were retained after successful grating of polymer on the outer silica surface. The pore volume thus can provide enough space to encapsulate high contents of cargo molecules for applications. The narrow pore width distribution of the main mesopores of silica determined by PALS analysis corresponds to the N2 sorption analysis and further confrms the uniformity of the mesopores.
Keywords: MCM-48-type mesoporous silica nanoparticles; Hybrid material; Core-shell structure; Polymer; Grafting; Synthesis
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- P-ELBE
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 36269) publication
- DOI: 10.1007/s11051-022-05666-2 references this (Id 36269) publication
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Core-shell structured MCM-48-type silica-polymer hybrid material synthesis and …
ROBIS: 36268 has used this (Id 36269) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-01-16 Open access
DOI: 10.14278/rodare.2087
Versions: 10.14278/rodare.2088
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-36269
Core-shell structured MCM-48-type silica-polymer hybrid material synthesis and characterization
Yismaw, S.; Wenze, M.; Attallah, A. G.; Zaleski, R.; Matysik, J.; Poppitz, D.; Gläser, R.; Ebbinghaus, S. G.; Enke, D.
Abstract
In the current study, a core-shell structured material of MCM-48-type mesoporous silica
nanoparticles (MSNs) and cross-linked poly(N-isopropylacrylamide) homopolymer and its copolymer
with methacrylic acid was synthesized. The polymer
was preferentially grafted on the outer surface of
silane linker-functionalized MSNs based on free radical polymerization. The successful chemical grafting
of the polymer on the silica surface was confrmed by
FTIR, NMR, TG, and elemental analyses. The polymer contents of the hybrid particles vary from 18 to
40 % as determined by thermogravimetric and elemental analyses. The polymer content was tailored by varying diferent reaction parameters including monomer concentration, linker content/type, and reaction time. Well-defned uniform core-shell structured
spherical particles with an average particle size of
367 ± 25 nm and shell thickness of 29 ± 8 nm were
observed in TEM analysis. According to XRD and
nitrogen physisorption studies, the ordered mesopore
structure of the core MCM-48-type MSNs was maintained after an extended polymer grafting process and
surface coverage with a high content of polymer. No
signifcant pore blockage was observed in porosimetry analysis. More than 75% of specifc surface area,
68% of total pore volume, and the mean mesopore
diameter were retained after successful grating of
polymer on the outer silica surface. The pore volume
thus can provide enough space to encapsulate high contents of cargo molecules for applications. The narrow pore width distribution of the main mesopores of
silica determined by PALS analysis corresponds to
the N2 sorption analysis and further confrms the uniformity of the mesopores.
Keywords: MCM-48-type mesoporous silica nanoparticles; Hybrid material; Core-shell structure; Polymer; Grafting; Synthesis
Involved research facilities
- P-ELBE
Related publications
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Data publication: Core-shell structured MCM-48-type silica-polymer hybrid …
ROBIS: 36269 HZDR-primary research data are used by this (Id 36268) publication
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Journal of Nanoparticle Research 25(2023), 21
DOI: 10.1007/s11051-022-05666-2
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Permalink: https://www.hzdr.de/publications/Publ-36268
Oxygen K-edge X-ray Absorption Spectra of ThO2 and CeO2: experiment, interpretation and structural effects.
Amidani, L.; Dumas, T.; Shuh, D. K.; Butorin, S. M.; Sahle, C. J.; Longo, A.; Kvashnina, K.
Abstract
Experimental oxygen K-edge spectra of ThO2 and CeO2 are presented and interpreted based on density functional theory (DFT). The contribution of d and f orbitals to the O K-edge spectrum are identified as well distinguished peaks, the presence of which evidences the strong hybridization of Th and Ce metal centers with O orbitals. The sensitivity of the O K-edge to both f- and d-states in the absence of a core-hole on the metal ion results in an insightful overview of the electronic structure involved in the chemical bond. In particular, the large bandwidth of the Th 5f band as compared to the Ce 4f band is observed as a set of wider and more substantial set of peaks in the O K-edge, confirming the stronger hybridization of the former with O orbitals. The peak ascribed to the 5f band of ThO2 is found at higher energy than the 6d band, as predicted from DFT calculations on actinide dioxides. To highlight the sensitivity and the potential use of the O K-edge for the characterization of ThO2-based systems, the sensitivity of the spectrum to structural changes such as lattice expansion and size reduction are calculated and discussed.
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Journal of Physical Chemistry C 127(2023)6, 3077-3084
DOI: 10.1021/acs.jpcc.2c07771
Cited 1 times in Scopus
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- Open Access Version from escholarship.org
- Secondary publication expected
Permalink: https://www.hzdr.de/publications/Publ-36266
Modelling based approach for the identification of germanium- and indium - binding siderophores
Hintersatz, C.; Tsushima, S.; Jain, R.; Pollmann, K.
Abstract
Density functional theory was used in order to screen for siderophores selective for gallium, indium, and germanium, respectively.
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Lecture (Conference)
(Online presentation)
BioCuInGe Workshop on Waste to Wealth, 25.-26.11.2022, Delhi, Indien
Permalink: https://www.hzdr.de/publications/Publ-36265
Bottom-up Fabrication of FeSb₂ Nanowires on Crystalline GaAs Substrates with Ion-induced Pre-patterning
Weinert, T.; Erb, D.; Hübner, R.; Facsko, S.
Abstract
Most industrial processes are generating waste heat that can be converted into electrical energy with thermoelectric generators (TEGs). For efficient energy harvesting, it is necessary to significantly improve the properties like Seebeck coefficient, electrical and thermal conductivity of the thermoelectric materials in the TEGs. One promising approach are thermoelectric nanostructures to reduce the thermal conductivity while maintaining constant electrical conductivity and Seebeck coefficient. For that reason, this study investigated the possibility of preparing nanowires of the thermoelectric material iron antimonide (FeSb₂) on crystalline gallium arsenide GaAs(001) substrates with ion-induced surface nanopatterning.
The GaAs(001) substrates were pre-patterned using 1 keV Ar⁺ ion irradiation. By using an ion source with a broad, unfocused ion beam at normal incidence, the patterned area can be scaled to nearly any size. The self-organized surface structure is formed by reverse epitaxy and is characterized by almost perfectly parallel-aligned ripples at the nanometer scale. For the fabrication of FeSb₂ nanowires, iron and antimony were successively deposited on the prepatterned GaAs substrates at grazing incidence and then annealed. They were characterized using transmission electron microscopy (TEM), in particular high-resolution TEM imaging for structure analysis and spectrum imaging analysis based on energy-dispersive X-ray spectroscopy
for element characterization.
With the presented fabrication method, FeSb₂ nanowires were produced successfully on GaAs(001) substrates with an ion-induced nanopatterned surface. The nanowires have a polycristalline structure and a cross-sectional area which is scalable up to 22×22nm². Due to the highly ordered nanostructure of the GaAs substrates, the nanowires have a length of several micrometer. These bottom-up nanofabrication based on ion-induced patterning can be a viable alternative to top-down procedures regarding to efficiency and costs.
Keywords: bottom-up nanofabrication; ion-induced nanopatterning; physical vapor deposition; transmission electron microscopy; energy-dispersive X-ray spectroscopy
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36264) publication
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Data publication: Bottom-up Fabrication of FeSb₂ Nanowires on Crystalline GaAs …
ROBIS: 36517 HZDR-primary research data are used by this (Id 36264) publication
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Frontiers in Physics 11(2023), 1149608
DOI: 10.3389/fphy.2023.1149608
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Permalink: https://www.hzdr.de/publications/Publ-36264
Selection and production of siderophores suitable germanium-, indium and gallium - recovery
Hintersatz, C.; Rojas, L. A.; Kutschke, S.; Jain, R.; Tsushima, S.; Pollmann, K.
Abstract
Siderophores are a diverse group of small iron-chelating molecules that are synthesized by a vast number of bacteria, fungi and graminaceous plants in order to sequester the essential metal under iron-limited conditions. Their capability to complex other metals as well makes them possibly suited compounds for the usage in bio-based recycling technologies.
The aim of this work is to find siderophores, which selectively bind the critical elements indium, gallium and germanium. Due to the vast number of different known siderophores the complete experimental evaluation is impractical, though. Hence, density functional theory (DFT) is used to simulate the chelation reaction in order to estimate the affinities of various siderophores towards gallium and indium as well as the stability of the resulting coordination complexes. Additionally, environmental samples from lagoons of the Atacama Desert are screened for novel siderophore-producing organisms. The siderophores excreted by those organisms might possess unique binding abilities due to the highly saline and alkaline conditions of the isolation sites. Siderophores selected via DFT as well as those produced by isolated microorganisms are tested experimentally for their affinity towards the metals of interest.
Proving the applicability of siderophores in the recovery of indium and gallium from low concentrated waste waters would create a vast amount of further possible applications of the biomolecules to aid securing the future supply of not just said energy-critical elements, but all strategic metals.
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Lecture (Conference)
(Online presentation)
ACS Spring 2022, 20.-24.03.2022, San Diego, USA
Permalink: https://www.hzdr.de/publications/Publ-36263
Chlorine doping of MoSe2 flakes by ion implantation
Prucnal, S.; Li, Y.; Ghorbani Asl, M.; Hübner, R.; Ziegenrücker, R.; Kentsch, U.; Krasheninnikov, A.; Helm, M.; Zahn, D. R. T.; Zhou, S.
Abstract
The efficient integration of transition metal dichalcogenides (TMDs) into the current electronic device technology requires mastering the techniques of effective tuning of their optoelectronic properties. Specifically, controllable doping is essential. For conventional bulk semiconductors, ion implantation is the most developed method offering stable and tunable doping. In this work, we demonstrate n-type doping in MoSe2 flakes realized by low-energy ion implantation of Cl+ ions followed by millisecond-range flash lamp annealing (FLA). We further show that FLA for 3 ms with a peak temperature of about 1000 °C is enough to recrystallize implanted MoSe2. The Cl distribution in few-layer-thick MoSe2 is measured by secondary ion mass spectrometry. An increase in the electron concentration with increasing Cl fluence is determined from the softening and red shift of the Raman-active A1g phonon mode due to the Fano effect. The electrical measurements confirm the n-type doping of Cl-implanted MoSe2. A comparison of the results of our density functional theory calculations and experimental temperature-dependent micro-Raman spectroscopy data indicates that Cl atoms are incorporated into the atomic network of MoSe2 as substitutional donor impurities.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36262) publication
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Poster
German Conference for Research with Synchrotron Radiation, Neutrons and Ion Beams at Large Facilities, 05.-07.09.2022, Berlin, Germany
Permalink: https://www.hzdr.de/publications/Publ-36262
Data publication: A network-based approach to identifying correlations between phylogeny, morphological traits and occurrence of fish species in US river basins.
Tripathi, R.; Reza, A.; Su, G.; Mertel, A.; Calabrese, J.
Abstract
There are three primary datasets used in this work.These were obtained from Dr. Guohuan Su (co-author on the paper) . 1. Phylogenetic distance data sets between all fish species in the US. 2. Morphological traits dataset that list 10 traits information of fish species. 3. Occurrence dataset that list occurrence information of fish species in HUC8 regions of the US There is one dataset that lists exotic species in the US. The entries for exotic species are removed from about datasets before analysis.
Keywords: Complex Networks; Phylogenetic Distance; Morphological Traits; Species Co-occurrence
Related publications
- DOI: 10.1101/2023.01.09.523236 references this (Id 36260) publication
- DOI: 10.1371/journal.pone.0287482 references this (Id 36260) publication
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A network-based approach to identifying correlations between phylogeny …
ROBIS: 36259 has used this (Id 36260) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-01-16 Open access
DOI: 10.14278/rodare.2085
Versions: 10.14278/rodare.2086
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-36260
A network-based approach to identifying correlations between phylogeny, morphological traits and occurrence of fish species in US river basins.
Tripathi, R.; Reza, A.; Su, G.; Mertel, A.; Calabrese, J.
Abstract
The complex network framework has been successfully used to model interactions between entities in Complex Systems in the Biological Sciences such as Proteomics, Genomics, Neuroscience, and Ecology. Networks of organisms at different spatial scales and in different ecosystems have provided insights into
community assembly patterns and emergent properties of ecological systems. In the present work, we investigate two questions pertaining to fish species assembly rules in US river basins, a) if morphologically similar fish species also tend to be phylogenetically closer, and b) to what extent are co-occurring species that are phylogentically close also morphologically similar? For the first question, we construct a network of Hydrologic Unit Code 8 (HUC8) regions as nodes with interaction strengths (edges) governed by the number of common species. For each of the modules of this network, which are found to be geographically separated, there is differential yet significant evidence that phylogenetic distance predicts morphological distance. For the second question, we construct and analyze nearest neighbor directed networks of species based on their morphological distances and phylogenetic distances. Through module detection on these networks and comparing the module-level mean phylogenetic distance and mean morphological distance with the number of basins of common occurrence of species in modules, we find that both phylogeny and morphology of species have significant roles in governing species co-occurrence, i.e. phylogenetically and morphologically distant species tend to co-exist more. In addition, between the two quantities (morphological distance and phylogentic distance), we find that morphological distance is a stronger determinant of species co-occurrences
Keywords: Complex Networks; Phylogenetic Distance; Morphological Traits; Species Co-occurrence
Related publications
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Data publication: A network-based approach to identifying correlations between …
ROBIS: 36260 HZDR-primary research data are used by this (Id 36259) publication
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Contribution to WWW
https://www.biorxiv.org/content/10.1101/2023.01.09.523236v1
DOI: 10.1101/2023.01.09.523236 -
PLOS ONE 18(2023), e0287482
DOI: 10.1371/journal.pone.0287482
Permalink: https://www.hzdr.de/publications/Publ-36259
Animal movement as a cross-cutting theme at CASUS
Calabrese, J.; Simoes Silva, I. M.; Alston, J.; Fleming, C.
Abstract
The movement of animals through landscapes worldwide drives ecological processes, influences disease transmission, and governs how humans and wildlife interact. High resolution animal tracking data have transformed our ability to understand when, where, how, and why animals move. However, these data come with formidable statistical challenges including strong autocorrelation and context-dependent location errors and fix rates. Overcoming these hurdles requires an interdisciplinary effort that combines ecology, physics, geostatistics, signal processing, and computer science.
In this talk, I detail ongoing work at CASUS in animal movement research, covering statistical methods and software development as well as applications in ecology, wildlife management, and autonomous vehicles research. I also highlight the role that aggregated, multispecies tracking datasets play in understanding animal movement and its consequences at the global scale. Finally, I discuss future directions for this research program, outlining potential points of collaboration with researchers coming from different disciplines.
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Invited lecture (Conferences)
Big data analytical methods for complex systems, 06.10.2022, Wroclaw, Poland -
Invited lecture (Conferences)
CASUSCON, 14.07.2022, Wroclaw, Poland
Permalink: https://www.hzdr.de/publications/Publ-36258
Growth and Martensitic Transformation of Ferromagnetic Co-Cr-Ga-Si Epitaxial Films
Ge, Y.; Lünser, K.; Ganss, F.; Gaal, P.; Fink, L.; Fähler, S.
Abstract
During cooling, conventional martensitic transformation can only be realized from austenite to martensite. Recently, a so-called reentrant martensitic transformation obtained much interest due to an additional transformation from martensite to austenite during further cooling. Obviously, materials with this reentrant transformation will increase the number of physical effects and possible applications. However, until now, only bulk samples are reported available, which are not suitable for applications in micro-devices. In this work, ferromagnetic Co-Cr-Ga-Si films were selected as a model system to explore the reentrant transformation behavior in thin films. We observed that the films grow epitaxially on MgO (100) substrates and exhibit a martensitic transformation if deposited at a sufficiently high temperature or with an additional heat treatment. Film within the austenite state are ferromagnetic while films within the martensitic state just exhibit a very low ferromagnetism order.
Keywords: Co-Cr-Ga-Si; martensitic transformation; reentrant martensite; epitaxial film; ferromagnetism
Related publications
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Data Publication: Growth and Martensitic Transformation of Ferromagnetic …
ROBIS: 36476 HZDR-primary research data are used by this (Id 36257) publication
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Science and Technology of Advanced Materials 24(2023)1, 2251368
DOI: 10.1080/14686996.2023.2251368
Permalink: https://www.hzdr.de/publications/Publ-36257
Spaceborne GNSS-Receiver Evolution – From Classical HiRel to NewSpace Constellation
Schütz, M.; Zehetmayer, S.; Zajac, K.; Laabs, M.; Borany, J.; Zangl, R.; Sust, M.
Abstract
Spaceborne Global Navigation Satellite System (GNSS) receivers have become indispensable components of satellites, in particular for real-time navigation as part of the attitude and orbit control system and for precise orbit determination in support of highly accurate earth observation instruments. In cooperation with the project partners TU Dresden and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Beyond Gravity (formerly RUAG Space) has developed a flexible GNSS receiver platform targeting NewSpace applications but leveraging the performance of the current gold standards with respect to spaceborne GNSS-receiver technology. A novel radiation test environment was introduced, and selected components were radiation tested to ensure a consistent reliability.
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Lecture (Conference)
Deutscher Luft- und Raumfahrtkongress (DLRK 2022), 27.-29.09.2022, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-36256
Species invasiveness and community invasibility of US freshwater fish fauna revealed via trait-based analysis
Su, G.; Mertel, A.; Brosse, S.; Calabrese, J.
Abstract
While biological invasions are recognized as a major threat to global biodiversity, determining species’ abilities to invade new areas (species invasiveness) and the vulnerability of those areas to invasions (community invasibility) are still poorly understood. Here, we used trait-based analysis to profile invasive species and quantify the community invasibility for >1,800 North American freshwater fish communities. We show that species with higher reproduction rates, longer life spans and larger sizes tend to be more invasive. Community invasibility peaked when the functional distance among native species was high, leaving unoccupied functional space for the establishment of potential invaders. Invasion success is therefore governed by both the functional traits of non-native species determining their invasiveness, and by the functional characteristics of the invaded community determining its invasibility. Considering those two determinants together will allow better predictions of invasions.
Related publications
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data and code for "Species invasiveness and community invasibility of US …
ROBIS: 35623 HZDR-primary research data are used by this (Id 36255) publication
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Contribution to WWW
https://www.biorxiv.org/content/10.1101/2022.03.04.481515v1.full.pdf
DOI: 10.1101/2022.03.04.481515 -
Nature Communications 14(2023)1, 2332
DOI: 10.1038/s41467-023-38107-2
Cited 13 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36255
Efforts towards PET-activatable red-shifted silicon rhodamines and silicon pyronine dyes
Kramer, C. S.; Kanagasundaram, T.; Matthias, J.; Kopka, K.
Abstract
Tracers for bimodal optical imaging and positron emission tomography unite multiple ad-vantages in a single molecule. Their tumor-specific uptake can be visualized after their PET-activation by radiofluorination via PET/CT or PET/MRI allowing for staging or therapy planning, while their non-radioactive moiety additionally facilitates the visualization of malig-nant tissue during intraoperative fluorescence-guided surgery or in histological assessments. The silicon-bridged xanthene core offers the opportunity for radiofluorination with SiFA isotope exchange to obtain a small molecule PET-activatable NIR dye that can be linked to different tar-get vectors. Herein, we demonstrate the PET-activation of a fluorinated silicon pyronine, be-longing to a class of low-molecular weight fluorescence dyes with a large Stokes shift and sol-vent-dependent NIR dye properties, with successful radiochemical conversion. Moreover, a li-brary of unusually functionalized, red-shifted silicon rhodamines was synthesized, which can be easily conjugated by amide bond formation or ‘click-reaction’ approaches.
Keywords: tracer; bimodal imaging; PET tracer; fluorine-18; radiofluorination; optical imaging; pyronine; silicon rhodamine; fluorescence dye; near-infrared dye; SiFA-IE
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Pharmaceuticals 16(2023), 401
DOI: 10.3390/ph16030401
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36254
Using mini-CT specimens for the fracture characterization of ferritic steels within the ductile to brittle transition range: a review
Sánchez, M.; Cicero, S.; Kirk, M.; Altstadt, E.; Server, W.; Yamamoto, M.
Abstract
The use of mini-CT specimens for the fracture characterization of structural steels is currently a topic of great interest from both scientific and technical points of view, mainly driven by the needs and requirements of the nuclear industry. In fact, the long-term operation of nuclear plants requires accurate characterization of the reactor pressure vessel materials and evaluation of the embrittlement caused by neutron irradiation without applying excessive conservatism. However, the amount of material placed inside the surveillance capsules used to characterize the resulting degradation is generally small. Consequently, in order to increase the reliability of fracture toughness measurements and reduce the volume of material needed for the tests, it is necessary to develop innovative characterization techniques, among which the use of mini-CT specimens stands out. In this context, this paper provides a review of the use of mini-CT specimens for the fracture characterization of ferritic steels, with particular emphasis on those used by the nuclear industry. The main results obtained so far, revealing the potential of this technique, together with the main scientific and technical issues will be thoroughly discussed. Recommendations for several key topics for future research are also provided.
Keywords: mini-CT; ductile-to-brittle transition range; reference temperature; master curve
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Metals 13(2023), 176
DOI: 10.3390/met13010176
Cited 9 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36253
PIConGPU -- High-Fidelity Plasma Simulations on Desktop Computers up to Exascale Compute Systems and a View on its Recent Applications
Debus, A.; Steiniger, K.; Bastrakov, S.; Bastrakova, K.; Bussmann, M.; Carstens, F.-O.; Chandrasekaran, S.; Garten, M.; Gruber, B. M.; Hernandez Arreguin, B.; Hübl, A.; Juckeland, G.; Kelling, J.; Lebedev, A.; Leinhauser, M.; Marre, B. E.; Meyer, F.; Ordyna, P.; Pausch, R.; Pöschel, F.; Rogers, D.; Schramm, U.; Sprenger, L.; Starke, S.; Thévenet, M.; Trojok, J.; Wang, M.; Widera, R.; Young, J.
Abstract
PIConGPU’s latest release 0.6.0 in December 2021 brought a number of new features. Among these are an arbitrary-order Maxwell solver, the Higuera-Cary pusher, collisions, and incident field generation via the total field/scattered field technique enhancing its numerical stability and predictive capabilities.
Furthermore, there are various technical advances, most notably support of the HIP computational backend allowing to run on AMD GPUs. These advances are mainly driven by our participation in OLCF’s Frontier Center for Accelerated Application Readiness providing access to the hardware platform of the Frontier exascale supercomputer scheduled for deployment in 2022. We show performance data and present recent applications of PIConGPU profiting from these developments. To these applications belongs the advanced laser-plasma accelerator scheme Traveling-wave electron acceleration (TWEAC), providing scalability to energies beyond 10 GeV while avoiding staging. We further present simulation campaigns modeling and delivering valuable insight into the micrometer and femtosecond plasma dynamics of existing experimental
campaigns.
Keywords: particle-in-cell code; TWEAC; PIConGPU; performance portable
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Poster
767. WE-Heraeus-Seminar: Science and Applications of Plasma‐Based Accelerators, 15.-18.05.2022, Physikzentrum, Bad Honnef, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36252
minterpy: Multivariate Interpolation in Python
Schreiber, J.; Wicaksono, D. C.; Thekke Veettil, S. K.; Hajizade, A.; Zavalani, G.; Suarez Cardona, J. E.; Hernandez Acosta, U.; Hecht, M.
Abstract
Many solutions to the computational challenges arising in the fields of computational science and engineering rely on solving interpolation tasks of highly-varying sparse and scattered data. The tasks include surrogate modeling, sparse data regression, global black-box optimization, model inference, as well as solutions for partial differential equations (PDE) on complex geometries.
Interpolation tasks in multi-dimensional space typically suffer from the curse of dimensionality in which the computational cost of interpolation scales exponentially with the number of dimensions.
The open-source Python package minterpy developed and maintained by the Hecht-Lab, CASUS, aims to lift the curse of dimensionality from a brand field of interpolation tasks arising across scientific disciplines.
Keywords: interpolation; multivariate interpolation; surrogate modeling; sparse data regression; global black-box optimization; model inference; partial differential equations (PDE)
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Poster
Big data analytical methods for complex systems, 06.-07.10.2022, Wroclaw, Poland
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36251
Transverse Emittance Measurements and Optimization for a Superconducting RF Photon Injector
Abstract
As one of the most promising continuous wave (CW) injectors for high brightness electron
beams, ELBE superconducting radio-frequency (SRF) gun has been developed and optimized.
This gun can provide beams with good quality for the ELBE user facility. One important
aspect is to measure the transverse emittance accurately and efficiently. This thesis contributes
to the progress in this field and focuses on measuring and optimizing the transverse emittance
for ELBE SRF gun. The slit-scan, quadrupole scan, and an advanced thermal emittance
measurement method, called single shot cathode transverse momentum imaging, have been
studied and applied at this SRF gun.
A fast slit-scan emittance measurement system consisting of a continuously moving slit and
a yttrium aluminium garnet (YAG) screen has been developed. During the beamlet image
processing, the machine learning (ML) algorithms have been integrated in order to improve
the signal-to-noise ratio effectively. This is the first time to successfully apply the ML in such
diagnostic methods. The measurement speed is improved about ten times and accuracy is also
better than before. The errors of slit-scan emittance measurement, arising from slit position,
beamlet intensity, center position and root mean square (RMS) width uncertainties, have been
analyzed. The quadrupole scan emittance measurement method has been studied too. The
influence of the space charge effect on quadrupole scan results has been revealed. The error of
the quadrupole scan measurement has also been analyzed.
To compensate the transverse emittance due to space charge effect, a superconducting (SC)
solenoid is placed as close as possible to the exit of the SRF cavity. Another important part in
this thesis is the investigation and optimization of the SC solenoid. The spherical aberration
of the SC solenoid has been analyzed. In order to decrease it, a new yoke geometry of SC
solenoid for the next generation SRF gun has been designed. The multipole transverse field
modes of the solenoid caused by an axis tilt have bean analyzed by means of simulations and
experimental investigations using a formalism fitting method. The influences of the multipole
modes, especially the quadrupole and sextupole fields on transverse emittance have been
calculated. A pair of a normal quadrupole and a skew quadrupole, called correctors, have been
adopted to compensate the influence of the quadrupole field on the emittance.
The cathode intrinsic emittance can contribute a non-negligible part to the transverse emittance.
So in this thesis the cathode intrinsic emitttance is measured too. The single shot transverse
momentum imaging method has been used to measure the cathode intrinsic emittance. A
further advantage is that this method allows to determine the transverse momentum locally at
different positions on the cathode.
Keywords: accelerator; superconducting RF photo injector; beam dynamic; emittance measurement
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- Superconducting Electron Linear Accelerator
- SRF Gun
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 36250) publication
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Doctoral thesis
Universität Hamburg, 2022
125 Seiten
Permalink: https://www.hzdr.de/publications/Publ-36250
Numerical Transfer Towards Unresolved Morphology Representation in the MultiMorph Model
Meller, R.; Krull, B.; Schlegel, F.; Tekavcic, M.
Abstract
The morphology adaptive multifield two-fluid model OpenFOAM-Hybrid focuses on the reliable and robust simulation of interfacial two-phase flows in real size industrial applications. This requires to combine the Volume-of-Fluid approach with the Euler-Euler model for large and small scale interfacial structures, respectively. The choice of the local representation of interfacial structures, such as bubbles or droplets, by either the first or the second of the aforementioned basic method strongly depends on the ratio of the length scale of the interface feature to the grid spacing. In case the computational grid gets too coarse to locally resolve an interfacial structure anymore, a morphology transfer is required. Such a transfer process allows to convert resolved fluid into non-resolved one, i.e. changing from a continuous description to a dispersed one. A formulation for such a numerically motivated disintegration process is presented and validated with a case of a two-dimensional single rising bubble on a grid with gradually varying cell size. The model is then applied to two further cases: an oil-water phase inversion and a water jet plunging into a free water surface. Hereby, functionality, robustness and feasibility of the proposed morphology transfer mechanism are demonstrated. This work contributes to a hybrid modelling approach for the simulation of two-phase flows adapting the numerical representation depending on local flow morphology and on available computational resources.
Keywords: Multiphase Flows; Numerical Simulation; Euler-Euler; OpenFOAM; Morphology-adaptive Model
Related publications
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Basic verification of a numerical framework applied to a morphology adaptive …
ROBIS: 29742 is cited by this (Id 36249) publication -
A workflow for the sustainable development of closure models for bubbly flows
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Momentum exchange modelling for coarsely resolved interfaces in a multifield …
ROBIS: 35412 is cited by this (Id 36249) publication -
OpenFOAM hybrid - A Morphology Adaptive Multifield Two-fluid Model
ROBIS: 32308 is cited by this (Id 36249) publication -
The morphology adaptive multifield solver OpenFOAM-Hybrid and its application …
ROBIS: 36560 is cited by this (Id 36249) publication -
Multiphase Code Repository by HZDR for OpenFOAM Foundation Software
ROBIS: 32194 HZDR-primary research data are used by this (Id 36249) publication -
Multiphase Code Repository by HZDR for OpenFOAM Foundation Software
RODARE: 1877 HZDR-primary research data are used by this (Id 36249) publication -
Multiphase Code Repository by HZDR for OpenFOAM Foundation Software
RODARE: 2185 HZDR-primary research data are used by this (Id 36249) publication
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Contribution to proceedings
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington, D.C., USA
Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), Downers Grove, Illinois, 60515: American Nuclear Society, Incorporated, 978-0-89448-793-4, 693-706 -
Lecture (Conference)
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington, D.C., USA
Permalink: https://www.hzdr.de/publications/Publ-36249
In-situ observation of ion-induced nanoscale patterning on a crystalline Ge(001) surface
Erb, D.; Myint, P.; Evans-Lutterodt, K.; Ludwig, K.; Facsko, S.
Abstract
Ion-induced surface patterning has turned out to be a highly versatile technique for many applications where large areas of nanostructured surfaces or thin films are required. Both fundamental and applied research may benefit from in-situ studies revealing the kinetics of the patterning process, yielding further insight into the dominant mechanisms and thus enabling to gain precise process control. The surface-sensitive X-ray scattering technique of Grazing Incidence Small Angle X-Ray Scattering (GISAXS) is a well-suited method for such in-situ investigations, allowing for contact-less examination under various external conditions.
Here, we present a real-time in-situ GISAXS investigation of reverse epitaxy patterning in crystalline Ge(001). From the X-ray scattering pattern we deduce the significant morphological parameters of the surface, thus tracking the development of the surface morphology with time during ion irradiation.
These findings are compared with results from simulations based on a continuum equation of the local surface height. Good agreement of the simulation with both experiment and theory was only achieved when including in the continuum equation an additional term for regulating the pattern anisotropy. We then find that a continuum equation considering only diffusive effects reproduces the experimentally observed surface patterning kinetics well.
Observing the kinetics of pattern formation in the non-linear regime, we find that the temporal evolutions of characteristic length and roughness conform to power laws, their exponents agreeing with scaling laws for conserved continuum equations with four-fold symmetry. Moreover, we find that the facet angle kinetics can be described by the Austin-Rickett equation for diffusion-controlled transformation processes, corroborating our assumption of a predominantly diffusive mechanism of pattern formation.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36248) publication
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Lecture (Conference)
International Conference on Ion Beam Modification of Materials IBMM-2022, 10.-15.07.2022, Lisbon, Portugal
Permalink: https://www.hzdr.de/publications/Publ-36248
Nanopatterning of the (001) surface of crystalline Ge by ion irradiation at off-normal incidence
Erb, D.; de Schultz, R.; Ilinov, A.; Nordlund, K.; Bradley, R. M.; Facsko, S.
Abstract
Intricate topographical patterns can form on the surface of crystalline Ge(001) subject to low-energy ion irradiation in the reverse epitaxy regime, i.e., at elevated temperatures which enable dynamic recrystallization. We compare such nanoscale patterns produced by irradiation from varied polar and azimuthal ion incidence angles with corresponding calculated surface topographies. To this end, we propose a continuum equation including both anisotropic erosive and anisotropic diffusive effects. Molecular dynamics simulations provide the coefficients of angle-dependent sputter erosion for the calculations. By merely changing these coefficients accordingly, the experimentally observed surface morphologies can be reproduced, except for extreme ion incidence angles. Angle-dependent sputter erosion is thereby identified as a dominant mechanism in ion-induced pattern formation on crystalline surfaces under irradiation from off-normal incidence angles.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36247) publication
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Invited lecture (Conferences)
(Online presentation)
6th International Conference on Nanostructuring by Ion Beams ICNIB 2021, 05.-08.10.2021, online only, online
Permalink: https://www.hzdr.de/publications/Publ-36247
Capture the morphology transfer process in a pool-scrubbing column with a hybrid multi-field two-fluid model
Abstract
The role of pool scrubbing in attenuating radioactivity release after severe accidents has been explored extensively. It is known that the scrubbing efficiency is largely determined by the hydrodynamic phenomenology in pools. The aerosol gas forms large globules at the nozzle exit, which subsequently break up to a swarm of stable bubbles, where the change of bubble size can reach over two orders. Furthermore, with the increase of flow rates, the injection regime changes from globule to jet characterized by a continuous gas structure. The flow field in the pool can be divided into injection and rise (swarm) two zones according to the gas-liquid interface morphology. In different zones, the scrubbing is governed by different mechanisms such as inertial impact, diffusion and gravity, and bubble shape, size and velocity in addition to particle size are major influential parameters. So far, numerical analysis of pool scrubbing is routinely based on system codes, which rely on empirical correlations for the determination of these parameters. More recently, owing to the increasing availability of computational resources, the knowledge is improved through three-dimensional computational fluid hydrodynamics simulations. Nevertheless, the morphology and regime change represents still a challenge. The conventional two-fluid model is generally effective for bubble size smaller than the cell size, while interface-tracking (capturing) methods demands dozens of cells per bubble size. The present work aims to capture the complex hydrodynamic process in the pool scrubbing with a hybrid multi-field two-fluid model. By comparing with experimental data, the results are shown to be promising.
Keywords: Computational Fluid Dynamics; Hybrid Two-Fluid Model; Pool Scrubbing; Severe Accident
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Contribution to proceedings
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington, D.C., USA -
Lecture (Conference)
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington, D.C., USA -
Nuclear Science and Engineering (2024)
DOI: 10.1080/00295639.2024.2365035
Downloads
- Secondary publication expected from 27.06.2025
Permalink: https://www.hzdr.de/publications/Publ-36246
Multiscale approach for boiling flow simulation
Ding, W.; Zhang, J.; Setoodeh, H.; Lucas, D.; Hampel, U.
Abstract
Numerical modeling of boiling flow is challenging due to the wide range characteristic lengths of the physics at play: from nano/micrometers bubble nucleus to sub-meters flow pattern, particularly, when the role of the nano/micro surface structure attracts more attention recently. To address this, we present here our activities in multiscale approaches e.g the Euler Euler (EE) of boiling flow considering the bubble void fraction distribution and GEneralized TwO Phase flow (GENTOP) model to simulate the large free surface structure, the Direct Numerical Simulation (DNS) of bubble dynamics considering detailed surface structure, the Molecular Dynamics (MD) simulation of bubble static/dynamics wetting, and also the bridging concept between each scale activities. The works are demonstrated on several problems including the contact line region of a nucleation bubble, microlayer beneath the bubble, bubble dynamics on a structured surface, bubble population balance, interfacial forces between dispersed phases, and free surface. These activities highlight the capability of the developed multiscale concept to enhance the robustness of boiling flow simulation, though whose application in nuclear-related processes should be an industry-oriented theme that should be with low time and computer hardware requirements.
Keywords: boiling flow; MD; DNS; EE; GENTOP
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Lecture (Conference)
20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20), 20.-25.08.2023, Washington D.C., USA
Permalink: https://www.hzdr.de/publications/Publ-36245
15-N NRA Data for article: Tracer diffusion in proton-exchanged congruent LiNbO3 crystals as a function of hydrogen content
Dörrer, L.; Heller, R.; Schmidt, H.
Abstract
Raw data from 15N NRA measurements including data evaluation.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36244) publication
- DOI: 10.1039/d2cp01818g references this (Id 36244) publication
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Tracer diffusion in proton-exchanged congruent LiNbO3 crystals as a function …
ROBIS: 36243 has used this (Id 36244) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-01-13 Open access
DOI: 10.14278/rodare.2081
Versions: 10.14278/rodare.2082
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36244
Tracer diffusion in proton-exchanged congruent LiNbO3 crystals as a function of hydrogen content
Dörrer, L.; Heller, R.; Schmidt, H.
Abstract
The proton-exchange process is an effective method of fabricating low-loss waveguides based on LiNbO3 crystals. During proton-exchange, lithium is replaced by hydrogen and Li1 xHxNbO3 is formed.
Currently, mechanisms and kinetics of the proton-exchange process are unclear, primarily due to a lack in reliable tracer diffusion data. We studied lithium and hydrogen tracer diffusion in proton-exchanged congruent LiNbO3 single crystals in the temperature range between 130–230 1C. Proton-exchange was done in benzoic acid with 0, 1, 2, or 3.6 mol% lithium benzoate added, resulting in micrometre thick surface layers where Li is substituted by H with relative fractions between x = 0.45 and 0.85 as determined by Nuclear Reaction Analysis. For the diffusion experiments, ion-beam sputtered isotope enriched 6LiNbO3 was used as a Li tracer source and deuterated benzoic acid as a H tracer source.
Isotope depth profile analysis was carried out by secondary ion mass spectrometry. From the experimental results, effective diffusivities governing the lithium/hydrogen exchange as well as individual hydrogen and lithium tracer diffusivities are extracted. All three types of diffusivities can be described by the Arrhenius law with an activation enthalpy of about 1.0–1.2 eV and increase as a function of hydrogen content nearly independent of temperature. The effective diffusivities and the lithium tracer diffusivities are identical within a factor of two to five, while the hydrogen diffusivities are higher by three orders of magnitude. The results show that the diffusion of Li is the rate determining step governing the protonexchange process. Exponential dependencies between diffusivities and hydrogen concentrations are determined. The observed increase of Li tracer diffusivities and effective diffusivities as a function of hydrogen concentration is attributed to a continuous reduction of the migration enthalpy of diffusion by a maximum factor of about 0.2 eV. Simulations based on the determined diffusivities can reproduce the step-like profile of hydrogen penetration during proton-exchange.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36243) publication
-
15-N NRA Data for article: Tracer diffusion in proton-exchanged congruent …
ROBIS: 36244 HZDR-primary research data are used by this (Id 36243) publication
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Physical Chemistry Chemical Physics 24(2022), 16139-16147
DOI: 10.1039/d2cp01818g
Cited 6 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36243
RBS Raw Data for publication: Investigation of matrix independent calibration of oxygen in glow discharge optical emission spectrometry
Hoffmann, V.; Gebel, B.; Heller, R.; Gemming, T.
Abstract
Raw RBS data for article Investigation of matrix independent calibration of oxygen in glow discharge optical emission spectrometry. All raw data as well as simulation files (SIMNRA) are included.
Keywords: glow discharge; optical emission spectroscopy; material science
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36242) publication
- DOI: 10.1039/D2JA00043A references this (Id 36242) publication
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Investigation of matrix independent calibration of oxygen in glow discharge …
ROBIS: 36241 has used this (Id 36242) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2023-01-13 Open access
DOI: 10.14278/rodare.2079
Versions: 10.14278/rodare.2080
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-36242
Investigation of matrix independent calibration of oxygen in glow discharge optical emission spectrometry
Hoffmann, V.; Gebel, B.; Heller, R.; Gemming, T.
Abstract
The performance of glow discharge optical emission spectrometry for matrix independent oxygen determination was
investigated using the spectral lines of atomic oxygen at 130 nm and 777 nm and standard conditions for dc discharge with a
4 mm anode (700 V, 20 mA). Using hot-pressed calibration samples of Cu-, Al- and Mg-powder mixed with their oxides, at
130 nm the dependence of the emission yield on these matrices was confirmed. However, at 777 nm oxygen has the same
emission yield in these matrices. In order to compare the emission yield of oxygen with the emission yield in iron a thick 43
μm FeO-layer was prepared and characterized by Rutherford backscattering spectrometry, X-ray diffraction and glow
discharge optical emission spectrometry. At 130 nm, the emission yield of oxygen in FeO is most similar to that in an Almatrix.
At 777 nm, the calibration revealed a higher emission yield of oxygen in FeO in comparison to the common emission
yield of oxygen in Cu-, Al- and Mg-matrices. © 2022 The Royal Society of Chemistry
Keywords: glow discharge; optical emission spectroscopy; material science
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36241) publication
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RBS Raw Data for publication: Investigation of matrix independent calibration …
ROBIS: 36242 HZDR-primary research data are used by this (Id 36241) publication
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Journal of Analytical Atomic Spectrometry 32(2022)6, 1223-1228
DOI: 10.1039/D2JA00043A
Cited 2 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36241
Applicability of gas flow modulation technique for measuring axial gas dispersion coefficients in bubble columns
Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.
Abstract
Dispersion phenomena significantly influence the residence time of the fluid phases in gas-liquid contactors and, thus, their yield. With the axial dispersion model (ADM), the effect of dispersion is considered during the process design. However, this requires a reliable quantification of the axial dispersion coefficients.
A novel non-intrusive approach to determine the axial gas dispersion coefficient in bubble columns was recently pronounced by Hampel [1], called gas flow modulation technique (GFM). This approach is based on an imposed marginal sinusoidal modulation on the constant gas inlet flow. This leads to a modulation of the gas holdup in the bubble column, called holdup wave. Along the column axial direction, the gas dispersion damps the rising holdup wave in amplitude and shifts its phase. Amplitude damping and phase shift can be non-invasively determined, e.g., using gamma-ray densitometry to relate it to the value of the axial dispersion coefficient using the ADM. Figure 1 shows the principle of GFM and a simplified scheme of the experimental setup.
Döß et al. [2] applied the GFM to bubble columns for the first time, although only for a narrow range of operating conditions in a 100 mm ID bubble column. The present study proves the applicability of the GFM to larger columns and for a wider range of gas superficial velocities and liquid properties. Experiments were performed in columns of 100, 150 and 330 mm ID at gas superficial velocities ranging from 17 to 47 mm/s. Air was used as the gas phase. Water, aqueous solutions with 2% wt. ethanol and 30% wt. glycerin were used as the liquid phase. This study, together with the uncertainty analyses recently performed by Marchini et al. [3, 4], qualifies the GFM as a viable non-invasive alternative to traditional tracer studies, for measuring the axial gas dispersion coefficient in bubble columns.
Keywords: gas flow modulation; bubble columns; axial gas dispersion coefficient
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Contribution to proceedings
ECCE14, 17.-20.09.2023, Berlin, Germany
Permalink: https://www.hzdr.de/publications/Publ-36240
Analysis of sparger effects on axial gas dispersion in bubble columns
Marchini, S.; Caggia, V.; Bieberle, A.; Schubert, M.; Brunazzi, E.; Hampel, U.
Abstract
The uniformity of the gas distribution in bubble columns strongly depends on the gas sparger design. For example, not all holes of a perforated plate sparger with relatively high fractional free area are active at the same time. This is true especially at low gas flow rates. Consequently, the random activation of the holes causes gas maldistribution in the radial as well as in the axial directions. Contrary, needle spargers provide rather uniform distribution at the same operating conditions.
Since dispersion phenomena depend on the gas holdup gradient, the gas maldistribution is expected to affect the dispersion. Surprisingly, only few publications address the possible influence of the sparger on gas dispersion. An exception is the study of Kölbel [1]. They measured the axial gas dispersion coefficient in a bubble column using a monolithic type of sparger. Here, the obtained gas dispersion coefficients run through a minimum while increasing the gas superficial velocity. Contrary, literature frequently reports axial dispersion coefficients that increase monotonously with the gas superficial velocity (e.g., [2], [3]).
The objective of the present study was to resolve this discrepancy. Experiments were performed in a 100 mm ID column using three different spargers, namely: a perforated plate sparger with (a) 50 holes of 0.6 mm diameter corresponding to a fractional free area of 0.18%, (b) with 38 holes of 1.0 mm and 12 holes of 1.5 mm corresponding to a fractional free area of 0.66%, and (c) a needle sparger made of 31 needles with 0.8 mm inner diameter each.
Axial dispersion was experimentally measured applying the gas flow modulation technique, which is a tracer-free approach explained by Marchini et al. [4, 5].
The results showed that the above mentioned minimum found by Kölbel [1] is reproducible for spargers with high fractional free area. Figure 1 reports the determined axial dispersion coefficients as a function of the gas superficial velocity for all considered spargers. The minimum is less evident for the considered sparger with lower fractional free area and, finally, it is not identified for the needle sparger.
Considering that dispersion causes back-mixing, which often has a detrimental effect on process yield, the presence of such a dispersion minimum can be considered as an additional option for process optimization in the future. However, more studies are required to reliably predict the occurrence of such dispersion minimum depending on sparger design and operating conditions.
Keywords: gas flow modulation; bubble column; axial disperision coefficient; gas sparger
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Contribution to proceedings
ECCE14, 17.-20.09.2023, Berlin, Germany
Permalink: https://www.hzdr.de/publications/Publ-36239
Survey of spatio-temporal couplings throughout high-power ultrashort lasers
Jeandet, A.; Jolly, S. W.; Borot, A.; Bussière, B.; Dumont, P.; Gautier, J.; Gobert, O.; Goddet, J.-P.; Gonsalves, A.; Irman, A.; Leemans, W. P.; Lopez-Martens, R.; Mennerat, G.; Nakamura, K.; Ouillé, M.; Pariente, G.; Pittman, M.; Püschel, T.; Sanson, F.; Sylla, F.; Thaury, C.; Zeil, K.; Fabien Quéré, A.
Abstract
The investigation of spatio-temporal couplings (STCs) of broadband light beams is
becoming a key topic for the optimization as well as applications of ultrashort laser systems.
This calls for accurate measurements of STCs. Yet, it is only recently that such complete
spatio-temporal or spatio-spectral characterization has become possible, and it has so far mostly
been implemented at the output of the laser systems, where experiments take place. In this survey,
we present for the first time STC measurements at different stages of a collection of high-power
ultrashort laser systems, all based on the chirped-pulse amplification (CPA) technique, but with
very different output characteristics. This measurement campaign reveals spatio-temporal effects
with various sources, and motivates the expanded use of STC characterization throughout CPA
laser chains, as well as in a wider range of types of ultrafast laser systems. In this way knowledge
will be gained not only about potential defects, but also about the fundamental dynamics and
operating regimes of advanced ultrashort laser systems.
Involved research facilities
- Draco
-
Optics Express 30(2022)3, 3262-3288
DOI: 10.1364/OE.444564
Cited 30 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36238
Characterization of the plasma mirror system at the J-KAREN-P facility
Kon, A.; Nishiuchi, M.; Fukuda, Y.; Kondo, K.; Ogura, K.; Sagisaka, A.; Miyasaka, Y.; Dover, N. P.; Kando, M.; Pirozhkov, A. S.; Daito, I.; Chang, L.; Woo Choi, I.; Hee Nam, C.; Ziegler, T.; Schlenvoigt, H.-P.; Zeil, K.; Schramm, U.; Kiriyama, H.
Abstract
We report on the design and characterization of the plasma mirror system installed on the J-KAREN-P laser at the Kansai
Photon Science Institute, National Institutes for Quantum Science and Technology. The reflectivity of the single plasma
mirror system exceeded 80%. In addition, the temporal contrast was improved by two orders of magnitude at 1 ps before
the main pulse. Furthermore, the laser near-field spatial distribution after the plasma mirror was kept constant at plasma
mirror fluence of less than 100 kJ/cm2. We also present the results of investigating the difference and the fluctuation in
energy, pulse width and pointing stability with and without the plasma mirror system.
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High Power Laser Science and Engineering 10(2022), e25
DOI: 10.1017/hpl.2022.15
Cited 5 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-36237
High energy proton acceleration at DRACO-PW and radio-biological applications
Abstract
Exploiting the strong electromagnetic fields that can be supported by a plasma, high-power laser driven compact plasma accelerators can generate short, high-intensity pulses of high energy ions with special beam properties. By that they may expand the portfolio of conventional machines in many application areas. The maturation of laser driven ion accelerators from physics experiments to turn-key sources for these applications will rely on breakthroughs in both, generated beam parameters (kinetic energy, flux), as well as increased reproducibility, robustness and scalability to high repetition rate.
Recent developments at the high-power laser facility DRACO-PW enabled the production of polychromatic proton beams with unprecedented stability [1]. This allowed the first in vivo radiobiological study to be conducted using a laser-driven proton source [2]. Yet, the ability to achieve energies beyond the 100 MeV frontier is matter of ongoing research, mainly addressed by exploring advanced acceleration schemes like the relativistically induced transparency (RIT) regime.
In this talk we report on experimental proton acceleration studies at the onset of relativistic transparency using pre-expanded plastic foils. Combined hydrodynamic and 3D particle-in-cell (PIC) simulations helped to identify the most promising target parameter range matched to the prevailing laser contrast conditions carefully mapped out in great detail beforehand. A complex suite of particle and optical diagnostics allowed characterization of spatial and spectral proton beam parameters and the stability of the regime of best acceleration performance, yielding cut-off energies larger than 100 MeV in the best shots.
Involved research facilities
- Draco
-
Invited lecture (Conferences)
20th Advanced Accelerator Concepts Workshop (AAC’22), 07.11.2022, Long Island, USA
Permalink: https://www.hzdr.de/publications/Publ-36236
Laser-plasma ion accelerators for radio-biological research
Abstract
Particle accelerators have always been fundamental engines of discovery and drivers of innovations in industry, basic research, and life sciences. Exploiting the strong electromagnetic fields that can be supported by a plasma, high-power laser-driven compact plasma accelerators can generate short, high-intensity pulses of high energy electrons and ions with special beam properties. By that they may expand the portfolio of conventional machines in many application areas.
For laser-driven ion accelerators, the full application in ultra-high dose rate radiotherapy (RT) research marks one of the most important research objectives and is perfectly timed with the emerging interest on ultra-high dose rate RT. Laser proton accelerators are ideal instruments to investigate ultra-high dose rate effects, yet their ability to provide radiobiological in-vivo data comparable in quality to a clinical reference standard has called for demonstration for a long time.
The talk will introduce the concept of laser-driven ion accelerators and challenges of this technology. For the example of the high power laser source DRACO operated at HZDR, key developments for the production of reliable polychromatic proton beams with maximum energies of around 60 MeV are presented. Most recently, these achievements enabled the first successful small animal pilot study on radiation-induced tumor growth delay in mice using a laser-driven proton source and a clinical reference.
Involved research facilities
- Draco
-
Invited lecture (Conferences)
(Online presentation)
Virtual DPG Spring Meeting - Symposium Plasma Induced Accelerators, 31.03.2022, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36235
Laser driven proton accelerators with solid hydrogen jets for application
Abstract
Laser plasma-based particle accelerators attract great interest in fields where conventional accelerators reach limits based on size, cost or beam parameters. However, despite the fact that first principles particle in cell simulations have predicted several advantageous ion acceleration schemes,
laser accelerators have not yet reached their full potential in producing simultaneous high-radiation
doses at high particle energies. The most stringent limitation is the lack of a suitable high-repetition
rate target that also provides a high degree of control of the plasma conditions which is required
to access these advanced regimes. Here, we demonstrate that the interaction of petawatt-class laser
pulses with a pre-formed micrometer-sized cryogenic hydrogen jet plasma overcomes these limitations. Controlled pre-expansion of the initially solid target by low intensity pre-pulses allowed for tailored density scans from the solid to the underdense regime. Our experiment demonstrates that
the near-critical plasma density profile produces proton energies of 80 MeV. This energy presents
more than a factor of two increase compared to the solid hydrogen target. Our three-dimensional
particle in cell simulations show the transition between different acceleration mechanisms and suggest enhanced proton acceleration at the relativistic transparency front for the optimal case.
Involved research facilities
- Draco
-
Invited lecture (Conferences)
13th International Particle Accelerator Conference (IPAC’22), 15.06.2022, Bangkok, Thailand
Permalink: https://www.hzdr.de/publications/Publ-36234
High energy proton detection in Draco PW experiments
Zeil, K.; Assenbaum, S.; Bernert, C.; Brack, F.-E.; Cowan, T.; Garten, M.; Gaus, L.; Göthel, I.; Kluge, T.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Reimold, M.; Rehwald, M.; Schlenvoigt, H.-P.; Umlandt, M. E. P.; Vescovi Pinochet, M. A.; Ziegler, T.; Schramm, U.
Abstract
Exploiting the strong electromagnetic fields that can be supported by a plasma, high-power
laser driven compact plasma accelerators can generate short, high-intensity pulses of high
energy ions with special beam properties interesting for many application areas. The transition
of laser driven ion accelerators from physics experiments to turn-key sources for these
applications relies on improvement of generated beam parameters (kinetic energy, flux), as
well as increased reproducibility, robustness and scalability to high repetition rate.
Recent developments at the high-power laser facility DRACO-PW enabled the production
of polychromatic proton beams with unprecedented stability [1] which enabled the first in vivo
radiobiological study to be conducted using a laser-driven proton source [2]. Yet, the ability to
achieve highest energies around or even beyond the 100 MeV frontier is matter of ongoing
research, mainly addressed by exploring advanced acceleration schemes.
In parallel to the testing of these schemes an important challenge is to provide convincing
evidence that these very high energies could be reached at all for a significant number of
particles. Occurring complications are due to the nature of the multi-species beams with
typically exponentially decaying spectra and low shot statistics of laser-plasma experiments
at the necessary laser pulse energy levels. The latter is in particular complicated for highly
non-linear acceleration regimes with intrinsically low reproducibility.
In this talk we summarize our approaches for the spatial and spectral characterization of our
proton beam parameters with cut-off energies larger than 80 MeV. Key is the combination of
a multitude of different methods based on different detection principles established for single
shot measurements. Time-of-flight methods are discussed for energy cross-calibration of our
Thomson parabola spectrometers and the use of different screen types for on-shot particle
number calibration is presented.
Involved research facilities
- Draco
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Lecture (Conference)
BLIN5 Workshop 2022, 14.10.2022, Garching, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36233
Preliminary results from the x-ray spectrometers at Draco PW laser facility
Stefanikova, R.; Pan, X.; Smid, M.; Schlenvoigt, H.-P.; Prencipe, I.; Gaus, L.; Umlandt, M. E. P.; Vescovi Pinochet, M. A.; Reimold, M.; Ziegler, T.; Kroll, F.; Kraft, S.; Schramm, U.; Zeil, K.; Metzkes-Ng, J.; Falk, K.
Abstract
A large amount of complex processes within laser-produced plasmas put a huge demand for precise diagnostics methods. For example, x-ray emission spectroscopy can be used to study atomic physics and plasma conditions. Here, we introduce two new x-ray spectrometers installed in the Ion acceleration lab at the Draco PW laser facility. Availability of such diagnostics at the Draco PW Ti:sapphire 30 fs laser system (i.e. ultra-short pulse system) allows not only for studying unique plasma conditions driving the ion acceleration, but also exploring new possibilities for x-ray backlighters suitable for high energy density experiments.
Both spectrometers are utilized for acquisition of Ti spectral lines, but offer different spectral resolution and range. Quartz crystal spectrometer has wider spectral range, including Ti K-α and He-α emission lines in the spectrum, whereas Ge crystal spectrometer focuses on K-α emission lines and offers 1D spatial imaging. We present first results demonstrating the capabilities of both spectrometers.
The first spectroscopic measurements include the emission spectra measurements from flat Ti targets used for proton acceleration calibration and optimization with and without laser pre-pulse and the use of structured targets for enhanced x-ray emission as well as tailoring of the electron spectra for optimization of the proton acceleration process.
Keywords: x-ray spectrometer; laser-produced plasma; characteristic emission lines
Involved research facilities
- Draco
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Poster
17th International Conference on the Physics of Non-Ideal Plasmas, 22.09.2021, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-36232
Fabrication of highly n-type-doped germanium nanowires and Ohmic contacts using ion implantation and flash lamp annealing
Echresh, A.; Prucnal, S.; Li, Z.; Hübner, R.; Ganss, F.; Steuer, O.; Bärwolf, F.; Jazavandi Ghamsari, S.; Helm, M.; Zhou, S.; Erbe, A.; Rebohle, L.; Georgiev, Y.
Abstract
Accurate control of doping and fabrication of metal contacts on n-type germanium nanowires (GeNWs) with low resistance and linear characteristics remain a major challenge in germanium-based nanoelectronics. Here, we present a combined approach to fabricate Ohmic contacts on n-type-doped GeNWs. Phosphorus (P) implantation followed by millisecond rear-side flash lamp annealing was used to produce highly n-type doped Ge with an electron concentration in the order of 10^19 − 10^20 cm^(−3). Electron beam lithography, inductively coupled plasma reactive ion etching, and nickel (Ni) deposition were used to fabricate GeNW-based devices with symmetric Hall bar configuration, which allows detailed electrical characterization of the NWs. Afterward, rear-side flash lamp annealing was applied to form Ni germanide at the Ni-GeNWs contacts to reduce the Schottky barrier height. The two-probe current-voltage measurements on n-type-doped GeNWs exhibit linear Ohmic behavior. Also, the size-dependent electrical measurements showed that carrier scattering near the NW surfaces and reduction of the effective NW cross-section dominate the charge transport in the GeNWs.
Keywords: Germanium nanowires; ion implantation; flash lamp annealing; n-type doped; Ohmic contacts; Hall bar configuration
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 36230) publication
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Fabrication of highly n-type-doped germanium nanowires and Ohmic contacts …
ROBIS: 34995 HZDR-primary research data are used by this (Id 36230) publication -
Fabrication of highly n-type-doped germanium nanowires and Ohmic contacts …
RODARE: 1824 HZDR-primary research data are used by this (Id 36230) publication
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ACS Applied Electronic Materials 4(2022), 5256-5266
DOI: 10.1021/acsaelm.2c00952
Cited 1 times in Scopus
Downloads
- Final Draft PDF 30,8 MB Secondary publication
Permalink: https://www.hzdr.de/publications/Publ-36230
Impact of pre-plasma tailoring on K-ɑ emission and proton acceleration
Stefanikova, R.; Pan, X.; Smid, M.; Gaus, L.; Kraft, S.; Kroll, F.; Kozlová, M.; Prencipe, I.; Reimold, M.; Schlenvoigt, H.-P.; Umlandt, M. E. P.; Schramm, U.; Zeil, K.; Metzkes-Ng, J.; Falk, K.
Abstract
Laser-produced plasmas are widely studied complex systems. In order to get better understanding of their inner processes, advanced diagnostics methods have to be used to get a valuable insight – for example, x-ray emission spectroscopy has the capability to unfold atomic processes and plasma conditions and reveal information about the hot electron population.
Recently, two x-ray crystal spectrometers were installed in the Ion Acceleration Lab at Draco PW laser facility, which allows to acquire characteristic emission spectra including Ti K-α and He-α lines from Ti targets. While quartz spectrometer offers wide spectral range and excellent spectral resolution of ∼ 0.3 eV, Ge spectrometer focuses on Ti K-α emission lines and provides 1D spatial imaging with resolution below 10 μm.
Here, we present the first results from the x-ray spectroscopic measurements from proton acceleration targets at the DRACO PW laser facility uncovering the plasma conditions and electron dynamics for various target and laser configurations including inclusion artificial pre-pulse or the use of reduced mass targets.
Involved research facilities
- Draco
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Poster
(Online presentation)
The 48th European Conference on Plasma Physics (2022), 01.07.2022, Maastricht (online), Netherlands
Permalink: https://www.hzdr.de/publications/Publ-36229
Clarifying space use concepts in ecology: range vs. occurrence distributions
Alston, J.; Fleming, C.; Noonan, M.; Tucker, M.; Silva, I.; Folta, C.; Akre, T.; Ali, A.; Belant, J.; Beyer, D.; Blaum, N.; Boehning-Gaese, K.; Cunha De Paula, R.; Dekker, J.; Drescher-Lehman, J.; Farwig, N.; Fichtel, C.; Fischer, C.; Ford, A.; Janssen, R.; Jeltsch, F.; Kappeler, P.; Lapoint, S.; Markham, A.; Medici, P.; Morato, R.; Nathan, R.; Olson, K.; Patterson, B.; Petroelje, T.; Ramalho, E.; Roesner, S.; Santos, L.; Schabo, D.; Selva, N.; Sergiel, A.; Spiegel, O.; Ullman, W.; Zieba, F.; Zwijacz-Kozica, T.; Wittemyer, G.; Fagan, W.; Mueller, T.; Calabrese, J.
Abstract
Quantifying animal movements is necessary for answering a wide array of research questions in ecology and conservation biology. Consequently, ecologists have made considerable efforts to identify the best way to estimate an animal’s home range, and many methods of estimating home ranges have arisen over the past half century. Most of these methods fall into two distinct categories of estimators that have only recently been described in statistical detail: those that measure range distributions (methods such as Kernel Density Estimation that quantify the long-run behavior of a movement process that features restricted space use) and those that measure occurrence distributions (methods such as Brownian Bridge Movement Models and the Correlated Random Walk Library that quantify uncertainty in an animal movement path during a specific period of observation). In this paper, we use theory, simulations, and empirical analysis to demonstrate the importance of applying these two classes of space use estimators appropriately and distinctly. Conflating range and occurrence distributions can have serious consequences for ecological inference and conservation practice. For example, in most situations, home-range estimates quantified using occurrence estimators are too small, and this problem is exacerbated by ongoing improvements in tracking technology that enable more frequent and more accurate data on animal movements. We encourage researchers to use range estimators to estimate the area of home ranges and occurrence estimators to answer other questions in movement ecology, such as when and where an animal crosses a linear feature, visits a location of interest, or interacts with other animals.
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Contribution to WWW
https://www.biorxiv.org/content/10.1101/2022.09.29.509951v1.full.pdf
DOI: 10.1101/2022.09.29.509951
Permalink: https://www.hzdr.de/publications/Publ-36228
Study of x-ray emission from proton acceleration targets at Draco PW laser facility
Stefanikova, R.; Pan, X.; Meckel, N.; Smid, M.; Schlenvoigt, H.-P.; Prencipe, I.; Kozlová, M.; Gaus, L.; Umlandt, M. E. P.; Vescovi Pinochet, M. A.; Reimold, M.; Ziegler, T.; Kroll, F.; Kraft, S.; Schramm, U.; Zeil, K.; Metzkes-Ng, J.; Falk, K.
Abstract
Laser plasma-based ion accelerators are very promising candidates for many applications. In order to ensure the reliability of such accelerators a comprehensive set of diagnostics is required. X-ray emission spectroscopy allows us to directly measure the plasma conditions of the laser-plasma interaction and also provides information about the hot electron population through the cold K-α emission production.
Here, we present preliminary results from two new x-ray spectrometers used to study interaction regimes relevant for laser-driven ion acceleration at ultra-short pulse PW-class laser facility. We acquired the emission spectra from flat Ti targets for a range of target thicknesses and laser energies. Additionally, artificial laser pre-pulses were added to alter the laser absorption efficiency.
Keywords: x-ray spectroscopy; laser-produced plasma; characteristic emission lines; laser-plasma ion acceleration
Involved research facilities
- Draco
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Lecture (Conference)
(Online presentation)
DPG-Frühjahrstagung, 28.03.2022, Mainz, online, Germany
Permalink: https://www.hzdr.de/publications/Publ-36227
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