12 Works

Neutron study of the topological flux model of hydrogen ions in water ice

J.-U. Hoffmann, K. Siemensmeyer, S. Isakov, D. J. P. Morris, B. Klemke, I. Glavatskyi, K. Seiffert, D. A. Tennant, S. Sondhi & R. Moessner
The familiarity of water ice means we often overlook its non-trivial character illustrated, for example, by the many snowflake morphologies resulting from disordered combinations of covalent and hydrogen bonds between hydrogen and oxygen atoms in water ice’s most common phase (Ih) that keep the H_2 O molecular character. Using neutron diffraction on the flat-cone diffractometer E2 at BER-II, Helmholtz-Zentrum Berlin, we probe the atomic scale configuration in the Ih phase of water ice to test...

Helmholtz Open Science Briefing. Helmholtz Open Science Praxisforum Forschungsdatenmanagement. Report

Nina Leonie Weisweiler, Roland Bertelmann, Jan Bumberger, Kirsten Elger, Maik Fiedler, Patrick Fuhrmann, Oliver Knodel, Rolf Krahl, Özlem Özkan, Florian Rhiem, Ines Schmahl, Sophie Servan, Arne Upmeier & Kerstin Vanessa Wedlich-Zachodin
Zum Austausch von Best Practices aus den Zentren und zur Förderung der FDM-Community in Helmholtz veranstaltete das Helmholtz Open Science Office am 3. Februar 2022 das erste „Helmholtz Open Science Praxisforum Forschungsdatenmanagement“. In dem Helmholtz-internen Forum wurden exemplarisch verschiedene Herangehensweisen aus Zentren zur Organisation des FDM vorgestellt. Darüber hinaus standen konkrete Service-Angebote zu FDM im Mittelpunkt. Außerdem wurde die Vernetzung mit externen Akteuren, z. B. im Rahmen der NFDI, EOSC oder der RDA, beleuchtet. Die...

3D Neutron Computed Laminography of Maize Plants

Nicole Rudolph-Mohr, Sarah Bereswill, Christian Tötzke, Nikolay Kardjilov & Sascha E. Oswald
Plant root systems induce biogeochemical patterns in the soil by respiration, water uptake and root exudation that can be measured with in-situ imaging techniques. Slab-shaped rhizoboxes represent the optimum design for 2D optical fluorescence imaging of pH and oxygen dynamics in the rhizosphere as well as measurement of soil water content by neutron radiography. However, quality of standard tomographic (3D) imaging of laterally extended samples suffers from insufficient neutron transmission over a significant angular range....

Focused Ion Beam tomography on fossilized osteocytes

Yara Haridy, Markus Osenberg, André Hilger, Ingo Manke, Donald Davesne & Florian Witzmann
Osteocytes play a central role in bone metabolism in extant vertebrates, but their evolutionary history is poorly understood. Therefore osteocyte lacunae microstructure of fossil bone was studied on the nanometer scale by means of focused ion beam tomography (FIB). A osteostracan and a “placoderm” were imaged, the earliest groups with cellular bone, and secondary osteons respectively. To visualize and characterize the early bone composition via the morphology and distribution of osteocyte lacunae, thereby imaging the...

Dataset associated with \"Magnetoelastic resonance as a probe for exchange springs at antiferromagnet-ferromagnet interfaces\"

Klaus Seemann, Gomonay, Y. Mokrousov, Andreas Hörner, S. Valencia, Pascal Klamser, Florian Kronast, Andreas Erb, Aidan Hindmarch, A. Wixforth, Christopher Marrows & Peter Fischer
Dataset associated with "Magnetoelastic resonance as a probe for exchange springs at antiferromagnet-ferromagnet interfaces" by K. M. Seemann et al.

Using the photo-induced L_3 resonance shift in Fe and Ni as time reference for ultrafast experiments at low flux soft X-ray sources

Somnath Jana, Shreyas Muralidhar, Johan Åkerman, Christian Schüßler-Langeheine & Niko Pontius
We study the optical-pump induced ultrafast transient change of the X-ray absorption at the L_3 absorption resonances of the transition metals Ni and Fe in Fe_{0.5}Ni_{0.5} alloy. We find the effect for both elements to occur simultaneously on a femtosecond timescale. This effect may hence be used as a handy cross-correlation scheme providing a time-zero reference for ultrafast optical-pump soft X-ray-probe measurement. The method benefits from a relatively simple experimental setup as the sample itself...

Optical simulations of nanotextured perovskite/silicon tandem solar cell

Klaus Jäger, Johannes Sutter, Philipp-Immanuel Schneider, Martin Hammerschmidt & Christiane Becker
Perovskite/silicon tandem solar cells (PSTSC) are amongst the most promising routes to increase the power conversion efficiency (PCE) of silicon-based solar cells. Many of the highly efficiency PSTSC use planar perovskite top cell layer stacks because of the compatibility with solution processing, which is the preferred fabrication process for perovskite solar cells. However, light management can further improve the optical performance of PSTSC. For example, smooth nanotextures can help to reduce reflective losses and increase...

Supplement to: Machine learning classification for field distributions of photonic modes

Carlo Barth & Christiane Becker
Electromagnetic modes of photonic nanostructures can exhibit increased near-field energy densities which can be applied in many fields such as biosensing, quantum dot solar cells or photon upconversion. Optimizing such systems enforces to systematically analyze large amounts of numerically obtained three-dimensional field distribution data, as in the presented dataset. The simulated system is a silicon photonic crystal slab on glass (subspace) with a hexagonal lattice of cylindrical holes. The holes are filled with a medium...

Optimizing metal grating back reflectors for III-V-on-silicon multijunction solar cells

Peter Tillmann, Benedikt Bläsi, Sven Burger, Martin Hammerschmidt, Oliver Höhn, Christiane Becker & Klaus Jäger
Multi-junction solar cells allow to utilize sunlight more effectively than single junction solar cells. In our work, we present optical simulations of III-V-on-silicon solar cells with a metal grating at the back, which experimentally have reached more than 33% power conversion efficiency. First, we perform simulations with the finite element method and compare them with experimental data to validate our model. We find that accurately modeling the investigated geometrical structure is necessary for best agreement...

Metadata Schema for the Persistent Identification of Instruments

Rolf Krahl, Louise Darroch, Robert Huber, Anusuriya Devaraju, Jens Klump, Ted Habermann, Markus Stocker &

Checklist to Support the Helmholtz Centers in Implementing Policies on Sustainable Research Software

Reinhard Messerschmidt, Heinz Pampel, Felix Bach, Wolfgang zu Castell, Michael Denker, Ants Finke, Bernadette Fritzsch, Martin Hammitzsch, Uwe Konrad, Yvonne Leifels, Christoph Möhl, Marco Nolden, Markus Scheinert, Tobias Schlauch, Thomas Schnicke & Dirk Steglich
As the digitalization of research and teaching progresses, the number of software solutions developed at scientific institutions and used for the purpose of knowledge production is increasing. The accessibility and reuse of scientific results called for under the heading “open science” can be ensured in many fields only if, in addition to research data, program code is also made openly accessible. The present guide is addressed to decision-makers at the Helmholtz Centers who deal with...

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

Reinhard Messerschmidt, Heinz Pampel, Felix Bach, Wolfgang zu Castell, Michael Denker, Ants Finke, Bernadette Fritzsch, Martin Hammitzsch, Uwe Konrad, Yvonne Leifels, Christoph Möhl, Marco Nolden, Markus Scheinert, Tobias Schlauch, Thomas Schnicke & Dirk Steglich
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....

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  • Helmholtz Association of German Research Centres
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  • Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
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  • Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
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  • Optics for Solar Energy, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 16, 12489 Berlin
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