Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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35670 Publications

Data publication: Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock

Demnitz, M.; Molodtsov, K.; Schymura, S.; Schierz, A.; Müller, K.; Jankovsky, F.; Havlova, V.; Stumpf, T.; Schmidt, M.

In the following we have compiled the data used in publication (mappings, taken pictures and measurements) as well as the used python scripts.

Keywords: curium; luminescence; crystalline rock; granite; sorption; correlative spectroscopy

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-09-21
    DOI: 10.14278/rodare.1190
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33137
Publ.-Id: 33137


Tungsten Oxide/Reduced Graphene Oxide Aerogel with Low-Content Platinum as High-Performance Electrocatalyst for Hydrogen Evolution Reaction

Li, Y.; Jiang, K.; Yang, J.; Zheng, Y.; Hübner, R.; Ou, Z.; Dong, X.; He, L.; Wang, H.; Li, J.; Sun, Y.; Lu, X.; Zhuang, X.; Zheng, Z.; Liu, W.

Designing cost-effective, highly active, and durable platinum (Pt)-based electrocatalysts is a crucial endeavor in electrochemical hydrogen evolution
reaction (HER). Herein, the low-content Pt (0.8 wt%)/tungsten oxide/reduced graphene oxide aerogel (LPWGA) electrocatalyst with excellent HER activity and durability is developed by employing a tungsten oxide/reduced graphene oxide aerogel (WGA) obtained from a facile solvothermal process as a support, followed by electrochemical deposition of Pt nanoparticles. The WGA support with abundant oxygen vacancies and hierarchical pores plays the roles of anchoring the Pt nanoparticles, supplying continuous mass transport and electron transfer channels, and modulating the surface electronic state of Pt, which endow the LPWGA with both high HER activity and durability. Even under a low loading of 0.81 μgPt cm-2, the LPWGA exhibits a high HER activity with an overpotential of 42 mV at 10 mA cm-2, an excellent stability under 10000-cycle cyclic voltammetry and 40 h chronopotentiometry at 10 mA cm-2, a low Tafel slope (30 mV dec-1), and a high turnover frequency of 29.05 s-1 at η = 50 mV, which is much superior to the commercial Pt/C and the low-content Pt/reduced graphene oxide aerogel. This work provides a new strategy to design high-performance Pt-based electrocatalysts with greatly reduced use of Pt.

Permalink: https://www.hzdr.de/publications/Publ-33133
Publ.-Id: 33133


Development and preliminary evaluation of [18F]JHU94620-d8 for PET imaging of cannabinoid receptors type 2

Moldovan, R. P.

The development PET radioligands for imaging of the cannabinoid type 2 receptors (CB2R) has been intensively explored due to their upregulation in various pathological conditions [1]. Recently, we reported the development of [18F]JHU94620 [2], however, this radioligand suffered from low metabolic stability in vivo. Here, we describe the development of the deuterated analogues [18F]JHU94620-d4 and -d8 as well as their biological evaluation (Figure 1). The precursors for radiofluorination were obtained by coupling 4,5-dimethylthiazol-ylidene-2,2,3,3-tetramethylcyclopropane-1-carboxamide with either d4 or d8 1,4-butanediol-bistosylate and radiofluorinated in the presence of Kryptand K2.2.2. and K2CO3. [18F]JHU94620-d4 and -d8 were obtained in 10% radiochemical yield and >99% radiochemical purity. The fraction of radiometabolites was quantified in mice plasma, brain and spleen of CD1 mice at 30 min p.i. Both [18F]JHU94620-d4 and -d8 demonstrated an improved metabolic stability with 80% intact radioligand detected in the brain vs. 36% for [18F]JHU94620. The CB2 affinity and specificity of [18F]JHU94620-d8 was determined by in vitro binding experiments and a KD(rCB2) of 0.36 nM was determined. Additionally, we evaluated the [18F]JHU94620-d8 uptake by PET-studies into the spleen of healthy rats and in a rat model carrying an adeno-associated viral (AAV2/7) vector expressing hCB2R(D80N) at high densities in the right striatum (hCB2-rs) [3, 4]. Our PET study with [18F]JHU94620-d8 revealed a rCB2 specific uptake into the spleen (AUC0-30min = 33 vs. 17 SUV min after blocking with GW405833). In the hCB2-rs model we could show a target specific uptake of [18F]JHU94620-d8 with a constant SUV of 6.7±0.3 from 6 to 60 min p.i. and an SUVr (right striatum-to-cerebellum) of 43±7at 60 min p.i., as well as a reversible binding in displacement studies. Thus, [18F]JHU94620-d8 is a new PET tracer with improved metabolic stability and excellent ability to image the CB2 receptors in-vivo. Its further evaluation is underway.

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    DPhG Annual Meeting 2021 Trends and Perspectives in Pharmaceutical Sciences, 30.09.2021, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-33132
Publ.-Id: 33132


LDOS/SNAP data for MALA: Aluminium at 298K and 933K

Ellis, J. A.; Fiedler, L.; Popoola, G. A.; Modine, N. A.; Stephens, J. A.; Thompson, A. P.; Cangi, A.; Rajamanickam, S.

LDOS/SNAP data for MALA: Aluminium at 298K and 933K (liquid+solid).

Code development was done jointly by the authors.

The calculations have mainly been performed by:
DFT-MD snapshots / DFT calculations (LDOS data): N. A. Modine (at SNL)

SNAP data generation: A. P. Thompson (at SNL)

Neural network training: J. A. Ellis (ORNL, formerly SNL), G. A. Popoola (SNL), L. Fiedler (HZDR)

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-08
    DOI: 10.14278/rodare.1106
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33121
Publ.-Id: 33121


Data associated with the publication "The relevance of electronic perturbations in the warm dense electron gas"

Moldabekov, Z.; Dornheim, T.; Böhme, M.; Vorberger, J.; Cangi, A.

This repository contains the Kohn-Sham density functional theory (KS-DFT) and path-integral Monte-Carlo (PIMC) data used in the journal publication "The relevance of electronic perturbations in the warm dense electron gas".

Keywords: Density Functional Theory; Path-Integral Monte-Carlo; Electronic Structure Theory

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-09-15
    DOI: 10.14278/rodare.1186
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33115
Publ.-Id: 33115


Advancement of Mineral Processing Simulation Platforms for the Integration of Water Quality – Process Performance Interactions in Water Management Systems (Raw Data)

Michaux, B.

Files are containing the raw data of the dissertation:

Title: Advancement of Mineral Processing Simulation Platforms for the Integration of Water Quality – Process Performance Interactions in Water Management Systems

Author: M.Sc. Bruno Benjamin Xavier Michaux

Faculty: Faculty of Mechanical, Process and Energy Engineering of the Technische Universität Bergakademie Freiberg

Year: 2021

It contains 3 Excel sheets:

  • One for the flotation kinetics data
  • One for the water composition data in flotation
  • One for the water composition data in the mill.

Furthermore it contains a student report from 2017 which is describing the preparation of the synthetic water by

Miaad Farhan Fadami
Research Intern
miaad.farhanfadami@mail.mcgill.ca

Keywords: Flotation; Mineral Processing; Mining; Water

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-09-14
    DOI: 10.14278/rodare.1184
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33111
Publ.-Id: 33111


SIMS analytics of quartz

Renno, A.

Secondary ion mass spectrometry (SIMS), as a high-precision, spatially resolved analytical method, is an alternative to the standard LA-ICP-MS and EPMA methods of quartz analysis. Quartz, with its "notoriously low" trace element contents, presented a welcome challenge from the beginning of the routine application of SIMS methods in mineralogy. In the course of instrument development, there has been an increasingly intensive instrumental differentiation of SIMS instruments. Today, it is possible to analyze almost all naturally occurring elements (H-U), isotope ratios as well as molecular ions and molecular fragments with resolutions from the millimeter to the nanometer range using SIMS. In principle, this allows its use in solving a variety of scientific problems closely related to quartz. Examples are the clarification of crystallochemical questions of the incorporation of different ions into the quartz lattice, questions of element diffusion (e.g. Li, Ti or H) in quartz, the determination of causes for certain spectroscopic features (e.g. CL or EPR), the reconstruction of formation conditions via isotope ratios (O, Si, Li or H), the application of geothermometers (e.g. TitaniQ), the mechanical behavior of quartz as a function of hydrogen content, provenance analyses for natural rocks but also archaeological artifacts, exploration-related questions for quartz deposits and in particular for deposits in which quartz occurs as a genetic-critical accompanying mineral, up to problems of quality testing and quality assurance of high-purity quartz and the engineering evaluation of processing technologies in particular flotation for quartz extraction.
The main limitation of SIMS is the extreme matrix dependence of secondary ion yield. This requires the use of meticulously characterized reference materials (Audétat et al., 2015). New promising developments in this field will be presented (Nachlas, 2016; Wu et al., 2019).
New instrumental developments such as the positive ion SIMS-SSAMS (Grabowski et al., 2019), the Super-SIMS (Rugel et al., 2016) or SIMS analysis in specially modified helium microscopes (Wirtz et al., 2019) and associated enhanced analytical capabilities of quartz will be presented.

References:

Audétat, A., Garbe-Schönberg, D., Kronz, A., Pettke, T., Rusk, B., Donovan, J.J. and Lowers, H.A. (2015) Characterisation of a Natural Quartz Crystal as a Reference Material for Microanalytical Determination of Ti, Al, Li, Fe, Mn, Ga and Ge. Geostandards and Geoanalytical Research 39, 171-184.
Grabowski, K.S., Groopman, E.E., Rock, B.Y. and Imam, M.A. (2019) Positive ion SIMS-SSAMS for trace analysis of materials. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 455, 158-164.
Nachlas, W.O. (2016) Precise and Accurate Doping of Nanoporous Silica Gel for the Synthesis of Trace Element Microanalytical Reference Materials. Geostandards and Geoanalytical Research 40, 505-516.
Rugel, G., Pavetich, S., Akhmadaliev, S., Baez, S.M.E., Scharf, A., Ziegenrucker, R. and Merchel, S. (2016) The first four years of the AMS-facility DREAMS: Status and developments for more accurate radionuclide data. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms 370, 94-100.
Wirtz, T., Castro, O.D., Audinot, J.-N. and Philipp, P. (2019) Imaging and Analytics on the Helium Ion Microscope. Annual Review of Analytical Chemistry 12, 523-543.
Wu, H., Böttger, R., Couffignal, F., Gutzmer, J., Krause, J., Munnik, F., Renno, A.D., Hübner, R., Wiedenbeck, M. and Ziegenrücker, R. (2019) ‘Box-Profile’ Ion Implants as Geochemical Reference Materials for Electron Probe Microanalysis and Secondary Ion Mass Spectrometry. Geostandards and Geoanalytical Research 43, 531-541.

Keywords: SIMS; Mineralogy; Geochemistry; Quartz

  • Lecture (Conference)
    QUARTZ2021 - International Symposium on Quartz, 05.-07.09.2021, Tønsberg, Norge

Permalink: https://www.hzdr.de/publications/Publ-33110
Publ.-Id: 33110


Temperature determination during Flash Lamp Annealing

Begeza, V.; Rebohle, L.; Schumann, T.

Flash lamp annealing (FLA) is a modern technology for the thermal treatment of materials which currently opens up new application areas. During FLA, an intense pulse of light with a pulse duration of milliseconds and below is applied to the surface of a material. In contrast to traditional methods like furnace annealing, temperature now strongly depends on the material properties and the thickness of the sample. In addition, the short time scale leads to a temperature distribution over depth and makes direct temperature measurements very challenging.
In this work we first review in brief the existing possibilities for a direct temperature measurement during FLA. The main part presents our own concept which is a combination of direct measurements, calibration and thermodynamic simulation. The latter point is of special interest as it allows to get information about the temperature distribution within the material, provided that the relevant material parameters are known. Finally, the impact of such temperature distributions on physical processes like diffusion, crystallization and phase formation is discussed.

Keywords: Flash Lamp Annealing; Short time annealing; Temperature determination

  • Invited lecture (Conferences) (Online presentation)
    CERC 2021, 09.-10.09.2021, Cork, Irland

Permalink: https://www.hzdr.de/publications/Publ-33106
Publ.-Id: 33106


Not just a background: pH buffers do interact with lanthanide ions – a Europium(III) case study

Mandal, P.; Kretzschmar, J.; Drobot, B.

The interaction between Eu(III) ion and different pH buffers, popular in biology and biochemistry viz. HEPES, PIPES, MES, MOPS, and TRIS have been studied by solution nuclear magnetic resonance spectroscopy (NMR) and time-resolved laser-induced fluorescence spectroscopy (TRLFS) techniques. The Good’s buffers reveal non-negligible interaction with Eu(III) as determined from their complex stability constants, where the sites of interaction are the morpholine and piperazine nitrogen atoms, respectively. In contrast, TRIS buffer shows practically no affinity towards Eu(III). Therefore, when investigating lanthanides, TRIS buffer should be preferred over Good’s buffers. 

Keywords: Europium; Buffer; TRLFS; NMR; Stability Constant

  • Software in the HZDR data repository RODARE
    Publication date: 2021-09-09
    DOI: 10.14278/rodare.1147
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33100
Publ.-Id: 33100


Raw data related to publication entitled "Turbulent resuspension of micron particles from a wall surface functionalized with cylindrical micropillars" by Banari, A. et al.

Lecrivain, G.
Project Leader: Lecrivain, Gregory

# 'Flowrate.JPG': Table associating a raw image (see 'org' folder below) with the flow rate (Q) in L/min

# 'Rough': raw data obtained with the rough substrate

# 'Smooth': raw data obtained with the smooth substrate

# "Smooth" and "Rough" folders contain a list of subfolders Mi, with i=0,1,2,... the measurement index. Ex: M1: is a first series of measurements and M2: a second series of measurements. Each Mi folder contains the following data:

## 'org': List of pictures (Acquisition_AAA_-BBBBBB.jpg) taken with the high-resolution camera. With AAA=000,001,002,... is the flow rate association. To associate AAA with the flow rate, see 'Flowrate.JPG'. Ex: '000' -> Q = 0 L/min, '001' -> Q = 20 L/min. BBB=000001,000002 or 000003 are pictures of the same particle bed taken at increasing time interval. These 3 pictures are used to check particle bed equilibrium.

## 'pic_CCC.jpg' with CCC=001, 002, 003: simply a copy of the raw picture in 'org' with bed at equilibrium. The association between the index (CCC) and the  flow rate (Q) is identical to that described in 'org' (AAA).

## 'Particles_CCC.csv' with CCC=001, 002, 003: List of particle positions (called tags in the manuscript) in each respective image.

Keywords: Particle resuspension; Particle adhesion; Turbulent gas flow; Surface functionalization; Surface roughness.

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2022-02-01
    DOI: 10.14278/rodare.1145
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33098
Publ.-Id: 33098


Data Publication: Pump-induced terahertz anisotropy in bilayer graphene

Seidl, A.; Anvari, R.; Dignam, M. M.; Richter, P.; Seyller, T.; Schneider, H.; Helm, M.; Winnerl, S.

The raw data and lab book pages are given in the .zip folders. The results of the theoretical calculations in comparison to the experiment are given in Roozbeh_plot.opju. In the other two Origin files, the differential transmission signals and other relevant values are calculated from the raw data.The 2 THz measurement was performed in 2019, the 3.4 THz measurement in 2020.

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-26
    DOI: 10.14278/rodare.1136

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Permalink: https://www.hzdr.de/publications/Publ-33093
Publ.-Id: 33093


Data publication: Controlled and deterministic creation of synthetic antiferromagnetic domains by focused ion beam irradiation

Samad, F.; Hlawacek, G.; Arekapudi, S. S. P. K.; Xu, X.; Koch, L.; Lenz, M.; Hellwig, O.

This data contains results from magnetometry and magnetic force microscopy from the irradiated synthetic antiferromagnets.

Keywords: Bubble domains; Focused ion beam; Sputter deposition; Interlayer exchange coupling; Magnetic hysteresis

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-09-06
    DOI: 10.14278/rodare.1142
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33091
Publ.-Id: 33091


Controlled and deterministic creation of synthetic antiferromagnetic domains by focused ion beam irradiation

Samad, F.; Hlawacek, G.; Arekapudi, S. S. P. K.; Xu, X.; Koch, L.; Lenz, M.; Hellwig, O.

We study layered synthetic antiferromagnets (SAFs) with out-of-plane interface anisotropy, where the layer-wise antiferromagnetic (AF)
alignment is induced by interlayer exchange coupling (IEC). By applying low energy He+ focused ion beam irradiation to the SAF, a depth-dependent
reduction of the IEC and anisotropy can be achieved due to layer intermixing. As a consequence, after irradiation, a specific field
reversal sequence of the SAF is energetically preferred. When tuning the pristine SAF to exhibit an inverted field reversal, we are thus able to
create AF domains in the irradiated regions. When irradiated with a fluence gradient, these AF domains can be further deterministically
manipulated by an external magnetic field. Among other applications, this could be utilized for engineering a controllable and local magnetic
stray field landscape, for example, at AF domain walls, within the otherwise stray field free environment provided by the SAF.

Keywords: Bubble domains; Focused ion beam; Sputter deposition; Interlayer exchange coupling; Magnetic hysteresis

Related publications

Permalink: https://www.hzdr.de/publications/Publ-33090
Publ.-Id: 33090


DYN3D and CTF Coupling within a Multiscale and Multiphysics Software Development (Part I)

Davies, S.; Litskevich, D.; Rohde, U.; Detkina, A.; Merk, B.; Bryce, P.; Levers, A.; Ravindra, V.

Understanding and optimizing the relation between nuclear reactor components or physical phenomena allows us to improve the economics and safety of nuclear reactors, deliver new nuclear reactor designs, and educate nuclear staff. Such relation in the case of the reactor core is described by coupled reactor physics as heat transfer depends on energy production while energy production depends on heat transfer with almost none of the available codes providing full coupled reactor physics at the fuel pin level. A Multiscale and Multiphysics nuclear software development between NURESIM and CASL for LWRs has been proposed for the UK. Improved coupled reactor physics at the fuel pin level can be simulated through coupling nodal codes such as DYN3D as well as subchannel codes such as CTF. In this journal article, the first part of the DYN3D and CTF coupling within the Multiscale and Multiphysics software development is presented to evaluate all inner iterations within one outer iteration to provide partially verified improved coupled reactor physics at
the fuel pin level. Such verification has proven that the DYN3D and CTF coupling provides improved feedback distributions over the DYN3D coupling as crossflow and turbulent mixing are present in the former.

Keywords: Nuclear Reactor; Coupled reactor physics; Nodal code; Subchannel code; DYN3D; CTF; KAIST

Permalink: https://www.hzdr.de/publications/Publ-33089
Publ.-Id: 33089


Modulated rotating waves and triadic resonances in spherical fluid systems: The case of magnetized spherical Couette flow

Garcia Gonzalez, F.; Giesecke, A.; Stefani, F.

The existence of triadic resonances in the magnetized spherical Couette system is related to the development of modulated rotating waves, which are quasiperiodic flows understood in terms of bifurcation theory in systems with symmetry. In contrast to previous studies in spherical geometry, the resonant modes are not inertial waves but related to the radial jet instability, which is strongly equatorially antisymmetric. We propose a general framework in which triadic resonances are generated through successive Hopf bifurcations from the base state. The study relies on an accurate frequency analysis of different modes of the flow, for solutions belonging to two different bifurcation scenarios. The azimuthal and latitudinal nonlinear coupling among the resonant modes is analyzed and interpreted using spherical harmonics, and the results are compared with previous studies in spherical geometry.

Keywords: Spherical Couette Flow

Permalink: https://www.hzdr.de/publications/Publ-33087
Publ.-Id: 33087


Size-Tunable Gold Aerogels: A Durable and Misfocus-Tolerant 3D Substrate for Multiplex SERS Detection

Zhou, L.; Peng, Y.; Zhang, N.; Du, R.; Hübner, R.; Wen, X.; Li, D.; Hu, Y.; Eychmüller, A.

The research on surface-enhanced Raman scattering (SERS) continuously draws wide attention because of its high detection sensitivity. However, the commonly investigated 2D SERS substrates cannot fully utilize the 3D active focal volume and require a tight focus on the correct plane, retarding signal enhancement and flexible use. Here, self-supported gold aerogels of centimeter-dimension with tunable ligament sizes are designed as 3D SERS substrates, featuring hot spots throughout the entire network. Unveiling a universal ligament-size-effect, the optimized gold aerogel showcases much larger enhancement factors compared to a 8 nm Au film toward dyes, pesticides, and carcinogens (up to 109). Aside from an excellent reusability and an exceptional stability (> 1 month), an outstanding misfocus tolerance (>300 μm along the z-axis) is also demonstrated for such aerogel-based SERS substrates for multiplex detection. This work may expand the application scope of metal aerogels and lay the foundation for designing next-generation 3D SERS substrates.

Permalink: https://www.hzdr.de/publications/Publ-33086
Publ.-Id: 33086


The Al Doping Effect on Epitaxial (In,Mn)As Dilute Magnetic Semiconductors Prepared by Ion Implantation and Pulsed Laser Melting

Yuan, Y.; Xie, Y.; Yuan, N.; Wang, M.; Heller, R.; Kentsch, U.; Zhai, T.; Wang, X.

One of the most attractive characteristics of diluted ferromagnetic semiconductors is the possibility to modulate their electronic and ferromagnetic properties, coupled by itinerant holes through various means. A prominent example is the modification of Curie temperature and magnetic anisotropy by ion implantation and pulsed laser melting in III–V diluted magnetic semiconductors. In this study, to the best of our knowledge, we performed, for the first time, the co-doping of (In,Mn)As diluted magnetic semiconductors by Al by co-implantation subsequently combined with a pulsed laser annealing technique. Additionally, the structural and magnetic properties were systematically investigated by gradually raising the Al implantation fluence. Unexpectedly, under a well-preserved epitaxial structure, all samples presented weaken Curie temperature, magnetization, as well as uniaxial magnetic anisotropies when more aluminum was involved. Such a phenomenon is probably due to enhanced carrier localization introduced by Al or the suppression of substitutional Mn atoms.

Permalink: https://www.hzdr.de/publications/Publ-33083
Publ.-Id: 33083


Phase evolution of Te-hyperdoped Si upon furnace annealing

Shaikh, M. S.; Wang, M.; Hübner, R.; Liedke, M. O.; Butterling, M.; Solonenko, D.; Madeira, T. I.; Li, Z.; Xie, Y.; Hirschmann, E.; Wagner, A.; Zahn, D. R. T.; Helm, M.; Zhou, S.

Si hyperdoped with chalcogens via ion implantation and pulsed laser melting is known to exhibit strong room-temperature sub-bandgap photoresponse. As a thermodynamically metastable system, an impairment of the optoelectronic properties in hyperdoped Si materials occurs upon subsequent high-temperature thermal treatment (>500 °C). The substitutional Te atoms that cause the sub-bandgap absorption are removed from the Si matrix to form Te-related complexes, which are electrically and optically inactive. In this work, we explore the formation of defects in Te-hyperdoped Si layers which leads to the electrical deactivation upon furnace annealing through the analysis of optical and microstructural properties as well as positron annihilation lifetime spectroscopy. Particularly, Te-rich clusters are observed in samples thermally annealed at temperatures reaching 950 °C and above. Combined with polarized Raman analysis and transmission electron microscopy, the observed crystalline clusters are suggested to be Si2Te3.

Keywords: Defect analysis; Furnace annealing; Ion-implantation; Positron annihilation spectroscopy; Raman spectroscopy; Silicon telluride; Te-hyperdoped Si; Transmission electron microscopy

Permalink: https://www.hzdr.de/publications/Publ-33082
Publ.-Id: 33082


Strain-induced switching between noncollinear and collinear spin configuration in magnetic Mn5Ge3 films

Xie, Y.; Yuan, Y.; Birowska, M.; Zhang, C.; Cao, L.; Wang, M.; Grenzer, J.; Kriegner, D.; Doležal, P.; Zeng, Y.-J.; Zhang, X.; Helm, M.; Zhou, S.; Prucnal, S.

We report the temperature-dependent magnetic and structural properties of epitaxial Mn5Ge3 thin films grown
on Ge substrates. Utilizing density-functional theory (DFT) calculations and various experimental methods, we
reveal mechanisms governing the switching between collinear and noncollinear spin configuration in Mn5Ge3.
The Mn atoms in Mn5Ge3 occupy two distinct Wyckoff positions with fourfold (Mn1) and sixfold (Mn2)
multiplicity. The DFT calculations reveal that below a critical distance of approximately 3.002 Å the coupling
between Mn2 atoms is antiferromagnetic (AFM) while ferromagnetic (FM) above that critical distance. The FM
coupling between Mn1 atoms is weakly affected by the strain. The observed noncollinear spin configuration is
due to the coexistence of AFM and FM coupling at low temperatures. The findings give insight in developing
strain-controlled spintronic devices.

Permalink: https://www.hzdr.de/publications/Publ-33081
Publ.-Id: 33081


Interfacial Synthesis of Layer-Oriented 2D Conjugated Metal-Organic Framework Films toward Directional Charge Transport

Wang, Z.; Walter, L. S.; Wang, M.; Petkov, P. S.; Liang, B.; Qi, H.; Ngan Nguyen, N.; Hambsch, M.; Zhong, H.; Wang, M.; Park, S.; Renn, L.; Watanabe, K.; Taniguchi, T.; Mannsfeld, S. C. B.; Heine, T.; Kaiser, U.; Zhou, S.; Weitz, T. R.; Feng, X.; Dong, R.

The development of layer-oriented two-dimensional conjugated metal-organic frameworks (2D c-MOFs) enables access to direct charge transport, dial-in lateral/vertical electronic devices, and the unveiling of transport mechanisms but remains a significant synthetic challenge. Here we report the novel synthesis of metal-phthalocyanine-based p-type semiconducting 2D c-MOF films (Cu2[PcM-O8], M = Cu or Fe) with an unprecedented edge-on layer orientation at the air/water interface. The edge-on structure formation is guided by the preorganization of metal-phthalocyanine ligands, whose basal plane is perpendicular to the water surface due to their π-πinteraction and hydrophobicity. Benefiting from the unique layer orientation, we are able to investigate the lateral and vertical conductivities by DC methods and thus demonstrate an anisotropic charge transport in the resulting Cu2[PcCu-O8] film. The directional conductivity studies combined with theoretical calculation identify that the intrinsic conductivity is dominated by charge transfer along the interlayer pathway. Moreover, a macroscopic (cm2 size) Hall-effect measurement reveals a Hall mobility of ∼4.4 cm2 V-1 s-1 for the obtained Cu2[PcCu-O8] film. The orientation control in semiconducting 2D c-MOFs will enable the development of various optoelectronic applications and the exploration of unique transport properties.

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Permalink: https://www.hzdr.de/publications/Publ-33080
Publ.-Id: 33080


Physicochemical constraints on indium-, tin-, germanium-, gallium-, gold-, and tellurium-bearing mineralizations in the Pefka and St Philippos polymetallic vein- and breccia-type deposits, Greece

Voudouris, P.; Repstock, A.; Spry, P. G.; Frenzel, M.; Mavrogonatos, C.; Keith, M.; Tarantola, A.; Melfos, V.; Tombros, S.; Zhai, D.; Cook, N. J.; Ciobanu, C. L.; Schaarschmidt, A.; Rieck, B.; Kolitsch, U.; Falkenberg, J. J.

The Pefka Cu-Au-Te-In-Se and nearby St Philippos Pb-Zn-Bi-Sn-Ge-Ga-In vein- and breccia-type deposits in western Thrace, Greece, display strong similarities, but also differences in terms of mineralization style, ore mineralogy, and chemistry, and host rock compositions. The Pefka mineralization consists of two crosscutting vein systems with high sulfidation (HS)- and intermediate-sulfidation (IS) assemblages hosted by andesitic lavas and is unusually enriched in In (up to 700 ppm), Te (>1000 ppm), Se (>100 ppm), and Cu (>1 wt%). The main In-carriers are roquesite (CuInS2) and In-bearing “tennantite-(Cu)” and Cu-rich “tennantite-(In)” which contains up to 6.5 wt% In, substituting into the C site. Roquesite is associated with enargite and arsenosulvanite/colusite, as part of the HS assemblage at Pefka. Selenium-bearing galena and a large suite of tellurides including calaverite, sylvanite, petzite, hessite, kostovite, empressite, tellurantimony, and coloradoite, in addition to native tellurium, account for the marked tellurium and selenium enrichment in the ores from Pefka. Tellurides and native gold at Pefka accompany the precipitation of Te-bearing minerals of the tetrahedrite group, such as “stibiogoldfieldite” and “arsenogoldfieldite”, and Cu-excess varieties of tetrahedrite and tennantite. However, the bulk of telluride deposition is associated with normal, fully substituted tetrahedrite-tennantite varieties.

The St Philippos deposit is associated with a brecciated fault zone hosted by Eocene sandstones and Oligocene quartz-feldspar porphyry dikes. It is enriched in a large suite of incompatible elements, including Bi (>2000 ppm), Sn (>100 ppm), U (up to 200 ppm), Pb (>1 wt%), Zn (>1 wt%), Mo (up to 62 ppm), Ge (>100 ppm), Ga (up to 466 ppm) and In (up to 222 ppm), contrasting with the element suite defining the nearby Pefka deposit. The main carrier of In, Ga, and Ge is sphalerite (and wurtzite) with In-rich zones in sphalerite containing up to 6.1. wt% In. Germanium and Ga in sphalerite reach concentrations of up to 0.27 and 0.32 wt%, respectively. Sphalerite from the St Philippos deposit is extremely Fe-poor (<0.04 wt%), and is associated with an unusual suite of Sn-bearing sulfosalts (kësterite-stannite, Mn-bearing kësterite, unnamed Cu2MnSnS4), and enargite, marking an early HS event. Kësterite also hosts indium (up to 0.6 wt% In). Mn-bearing varieties of tennantite host inclusions of minor tellurides (e.g., hessite, altaite, and tsumoite) and formed later in the paragenetic sequence under transitional HS-IS and IS conditions.

Both deposits are characterized by early high-temperature (>300 °C) and HS fluid conditions, followed by IS assemblages as temperatures waned. Rhyolitic oxidized magmas are considered to be the sources of metals in the St Philippos deposit; however, their anomalous W, Sn, U, and Bi contents suggest a contamination by crustal rocks. The Cu-Au-Te signature of the Pefka deposit is compatible with a genetic relationship to less fractionated andesitic magmas, although a possible contribution of In from rhyolitic magmas could explain the high In contents of the ore. However, other factors, as for example different metal-deposition mechanisms resulting in metal zonation around causative porphyry centers at depth, may also account for the observed metal endowment in these two deposits. The Sn-Te-In-(Ge-Ga) element association at Pefka and St Philippos is unusual in that it has been previously reported from only a few other places in the world (e.g., Capillitas deposit, Argentina, and the Kawazu deposit, Japan). We conclude based on this exotic mineralization-style that the northeastern part of Greece represents an area of great potential for the exploitation of critical metals and metalloids.

Keywords: Critical metals; Greece; High-intermediate sulfidation; Magmatic-hydrothermal

Permalink: https://www.hzdr.de/publications/Publ-33079
Publ.-Id: 33079


Probing charged lepton flavor violation with the Mu2e experiment

Müller, S.; Ferrari, A.; Knodel, O.; Rachamin, R.

Presentation a 2021 DPG meeting (section "Matter & Cosmos"), September1, 2021

Keywords: MU2E; Charged Lepton Flavor Violation; DPG

  • Lecture (Conference) (Online presentation)
    DPG Meeting SMUK, 30.08.-03.09.2021, virtuell, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-33077
Publ.-Id: 33077


Checkliste zur Unterstützung der Helmholtz-Zentren bei der Implementierung von Richtlinien für nachhaltige Forschungssoftware

Messerschmidt, R.; Pampel, H.; Bach, F.; Zu Castell, W.; Denker, M.; Finke, A.; Fritzsch, B.; Hammitzsch, M.; Konrad, U.; Leifels, J.; Möhl, C.; Nolden, M.; Scheinert, M.; Schlauch, T.; Schnicke, T.; Steglich, D.

Mit der voranschreitenden Digitalisierung von Forschung und Lehre steigt die Zahl an Software-Lösungen, die an wissenschaftlichen Einrichtungen entstehen und zur Erkenntnisgewinnung genutzt werden. Die – unter dem Stichwort Open Science geforderte – Zugänglichkeit und Nachnutzung von wissenschaftlichen Ergebnissen kann in vielen Fachgebieten nur sichergestellt werden, wenn neben Forschungsdaten auch Programmcode offen zugänglich gemacht wird. Die vorliegende Handreichung richtet sich an Entscheider*innen in den Helmholtz-Zentren, die sich mit der Implementierung von Richtlinien für nachhaltige Forschungssoftware befassen. Sie ergänzt eine Muster-Richtlinie, die den Zentren bereits eine richtungsweisende und nachnutzbare Vorlage zur Erstellung von Regelungen für einen nachhaltigen Umgang mit Forschungssoftware gibt.

Keywords: Research Software; Open Access; Checkliste; Regelung; Software Policy

Permalink: https://www.hzdr.de/publications/Publ-33076
Publ.-Id: 33076


ARIEL - Accelerator and Research reactor Infrastructures for Education and Learning

Beyer, R.; Junghans, A.

Status and news from ARIEL

Keywords: ARIEL; nELBE

  • Invited lecture (Conferences) (Online presentation)
    ENEN Special Event 2021 - Outlook of nuclear ETKM activities, 03.03.2021, Brussels, Belgium

Permalink: https://www.hzdr.de/publications/Publ-33073
Publ.-Id: 33073


The nELBE neutron time-of-flight facility

Beyer, R.; Junghans, A.; Kögler, T.; Schwengner, R.; Urlaß, S.; Wagner, A.

The neutron time-of-flight facility nELBE at Helmholtz-Zentrum Dresden-Rossendorf features the first photo-neutron source at a superconducting electron accelerator. The electrons are focused onto a liquid lead target to produce bremsstrahlung which in turn produces neutrons via photo-nuclear reactions. The emitted neutron spectrum ranges from about 10 keV up to 15 MeV with a source strength of above 10¹¹ neutrons per second. The very precise time structure of the accelerator with a bunch width of a few ps enables time-of-flight measurements at very short flight path and experiments to investigate the time response of novel detector concepts.
The high repetition rate of 100 to 400 kHz in combination with the low instantaneous flux and the absence of any moderating materials provide favorable background conditions.
The very flexible beam properties at nELBE enable a broad range of nuclear physics experiments. Examples for the versatility of nELBE will be presented: From transmission measurements and inelastic neutron scattering and fission experiments to determine nuclear reaction cross sections with relevance for fundamental nuclear physics, reactor safety calculations, nuclear transmutation or particle therapy to experiments to investigate the response of novel particle detectors e.g. for dark matter search experiments, nuclear instrumentation or the range verification in cancer treatment.

  • Poster (Online presentation)
    The 7th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications ANIMMA 2021, 21.-25.06.2021, Prague, Czech Republic
  • Lecture (Conference) (Online presentation)
    The 7th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications ANIMMA 2021, 21.-25.06.2021, Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-33072
Publ.-Id: 33072


Timing of native metal-arsenide (Ag-Bi-Co-Ni-As±U) veins in continental rift zones – In situ U-Pb geochronology of carbonates from the Erzgebirge/Krušné Hory province

Guilcher, M.; Albert, R.; Gerdes, A.; Gutzmer, J.; Burisch, M.

Hydrothermal native metal-arsenide (five-element or Ag-Bi-Co-Ni-As±U) veins are a globally occurring mineralization style, which is particularly prevalent across Central Europe. Due to the limited amount of geochronological data available, the timing and the detailed geodynamic setting in which this mineralization style formed remains insufficiently understood. To fill this gap in knowledge, we applied innovative LA-ICP-MS U-Pb geochronology on carbonates from six districts in the Erzgebirge/Krušné Hory province of Germany and Czech Republic in order to constrain the timing of ore formation in the context of the geodynamic framework of Central Europe. In situ U-Pb ages of twelve samples, including dolomite-ankerite, calcite, and siderite coeval with Ni-Co-Fe-arsenides, range from ~129 to ~86 Ma. The ages of native metal-arsenide and fluorite-barite-Pb-Zn veins from the same occurrence (Annaberg-Buchholz district) are found to be consistent with each other, providing new and direct geochronological evidence that these two styles of mineralization are genetically related and may form coevally within one hydrothermal system. Complemented with available geochronological data from other occurrences, the formation of native metal-arsenide assemblage in Central Europe can be related to continental rifting affiliated with the Mesozoic opening of the Atlantic and Alpine Tethys Oceans (~200–100 Ma). The youngest age of ~86 Ma coincide with basin inversion associated with the onset of Alpine compressional tectonics, which most likely terminates the conditions favorable for the formation of native metal-arsenide mineralization in Europe. The onset of native metal-arsenide formation in proximal positions to the main rift axis starts at ~230–200 Ma (Penninic Alps, Anti-Atlas). In contrast, it occurs systematically later with increasing distance to the rift axis – namely at ~200–130 Ma in intermediate (Schwarzwald, Odenwald, Spessart) and ~140–86 Ma in distal (Erzgebirge, Harz) positions to the main rift axis.

Keywords: Arsenide; Carbonate geochronology; Cobalt; Erzgebirge; Five-element mineralization; U-Pb LA-ICP

Permalink: https://www.hzdr.de/publications/Publ-33064
Publ.-Id: 33064


DFT Surrogate modeling with the Materials Learning Algorithms (MALA) – Theoretical Background

Fiedler, L.

MALA (Materials Learning Algorithms) is a data-driven framework to generate surrogate models of density functional theory calculations based on machine learning. Its purpose is to enable multiscale modeling by bypassing computationally expensive steps in state-of-the-art density functional simulations. In this talk, an overview over the theoretical background that enables estimation of physical quantities based on the local density of states (LDOS) is given.

Keywords: Density Functional Theory; Machine Learning

  • Open Access Logo Lecture (Conference) (Online presentation)
    (TD)DFT Student Seminar Series (#5), 03.08.2021, Newark, USA

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Permalink: https://www.hzdr.de/publications/Publ-33063
Publ.-Id: 33063


Scale-dependent anisotropy, energy transfer and intermittency in bubble-laden turbulent flows

Ma, T.; Ott, B.; Fröhlich, J.; Bragg, A.

Data from Direct Numerical Simulations of disperse bubbly flows in a vertical channel are used
to study the effect of the bubbles on the carrier-phase turbulence. We developed a new method,
based on an extension of the barycentric map approach, that allows to quantify and visualize the
anisotropy and componentiality of the flow at any scale. Using this we found that the bubbles
significantly enhance anisotropy in the flow at all scales compared with the unladen case, and
that for some bubble cases, very strong anisotropy persists down to the smallest scales of the
flow. The strongest anisotropy observed was for the cases involving small bubbles. Concerning
the energy transfer among the scales of the flow, our results indicate that for the bubble-laden
cases, the energy transfer is from large to small scales, just as for the unladen case. However,
there is evidence of an upscale transfer when considering the transfer of energy associated with
particular components of the velocity field. Although the direction of the energy transfer is the
same with and without the bubbles, the behaviour of the energy transfer is significantly modified
by the bubbles, suggesting that the bubbles play a strong role in altering the activity of the
nonlinear term in the flow. The skewness of the velocity increments also reveal a strong effect of
the bubbles on the flow, changing both its sign and magnitude compared with the single-phase
case. We also consider the normalized forms of the fourth-order structure functions, and the
results reveal that the introduction of bubbles into the flow strongly enhances intermittency in the
dissipation range, but suppresses it at larger scales. This strong enhancement of the dissipation
scale intermittency has significant implications for understanding how the bubbles might modify
the mixing properties of turbulent flows.

Keywords: turbulence; bubbly flows

Permalink: https://www.hzdr.de/publications/Publ-33057
Publ.-Id: 33057


Implementing Heterogeneous Crystal Surface Reactivity in Reactive Transport Simulations: The Example of Calcite Dissolution

Karimzadeh, L.; Fischer, C.

Both surface reactivity and fluid dynamics control the dissolution kinetics of crystalline material. In this study, we performed a 3D reactive transport simulation to investigate the impact of surface topography heterogeneity superimposed to fluid transport heterogeneity on the dissolution rate of calcite. The
model simulates the chemical reaction of calcite dissolution, solute transport, and crystal surface geometry evolution. Importantly, we introduce heterogeneous surface reactivity into the reactive transport simulation. We test the surface slope factor as a proxy value for the intrinsic surface reactivity of dissolving crystal surface nanotopographies. Experimental data sets collected using vertical scanning interferometry validate this approach. The novel parametrization allows for the simulation of surface-controlled heterogeneous reactivity in reactive transport simulations of mineral surface dissolution.

Keywords: reactive transport modeling; crystal surface reactivity; rate map; dissolution rate variability; calcite dissolution

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  • Secondary publication expected from 26.08.2022

Permalink: https://www.hzdr.de/publications/Publ-33053
Publ.-Id: 33053


Multiscale modelling for fusion and fission materials: the M4F project

Malerba, L.; Caturla, M. J.; Gaganidze, E.; Kaden, C.; Konstantinović, M. J.; Olsson, P.; Robertson, C.; Rodney, D.; Ruiz-Moreno, A. M.; Serrano, M.; Aktaa, J.; Anento, N.; Austin, S.; Bakaev, A.; Balbuena, J. P.; Bergner, F.; Boioli, F.; Boleininger, M.; Bonny, G.; Castin, N.; Chapman, J. B. J.; Chekhonin, P.; Clozel, M.; Devincre, B.; Dupuy, L.; Diego, G.; Dudarev, S. L.; Fu, C. C.; Gatti, R.; Gélébart, L.; Gómez-Ferrer, B.; Gonçalves, D.; Guerrero, C.; Gueye, P. M.; Hähner, P.; Hannula, S. P.; Hayat, Q.; Hernández-Mayoral, M.; Jagielski, J.; Jennett, N.; Jiménez, F.; Kapoor, G.; Kraych, A.; Khvan, T.; Kurpaska, L.; Kuronen, A.; Kvashin, N.; Libera, O.; Ma, P. W.; Manninen, T.; Marinica, M. C.; Merino, S.; Meslin, E.; Mompiou, F.; Mota, F.; Namburi, H.; Ortiz, C. J.; Pareige, C.; Prester, M.; Rajakrishnan, R. R.; Sauzay, M.; Serra, A.; Simonovski, I.; Soisson, F.; Spätig, P.; Tanguy, D.; Terentyev, D.; Trebala, M.; Trochet, M.; Ulbricht, A.; Vallet, M.; Vogel, K.; Yalcinkaya, T.; Zhao, J.

The M4F project brings together the fusion and fission materials communities working on the prediction of radiation damage production and evolution and its effects on the mechanical behaviour of irradiated ferritic/martensitic (F/M) steels. It is a multidisciplinary project in which several different experimental and computational materials science tools are integrated to understand and model the complex phenomena associated with the formation and evolution of irradiation induced defects and their effects on the macroscopic behaviour of the target materials. In particular the project focuses on two specific aspects: (1) To develop physical understanding and predictive models of the origin and consequences of localised deformation under irradiation in F/M steels; (2) To develop good practices and possibly advance towards the definition of protocols for the use of ion irradiation as a tool to evaluate radiation effects on materials. Nineteen modelling codes across different scales are being used and developed and an experimental validation programme based on the examination of materials irradiated with neutrons and ions is being carried out. The project enters now its 4th year and is close to delivering high-quality results. This paper overviews the work performed so far within the project, highlighting its impact for fission and fusion materials science.

Permalink: https://www.hzdr.de/publications/Publ-33052
Publ.-Id: 33052


Metal–Insulator Transition via Ion Irradiation in Epitaxial La0.7Sr0.3MnO3-δ Thin Films

Cao, L.; Herklotz, A.; Rata, D.; Yin, C.; Petracic, O.; Kentsch, U.; Helm, M.; Zhou, S.

Complex oxides provide rich physics related to ionic defects. For the proper tuning of functionalities in oxide heterostructures, it is highly desired to develop fast, effective and low temperature routes for the dynamic modification of defect concentration and distribution. In this work, we report on the use of helium-implantation to efficiently control the vacancy profiles in epitaxial La0.7Sr0.3MnO3-δ thin films. The viability of this approach is supported by lattice expansion in the out-of-plane lattice direction and dramatic change in physical properties, i.e., a transition from ferromagnetic metallic to antiferromagnetic insulating. In particular, a significant increase of resistivity up to four orders of magnitude is evidenced at room temperature, upon implantation of highly energetic He-ions. Our result offers an attractive means for tuning the emergent physical properties of oxide thin films, via strong coupling between strain, defects and valence.

Permalink: https://www.hzdr.de/publications/Publ-33050
Publ.-Id: 33050


APR files

Nour, A.

APR  files for 4 different functions

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-24
    DOI: 10.14278/rodare.1134
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33049
Publ.-Id: 33049


Internal Access: Full source data of publication: "Tumor irradiation in mice with a laser-accelerated proton beam"

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

All source data and scripts for publication: "Tumor irradiation in mice with a laser-accelerated proton beam"

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-23
    DOI: 10.14278/rodare.1130

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-33048
Publ.-Id: 33048


Source Data: Tumor irradiation in mice with a laser-accelerated proton beam (Open Access)

Kroll, F.; Brack, F.-E.; Bernert, C.; Bock, S.; Bodenstein, E.; Brüchner, K.; Cowan, T.; Gaus, L.; Gebhardt, R.; Helbig, U.; Karsch, L.; Kluge, T.; Kraft, S.; Krause, M.; Leßmann, E.; Masood, U.; Meister, S.; Metzkes-Ng, J.; Nossula, A.; Pawelke, J.; Pietzsch, J.; Püschel, T.; Reimold, M.; Rehwald, M.; Richter, C.; Schlenvoigt, H.-P.; Schramm, U.; Umlandt, M. E. P.; Ziegler, T.; Zeil, K.; Beyreuther, E.

Source data for all figures of publication: "Tumor irradiation in mice with a laser-accelerated proton beam". Folder structure according to figures.

Keywords: Laser acceleration; TNSA; Radiobiology; FLASH

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-23
    DOI: 10.14278/rodare.1128
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33047
Publ.-Id: 33047


Layer-Dependent Band Gaps of Platinum-Dichalcogenides

Li, J.; Kolekar, S.; Ghorbani Asl, M.; Lehnert, T.; Biskupek, J.; Kaiser, U.; Krasheninnikov, A.; Batzill, M.

Owing to the relatively strong inter-layer interaction, the platinum-dichalcogenides exhibit tunability of their electronic properties by controlling the number of layers. Both PtSe2 and PtTe2 display a semi-metal to semi-conductor transition as they are reduced to bi- or single-layer. The value of the fundamental band gap, however, has been inferred only from density functional theory (DFT) calculations, which are notoriously challenging, as different methods give different results, and currently there is no experimental data. Here we determine the band gap as a function of the number of layers by local scanning tunneling spectroscopy on MBE-grown PtSe2 and PtTe2 islands. We find band gaps of 1.8 eV and 0.6 eV for mono- and bi-layer PtSe2, respectively, and 0.5 eV for monolayer PtTe2. Tri-layer PtSe2 and bilayer PtTe2 are semi-metallic. The experimental data are compared to DFT calculations carried out at different levels of theory. The calculated band gaps may differ significantly from the experimental values, emphasizing the importance of the experimental work. We further show that the variations in the calculated fundamental band gap in bilayer PtSe2 are related to the computed separation of the layers, which depends on the choice of the van der Waals functional. This sensitivity of the band gap to inter-layer separation also suggests that the gap can be tuned by uniaxial stress and our simulations indicate that only modest pressures are required for a significant reduction of the gap, making Pt-dichalcogenides suitable materials for pressure-sensing.

Keywords: 2D materials; layer dependence; PtSe2; PtTe2; scanning tunneling spectroscopy; van der Waals materials; transition metal dichalcogenides

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  • Secondary publication expected from 16.08.2022

Permalink: https://www.hzdr.de/publications/Publ-33046
Publ.-Id: 33046


data set ELBE experiment POS19101496, Sabrina Fernandes, Rez, CZ

Wagner, A.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Elsherif, A. G. A.

Positron annihilation lifetime spectroscopy data for ELBE experiment POS19101496 by Sabrina Fernandes, Rez, CZ

Keywords: positron annihilation lifetime spectroscopy; depth dependence; ion irradiation

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-19
    DOI: 10.14278/rodare.1122

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Permalink: https://www.hzdr.de/publications/Publ-33041
Publ.-Id: 33041


Rapid synthesis of gold-palladium core-shell aerogels for selective and robust electrochemical CO2 reduction

Du, R.; Jin, W.; Wu, H.; Hübner, R.; Zhou, L.; Xue, G.; Hu, Y.; Eychmüller, A.

Noble metal aerogels (NMAs), one class of the youngest members in the aerogel family, have drawn increasing attention in the last decade. Featuring the high catalytic activity of noble metals and a 3D self-supported porous network of the aerogels, they have displayed profound potential for electrocatalysis. However, considerable challenges reside in the rapid fabrication of NMAs with a well-tailored architecture, constraining the manipulation of their electrochemical properties for optimized performance. Here, a disturbance-assisted dynamic shelling strategy is developed, generating self-supported Au–Pd core–shell gels within 10 min. Based on suitable activation and desorption energies of the involved species as suggested by theoretical calculations, the Au–Pd core–shell aerogel manifests outstanding CO selectivity and stability at low overpotential (faradaic efficiency > 98% at -0.5 V vs. RHE over 12 hours) for the electrochemical CO2 reduction reaction (CO2RR). The present strategy offers a new perspective to facilely design architecture-specified high-performance electrocatalysts for the CO2RR.

Permalink: https://www.hzdr.de/publications/Publ-33038
Publ.-Id: 33038


Integrated complementary inverters and ring oscillators based on vertical-channel dual-base organic thin-film transistors

Guo, E.; Xing, S.; Dollinger, F.; Hübner, R.; Wang, S.-J.; Wu, Z.; Leo, K.; Kleemann, H.

Lateral-channel dual-gate organic thin-film transistors have been used in pseudo complementary metal-oxide-semiconductor (CMOS) inverters to control switching voltage. However, their relatively long channel lengths, combined with the low charge carrier mobility of organic semiconductors, typically leads to slow inverter operation. Vertical-channel dual-gate organic thin-film transistors are a promising alternative because of their short channel lengths, but the lack of appropriate p- and n-type devices has limited the development of complementary inverter circuits. Here, we show that organic vertical n-channel permeable single- and dual-base transistors, and vertical p-channel permeable base transistors can be used to create integrated complementary inverters and ring oscillators. The vertical dual-base transistors enable switching voltage shift and gain enhancement. The inverters exhibit small switching time constants at 10 MHz, and the seven-stage complementary ring oscillators exhibit short signal propagation delays of 11 ns per stage at a supply voltage of 4 V.

Permalink: https://www.hzdr.de/publications/Publ-33037
Publ.-Id: 33037


Data for: On Inter-bubble Distances and Bubble Clustering in Bubbly Flows: An Experimental Study

Kipping, R.; Hampel, U.

This data set contains the processed data from ultrafast X-ray tomography measurements in a bubble column. Measurements were performed in a bubble column with 100 mm inner diameter and with deionized water and nitrogen as liquid and gas phase, respectively. This data set contains the measurement from the measurement height located 0.7m above the gas sparger. 

Hydrodynamic data, such as bubble size distribution and gas holdup distribution are provided. Furthermore, inter-bubble distances of gas bubbles (distance of the nearest neighbours) are given.

Further detailes on the experiments and the processed data is provided in the corresponding journal paper.

Keywords: bubbly flows; clustering; UFXCT

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-12
    DOI: 10.14278/rodare.1112

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Permalink: https://www.hzdr.de/publications/Publ-33036
Publ.-Id: 33036


Data publication: FPGA-based Real-Time Data Acquisition for Ultrafast X-Ray Computed Tomography

Windisch, D.; Knodel, O.; Juckeland, G.; Hampel, U.; Bieberle, A.

This data contains the firmwares used for all descirbed tests in the paper.

Keywords: Computed tomography; Data acquisition; Field programmable gate arrays

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-16
    DOI: 10.14278/rodare.1118

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Permalink: https://www.hzdr.de/publications/Publ-33035
Publ.-Id: 33035


Evidence of collision-induced resuspension of microscopic particles from a monolayer deposit

Banari, A.; Henry, C.; Fank Eidt, R. H.; Pierre, L.; Klaus, Z.; Hampel, U.; Lecrivain, G.

The present Letter addresses the resuspension of microscopic glass particles from a monolayer bed into a turbulent gas flow. With an intermediate surface coverage, here set to about 10% of the field of view, we report two distinct detachment mechanisms. At relatively low flow velocities, few loosely adhering particles move on the wall to eventually collide with neighboring particles resulting in a clustered resuspension. At higher fluid velocities, mostly individual particles resuspend due to their interaction with the turbulent flow. The resuspension curve, showing the remaining particle fraction as a function of the flow velocity, exhibits a strong bimodal character.

Keywords: paticle resuspension; Inter-particle collisions; experimental test

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Permalink: https://www.hzdr.de/publications/Publ-33034
Publ.-Id: 33034


A stable home: Autocorrelated Kernel Density Estimated home ranges of the critically endangered Elongated Tortoise

Montano, Y.; Michael Marshall, B.; Ward, M.; Simoes Silva, I. M.; Artchawakom, T.; Waengsothorn, S.; Strine, C. T.

Home range is a fundamental concept in ecology used to describe animal space use over their lifetimes. Numerous studies use a variety of metrics to quantify home range; however, most of these treat spatial data inappropriately. Here we re-analyse a publicly available data-set, collected by the authors of this study, using a relatively novel and appropriate home range metric Autocorrelated Kernel Density Estimators (AKDE). Our data includes the movements of 17 Elongated Tortoises (Indotestudo elongata; 12 females, 5 males) located on average once every three days for an average duration of 353.76 ±33.10 days. We found 14 of 17 individuals appear to be occupying a stable home range (using variograms to determine range residency). We made use of AKDEs bias-mitigating measures to counteract the low effective sample sizes stemming from low temporal resolution radio-tracking data. The average AKDE home range for all 14 individuals with range residency was 44.81 ±10.44 ha. Bayesian Regression Models suggest considerable overlap between male and female home range estimates despite males being physically larger than females in both mass and carapace length. These home range estimates have the added utility of being comparable with other studies, less susceptible to errors from a suboptimal tracking regime, and are optimised with code and data for inclusion in future meta-analyses.

Keywords: ecology; testudine; autocorrelated kernel density estimator; spatial ecology; space use; Thailand; Indotestudo elongata

Permalink: https://www.hzdr.de/publications/Publ-33031
Publ.-Id: 33031


Data and code for: Lots of movement, little progress: A review of reptile home range literature

Crane​, M.; Simoes Silva, I. M.; Marshall, B. M.; Strine​, C. T.

Datasets, R code and figures pertaining to the manuscript: Crane, M., Silva, I., Marshall, B. M., & Strine, C. T. (2021). Lots of movement, little progress: A review of reptile home range literature. PeerJ, 9, e11742. DOI: 10.7717/peerj.11742

Keywords: ecology; reptiles; home range; open science; reproducibility; biotelemetry; space use; spatial ecology

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Permalink: https://www.hzdr.de/publications/Publ-33030
Publ.-Id: 33030


Lots of movement, little progress: A review of reptile home range literature

Crane​, M.; Simoes Silva, I. M.; Marshall, B. M.; Strine​, C. T.

Reptiles are the most species-rich terrestrial vertebrate group with a broad diversity of life history traits. Biotelemetry is an essential methodology for studying reptiles as it compensates for several limitations when studying their natural history. We evaluated trends in terrestrial reptile spatial ecology studies focusing upon quantifying home ranges for the past twenty years. We assessed 290 English-language reptile home range studies published from 2000–2019 via a structured literature review investigating publications’ study location, taxonomic group, methodology, reporting, and analytical techniques. Substantial biases remain in both location and taxonomic groups in the literature, with nearly half of all studies (45%) originating from the USA. Snakes were most often studied, and crocodiles were least often studied, while testudines tended to have the greatest within study sample sizes. More than half of all studies lacked critical methodological details, limiting the number of studies for inclusion in future meta-analyses (55% of studies lacked information on individual tracking durations, and 51% lacked sufficient information on the number of times researchers recorded positions). Studies continue to rely on outdated methods to quantify space-use (including Minimum Convex Polygons and Kernel Density Estimators), often failing to report subtleties regarding decisions that have substantial impact on home range area estimates. Moving forward researchers can select a suite of appropriate analytical techniques tailored to their research question (dynamic Brownian Bridge Movement Models for within sample interpolation, and autocorrelated Kernel Density Estimators for beyond sample extrapolation). Only 1.4% of all evaluated studies linked to available and usable telemetry data, further hindering scientific consensus. We ultimately implore herpetologists to adopt transparent reporting practices and make liberal use of open data platforms to maximize progress in the field of reptile spatial ecology.

Keywords: ecology; reptiles; home range; open science; reproducibility; biotelemetry; space use; spatial ecology

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Permalink: https://www.hzdr.de/publications/Publ-33029
Publ.-Id: 33029


Simulating Multi Layer Targets for Grazing Incidence Small Angle X-ray Scattering

Paschke-Brühl, F.-L.

This bachelor thesis studies the feasibility of grazing-incidence small-angle x-ray scattering
(GISAXS) in the UHI laser-target interaction via computational simulations with SMILEI. In
this work we briefly analyze the front and back of the target. We find predominantly that the
compression of the target becomes apparent in the GISAXS pattern, while we can not observe
ablation. We will mainly focus on the density oscillation, a dynamic that has not been mentio-
ned in literature yet. The density oscillation dynamics depend on a simple pressure gradient
in between the layers. We observe the multi layers inversely oscillating in density and a global
density alteration moving through the target. The density alteration allows to recognize the
dynamic in a GISAXS pattern. We learn, that GISAXS is feasible in the high intensity regime,
but not for the same dynamics as in the lower intensity regime.

Keywords: GISAXS; SAXS; grazing-incidence small-angle x-ray scattering; SMILEI; Simulation; Density Oscialltion

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-27
    DOI: 10.14278/rodare.1116
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33027
Publ.-Id: 33027


Simulating Multi Layer Targets for Grazing Incidence Small Angle X-ray Scattering

Paschke-Brühl, Franziska-Luise

This bachelor thesis studies the feasibility of grazing-incidence small-angle x-ray scattering
(GISAXS) in the UHI laser-target interaction via computational simulations with SMILEI. In
this work we briefly analyze the front and back of the target. We find predominantly that the
compression of the target becomes apparent in the GISAXS pattern, while we can not observe
ablation. We will mainly focus on the density oscillation, a dynamic that has not been mentio-
ned in literature yet. The density oscillation dynamics depend on a simple pressure gradient
in between the layers. We observe the multi layers inversely oscillating in density and a global
density alteration moving through the target. The density alteration allows to recognize the
dynamic in a GISAXS pattern. We learn, that GISAXS is feasible in the high intensity regime,
but not for the same dynamics as in the lower intensity regime.

Keywords: GISAXS; SAXS; grazing incidence small angle x-ray scattering; SMILEI; Simulation; Density Oscillation

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-15
    DOI: 10.14278/rodare.1114
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33026
Publ.-Id: 33026


NeuLAND: The High-Resolution Neutron Time-of-Flight Spectrometer for R³B at FAIR

Boretzky, K.; Gašparic, I.; Heil, M.; Mayer, J.; Heinz, A.; Caesar, C.; Kresan, D.; Simon, H.; Törnqvist, H. T.; Körper, D.; Alkhazov, G.; Atar, L.; Aumann, T.; Bemmerer, D.; Bondarev, S. V.; Bott, L. T.; Chakraborty, S.; Cherciu, M. I.; Chulkov, L. V.; Ciobanu, M.; Datta, U.; de Filippo, E.; Douma, C. A.; Dreyer, J.; Elekes, Z.; Enders, J.; Galaviz, D.; Geraci, E.; Gnoffo, B.; Göbel, K.; Golovtsov, V. L.; Gonzalez Diaz, D.; Gruzinsky, N.; Haiduc, M.; Heftrich, T.; Heggen, H.; Hehner, J.; Hensel, T.; Hoemann, E.; Holl, M.; Horvat, A.; Horváth, Á.; Ickert, G.; Ignatov, A.; Jelavi Malencia, D.; Johansson, H. T.; Jonson, B.; Kahlbow, J.; Kalantar-Nayestanaki, N.; Kelic-Heil, A.; Kempe, M.; Koch, K.; Kozlenko, N. G.; Krivshich, A. G.; Kurz, N.; Kuznetsov, V.; Langer, C.; Leifels, Y.; Lihtar, I.; Löher, B.; Machado, J.; Martorana, N. S.; Miki, K.; Nilsson, T.; Nyman, G. H.; Orischin, E. M.; Pagano, E. V.; Pirrone, S.; Politi, G.; Potlog, P.-M.; Rahaman, A.; Reifarth, R.; Rigollet, C.; Röder, M.; Rossi, D. M.; Russotto, P.; Savran, D.; Scheit, H.; Schindler, F.; Stach, D.; Stan, E.; Stomvall Gill, J.; Teubig, P.; Trimarchi, M.; Uvarov, L.; Volknandt, M.; Wagner, A.; Wagner, V.; Wranne, S.; Yakorev, D.; Zanetti, L.; Zilges, A.; Zuber, K.

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5x5x250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250x250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.

Keywords: high-energy neutron detection; reactions with relativistic radioactive beams; plastic scintillator scintillator array; multi-neutron detection

Permalink: https://www.hzdr.de/publications/Publ-33023
Publ.-Id: 33023


Data publication: Simulation results of bubble growth and shrinkage using population balance model

Li, J.; Liao, Y.; Lucas, D.; Zhou, P.

This dataset includes the predicted bubble diameter, total bubble number, total bubble volume as well as the bubble number density for the cases described in the associated paper.

Keywords: Stability analysis; Internal CFL condition; Discretization; Population balance equation; Class method; Phase change

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-12
    DOI: 10.14278/rodare.1110
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33022
Publ.-Id: 33022


Laser-induced ionization of ions from high brightness ion sources

Machalett, F.; Ying, B.; Wustelt, P.; Huth, V.; Kübel, M.; Bischoff, L.; Klingner, N.; Pilz, W.; Stöhlker, T.; Paulus, G. G.

Au and Si ions from high brightness liquid metal ion sources (LMIS) are used as ionic targets for strong-field laser interaction with femtosecond laser beam. Field ionization processes in the field emission source at electrostatic fields of some 10 V/nm allow the generation of various metallic and metalloid ion beams with charge states such as Au^{2+} and Si^{2+}. Studying the ionization in strong femtosecond laser fields with intensities of up to 1E16 W/cm^2, we observed for these elements charge states up to Au^{11+} and Si^{4+}.

Keywords: liquid metal ion sources; femtosecond laser beam; charge states

  • Lecture (Conference) (Online presentation)
    32nd International Conference on Photonic, Electronic and Atomic Collisions, ViCPEAC2021, 20.-23.07.2021, European XFEL, Germany

Permalink: https://www.hzdr.de/publications/Publ-33016
Publ.-Id: 33016


Experimental and numerical investigations of Ni–Co–SiO2 alloy films deposited by magnetic-field-assisted jet plating

Jiang, W.; Huang, M.; Lao, Y.; Yang, X.; Wang, C.; Tian, Z.; Zhou, S.; Mutschke, G.; Eckert, K.

A new method of magnetic-field-assisted jet plating is presented to manufacture Ni-Co-SiO2 alloy films. The influence of different concentrations of Co2+ ions of the electrolyte is investigated with and without magnetic field to study the resulting properties of the deposits. The texture orientation, surface morphology, magnetic properties and corrosion resistance of the alloy films were characterized. The results show that with increasing Co2+ concentration in conventional jet-plating, the surface morphology changes from a granular crystal structure to a needle-like structure at 30 g/L caused by the hexagonal close-packed (HCP) structure of a large Co content. Differently, the assistance of the magnetic field leads to lower Co content in the films, even at a high Co2+ concentration of 30 g/L. The deposit layer remains in the face-centered cubic (FCC) structure and shows a granular morphology. The magnetic field in general leads to grain refinement and inhibits the abnormal Ni–Co co-deposition. The Ni–Co–SiO2 alloy films obtained by magnetic-field-assisted jet plating have a smooth and dense surface. The best soft magnetic properties and corrosion resistance are obtained at a Co2+ concentration of 20 g/L. The coercivity is as low as 7.5 Oe, and the corrosion current density is as low as 1.12 μA·cm-2 in 3.5 wt% NaCl solution without agitation and at room temperature, clearly showing the advantages of the method for preparing superior soft magnetic materials. In addition, a physical model of magnetic-field-assisted jet plating is established. The magnetic forces and the resulting electrolyte flow are analyzed with the help of numerical simulations, and the influence of the magnetic field on the deposition process is discussed from the perspective of magnetohydrodynamics.

Keywords: Ni–Co–SiO2 alloy film; Magnetic-field-assisted jet plating; Magnetic properties; Numerical simulation

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  • Secondary publication expected from 15.10.2022

Permalink: https://www.hzdr.de/publications/Publ-33014
Publ.-Id: 33014


Increased dephasing length in heavily doped GaAs

Duan, J.; Wang, C.; Vines, L.; Rebohle, L.; Helm, M.; Zeng, Y.-J.; Zhou, S.; Prucnal, S.

Ion implantation of S and Te followed by sub-second flash lamp annealing with peak temperature about 1100 oC is employed to obtain metallic n++-GaAs layers. The electron concentration in annealed GaAs is as high as 5×1019 cm-3, which is several times higher than the doping level achievable by alternative methods. We found that heavily doped n++-GaAs exhibits positive magnetoconductance in the temperature range of 3-80 K, which is attributed to the magnetic field suppressed weak localization. By fitting the magnetoconductance results with Hikami-Larkin-Nagaoka model, it is found that the phase coherence length increases with increasing carrier concentration at low temperature and is as large as 540 nm at 3 K. The temperature dependence of the phase coherence length follows〖 l〗_∅∝T^η (η~0.3), indicating defect-related scattering as the dominant dephasing mechanism. In addition, the high doping level in n-type GaAs provides the possibility to use GaAs as a plasmonic material for chemical sensors operating in the infrared range.

Keywords: ion implantation; heavily doped GaAs; phase coherence length; sub-second annealing; plasmonic

Permalink: https://www.hzdr.de/publications/Publ-33012
Publ.-Id: 33012


Supplementary material: Ph.D. dissertation of Lucas Pereira, TU Bergakademie Freiberg, 2021.

Pereira, L.
Supervisor: Frenzel, Max; Supervisor: Tolosana-Delgado, Raimon; Supervisor: Gutzmer, Jens

This supplementary material supports the Ph.D. dissertation of Lucas Pereira, submitted to the Faculty 3 of the TU Bergakademie Freiberg.

C2.SM1.Percentiles.xlsx: Mentioned in the chapter 2 of the dissertation, this file contains, in terms of percentiles, the distribution of every particle descriptive variable in the different samples used to train the logistic regression models of the case study presented in this chapter.

C2.SM2.Coefficients.xlsx: Mentioned in the chapter 2 of the dissertation, this file contains the complete list of coefficients assigned to each variable, in each separation unit, of the case study presented in this chapter.

C4.SM1.StatWeight.xlsx: Mentioned in the chapter 4 of the dissertation, this file contains a detailed explanation of the statistical weights of particles and how they can be used to integrate a set of particle datasets from different streams and size fractions into a single and balanced training dataset.

Keywords: Geometallurgy; Particle-based separation model

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-09
    DOI: 10.14278/rodare.1104
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33009
Publ.-Id: 33009


On the nature of Pb species in Pb-(over)exchanged zeolite: a combined experimental and theoretical study

Roos, D. P.; Scheinost, A.; Churakov, S. V.; Nagashima, M.; Cametti, G.

Structural properties of Pb-exchanged zeolites are of interest because of their applications in environmental remediation and in industrial processes. In this study, we report on a Pb-exchanged aluminosilicate zeolite (Pb-STI), with particular focus on the cationic species, which form inside the zeolitic pores as a result of the exchange experiments. The produced
zeolite had chemical composition Pb13.4(OH)10Al17.4Si54.6O144 ∙38H2O, indicating a Pb2+ overexchange of approximately 50%. The STI framework maintained the Fmmm space group characteristic of the type material. However, the extraframework occupants, Pb2+, H2O and OH-, were characterized by a strong positional-disorder. The latter was resolved and
interpreted combining Extended X-ray Absorption Fine Structure (EXAFS) analysis with Molecular Dynamics (MD) simulations. On average, Pb2+ ions are coordinated by 2 OH- and
1 H2O at distances < 2.5 Å, whereas bonds to framework oxygen-atoms were found only at longer distances (> 2.8 Å). Pb2+ adopts mainly a sided distorted coordination, indicating a
stereochemical activity of the lone pair electrons. The obtained results were compared with those of other mono-cationic forms of STI zeolites. Based on the analysis of the framework
distortion experienced after the incorporation of different metal ions, considerations are drawn on the potential effect of Pb2+ on the thermal stability of STI framework type zeolites.

Keywords: XAFS; Zeolite; XRD; Molecular dynamics; DFT

Permalink: https://www.hzdr.de/publications/Publ-33007
Publ.-Id: 33007


Compact spectroscopy of keV to MeV X-rays from a laser wakefield accelerator

Hannasch, A.; Laso García, A.; La Berge, M.; Zgadzaj, R.; Köhler, A.; Couperus Cabadağ, J. P.; Zarini, O.; Kurz, T.; Ferrari, A.; Molodtsova, M.; Naumann, L.; Cowan, T.; Schramm, U.; Irman, A.; Downer, M.

We reconstruct spectra of secondary X‑rays from a tunable 250–350 MeV laser wakefield electron accelerator from single‑shot X‑ray depth‑energy measurements in a compact (7.5 × 7.5 × 15 cm), modular X‑ray calorimeter made of alternating layers of absorbing materials and imaging plates. X‑rays range from few‑keV betatron to few‑MeV inverse Compton to > 100 MeV bremsstrahlung emission, and are characterized both individually and in mixtures. Geant4 simulations of energy deposition of single‑energy X‑rays in the stack generate an energy‑vs‑depth response matrix for a given stack configuration. An iterative reconstruction algorithm based on analytic models of betatron, inverse Compton and bremsstrahlung photon energy distributions then unfolds X‑ray spectra,
typically within a minute. We discuss uncertainties, limitations and extensions of both measurement and reconstruction methods.

Permalink: https://www.hzdr.de/publications/Publ-33005
Publ.-Id: 33005


Data publication: Broadband frequency filters with quantum dot chains

Ehrlich, T.; Schaller, G.

Rohdaten für Abbildungen (*.agr) und Mathematica Notebooks (*.nb) für die Berechnungen

Keywords: thermodynamic uncertainty relation; Levitov-Lesovik formula; transmission; reaction-coordinate mapping

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-05
    DOI: 10.14278/rodare.1101
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33004
Publ.-Id: 33004


Automated mineralogy particle dataset: dry magnetic separation of skarn ore

Buchmann, M.; Kern, M.; Pereira, L.; Frenzel, M.; Tolosana Delgado, R.; van den Boogaart, K. G.; Gutzmer, J.

This data set origins from the AFK (“Aufbereitung feinkörniger Komplexerze”, BMBF grant number 033R128) project. The main target within this project was to produce a cassiterite concentrate, which is suitable for the subsequent production of tin. Various processing steps and the material specific behaviour were investigated within the progress of the project. The present data set derives from dry magnetic separation tests. More information can be found in the "readme.pdf" file attached.

Keywords: Geometallurgy; Particle-based separation modelling; Magnetic separation; Cassiterite

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-04
    DOI: 10.14278/rodare.1095
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33003
Publ.-Id: 33003


Data publication: Microscopic and spectroscopic bioassociation study of uranium(VI) with an archaeal Halobacterium isolate

Hilpmann, S.; Bader, M.; Steudtner, R.; Müller, K.; Stumpf, T.; Cherkouk, A.

Bei diesem Datensatz handelt es sich um die Primärdaten der Untersuchung der Wechselwirkungen eines halophilen Archaeons mit Uran(VI). Dazu wurden Konzentrationsbestimmungen mittels ICP-MS durchgeführt, Lumineszenzspektren mittels zeitaufgelöster laserinduzierter Lumineszenzspektroskopie und IR Spektren aufgenommen. Darüber hinaus wurden Bilder der Zellen mit Hilfe der Fluoreszenzmikroskopie aufgenommen.

Keywords: uranium(VI) bioassociation; halophilic archaea; rock salt

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-05
    DOI: 10.14278/rodare.1099
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-33002
Publ.-Id: 33002


Monte Carlo methods in particle and nuclear physics

Müller, S.

Presentation at HZDR's 2021 summer student seminar

Keywords: Monte Carlo; Simulation

  • Lecture (Conference) (Online presentation)
    Summer Student seminar series, 27.07.2021, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-33001
Publ.-Id: 33001


P2001 - Vorrichtung zur gezielten Anordnung von in einem Analyten gelösten, elektrisch polarisierbaren Materialien, Verfahren zur Bestimmung eines isoelektrischen Punktes eines elektrisch isolierenden Materials, Verfahren zum gezielten Anordnen eines in einem Analyten gelösten elektrisch polarisierbaren Materials

Rebohle, L.; Fischer, C.; Skorupa, I.; Schmidt, H.; Krüger, S.; Blaschke, D.

Es wird eine Vorrichtung (10) zur gezielten Anordnung eines in einem Analyten gelösten, elektrisch polarisierbaren Materials (4), aufweisend eine siliziumhaltige Trägerstruktur (3), eine elektrisch isolierende erste Deckstruktur (1) mit einem ersten isoelektrischen Punkt und eine elektrisch isolierende zweite Deckstruktur (2) mit einem zweiten isoelektrischen Punkt vorgeschlagen, wobei der erste isoelektrische Punkt vom zweiten isoelektrischen Punkt verschieden ist. Weiterhin werden ein Verfahren zur Bestimmung eines ersten isoelektrischen Punktes eines Materials sowie ein Verfahren zum gezielten Anordnen eines in einem Analyten gelösten, elektrisch polarisierbaren Materials (4) vorgeschlagen.

  • Patent
    DE102020200470 - Erteilung 20.05.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32998
Publ.-Id: 32998


P1916 - Verfahren und Anordnung zum Charakterisieren der Positionierung eines Objekts

Hampel, U.

Die Erfindung betrifft ein Verfahren und eine Anordnung zum Charakterisieren der Positionierung eines Objekts innerhalb eines Aufenthaltsbereichs, wobei mittels eines Myonenteleskops darauf auftreffende Myonen als Myonenteleskop-Detektionsereignisse und deren Myonentrajektorien als Myonentrajektorien-Daten erfasst werden, wobei zudem mittels eines objektseitigen Myonendetektors darauf auftreffende Myonen als Myonendetektor-Detektionsereignisse erfasst werden, und wobei quasizeitgleiche Myonenteleskop-Detektionsereignisse und Myonendetektor-Detektionsereignisse ermittelt werden und basierend auf den zugehörigen Myonentrajektorien-Daten die Positionierung des Objekts charakterisiert wird.

  • Patent
    DE102019131006 - Erteilung 01.10.2020

Permalink: https://www.hzdr.de/publications/Publ-32997
Publ.-Id: 32997


P1915 - Magnetische Streufeld-Struktur, magnonisches Bauelement und Verfahren zur Herstellung einer magnetischen Streufeldstruktur

Samad, F.; Koch, L.; Arekapudi, S. S. P. K.; Hellwig, O.; Schultheiß, H.

Eine magnetische Struktur (510) weist einen synthetischen antiferromagnetischen Schichtstapel (100) mit senkrechter magnetischer Anisotropie auf. Ein erster und ein zweiter Teilbereich (110, 120) des synthetischen antiferromagnetischen Schichtstapels (100) sind lateral nebeneinander ausgebildet. Eine vertikaler erster Magnetisierungsverlauf im ersten Teilbereich (110) unterscheidet sich nach Betrag und/oder Orientierung von einem vertikalen zweiten Magnetisierungsverlauf im zweiten Teilbereich (120). Auf einer horizontalen Hauptoberfläche (101) des synthetischen antiferromagnetischen Schichtstapels (100) kann eine Entkopplungsschicht (200) ausgebildet sein. Auf der Entkopplungsschicht (200) oder der Hauptoberfläche (101) ist eine Funktionsschicht (300) ausgebildet. Die Funktionsschicht (300) wird lokal durch Kopplung mit dem synthetischen antiferromagnetischen Schichtstapel (100)oder durch die Streufelder des synthetischen antiferromagnetischen Schichtstapels (100)in ihrer Magnetisierung ausgerichtet, wodurch in der Funktionsschicht (300) beispielsweise eine variable und reprogrammierbare Infrastruktur für die Erzeugung, Verarbeitung, Übertragung und Detektion von Spinwellen erzeugt werden kann.

  • Patent
    DE102019129203 - Offenlegung 29.04.2021

Permalink: https://www.hzdr.de/publications/Publ-32996
Publ.-Id: 32996


P1909 - Mehrphasen-Messsystem mit Kalibrierwertnachführung und strömungstechnische Anordnung

Wiedemann, P.; Flaisz, A.; Schleicher, E.

Ein Mehrphasen-Messsystem (100) für ein mehrphasiges Fluid (205) weist eine Referenzwert-Messanordnung (160) und eine Mehrphasen-Messeinrichtung (130) auf. Die Referenzwert-Messanordnung (160) weist mindestens eine Kapillare (110) und eine Kapillaren- Messeinrichtung (120) auf. Innere Querschnittsfläche und Länge der Kapillare (110) sind so bemessen, dass bei Durchströmung der Kapillare (110) Phasen des mehrphasigen Fluids (205) in Durchströmungsrichtung separieren. Die Kapillaren-Messeinrichtung (120) ist zur Bestimmung mindestens einer physikalischen Eigenschaft mindestens einer der durch die Kapillare (110) fließenden Phasen eingerichtet. Das Mehrphasen-Messeinrichtung (130) ist für eine Messung
eines Volumen- und/oder Massenanteils von mindestens einer Phase des mehrphasigen Fluids und/oder für eine Messung eines Volumen- und/oder Massenstromes von mindestens einer der Phasen des mehrphasigen Fluids unter Berücksichtigung der durch die Kapillaren-Messeinrichtung (120) bestimmten physikalischen Eigenschaft(en) eingerichtet.

  • Patent
    DE102019125243 - Offenlegung 25.03.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32995
Publ.-Id: 32995


P1908 - Verfahren zum Herstellen eines gedruckten magnetischen Funktionselements und gedrucktes magnetisches Funktionselement

Canon Bermudez, G. S.; Mönch, J. I.; Makarov, D.

Die vorliegende Erfindung betrifft ein Verfahren zum Herstellen eines gedruckten magnetischen Funktionselements, bei dem ein Substrat (1) auf einer Oberfläche mit mindestens einem Kontakt (2) aus einem elektrisch leitfähigen Werkstoff versehen wird. Nachfolgend wird auf den oder an den mindestens einen Kontakt (2) und diesen unmittelbar berührend eine Struktur (3) aus einem einen magnetoresistiven Effekt aufweisenden Werkstoff als Paste, als Gel, als Dispersion oder als Suspension aufgedruckt sowie die Struktur (3) durch eine Bestrahlung mit elektromagnetischer Strahlung über einen Zeitraum im Millisekundenbereich elektrisch leitfähig und magnetfeldempfindlich.

  • Patent
    DE102019211970 - Offenlegung 11.02.2021; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32994
Publ.-Id: 32994


P1907 - Deuterierte 7-(3-(4-(2-([18F]Fluor)ethoxy)phenyl)propyl)-2-(furan-2-yl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amin-Derivate

Lai, T. H.; Teodoro, R.; Toussaint, M.; Gündel, D.; Deuther-Conrad, W.; Dukic-Stefanovic, S.; Schröder, S.; Moldovan, R.-P.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I worin die Reste X1a, X1b, X2a, X2b, X3a, X3b, X4a, X4b, X5a und X5b unabhängig voneinander jeweils Wasserstoff oder Deuterium sind, mit der Maßgabe, dass zumindest einer der Reste X1a, X1b, X2a, X2b, X3a, X3b, X4a, X4b, X5a und X5b Deuterium ist.

  • Patent
    DE102019116986 - Offenlegung 24.12.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32993
Publ.-Id: 32993


P1906 - 3-(4-Amino-2-methoxyphenyl)-2-cyanoacrylsäure-Derivate und deren Verwendung als Präkursoren für die Herstellung radiochemischer Verbindungen

Moldovan, R.-P.; Sadeghzadeh, M.; Wenzel, B.; Kranz, M.; Teodoro, R.; Ludwig, F.-A.; Fischer, S.; Toussaint, M.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel (E)-I oder (Z)-I worin Y eine Hydroxygruppe oder eine O-M+-Gruppe ist, wobei M+ ein Kation ist; Z1 aus der Gruppe ausgewählt ist, die aus einer substituierten oder unsubstituierten C1-C12-Alkylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkenylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkinylgruppe, einer substituierten oder unsubstituierten Arylgruppe, einer substituierten oder unsubstituierten Heteroarylgruppe, einer substituierten oder unsubstituierten Alkylarylgruppe, einer substituierten oder unsubstituierten Arylalkylgruppe und einer Gruppe -A1-X besteht, worin A1 eine Kohlenwasserstoffkette mit ein bis vier substituierten oder unsubstituierten Methylengruppen ist, wobei in der Kohlenwasserstoffkette zumindest ein Sauerstoffatom unter Ausbildung einer Ethergruppe angeordnet sein kann, und X aus der Gruppe ausgewählt ist, die aus einer Methylgruppe, einem Halogen und einer Hydroxygruppe besteht; und Z2 ein Rest ist, der eine Abgangsgruppe AG trägt, wobei Z2 aus der Gruppe ausgewählt ist, die aus einer substituierten oder unsubstituierten C1-C12-Alkylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkenylgruppe, einer substituierten oder unsubstituierten C2-C12-Alkinylgruppe, einer substituierten oder unsubstituierten Arylgruppe, einer substituierten oder unsubstituierten Heteroarylgruppe, einer substituierten oder unsubstituierten Alkylarylgruppe und einer substituierten...

  • Patent
    DE102019112040 - Offenlegung 12.11.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32992
Publ.-Id: 32992


P1905 - N-(4-methoxy-7-morpholinobenzo[d]thiazol-2-yl)-acetamid-Derivate und deren Verwendung

Lai, T. H.; Teodoro, R.; Moldovan, R.-P.; Kranz, M.; Dukic-Stefanovic, S.; Toussaint, M.; Spalholz, T.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I (Formel I)
worin Ar eine Phenylgruppe oder eine Pyridylgruppe ist; R1 Wasserstoff oder eine Nitrogruppe ist; und R2 Fluor oder eine Abgangsgruppe ist, wobei die Abgangsgruppe aus der Gruppe ausgewählt ist, die aus einer Nitrogruppe, einem Halogen, einem Diazoniumion oder -salz, einem Trialkylammoniumion oder -salz, einem Dialkoxyaren, einem Sulfoxid, einer Boronsäure, einem Boronsäureester, Alkylzinn, Arylzinn, einem Iodoniumion oder -salz, einem Iodonium-Ylid und einem Sulfonsäureester besteht.

  • Patent
    DE102019110904 - Offenlegung 29.10.2020

Permalink: https://www.hzdr.de/publications/Publ-32991
Publ.-Id: 32991


P1904 - Verwendung eines Komplexierungsmittels zur Rückgewinnung von Metallionen aus Industrieabwasser sowie ein Verfahren dazu

Jain, R.; Joshi, T.; Pollmann, K.

Die vorliegende Erfindung betrifft ein neues Komplexierungsmittel zur Rückgewinnung von Metallionen aus Industrieabwasser, aufweisend ein Trägermaterial, an dem Siderophore über einen Linker kovalent immobilisiert sind, wobei der Linker eine Polyethylenglykol-Kette enthält, und wobei der Linker eine Masse von 2000-3500 Da aufweist, sowie ein Verfahren zu dessen Herstellung und die Verwendung des Komplexierungsmittels bei der Rückgewinnung von Metallen aus Industrieabwässern.

  • Patent
    DE102019108803 - Offenlegung 08.10.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32990
Publ.-Id: 32990


P1903 - Anordnung zur berührungslosen Bestimmung der Geschwindigkeitsverteilung eines Schmelzvolumens in einer Stranggusskokille

Ratajczak, M.; Wondrak, T.; Stefani, F.; Primetals Austria

Die Erfindung betrifft eine Anordnung zur berührungslosen Bestimmung einer Geschwindigkeitsverteilung eines Schmelzvolumens in einer Stranggusskokille. Die erfindungsgemäße Anordnung soll eine Messung mit verbesserten Signal-Rausch-Verhältnis ermöglichen und in bestehende Bauteile integriert werden. Die Anordnung weist mindestens eine ein primäres Magnetfeld erzeugende Spule, deren primäres Magnetfeld das Schmelzvolumen durchdringt, und eine Mehrzahl von Magnetfeldsensoren zur Messung des durch die Wechselwirkung der Schmelzbewegung mit dem erzeugten primären Magnetfeld induzierten Magnetfeldes auf. Die Stranggusskokille weist mindestens ein Kokillenelement auf, welches in mindestens einem Bereich mit einem Anschlusselement verbunden ist. Spule und Magnetfeldsensoren sind derart innerhalb des Anschlusselements angeordnet, dass die Magnetfeldsensoren innerhalb des von der Spule umschlossenen Volumens des Anschlusselements angeordnet sind.

  • Patent
    DE102019105628 - Erteilung 19.03.2020; Nachanmeldungen: WO

Permalink: https://www.hzdr.de/publications/Publ-32989
Publ.-Id: 32989


Data publication: Stretchable Thin Film Mechanical Strain Gated Switches and Logic Gate Functions Based on a Soft Tunneling Barrier

Chae, S.; Jin Choi, W.; Fotev, I.; Bittrich, E.; Uhlmann, P.; Schubert, M.; Makarov, D.; Wagner, J.; Pashkin, O.; Fery, A.

Time-domain THz spectroscopy (raw data) and the analysis of the delay time (Origin file)

Keywords: Strain gated electric switch; logic gates; tunneling; stretchable circuit; thin film

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-03
    DOI: 10.14278/rodare.1092

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32988
Publ.-Id: 32988


P1902 - Verfahren und Vorrichtung zur Abtrennung von Kunststoffpartikeln

Nikpay, M.

Die Erfindung betrifft eine Verfahren zur Abtrennung von Kunststoffpartikeln aus einer Flüssigkeit oder einem heterogenen Gemisch, das eine Flüssigkeit enthält oder mit einer Flüssigkeit in Kontakt gebracht wird. Dabei ist vorgesehen, dass (a) die Kunststoffpartikel einem Magnetfeld ausgesetzt werden; (b) an der Oberfläche eines Sammlers Kunststoffpartikel adsorbiert werden; und (c) an der Oberfläche des Sammlers adsorbierte Kunststoffpartikel abgeführt werden.

  • Patent
    DE102019103936 - Offenlegung 20.08.2020

Permalink: https://www.hzdr.de/publications/Publ-32986
Publ.-Id: 32986


P1901 - Durchflussmessanordnung und strömungstechnische Anordnung

Arlit, M.; Hampel, U.; Schroth, C.

Eine Durchflussmessanordnung (400) weist einen Messkanal (100) mit einem Messkanaldurchmesser (D0) auf. In dem Messkanal (100) sind ein Strömungsteiler (300) und ein Anemometrie-Gittersensor (500) angeordnet. Der Anemometrie-Gittersensor (500) weist eine Vielzahl von Sensorelementen (510) mit temperaturabhängigem elektrischen Widerstand auf, die lateral voneinander beabstandet sind. Der Strömungsteiler (300) weist eine Vielzahl von Teilkanälen (310) auf. Eine Kanallänge (L1) der Teilkanäle (310) kann kleiner oder gleich dem Messkanaldurchmesser (D0) sein. Ein Abstand (L2) zwischen dem Anemometrie-Gittersensor (500) und dem Strömungsteiler (300) kann kleiner oder gleich dem Messkanaldurchmesser (D0) sein.

  • Patent
    DE102019103674 - Offenlegung 13.08.2020; Nachanmeldungen: WO, EP

Permalink: https://www.hzdr.de/publications/Publ-32985
Publ.-Id: 32985


P1827 - Microfluidic device, apparatus and method for enrichment and dilution of magnetic molecular entities

Mutschke, G.; Yang, X.; AGH Krakau

A microfluidic device (500) includes a substrate (100) with a fluid channel (250) extending from an inlet opening (210) to a channel branch (270). The fluid channel (250) includes a planar spiral portion (255) and at the channel branch (270) 10 the fluid channel (250) branches in at least two outlet channels (280). A ferromagnetic auxiliary structure (300) is formed in a plane parallel to the planar spiral portion (255).

  • Patent
    EP3669982 - Offenlegung 24.06.2020

Permalink: https://www.hzdr.de/publications/Publ-32984
Publ.-Id: 32984


Data publication: A new system for real-time data acquisition and pulse parameterization for digital positron annihilation lifetime spectrometers with high repetition rates

Hirschmann, E.; Butterling, M.; Hernandez Acosta, U.; Liedke, M. O.; Elsherif, A. G. A.; Petring, P.; Görler, M.; Krause-Rehberg, R.; Wagner, A.

Bei diesem Datensatz handelt es sich um die Bilder zur Publikation und Daten für die Leistungskurven

Keywords: Data reduction methods; Digital signal processing (DSP); Detection of defects; Online farms and online filtering

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-03
    DOI: 10.14278/rodare.1090

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Permalink: https://www.hzdr.de/publications/Publ-32980
Publ.-Id: 32980


A new system for real-time data acquisition and pulse parameterization for digital positron annihilation lifetime spectrometers with high repetition rates

Hirschmann, E.; Butterling, M.; Hernandez Acosta, U.; Liedke, M. O.; Elsherif, A. G. A.; Petring, P.; Görler, M.; Krause-Rehberg, R.; Wagner, A.

We present a new system for high repetition rate and real-time pulse analysis imple- mented at the Monoenergetic Positron Source (MePS) at the superconducting electron LINAC ELBE at Helmholtz-Zentrum Dresden-Rossendorf. Dedicated digital signal processing and op- timized algorithms are employed allowing for high bandwidth throughput, online pulse analysis and filtering. Positrons generated from radioisotopes and from bremsstrahlung pair production by means of highly intense accelerator-based positron beams serve as a microstructure probe allowing material characterizations with respect to chemical, mechanical, electrical, and magnetic properties. Positron annihilation lifetime events with up to 13 MHz repetition rate are being processed online without losses while performing signal selections for pile-up reduction, online energy calibration, and - for radioisotope-based measurements - identification of start and stop events.

Keywords: Data reduction methods; Digital signal processing (DSP); Detection of defects; Online farms and online filtering

Related publications

Downloads:

  • Secondary publication expected from 02.08.2022

Permalink: https://www.hzdr.de/publications/Publ-32979
Publ.-Id: 32979


Numerical dimensioning of a pre-cooler for sCO2 power cycles to utilize industrial waste heat

Unger, S.

These are the the processed data of the paper "Numerical dimensioning of a pre-cooler for sCO2 power cycles to utilize industrial waste heat". The data contain the heat transfer and fluid dynamic values of the simulation performed for the corresponding article.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-08-02
    DOI: 10.14278/rodare.1084
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32978
Publ.-Id: 32978


RawData for paper: Mounted Single Particle Characterization for 3D Mineralogical Analysis - MSPaCMAn

Da Assuncao Godinho, J. R.

Raw 3D images of the 3 types of samples used in the paper

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-30
    DOI: 10.14278/rodare.1080
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-32972
Publ.-Id: 32972


Designing chiral magnetic responses by tailoring geometry of thin films: curvilinear ferro- and antiferromagnets

Makarov, D.

Conventionally, tailoring of the Dzyaloshinskii-Moriya interaction (DMI) is done by optimizing materials, either doping a bulk single crystal or adjusting interface properties of thin films and multilayers. A viable alternative to the conventional material screening approach can be the exploration of the interplay between the sample geometry and topology of the order parameter. The research field in magnetism, which is dealing with the study of the impact of geometrical curvature on magnetic responses of curved 1D wires and 2D shells is known as curvilinear magnetism [1-3]. The lack of the inversion symmetry and the emergence of a curvature induced effective anisotropy and DMI stemming from the exchange interaction [4,5] are characteristic of curved surfaces, leading to curvature-driven magnetochiral effects. Volkov et al. has proven that the exchange-driven chiral effects in curvilinear ferromagnets are experimental observables [6] and can be used to realize nanostructures with tunable magnetochiral properties from standard magnetic materials.
A counterpart of the intrinsic DMI for the case of curvilinear magnets is the mesoscale Dzyaloshinskii-Moriya interaction, which is a result of the interplay between the intrinsic (spin-orbit-driven) and extrinsic (curvature-driven) DMI terms [7]. The mesoscale DMI governs the magnetochiral properties of any curvilinear ferromagnetic nanosystem and depends both on the material and geometrical parameters. Its strength and orientation can be tailored by properly choosing the geometry, which allows stabilizing distinct magnetic chiral textures including skyrmion and skyrmionium states as well as skyrmion lattices [8-10]. Interestingly, skyrmion states can be formed in a material even without an intrinsic DMI [8,10]. Very recently, Sheka et al. discovered a novel non-local chiral symmetry breaking effect, which does not exist in planar thin film magnets: it is essentially non-local and manifests itself even in static spin textures living in curvilinear magnetic nanoshells [5].
The field of curvilinear magnetism was recently extended towards curvilinear antiferromagnets. Pylypovskyi et al. demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnet behaves as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [11,12]. This positions curvilinear antiferromagnets as a novel platform for the realization of geometrically tunable chiral antiferromagnets for antiferromagnetic spinorbitronics.

[1] R. Streubel et al., J. Phys. D: Appl. Phys. 49 (2016), 363001.
[2] D. Sander et al., J. Phys. D: Appl. Phys. 50 (2017), 363001.
[3] E. Vedmedenko et al., J. Phys. D: Appl. Phys. 53 (2020), 453001.
[4] Y. Gaididei et al., Phys. Rev. Lett. 112 (2014), 257203.
[5] D. Sheka et al., Communications Physics 3 (2020), 128.
[6] O. Volkov et al., Phys. Rev. Lett. 123 (2019), 077201.
[7] O. Volkov et al., Scientific Reports 8 (2018), 866.
[8] V. Kravchuk et al., Phys. Rev. B 94 (2016), 144402.
[9] V. Kravchuk et al., Phys. Rev. Lett. 120 (2018), 067201.
[10] O. Pylypovskyi et al., Phys. Rev. Appl. 10 (2018), 064057.
[11] O. Pylypovskyi et al., Nano Letters 20 (2020), 8157.
[12] O. Pylypovskyi et al., Appl. Phys. Lett. 118 (2021), 182405.

Keywords: flexible magnetic field sensors; curvilinear magnetism

  • Invited lecture (Conferences) (Online presentation)
    IEEE Trends in Magnetism, 06.-10.09.2021, Palermo, Italy

Permalink: https://www.hzdr.de/publications/Publ-32968
Publ.-Id: 32968


Nanomagnetism and spintronics of Cr2O3 magnetoelectric antiferromagnets

Makarov, D.

Thin film antiferromagnets (AF) have potential to revolutionize spintronics due to their inherently magnetic-field stable magnetic order and high-frequency operation. To explore their application potential, it is necessary to understand modifications of the magnetic properties and magnetoelectric responses of AF thin films with respect to their bulk counterparts. Considering grainy morphology of thin films, questions regarding the change of the intergranular exchange, criticality behavior and switching of the order parameter need to be addressed.
Our approach is based on the electron transport characterization of magnetic responses of thin film antiferromagnets [1-4]. This task is difficult as minute uncompensated surface magnetization of antiferromagnets needs to be detected, which imposes strict requirements to the sensitivity of the method. We will outline our developments of zero-offset anomalous Hall magnetometry [1] applied to study the physics of conventional metallic IrMn and insulating magnetoelectric Cr2O3 antiferromagnets. To build a reliable description of the material properties, the analysis of the transport data is backed up by structural characterization and real space imaging of AF domain patterns using NV microscopy [2,5]. Based on this unique and novel combination, we for the first time observe the formation of nanoscale antiferromagnetic domains in thin films of Chromia (Cr2O3) across its ordering temperature at ~300 K. Our quantitative results yield a detailed understanding of the domain formation process in Cr2O3 and allow us to determine the efficiency of inter-granular magnetic exchange coupling [5]. This coupling strength has proven decisive in the decades long development of ferromagnetic memory media and will be of equal importance for future antiferromagnetic spintronics technologies, for which we here present a powerful new development tool.
The fundamental understanding of the magnetic microstructure of magnetoelectric α-Cr2O3 thin films and the possibility to read-out its antiferromagnetic order parameter all-electrically enabled the entirely new recording concept where a magnetoelectric memory cell can be addressed without using a ferromagnet. With this approach, we opened an appealing topic of purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) [2].
By exploring the interaction of antiferrmagnetic domain walls with morphological structures prepared on the surface of Cr2O3 single crystals, we access the nanoscale mechanics of AF domain walls. We propose to employ nanoscale patterns as engineered pinning centers for AF domain walls,
where binary information is encoded by the direction of the Neel vector. Our results bear significant potential for technological exploitation be it in the form of the proposed antiferromagnetic memory devices, or ultimately for the realisation of DW logic using antiferromagnets.
These recent developments on the fabrication and characterization of Cr2O3-based functional elements will be discussed in this presentation.
REFERENCES
[1] T. Kosub, M. Kopte, F. Radu, O. G. Schmidt, D. Makarov, “All-Electric access to the Magnetic-Field-Invariant Magnetization of Antiferromagnets”, Phys. Rev. Lett. 115, 097201 (2015).
[2] T. Kosub, M. Kopte, R. Hühne, P. Appel, B. Shields, P. Maletinsky, R. Hübner, M. O. Liedke, J. Fassbender, O. G. Schmidt, and D. Makarov, “Purely antiferromagnetic magnetoelectric random access memory”, Nature Communications 8, 13985 (2017).
[3] R. Schlitz, T. Kosub, A. Thomas, S. Fabretti, K. Nielsch, D. Makarov, and S. T. B. Goennenwein, “Evolution of the spin hall magnetoresistance in Cr2O3/Pt bilayers close to the Neel temperature”, Appl. Phys. Lett. 112, 132401 (2018).
[4] P. Muduli, R. Schlitz, T. Kosub, R. Hübner, A. Erbe, D. Makarov, and S. T. B. Goennenwein, “Local and nonlocal spin Seebeck effect in lateral Pt-Cr2O3-Pt devices at low temperatures”, Appl. Phys. Lett. Materials 9, 021122 (2021).
[5] P. Appel, B. J. Shields, T. Kosub, R. Hübner, J. Fassbender, D. Makarov, and P. Maletinsky, “Nanomagnetism of magnetoelectric granular thin film antiferromagnets”, Nano Letters 19, 1682 (2019).
[6] O. V. Pylypovskyi, A. V. Tomilo, D. D. Sheka, J. Fassbender, and D. Makarov, “Boundary conditions for the Neel order parameter in a chiral antiferromagnetic slab”, Phys. Rev. B 103, 134413 (2021).
[7] N. Hedrich, K. Wagner, O. V. Pylypovskyi, B. J. Shields, T. Kosub, D. D. Sheka, D. Makarov, and P. Maletinsky, “Nanoscale mechanics of antiferromagnetic domain walls”, Nature Physics (2021). https://doi.org/10.1038/s41567-020-01157-0.

Keywords: antiferromagnetic spintronics

  • Invited lecture (Conferences) (Online presentation)
    2021 IEEE 11th International Conference on "Nanomaterials: Applications & Properties", 05.-11.09.2021, Odesa, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-32967
Publ.-Id: 32967


Organische Synthese einer potenten Leitverbindung zur Entwicklung neuer Radioliganden für die molekulare Bildgebung der mutierten Form der Isocitrat-Dehydrogenase 1 im Gehirn mittels Positronen-Emissions-Tomographie

Linke, J.

Organische Synthese einer potenten Leitverbindung zur Entwicklung neuer Radioliganden für die molekulare Bildgebung der mutierten Form der Isocitrat-Dehydrogenase 1 im Gehirn mittels Positronen-Emissions-Tomographie

Keywords: Isocitrat-Dehydrogenase 1; mIDH1; Ligand; PET; molekulare Bildgebung

  • Master thesis
    Universität Leipzig, 2021
    Mentor: Dr. Rodrigo Teodoro, Dr. Matthias Scheunemann
    80 Seiten

Permalink: https://www.hzdr.de/publications/Publ-32960
Publ.-Id: 32960


Stretchable Thin Film Mechanical Strain Gated Switches and Logic Gate Functions Based on a Soft Tunneling Barrier

Chae, S.; Jin Choi, W.; Fotev, I.; Bittrich, E.; Uhlmann, P.; Schubert, M.; Makarov, D.; Wagner, J.; Pashkin, O.; Fery, A.

Mechanical strain gated switches are cornerstone components of material embedded circuits that perform logic operations without using conventional electronics. This technology requires a single material system to exhibit three distinct functionalities: strain-invariant conductivity and an increase or decrease of conductivity upon mechanical deformation. Herein, we demonstrate mechanical strain-gated electric switches based on a thin-film architecture that features an insulator-to-conductor transition when mechanically stretched. The conductivity changes by nine orders of magnitude over a wide range of tunable working strains (as high as 130%). Our approach relies on a nanometer-scale sandwiched bi-layer Au thin film with an ultrathin polydimethylsiloxane elastomeric barrier layer applied strain alters the electron tunneling currents through the barrier. Mechanical-force-controlled electric logic circuits are achieved by realizing strain-controlled basic (AND and OR) and universal (NAND and NOR) logic gates in a single system. The proposed material system can be used to fabricate material-embedded logics of arbitrary complexity for wide range of applications including soft robotics, wearable/implantable electronics, human machine interface and internet of things.

Keywords: Strain gated electric switch; logic gates; tunneling; stretchable circuit; thin film

Related publications

Permalink: https://www.hzdr.de/publications/Publ-32957
Publ.-Id: 32957


An updated strategic research agenda for the integration of radioecology in the european radiation protection research

Gilbin, R.; Arnold, T.; Beresford, N. A.; Berthomieu, C.; Brown, J. E.; de With, G.; Horemans, N.; Madruga, M. J.; Masson, O.; Merroun, M.; Michalik, B.; Muikku, M.; O’Toole, S.; Mrdakovic Popic, J.; Nogueira, P.; Real, A.; Sachs, S.; Salbu, B.; Stark, K.; Steiner, M.; Sweek, L.; Vandenhove, H.; Vidal, M.; Vives I. Batlle, J.

The ALLIANCE Strategic Research Agenda (SRA) for radioecology is a living document that defines a long-term vision (20 years) of the needs for, and implementation of, research in radioecology in Europe. The initial SRA, published in 2012, included consultation with a wide range of stakeholders (Hinton et al., 2013). This revised version is an update of the research strategy for identified research challenges, and includes a strategy to maintain and develop the associated required capacities for workforce (education and training) and research infrastructures and capabilities. Beyond radioecology, this SRA update constitutes a contribution to the implementation of a Joint Roadmap for radiation protection research in Europe (CONCERT, 2019a). This roadmap, established under the H2020 European Joint Programme CONCERT, provides a common and shared vision for radiation protection research, priority areas and strategic objectives for collaboration within a European radiation protection research programme to 2030 and beyond. Considering the advances made since the first SRA, this updated version presents research challenges and priorities including identified scientific issues that, when successfully resolved, have the potential to impact substantially and strengthen the system and/or practice of the overall radiation protection (game changers) in radioecology with regard to their integration into the global vision of European research in radiation protection. An additional aim of this paper is to encourage contribution from research communities, end users, decision makers and other stakeholders in the evaluation, further advancement and accomplishment of the identified priorities.

Keywords: Strategic Research Agenda for radioecology; Environmental exposure to radionuclides; Radiation protection of the environment; Integration of radiation protection research; Education and training; Infrastructures

Permalink: https://www.hzdr.de/publications/Publ-32953
Publ.-Id: 32953


Large magnetic entropy change in Nd2In near the boiling temperature of natural gas

Liu, W.; Scheibel, F.; Gottschall, T.; Bykov, E.; Dirba, I.; Skokov, K.; Gutfleisch, O.

Natural gas is useful for the transition from traditional fossil fuels to renewable energies. The consumption of liquid natural gas has been rising, and the demand is predicted to double by 2040. In this context, magnetocaloric gas liquefaction, as an emerging and energy-saving technology, could be an alternative to the traditional gas-compression refrigeration. In this work, we report a large magnetic entropy change of 7.42 J/kg K under a magnetic field change of 2 T in Nd2In at 109 K, which is near the boiling temperature of natural gas of 112 K. The maximum adiabatic temperature change reaches 1.13K under a magnetic field change of 1.95 T and is fully reversible. The magnetic phase transition is confirmed to be of the first-order type with the negligible thermal hysteresis. Further investigations on the thermal expansion and the magnetostriction reveal that the magnetic transition undergoes two stages with a negligible volume change. The longitudinal strain increases with magnetic fields and then decreases. These interesting properties are useful for the practical design of a magnetocaloric natural gas liquefaction system and for the fundamental understanding of the phase transitions in other RE2In intermetallics.

Permalink: https://www.hzdr.de/publications/Publ-32952
Publ.-Id: 32952


Influence of microstructure on the application of Ni-Mn-In Heusler compounds for multicaloric cooling using magnetic field and uniaxial stress

Pfeuffer, L.; Gracia-Condal, A.; Gottschall, T.; Koch, D.; Faske, T.; Bruder, E.; Lemke, J.; Taubel, A.; Ener, S.; Scheibel, F.; Durst, K.; Skokov, K. P.; Manosa, L.; Planes, A.; Gutfleisch, O.

Novel multicaloric cooling utilizing the giant caloric response of Ni-Mn-based metamagnetic shape- memory alloys to different external stimuli such as magnetic field, uniaxial stress and hydrostatic pressure is a promising candidate for energy-efficient and environmentally-friendly refrigeration. However, the role of microstructure when several external fields are applied simultaneously or sequentially has been scarcely discussed in literature. Here, we synthesized ternary Ni-Mn-In alloys by suction casting and arc melting and analyzed the microstructural influence on the response to magnetic fields and uniaxial stress. By combining SEM-EBSD and stress-strain data, a significant effect of texture on the stress- induced martensitic transformation is revealed. It is shown that a <001> texture can strongly reduce the critical transformation stresses. The effect of grain size on the material failure is demonstrated and its influence on the magnetic-field-induced transformation dynamics is investigated. Temperature-stress and temperature-magnetic field phase diagrams are established and single caloric performances are characterized in terms of ΔsT and ΔTad. The cyclic ΔTad values are compared to the ones achieved in the multicaloric exploiting-hysteresis cycle. It turns out that a suction-cast microstructure and the combination of both stimuli enables outstanding caloric effects in moderate external fields which can significantly exceed the single caloric performances. In particular for Ni-Mn-In, the maximum cyclic effect in magnetic fields of 1.9 T is increased by more than 200 % to -4.1 K when a moderate sequential stress of 55 MPa is applied. Our results illustrate the crucial role of microstructure for multicaloric cooling using Ni-Mn- based metamagnetic shape-memory alloys.

Permalink: https://www.hzdr.de/publications/Publ-32951
Publ.-Id: 32951


Evaluation of the effective temperature change in Gd-based composite wires assessed by static and pulsed-field magnetic measurements

Beyer, L.; Weise, B.; Freudenberger, J.; Hufenbach, J. K.; Gottschall, T.; Krautz, M.

Gd cladded in a seamless 316L austenitic steel tube has been swaged into wires by the powder-in-tube (PIT) technology, resulting in an outer diameter of 1 mm, a wall thickness of approx. 100 μm and a filling factor of around 62 vol%. Such wires provide an advantageous geometry for heat exchangers and have the benefit to protect the Gadolinium, i.e. from corrosion when being in contact with a heat transfer fluid. The magnetocaloric composite has been studied by static and pulsed magnetic-field measurements in order to evaluate the performance of Gd as a core material. By the analysis of magnetization and heat capacity data, the influences of deformation-induced defects on Gadolinium are presented. The subsequent heat treatment at 773 K for 1 h in Ar atmosphere allowed restoring the magnetic properties of the wire after deformation. Data of the pulsed magnetic-field measurements on the Gd-filled PIT-wires and a Gd–core separated from the jacket are presented, with an achievable temperature change of 1.2 K for the wire and 5.2 K for the Gd in 2 T, respectively. A comparison to previously studied La(Fe, Co, Si)13-filled composite wires is included. It indicates that performance losses due to the passive matrix material cannot be overcome only by an increased adiabatic temperature change of the core material, but instead the wire components need to be chosen regarding an optimized heat capacity ratio, as well.

Permalink: https://www.hzdr.de/publications/Publ-32950
Publ.-Id: 32950


Correlated effects of fluorine and hydrogen in fluorinated tin oxide (FTO) transparent electrodes deposited by sputtering at room temperature

Morán-Pedroso, M.; Gago, R.; Julin, J. A.; Salas-Colera, E.; Jimenez, I.; de Andrés, A.; Prieto, C.

The optical and electrical properties of fluorinated tin oxide (FTO) films deposited at room temperature by sputtering have been investigated varying the fluorine content and the hydrogen atmosphere. The complex behavior of the obtained films is disclosed using a wide set of characterization techniques that reveals the combined effects of these two parameters on the generated defects. These defects control the electrical transport (carrier density, mobility and conductivity), the optical properties (band gap and defects-related absorption and photoluminescence) and finally promote the amorphization of the samples. H₂ in the sputtering gas does not modify the H content in the films but induces the partial reduction of tin (from Sn4+ to Sn2+) and the consequent generation of oxygen vacancies with shallow energy levels close to the valence band. A variation of up to four orders of magnitude in electrical conductivity is reported in samples with the appropriate fluorine doping and hydrogen fraction in the sputtering gas, maintaining excellent optical transparency. Optimized room temperature grown electrodes reach sheet resistance ~20 Ω/□ and transparency >90%. This room temperature deposition process enables film preparation on flexible organic substrates, such as polyethylene terephthalate (PET), with identical performance of doubtless interest in flexible and large scale electronics.

Keywords: Transparent conductive materials; Fluorinated tin oxide; Room temperature film preparation

Permalink: https://www.hzdr.de/publications/Publ-32947
Publ.-Id: 32947


UDV methods for characterizing flows in liquid metal batteries

Cheng, J.; Wang, B.; Mohammad, I.; Horstmann, G. M.; Kelley, D.

We present ultrasound measurements from a laboratory model of a liquid metal battery (LMB). Two major flow
drivers interact within LMBs: thermal gradients due to the presence of internal heating, and electrovortex flow
(EVF) driven by diverging current densities. The product of these interactions remains poorly characterized. We
approach this problem with ultrasonic Doppler velocimetry (UDV) combined with a laboratory model of an LMB
fluid layer. Using ultrasound probes placed around a liquid gallium vessel, we elucidate typical velocities, flow
structures, and flow statistics in a representative volume of the flow field. UDV measurements reveal that pure
convection takes the form of the recently-discovered ‘jump rope vortex,’ with a characteristic frequency visible in
velocity statistics. They also indicate that EVF goes through stable, unstable, and oscillatory flow regimes. In
progress is an approach for training physics-informed neural networks (PINNs) on UDV data, allowing us to
reconstruct flow in regions where no probe measurements have taken place by leveraging the equations of motion.

  • Contribution to proceedings
    13th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (ISUD 2021), 13.-15.06.2021, Zürich, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-32944
Publ.-Id: 32944


Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Alves, F.; Antunes, I.; Cazzola, E.; Cleeren, F.; Cornelissen, B.; Denkova, A.; Engle, J.; Faivre-Chauvet, A.; Gillings, N.; Hendrikx, J.; Jalilian, A.; van der Meulen, N.; Mikolajczak, R.; Neels, O.; Pillai, M.; Reilly, R.; Rubow, S.; Seimbille, Y.; Spreckelmeyer, S.; Szymanski, W.; Taddei, C.

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to update the readership on trends in the field of radiopharmaceutical development.
Results: This commentary of highlights has resulted in 21 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals. Also the first contribution in relation to MRI-agents is included.
Conclusion: Trends in (radio)chemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry.

Permalink: https://www.hzdr.de/publications/Publ-32943
Publ.-Id: 32943


Hydrodynamic and efficiency data pertaining to an air-water column mockup (of 0.8 m internal diameter) equipped with sieve trays

Vishwakarma, V.; Marchini, S.; Schleicher, E.; Schubert, M.; Hampel, U.
DataCollector: Vishwakarma, Vineet; DataCollector: Marchini, Sara; RelatedPerson: Schleicher, Eckhard; ContactPerson: Schubert, Markus; Supervisor: Hampel, Uwe

The hydrodynamic data including effective froth height, liquid holdup and tracer flow and patterns related to an operational sieve tray inside a 0.8 m diameter air-water column simulator are provided here. These data were obtained via an advanced multiplex flow profiler at several gas and liquid loadings. The generated data were examined for predicting the tray efficiency using mathematical models. For model validation, the stripping of isobutyl acetate from the aqueous solution over the tray was employed, and the liquid samples at several tray locations were analyzed via UV spectroscopy. The resulting efficiencies and related information are provided here, too. All raw data files, data processing scripts and supporting information with proper indexing and sequencing are uploaded. All these data are intended for non-commercial use only.

Keywords: Column tray; two-phase crossflow; 3D liquid holdup; effective froth height; tracer-response analysis; tray efficiency calculations

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2021-07-21
    DOI: 10.14278/rodare.1071

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Permalink: https://www.hzdr.de/publications/Publ-32942
Publ.-Id: 32942


Superconducting solenoid field measurement and optimization

Ma, S.; Arnold, A.; Ryzhov, A.; Murcek, P.; Zwartek, P.; Schaber, J.; Qian, H.; Teichert, J.; Xiang, R.

The solenoid is a significant part of an electron injector to provide a proper focusing, and preserve the beam projected emittance. A superconducting solenoid is applied for the SRF photoinjector at HZDR. The solenoid itself can degrade electron beam quality due to magnetic field imperfections like multipole components. In order to determine the field aberrations in the solenoid, we measured the superconducting solenoid magnetic field in the cryomodule. A simple and effective method is used to analyze the multipole field components, which will be presented in this paper.

Keywords: solenoid; magnetic field

  • Open Access Logo Contribution to proceedings
    12th International Particle Accelerator Conference (IPAC’21), 24.-28.05.2021, Brasília, Brazil
    Proceedings of IPAC’21: JACoW

Permalink: https://www.hzdr.de/publications/Publ-32938
Publ.-Id: 32938


Generalized Landau-Khalatnikov-Fradkin transformations for arbitrary N-point fermion correlators

Ahmadiniaz, N.; Edwards, J. P.; Nicasio, J.; Schubert, C.

We examine the nonperturbative gauge dependence of arbitrary configuration space fermion correlators in quantum electrodynamics (QED). First, we study the dressed electron propagator (allowing for emission or absorption of any number of photons along a fermion line) using the first quantized approach to quantum field theory and analyze its gauge transformation properties induced by virtual photon exchange. This is then extended to the N-point functions where we derive an exact, generalized version of the fully nonperturbative Landau-Khalatnikov-Fradkin (LKF) transformation for these correlators. We discuss some general aspects of the application in perturbation theory and investigate the structure of the LKF factor aboutD¼2dimensions

Keywords: LKFT; Worldline formalism; Non-perturbative QED

Permalink: https://www.hzdr.de/publications/Publ-32937
Publ.-Id: 32937


High-entropy carbons: From high-entropy aromatic species to single-atom catalysts for electrocatalysis

Ding, J.; Wu, D.; Zhu, J.; Rodríguez-Hernández, F.; Chen, Y.; Lu, C.; Zhou, S.; Zhang, J.; Tranca, D.; Zhuang, X.

Single-atom catalysts (SACs) have rapidly entered the field of nanomaterials and demonstrated great potential for energy devices in recent years. Of all types of SACs, porous carbon-based SACs are the most popular species because of their excellent conductivity, large specific surface area, and easily tunable heteroatom and metal components. However, most of the reported cases focus on the metal centers and their coordination environments, while they do not pay much attention to carbon precursors and carbon transformation during high-temperature treatment. In this work, we use a high-entropy aromatic molecule, azulene, for rational synthesis of azulene-enriched, sandwich-like polymer nanosheets and corresponding single-Fe-dispersed porous carbon nanosheets. The azulene-based metal-free polymer nanosheets exhibit a narrow band gap and temperature-dependent magnetism. As proof-of-concept electrocatalysts for CO2 reduction, the prepared carbon nanosheets exhibit high activity and stability. Operando X-ray absorption spectroscopy and density functional theory studies reveal the high activity of Fe-N coordination sites in the presence of 5/7-membered carbon ring-based topological defects in the carbon skeleton. Taken together, this work provides a new method of synthesizing high-entropy carbons using azulene-based high-entropy molecule as precursor and paves the way toward high-efficiency SACs with rich topological defects for energy conversion.

Keywords: High-entropy aromatic molecule; Topological defect; Single-atom catalyst; Porous carbon nanosheet; Carbon dioxide conversion

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  • Secondary publication expected from 14.07.2022

Permalink: https://www.hzdr.de/publications/Publ-32934
Publ.-Id: 32934


QE and life time of Cs2Te photocathodes on copper for SRF gun-II at HZDR

Xiang, R.; Arnold, A.; Ma, S.; Murcek, P.; Ryzhov, A.; Schaber, J.; Teichert, J.

The SRF gun-II at HZDR has been stably applied as the electron
source for high power THz radiation since 2018, generating CW beams
with bunch charges up to 300 pC at 100 kHz. It is an excellent demonstration
that SRF guns can work reliably in a high power user facility.
In order to generate higher current beam with MHz repetition rate,
Cs2Te photocathodes are required. However, in last two experiments
with Cs2Te, the Mo substrate plugs were overheated in superconducting
rf cavity. The reason is that different thermal expansion coefficient
of Mo and Cu led to a bad thermal contact between the Mo plug and
Cu holder. Thus we decided to use Cu as new substratum of Cs2Te
cathodes. In last year we prepared several Cs2Te photocathodes on Cu
plugs and improved the vacuum of cathode transfer system in order
to achieve satisfied lifetime. In this contribution, we will present the
study result of QE and life time of Cs2Te photocathodes with different
thickness.

Keywords: SRF gun; photocathode; Cs2Te

  • Open Access Logo Lecture (Conference) (Online presentation)
    DPG-Frühjahrstagung (Dortmund), 15.-19.03.2021, Dortmund, Germany

Permalink: https://www.hzdr.de/publications/Publ-32933
Publ.-Id: 32933


Observability of Coulomb-assisted quantum vacuum birefringence

Ahmadiniaz, N.; Bussmann, M.; Cowan, T.; Debus, A.; Kluge, T.; Schützhold, R.

We consider the scattering of an x-ray free-electron laser (XFEL) beam on the superposition of
a strong magnetic field $\bf{B}_{\rm ext}$ with the Coulomb field $\bf{E}_{\rm ext}$
of a nucleus with charge number $Z$. In contrast to Delbr\"uck scattering
(Coulomb field only), the magnetic field $\bf{B}_{\rm ext}$
introduces an asymmetry (i.e., polarization dependence) and renders the effective interaction volume quite
large, while the nuclear Coulomb field facilitates a significant momentum transfer $\Delta\bf k$.
For a field strength of $B_{\rm ext}=10^6 T$ (corresponding to an intensity of order $10^{22}~\rm W/cm^2$)
and an XFEL frequency of 24~keV, we find a differential cross section
$d\sigma/d\Omega\sim10^{-25}~Z^2/(\Delta{\bf k})^2$ in forward direction for one nucleus.
Thus, this effect might be observable in the near future at facilities such as the
Helmholtz International Beamline for Extreme Fields (HIBEF) at the European XFEL.

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Permalink: https://www.hzdr.de/publications/Publ-32932
Publ.-Id: 32932


Caesium deposition on GaN to obtain a photocathode for particle accelerator

Schaber, J.; Xiang, R.; Teichert, J.; Arnold, A.; Ryzhov, A.; Murcek, P.; Zwartek, P.; Ma, S.

Negative electron affinity (NEA) GaAs- and GaN-based photocathodes are used in modern night vison detectors and light emitting diodes1. GaAs semiconductors are already used as electron sources in particle accelerators and well- studied2. Like GaAs, GaN belongs to the
III-V semiconductor group with similar properties. It is assumed that GaN, like GaAs, shows enormous potential as a novel electron source for particle accelerators.

P-type GaN on different substrate material (sapphire, silicon, copper or SiC) is activated by a thin layer of caesium and illuminated by ultra-violet (UV) light at the same time. As a consequence of negative electron affinity (NEA) and photoeffect, the generated photoelectrons enter into vacuum and are collected by a copper ring anode. The resulting photocurrent is detected during the whole activation process and stopped when a maximum photocurrent is reached.
The GaN is chemical cleaned and transferred into a UHV chamber where it undergoes a thermal heat treatment at 250°C for 20 min using a halogen lamp. The aim of the thermal treatment is to remove residual adsorbed gas molecules from the sample surface.
Afterwards when the sample is back at room temperature, the thermal-cleaned GaN is activated with a thin layer of caesium. The photocurrent and the QE is observed in the following days until the QE vanishes. Then it is tested to re-activate the cathode again, meaning to thermal clean it again and to activate it with caesium once more.

By a comparison of differences in substrate material, chemical pre-cleaning, thermal heat treatment and activation parameters (e.g. caesium-flux), the photocurrent, quantum efficiency and the re-activation of the photocathode is studied. Additionally the GaN samples are examined by AFM, SEM and EDX.
From the experimental results obtained so far, it appears that GaN:Cs could be used as a photocathode in particle accelerators, but further investigations are still required and needed.

Keywords: gallium nitride; photocathode; caesium deposition; SRF Gun

  • Open Access Logo Poster (Online presentation)
    DPG-Frühjahrstagung des Fachverbandes Oberflächenphysik, 01.-04.03.2021, Hannover, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32929
Publ.-Id: 32929


Status Report of GaN photocathode

Schaber, J.; Xiang, R.; Teichert, J.; Ryzhov, A.; Murcek, P.; Zwartek, P.; Ma, S.

The photocathodes determine the beam quality in linear accelerators and represent a key component for many accelerator projects. Free-electron lasers (FEL), synchrotron- and THz radiation sources require injector systems with high brightness electron beams.

High quantum efficiency, a long lifetime and good vacuum stability, fast response time and low thermal emittance are desirable parameters for a perfect photocathode used in accelerators. Semiconductors such as GaN and GaAs as novel materials for photocathodes are showing an enormous potential.
GaAs is a well-known material for photocathodes. After activation with caesium and oxygen, it has a high QE for visible light (red or green). An advantage of GaAs is the opportunity of the layers to emit spin-polarized electrons.
GaN is a semi-conductive material and well known for its high QE when lighted with UV light. For improving the QE only caesium for activation is required.
At the moment GaN is used for photocathode-based detectors such as photomultipliers or phototubes and for LEDs. They have characteristics of low dark current, high-speed response and high sensitivity. It is very new for application in SRF Guns. It seems to be more robust and achieves higher QE than other photocathodes [1].
Crystallinity and surface parameters define the photoemission properties. Modern analytical methods are used for identification of impurities, dislocations and characterization of the crystallinity of the semiconductors and the right cleaning treatment as well as the right caesium rating.
[1] Uchiyama, Shoichi et al. 2011. “GaN-Based Photocathodes with Extremely High Quantum Efficiency” 103511(2005):1–4.

Keywords: gallium nitride; photocathode; SRF Gun

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    High Brightness Electron beams generated from novel THermal resistant photocathodes (BETH) 3rd Collaboration Meeting, 01.03.2021, Siegen, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32928
Publ.-Id: 32928


Two Examples for AI Communities

Juckeland, G.; Steinbach, P.

This short talk presents two approaches for building AI communities in the Dresden area. First the top down approach of Helmholtz AI, where HZDR is one of six hubs of consultants to assist and train scientists. Second with the Machine Learning Community (MLC) Dresden a bottom up approach of practitioners just sharing experience and information in regular seminars and other asynchronous communication channels.

Keywords: Helmholtz AI

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Kick-Off of Scientific Area Network “Dimensions of Artificial Intelligence”, 16.07.2021, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-32923
Publ.-Id: 32923


Operational experience of photocathodes for HZDR SRF gun

Xiang, R.; Arnold, A.; Ma, S.; Murcek, P.; Teichert, J.; Schaber, J.; Zwartek, P.

The SRF gun-II at HZDR has been stably applied as the electron source for high power THz radiation since 2018, generating CW beams with bunch charges up to 300 pC at 100 kHz. It is an excellent demonstration that SRF guns can work reliably in a high power user facility.
As well known, that the quality of the photocathodes is critical for the stability and reliability of the gun operation. In last years, thank to the successful ps UV laser cleaning, Mg photocathodes were successfully used for gun operation at kHz repitition rate.
In order to satisfy user request of MHz operation, Cs2Te is still in demand. However, the Mo plugs were overheated in superconducting rf cavity due to thermal contact problem, and SRF Gun-II faced twice serious contamination in 2017. The Cs2Te could not be used in gun untill Cu is adopted in stead of Mo as new substratum. Up to now three Cs2Te cathodes on Cu plugs have been applied in the Gun-II.
In this contribution, we will present the operational aspect of the photocathodes for SRF gun, and discuss the possible improvement in the future application.

Keywords: SRF gun; photocathode

  • Open Access Logo Poster (Online presentation)
    2021 International Conference RF Superconductivity, 28.06.-02.07.2021, East Lansing, USA

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Permalink: https://www.hzdr.de/publications/Publ-32922
Publ.-Id: 32922


Review of superconducting radiofrequency gun

Xiang, Rong

The success of proposed high power free-electron lasers (FELs) and energy recovery linac (ERL) largely depends on the development of the electron source, which requires the best beam quality and CW operation. An elegant way to realize both high brilliance and high current is to com-bine the high beam quality of the normal conducting radio frequency photoinjector with the quick developing superconducting radio frequency technology, to build superconducting rf photoinjectors (SRF guns).
In last decade, several SRF gun programs based on dif-ferent approaches have achieved promising progress, even succeeded in routine operation at BNL and HZDR. In the near future SRF guns are expected to play an im-portant role for hard X-ray FEL facilities. In this contribu-tion, we will review the design concepts, parameters, and status of the major SRF gun projects.

Keywords: SRF gun

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    12th International Particle Accelerator Conference (IPAC’21), 24.-28.05.2021, virtual format, Brazil

Permalink: https://www.hzdr.de/publications/Publ-32921
Publ.-Id: 32921


Solving overheating of Cs2Te cathodes in the ELBE SRF gun

Arnold, A.

In 2014, the second-generation of the ELBE SRF gun replaced its predecessor, which had been in operation since 2007. In the first two years, copper and magnesium cathodes were initially used without any discernible problems. However, after switching to Cs2Te in 2017, it was found that the layers of two cathodes evaporated within a few days during RF operation in the Gun. Since this was never observed in Gun I, an extensive root cause search was conducted using a dedicated cathode test setup. The findings pointed to loose thermal contact between the cathode plug and the cathode body and ultimately resulted in a change
of the used cathode substrate from molybdenum to copper. Although this was accompanied by a lower quantum efficiency of about 5% after preparation, it stabilized to 1-2% during beam operation in the SRF gun. As of May 2020, three of these cathodes have now been successfully used for THz user beam time and a total charge of 26 C has been extracted. Together with the electrons still produced by Mg cathodes in 2019/2020, a total of 217 user shifts could be served and 2600h hours of beam time were delivered. This demonstrates the reliability of CW SRF in combination with normal conducting cathode and is so far unique in the world. During the talk, the reason for overheating, the preparation on Cu substrate as well as experiences from the past two years of user beam operation will be presented in detail.

Keywords: SRF gun; SRF; superconducting; radio frequency; ELBE

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    7th MT meeting (virtuell), 01.-03.02.2021, Online, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32920
Publ.-Id: 32920


RF Experience from 6 Years of ELBE SRF-Gun II Operation

Arnold, A.; Lu, P.; Ma, S.; Murcek, P.; Ryzhov, A.; Schaber, J.; Teichert, J.; Xiang, R.; Ciovati, G.; Kneisel, P.; Vennekate, H.

At the electron accelerator for beams with high bril-liance and low emittance (ELBE), the second version of a superconducting radio-frequency (SRF) pho-toinjector was brought into operation in 2014. After a period of commissioning, a gradual transfer to routine operation took place in 2017 and 2018, so that now more than 3400h of user beam have already been gen-erated since 2019. During this time, a total of 20 cath-odes (2 Cu, 12 Mg, 6 Cs2Te) were used, but no serious cavity degradation was observed. In this paper, we summarize the operational experience of the last 6 years of SRF gun operation, with special emphasis on main RF properties of the gun cavity.

Keywords: SRF gun; SRF; superconducting; radio frequency; ELBE

  • Open Access Logo Poster (Online presentation)
    2021 International Conference on RF Superconductivity (SRF'21), 28.06.-02.07.2021, East Lansing, Michican, USA

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Permalink: https://www.hzdr.de/publications/Publ-32919
Publ.-Id: 32919


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