Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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34122 Publications

Improving processing by adaptation to conditional geostatistical simulation of block compositions

Tolosana-Delgado, R.; Mueller, U.; van den Boogaart, K. G.; Ward, C.; Gutzmer, J.

Theoretically, exploitation of an ore deposit could be optimized by adapting the beneficiation processes to the properties of each individual ore block being extracted. Such an adaptation can involve switching on and off certain processes, or setting their controlling parameters. These decisions depend typically on physical and chemical attributes. Physical parameters are relevant both at macroscopic and microscopic scale, whereas chemical attributes include both the concentration of the value element, and the presence and abundance of penalty elements. As a first step towards adaptive processing, this contribution explores mapping those adaptive decisions which are based on the composition in value and penalty elements of the selective mining unit or mining block.

Cokriging and geostatistical simulation are reasonable tools to provide information about the concentration of these elements, both in expected value and uncertainty. However, when the sum of total penalty and value elements approaches 100%, it is mandatory that geostatistical results do not exceed that sum. Moreover, some processing techniques work by applying a filter to the composition of material that is being processed, so that their partial output concentration can be taken as a known portion of their input concentration. In such a context, the use of geostatistics on the raw data will deliver inconsistent results, which can be avoided via log-ratio methods: a one-to-one log-ratio transformation is applied to the raw data, followed by modelling via classical multivariate geostatistical tools, and subsequent back-transform of predictions and simulations. Results satisfy the constant sum constraints by construction, even in simulations. Furthermore, filtering processes behave linearly if expressed in terms of log-ratios.

To illustrate the approach, a toy example is used, where a 4-component system (consisting of a value element, two penalty elements and some liberable material, each representing a material type or a set of minerals) is beneficiated through a chain of technical processes. A sequence of milling, desliming and flotation is applied to separate most of the value element, and the product is classified in three qualities. Knowing all processing costs and selling prices, a compositional geostatistical simulation framework can be run to map the best processing choices and qualities as a function of the available measurements of the percentages of the four components, instead of mapping these percentages themselves. In doing so, the uncertainty about gains can be quantified at the same time.

Keywords: Change of support; compositional data analysis; geometallurgy; stochastic optimisation

  • Open Access Logo The Journal of the Southern African Institute of Mining and Metallurgy 115(2015), 13-26

Permalink: https://www.hzdr.de/publications/Publ-19459
Publ.-Id: 19459


Coolant mixing experiments in the upper plenum of the ROCOM test facility

Prasser, H.-M.; Kliem, S.

We have performed measurements of the turbulent mixing in the upper plenum of the ROCOM test facility sometimes ago (Grunwald et al., 2003). Since the data reflects the phenomenon very clearly, we are convinced that the results of the experiments can be used for the code validation with regard to the described effect.

Permalink: https://www.hzdr.de/publications/Publ-19458
Publ.-Id: 19458


Fracture mechanics characterisation of reactor pressure vessel multi-layer weld metal

Viehrig, H.-W.; Houska, M.; Kalkhof, D.; Schindler, H.-J.

Fracture toughness of the multi-layer beltline welding seam of the Biblis C reactor pressure vessel was characterized by the test standard ASTM E1921. The reference temperature, T0, was determined for different thickness positions of the multi-layer welding seam. Additionally, the influence of the specimen orientation on T0 was investigated. In contrast to the T-S orientation (crack extension through the thickness) the crack front of the T-L oriented specimens (crack extension in welding direction) penetrates several welding beads. By means of fractographic and metallographic analyses it was shown that the distribution of the crack initiation sites is not necessarily correlated to the structure of the different welding beads along the crack front. Furthermore, it was found that the scatter of the KJc values determined with T-S specimens is significantly higher than in case of the T-L specimens. T0 values measured at different thickness locations of the multi-layer welding seam vary in a range of about 40 K.

Keywords: reactor pressure vessel; multi-layer welding seam; specimen orientation; fracture toughness; Master Curve approach; reference temperature

Permalink: https://www.hzdr.de/publications/Publ-19457
Publ.-Id: 19457


Synthesis of a series of VAChT ligands as basis for the development of 18F-labelled radiotracers for imaging in brain

Barthel, C.; Wenzel, B.; Schüürmann, G.; Brust, P.

The department of Neuroradiopharmaceuticals is part of the Helmholtz-Zentrum Dresden-Rossendorf and deals with the development of radiotracers for brain research using positron emission tomography (PET).
Those tracers are ligands labelled with radioactive isotopes which bind to selected biomolecules in brain. Due to this specific binding it is possible to visualise neurotransmission processes in living organisms. For the development of such ligands it is necessary to synthesise various organic compounds and to determine their in-vitro binding affinity to the desired biological target. Afterwards, a promising candidate is selected for labelling with a short-lived radioactive nuclide such as fluorine-18.
The vesicular acetylcholine transporter (VAChT) is located in cholinergic areas in brain and is an interesting target for the in-vivo imaging of neuronal deficits as observed in Alzheimer’s disease. It is known that vesamicol (2-(4-phenylpiperidin-1-yl)cyclohexanol) acts as a high-potential inhibitor for this transporter and thus represents the chemical lead for the development of VAChT-radioligands. The aim of our studies is to develop a selective ligand by varying the vesamicol-skeleton in a systematic manner at its’ three ring structures and determining the binding profile of the resulting derivatives. These in-vitro data are correlated with the various chemical structures leading to a three dimensional computational model, a so-called quantitative structure affinity relationship (QSAR). Based on those results, we will be able to find a promising candidate for radiolabelling studies and further investigations.

  • Poster
    12. Research Festival Leipzig 2013, 19.12.2013, Leipzig, Deutschland
  • Contribution to proceedings
    Leipzig Research Festival for Life Sciences 2013, 19.12.2013, Leipzig, Deutschland
    Abstract Book, Leipzig: Universität Leipzig, 978-3-9810760-9-7, 162-162

Permalink: https://www.hzdr.de/publications/Publ-19456
Publ.-Id: 19456


Development of a 18F-labelled PDE2A ligand

Schröder, S.; Wenzel, B.; Kranz, M.; Teodoro, R.; Deuther-Conrad, W.; Fischer, S.; Steinbach, J.; Brust, P.

Phosphodiesterasen (PDE´s) sind Enzyme, die in allen menschlichen Zellen exprimiert werden und die zyklischen Nucleotide cAMP und/oder cGMP hydrolysieren. PDE-Inhibitoren verzögern den Abbau dieser sekundären Botenstoffe und beeinflussen physiologische Prozesse. Die PDE2A zeigt eine hohe, spezifische Expression im Gehirn sowie in bestimmten Tumoren und ist vermutlich an der Pathophysiologie entsprechender Erkrankungen beteiligt. Ziel unserer Arbeiten ist die Darstellung eines radiomarkierten PDE2A-Inhibitors für die Bildgebung der PDE2A mittels Positronen-Emissions-Tomographie (PET).
Auf Grundlage des Patents WO2010/054253 A1 wurde eine für die PDE2A hochaffine und selektive Triazin-Leitstruktur (TA-05, IC50: 4,12 nM) ausgewählt. Diese Leitstruktur wurde in einer fünfstufigen, optimierten Syntheseroute dargestellt und vollständig charakterisiert. Ausgehend von TA-05 wurden ein neues Fluorpropyl-Derivat (TA-P2) als Referenzverbindung für Affinitätsstudien sowie der entsprechende Tosylat-Präkursor (TA-P4) für eine einstufige 18F-Markierung entwickelt. Die nukleophile 18F-Fluorierung von TA-P4 führte zu einem neuen, hochaffinen PDE2A-Radioliganden (18F-TA-P2), der erfolgreich isoliert, gereinigt und mittels Radio-DC sowie Radio-HPLC analysiert wurde. Die biologische Charakterisierung von 18F-TA-P2 wird derzeit mittels TierPET/MR und Untersuchungen zur Metabolisierung sowie Autoradiographie bearbeitet.

  • Poster
    12th Leipzig Research Festival for Life Sciences 2013, 19.12.2013, Leipzig, Deutschland
  • Contribution to proceedings
    12th Leipzig Research Festival for Life Sciences 2013, 19.12.2013, Leipzig, Deutschland
    12th Leipzig Research Festival for Life Sciences 2013, Leipzig: Universität Leipzig, 978-3-9810760-9-7, 174-174

Permalink: https://www.hzdr.de/publications/Publ-19455
Publ.-Id: 19455


Topography-controlled alignment of DNA origami nanotubes on nanopatterned surfaces

Teshome, B.; Facsko, S.; Keller, A.

The controlled positioning of DNA nanostructures on technologically-relevant surfaces represents a major goal along the route toward the full-scale integration of DNA-based materials into nanoelectronic and sensoric devices. Previous attempts to arrange DNA nanostructures into defined arrays mostly relied on top-down lithographic patterning techniques combined with chemical surface functionalization. Here we combine two bottom-up techniques for nanostructure fabrication, i.e., self-organized nanopattern formation and DNA origami self-assembly, in order to demonstrate the electrostatic self-alignment of DNA nanotubes on topographically patterned silicon surfaces. Self-organized nanoscale ripple patterns with periodicities ranging from 20 nm to 50 nm are fabricated by low-energy ion irradiation and serve as substrates for DNA origami adsorption. Electrostatic interactions with the charged surface oxide during adsorption direct the DNA origami nanotubes to the ripple valleys and align them parallel to the ripples. By optimizing the pattern dimensions and the Debye length of the adsorption buffer, we obtain an alignment yield of ~ 70 %. Since this novel and versatile approach does not rely on any chemical functionalization of the surface or the DNA nanotubes, it can be applied to virtually any substrate material and any top-down or bottom-up nanopatterning technique. This technique thus may enable the wafer-scale fabrication of ordered arrays of functional DNA-based nanowires.

Keywords: DNA nanostructures; DNA origami; self-assembly; nanopatterning; atomic force microscopy

  • Nanoscale 6(2014), 1790-1796
    DOI: 10.1039/C3NR04627C
  • Poster
    DNA-Based Nanotechnology: Digital Chemistry, 05.-09.05.2014, Dresden, Germany
  • Poster
    DPG-Frühjahrstagung, 30.03.-04.04.2014, Dresden, Germany
  • Poster
    Trends in Nanotechnology International Conference (TNT2015), 07.-11.09.2015, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-19454
Publ.-Id: 19454


Potenziale der Rückgewinnung von Sekundärrohstoffen in Verbundprojekten der BMBF Fördermaßnahme r³ - Strategische Metalle und Mineralien; Tagungsband 9. Sächsischer Kreislaufwirtschaftstag Freiberg, 21. - 22.11.2013.

Dürkoop, A.

Um die Versorgung mit metallischen Rohstoffen für Deutschland zukünftig nachhaltig zu sichern, hat das BMBF im Jahr 2012 die r3-Fördermaßnahme mit dem Fokus auf strategische Metalle und Mineralien ins Leben gerufen. Die nichtenergetischen Rohstoffe sind von zunehmender Wichtigkeit für die internationale Wettbewerbsfähigkeit der deutschen Wirtschaft. Die Versorgungssicherheit dieser Rohstoffe nimmt jedoch in den letzten Jahren stark ab, da zum Einen der Bedarf an beispielsweise Hightech-Metallen steigt wodurch Verknappungen am Markt drohen und zum Anderen ist Deutschland im hohen Maße von Importen aus dem Ausland abhängig. Sekundärrohstoffe sind hingegen in Deutschland vorhanden, werden aber derzeit hinsichtlich Hightech-Metalle nicht ausgeschöpft.
Aus diesen Gründen setzt sich die Bundesregierung mit der Hightech-Strategie 2020 (2010a) und der Rohstoffstrategie (2010b) dafür ein, neue Technologien und innovative Verfahren mit dem Ziel des effizienten Umgangs mit diesen Rohstoffen zu entwickeln.
Ein zentraler Leitgedanke der Hightech-Strategie 2020 ist, die Wettbewerbsfähigkeit in Deutschland durch eine erhöhte Innovationskraft zu stärken. Dafür fördert das Bundesministerium für Bildung Forschung innerhalb des Rahmenprogrammes „Forschung für nachhaltige Entwicklung“ die Fördermaßnahme r³ mit 30 Millionen €. Die Fördermaßnahme „r³ – Innovative Technologie für Ressourceneffizienz – Strategische Metalle und Mineralien“ umfasst insgesamt 28 Verbundforschungsprojekte, die mit max. drei Jahren Laufzeit zwischen 2012 und Anfang 2016 auf den Themenfeldern Recycling, Einsparung und Substitution, städtischer Bergbau (Urban Mining) und Bewertungsmethoden forschen. Insgesamt umfasst r³ mehr als 128 Einzelprojekte, davon 69 Industrieprojekte. So wird die Förderung durch BMBF von 30 Millionen € durch den zusätzlichen Eigenanteil der Industrieunternehmen von 12 Millionen € auf insgesamt 42 Millionen € erhöht.

Keywords: Resource Efficiency; Strategic Metals and Minerals; Substitution; Recycling; Urban Mining

  • Invited lecture (Conferences)
    9. Sächsischer Kreislaufwirtschaftstag, 21.-22.11.2013, Freiberg, Deutschland
  • Contribution to proceedings
    9. Sächsischer Kreislaufwirtschaftstag, 21.-22.11.2013, Freiberg, Deutschland
    9. Sächsischer Kreislaufwirtschaftstag

Permalink: https://www.hzdr.de/publications/Publ-19453
Publ.-Id: 19453


Near-Surface Strain in Icosahedra of Binary Metallic Alloys: Segregational vs. Intrinsic Effects

Pohl, D.; Wiesenhütter, U.; Mohn, E.; Schultz, L.; Rellinghaus, B.

A systematic structural analysis of of FePt, CuAu and Au icosahedral nanoparticles is presented. The uncovered particles are prepared by inert gas condensation and thermally equilibrated through in-flight optical annealing. Aberration-corrected high resolution Transmission electron microscopy reveals that the crystal lattice is significantly expanded near the particle surface. These experimental findings are corroborated by molecular statics simulations which show that this near-surface strain originates from both intrinsic strain due to the icosahedral structure and a partial segregation of the larger of the two alloy constituents to the particle surface.

Keywords: FePt Nanoparticles HRTEM

Permalink: https://www.hzdr.de/publications/Publ-19452
Publ.-Id: 19452


Preprocessing of structured spectral data to improve the predictive accuracy of Self-Organising Maps

Domaschke, K.; Rossberg, A.; Villmann, T.

In this paper, we propose a new approach using structural information of spectral data during a preprocessing procedure to upgrade the ability of subsequent analysis methods. A composite data set of measured spectra is given, which contains dierent mixtures of a few spectral components. Using chemical knowledge and a small subset of the mixture information, we are able to evaluate these spectral components out of the given data set and use this information in addition for the following analysis of the composite data set. In our case, we apply the Self-Organizing Map according to Kohonen to predict the unknown mixture subset of the dierent spectral components within the measured data.

Keywords: Self-Organizing maps; spectral data; unmixing; blind source separation

  • Open Access Logo Contribution to proceedings
    European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning, 23.-25.04.2014, Bruges, Belgium
    Proceedings of the European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning

Permalink: https://www.hzdr.de/publications/Publ-19450
Publ.-Id: 19450


High magnetic field study of the Tm2Fe17 and Tm2Fe17D3.2 compounds

Isnard, O.; Andreev, A. V.; Kuz’Min, M. D.; Skourski, Y.; Gorbunov, D. I.; Wosnitza, J.; Kudrevatykh, N. V.; Iwasa, A.; Kondo, A.; Matsuo, A.; Kindo, K.

A magnetization study of a Tm2Fe17 single crystal and aligned powder of the deuteride Tm2Fe17D3.2 has been carried out in steady (14 T) and pulsed (60 T and, in one case, up to 74 T) magnetic fields at temperatures between 1.5 and 300 K. Tm2Fe17 is a ferrimagnet with TC = 295 K and a spontaneous moment of 22 μB/f.u. at T = 4.2 K. Of particular interest are low-temperature magnetization curves along the sixfold crystal axis c, which is an easy direction in Tm2Fe17 and a hard direction in the deuteride. In either case the magnetization increases with magnetic field undulatorily in broad steps whose height is a multiple of the atomic moment of Tm, μTm = 7 μB. In Tm2Fe17, the positions of the steps yield information on the Fe-Tm molecular field, 48 T on the Tm 2d site and 60 T on the Tm 2b site, whereas the crystal field parameter A66 is found from the widths of the steps: A66(b) = −35 Ka0−6 and A66(d) = −26 Ka0−6 (here a0 is the Bohr radius). It also proves possible to estimate the other sixth-order crystal field parameter: A60 ∼ −4 Ka0−6 (on average for both sites). Less information can be extracted from the powder data for the deuteride. Thus, the mean molecular field on Tm in Tm2Fe17D3.2 is found to be 49 T or 9% less than in the parent binary compound.

Permalink: https://www.hzdr.de/publications/Publ-19448
Publ.-Id: 19448


Similarities between single and multilayer particle deposition and resuspension experiments in turbulent flows

Barth, T.; Hampel, U.

This report is a comparative review of several particle transport experiments, which were performed within the framework of the two large scale European projects namely THINS (Thermal Hydraulics of Innovative Nuclear Systems) and ARCHER (Advanced Reactor for Cogeneration of Heat & Electricity R&d). Background motivation is the carbonaceous dust issue of the High Temperature Reactor (HTR). Radio-contaminated dust was found deposited all over the inner surfaces in the primary circuit of different HTR research reactors after a certain operational time. In case of an accidental scenario such as the depressurisation of the primary circuit the dust may be remobilised by the turbulent flow and becomes a considerable source term when escaping the system boundaries. The safety assessment requires a fundamental understanding of the interaction between the wall-deposited particle multilayer and the turbulent flow field. Thus, we performed a set of experiments to explore the particle deposition and resuspension characteristics in various geometries by means of high-end measurement instrumentation.
Two air-driven small-scale test facilities were designed to generate a particle laden turbulent flow field under well-defined conditions. The flow was downscaled using Reynolds similarity and the aerosol particles were described by its aerodynamic mobility. The first facility was designed for the THINS project and is called Gas Particle Loop. Here, the particle deposition and resuspension was studied in a horizontal turbulent duct flow. The flow field was captured by means of a stereoscopic Particle Image Velocimetry system. The airborne particles were classified using Aerodynamic Particle Sizer spectrometry and the wall deposited particles were captured by means of optical microscopy and laser distance sensors. It was found that the deposition of micron-sized particles mainly depends on the aerodynamic particle size and the fluid friction velocity. Particle resuspension was found to take place in intermittent events once a critical friction velocity was exceeded. The second facility was constructed for the ARCHER project and is called Pebble Bed Loop. Here, a particle laden turbulent flow in a pebble bed was generated. The aerosol particles were radio-labelled with the isotope fluorine 18 and the spatiotemporal distribution of the particle deposits in the pebble bed was recorded by means of positron emission tomography (PET) during various flow regimes. Assuming a homogeneous distribution of the initial activity over the particles, the activity recorded by the PET scanner directly correlates to the amount of deposited particles. The geometry of the pebble bed was captured by means of a gamma ray computed tomography (CT) scan. The result of this campaign is a time resolved 3D PET-CET overlay. Basic characteristics of the particle deposition and resuspension behaviour in the GPLoop were relocated in the results of the experiments in the PBLoop. The available data set provides a new insight into the particle transport behaviour in turbulent flows and may be used for the development of numerical methods for the prediction of the dust behaviour during accidental scenarios of HTRs.

  • Contribution to proceedings
    International Workshop on Thermal Hydraulics of Innovative Nuclear Systems, 20.-22.01.2014, Modena, Italien
    Proceedings of THINS 2014

Permalink: https://www.hzdr.de/publications/Publ-19447
Publ.-Id: 19447


Coexistence of Ising and XY Spin Systems on a Single Tb Atom in TbCoGa5

Sanada, N.; Amou, Y.; Watanuki, R.; Suzuki, K.; Yamamoto, I.; Mitamura, H.; Sakakibara, T.; Akatsu, M.; Nemoto, Y.; Goto, T.

The tetragonal compound TbCoGa5 exhibits two successive magnetic transitions at TN1 = 36.2 and TN2 = 5.4 K. The results of the measurement of the magnetic susceptibility and specific heat indicate that the c- and ab-components of the magnetic moments of Tb3+ show independent antiferromagnetic orderings at TN1 and TN2, respectively. In this work, we have investigated the physical properties of TbCoGa5 in a magnetic field. Single crystals of TbCoGa5 were grown and their specific heat, electrical resistivity, magnetization and elastic constant were measured. The magnetic exchange interactions in TbCoGa5 are discussed referring to the result of the magnetization process. Additionally, the present and previous results are summarized in a magnetic phase diagram. The magnetic phase diagram indicates that the behavior of TN1 in a changing magnetic field is similar to that of an Ising spin system, and the behavior of TN2 is similar to that of an XY spin system. Thus, we conclude that Ising and XY spin systems coexist on a single Tb atom in TbCoGa5.

Keywords: TbCoGa5; successive component-separated magnetic transitions; magnetization process; metamagnetic transition; magnetic phase diagram

Permalink: https://www.hzdr.de/publications/Publ-19446
Publ.-Id: 19446


Study of particle deposition and resuspension in pebble beds using positron emission tomography

Barth, T.; Kulenkampff, J.; Ludwig, M.; Bras, S.; Gründig, M.; Franke, K.; Lippmann-Pipke, J.; Hampel, U.

This report describes the application of gamma-ray computed tomography (CT) and positron emission tomography (PET) for the investigation of particle transport in a model of a High Temperature Reactor (HTR) pebble bed. Micron sized liquid and graphite particles were radioactively labelled and the deposition and resuspension of particle multilayers in the pebble bed was studied. The particle laden turbulent flow in a model pebble bed was scaled by Reynolds similarity and was generated by an air driven small-scale test facility at ambient conditions. The pebble bed geometry was recorded by a CT to determine the bed porosity and pebble orientation. Two sets of experiments were performed. Firstly, radio-labelled liquid particles were dispersed into the flow to study pure particle deposition over a wide fluid velocity range. In a second set of experiments, radio-labelled graphite particles were injected into the flow and particle deposition and resuspension was studied in succession. Activity spots appeared on the front sides of the single pebbles indicating the formation of particle multilayers on the pebble surfaces. After the deposition experiment, the aerosol generator was switched off and the fan speed was stepwise increased to induce particle resuspension. A time resolved 3D PET-CT overlay provides a completely new insight into the particle multilayer formation and removal.

Keywords: High Temperature Reactor; pebble bed; particle transport; Positron Emission Tomography"

  • Contribution to proceedings
    7th World Congress on Industrial Process Tomography, WCIPT7, 02.-05.09.2013, Krakau, Polen
    Proceedings of WCIPT7

Permalink: https://www.hzdr.de/publications/Publ-19445
Publ.-Id: 19445


Complex magnetic phase diagram of a geometrically frustrated Sm lattice: Magnetometry and neutron diffraction study of SmPd2Al3

Pospíšil, J.; Nénert, G.; Miyashita, S.; Kitazawa, H.; Skourski, Y.; Diviš, M.; Prokleška, J.; Sechovský, V.

Magnetism in SmPd2Al3 was investigated on a single crystal by magnetometry and neutron diffraction. SmPd2Al3 represents a distinctive example of a Sm magnetism exhibiting complex magnetic behavior at low temperatures with four consecutive magnetic phase transitions at 3.4, 3.9, 4.4, and 12.5 K. The rich magnetic phase diagram of this compound reflects the specific features of the Sm3+ ion, namely, the energy nearness of the ground-state multiplet J = 5/2 and the first excited multiplet J = 7/2 in conjunction with strong crystal field influence. Consequently, a significantly reduced Sm magnetic moment in comparison with the theoretical Sm3+ free-ion value is observed. Despite the strong neutron absorption by natural samarium and the small Sm magnetic moment (∼0.2 μB), we have successfully determined the magnetic k vector (1/3, 1/3, 0) of the phase existing in the temperature interval 12.5–4.4 K. This observation classifies the SmPd2Al3 compound as a magnetically frustrated system. The complex magnetic behavior of this material is further illustrated by kinetic effects of the magnetization, inducing a rather complicated magnetic structure with various metastable states.

Permalink: https://www.hzdr.de/publications/Publ-19444
Publ.-Id: 19444


Single particle resuspension experiments in turbulent channel flows

Barth, T.; Preuß, J.; Hampel, U.

The resuspension of spherical single particles from a hydraulically smooth wall into a turbulent flow is studied. Special attention is given to the particle diameter, the material composition, the critical friction velocity and the inceptive motion of the resuspending particles. The experiments were performed in an air-driven small-scale test facility. The particles on the channel floor were detected and classified by means of an optical microscope combined with a digital camera. Furthermore, the turbulent flow field was recorded using a conventional Particle Image Velocimetry (PIV) system. A statistical sufficient monolayer of spherical particles was generated on the channel floor by dispersing the particles into the flow during a pure deposition regime. Afterwards, particle resuspension was induced by the stepwise increase of the fluid velocity. The resuspension was quantified by the fraction of resuspended particles against the friction velocity for a diameter range between 3 and 45 µm. It was found that particles begin to resuspend when a critical friction velocity is exceeded. A decreasing tendency between the particle diameter and the critical friction velocity was found for particles in the present size range and the results are in good consistency to other investigations.

Keywords: resuspension; aerosol particle; turbulent channel flow; loss of coolant accident

  • Contribution to proceedings
    8th International Conference on Multiphase Flow, ICMF 2013, 26.-31.05.2013, Jeju, Korea
    Proceedings of ICMF 2013

Permalink: https://www.hzdr.de/publications/Publ-19443
Publ.-Id: 19443


Multilayer deposition and resuspension experiments of graphite particles between periodic steps in turbulent channel flows

Barth, T.; Reiche, M.; Hampel, U.

This report describes an experimental study about graphite particle multilayer deposition and resuspension between periodic steps in turbulent channel flows. Background motivation is the carbonaceous dust safety issue in the High Temperature Reactor. In the present study the particle deposition and resuspension scenarios were fluid dynamically downscaled and were reproduced under simplified conditions in an air-driven small-scale test facility. Periodic steps were placed in a square duct test section to induce a complex flow field characterized by flow separations, recirculation and reattachment zones.
The turbulent flow field was recorded by means of a stereo Particle Image Velocimetry system. Polydisperse graphite particles matching the size range of HTR dust were dispersed into the flow field during a pure deposition regime. The multilayer build up between the periodic steps was measured using a laser distance sensor coupled with a linear stage. The particle layer build up showed a linear tendency against time and the deposition velocities are in good agreement with similar investigations. After the deposition scenario the aerosol generator was switched off and the fan speed of the test facility was stepwise increased to initiate particle resuspension. It was found that the resuspension started to begin in the reattachment area between the steps. The entire multilayer was already removed by the flow at friction velocities at which single particle resuspension starts to begin. Furthermore, particle bed porosity determinations were performed by gravimetrical and x-ray methods to characterize the packing properties. The present results indicate similarities between the single and the multilayer particle deposition and resuspension process.

Keywords: deposition; resuspension; graphite particles; turbulent flow; periodic steps; high temperature reactor; loss of coolant accident

  • Contribution to proceedings
    8th International Conference on Multiphase Flow, ICMF 2013, 26.-31.05.2013, Jeju, Korea
    Proceedings of ICMF 2013

Permalink: https://www.hzdr.de/publications/Publ-19442
Publ.-Id: 19442


Magnetic properties and anisotropy of orthorhombic DyMnO3 single crystal

Pekala, M.; Wolff-Fabris, F.; Fagnard, J.-F.; Vanderbemden, P.; Mucha, J.; Gospodinov, M. M.; Lovchinov, V.; Ausloos, M.

An orthorhombic DyMnO3 single crystal has been studied in magnetic fields up to 14 T and between 3 K and room temperature. The field dependent ordering temperature of Dy moments is deduced. The paramagnetic Curie Weiss behavior is related mainly to the Dy3+ sublattice whereas the Mn sublattice contribution plays a secondary role. DC magnetization measurements show marked anisotropic features, related to the anisotropic structure of acubic system stretched along a body diagonal, with a magnetic easy axis parallel to the crystallographic b axis. A temperature and field dependent spin flop transition is observed below 9 K, when relatively weak magnetocrystalline anisotropy is overcome by magnetic fields upto 1.6 T.

Keywords: Manganite; Magnetization; Magnetic anisotropy

Permalink: https://www.hzdr.de/publications/Publ-19441
Publ.-Id: 19441


Study of particle deposition and resuspension in pebble beds using positron emission tomography

Barth, T.; Kulenkampff, J.; Ludwig, M.; Bras, S.; Gründig, M.; Franke, K.; Lippmann-Pipke, J.; Hampel, U.

This work describes an experimental study about the transport behavior of carbonaceous dust in a High Temperature Reactor (HTR) pebble bed. Carbonaceous dust may be formed during reactor operation and deposits on the inner surfaces of the HTR primary circuit. In case of a loss of coolant accident (LOCA) this dust may be resuspended and released into the environment. Since the dust is a carrier of fission products this dust is a considerable source term and has to be analyzed with respect to such accidental scenarios.
The particle deposition and resuspension behavior was experimentally investigated in a pebble bed by means of Positron Emission Tomography (PET). The turbulent flow field was generated by an air-driven small scale test facility. The pebble bed was fluid mechanically downscaled by the pebble bed related Reynolds number. The pebble bed geometry was analyzed by a 3D gamma ray computed tomography scan for the precise determination of the pebble orientation and the bed porosity.
Two sets of PET experiments were conducted. First, monodisperse liquid aerosol particles were labeled with the radioisotope (18F) and dispersed into the turbulent flow field. PET was used for the temporal and spatial recording of the particle deposition process.
In the second set of PET measurements, the liquid particles were replaced by technical graphite dust matching the particle size distribution usually found in the HTR primary circuit. The graphite dust was also labeled with 18F before being dispersed into the turbulent flow field. Deposition experiments were conducted at rather low fluid velocities to purely study the particle precipitation. Subsequently, the fan power of the facility was stepwise increased and the PET scanner recorded the particle resuspension process online. The existing data sets give a unique 3D and time resolved insight into the particle transport process in such a complex geometry. The data can be further used for CFD code development to predict the particle behavior during a LOCA in an HTR.

  • Contribution to proceedings
    The 15th International Topical Meeting on Nuclear Reactor Thermalhydraulics, NURETH-15, 12.-15.05.2013, Pisa, Italien
    Proceedings of NURETH-15

Permalink: https://www.hzdr.de/publications/Publ-19440
Publ.-Id: 19440


DNA Origami Substrates for Highly Sensitive Surface-Enhanced Raman Scattering

Prinz, J.; Schreiber, B.; Olejko, L.; Oertel, J.; Rackwitz, J.; Keller, A.; Bald, I.

DNA nanotechnology holds great promise for the fabrication of novel plasmonic nanostructures and the potential to carry out single-molecule measurements using optical spectroscopy. Here, we demonstrate for the first time that DNA origami nanostructures can be exploited as substrates for surface-enhanced Raman scattering (SERS). Gold nanoparticles (AuNPs) have been arranged into dimers to create intense Raman scattering hot spots in the interparticle gaps. 15 nm AuNPs covered with TAMRA-modified DNA have been placed at a nominal distance of 25 nm to demonstrate the formation of Raman hot spots. To control the plasmonic coupling between the nanoparticles and thus the field enhancement in the hotspot, the size of AuNPs has been varied from 5 nm to 28 nm by electroless Au deposition. By the precise positioning of a specific number of TAMRA molecules in these hot spots, surface-enhanced Raman scattering (SERS) with highest sensitivity down to the few-molecule level is obtained.

Keywords: DNA origami; Nanoparticles; Raman spectroscopy; Self-assembly

  • The Journal of Physical Chemistry Letters 4(2013), 4140-4145
    DOI: 10.1021/jz402076b

Permalink: https://www.hzdr.de/publications/Publ-19439
Publ.-Id: 19439


Magnetic phase diagram of clathrate compound Ce3Pd20Si6 with quadrupolar ordering

Ono, H.; Nakano, T.; Takeda, N.; Ano, G.; Akatsu, M.; Nemoto, Y.; Goto, T.; Dönni, A.; Kitazawa, H.

We present results of specific heat measurements on a Ce3Pd20Si6 single crystal and construct the magnetic phase diagram for the three cubic principal directions [100], [110] and [111]. The highly anisotropic phase diagram is discussed and can be qualitatively explained by the Zeeman splitting at the 8c-site. For B ‖ [100], the present study found two different quadrupolar ordered phases, which meet the paramagnetic phase at a tri-critical point and establish the new phase boundaries.

Permalink: https://www.hzdr.de/publications/Publ-19438
Publ.-Id: 19438


Paramagnetic Meissner Effect and Strong Time Dependence at High Fields in Melt-Textured High-TC Superconductors

Gouvea, C. D. P.; Dias, F. T.; Vieira, V. D. N.; Silva, D. L. D.; Schaf, J.; Wolff-Fabris, F.; Rovira, J. J. R.

In this work we report on systematic field-cooled magnetization experiments in melt-textured YBa2Cu3O7−δ samples containing Y211 precipitates. Magnetic fields up to 14 T were applied either parallel or perpendicular to the ab planes and a strong paramagnetic response related to the superconducting state was observed. This effect is known as paramagnetic Meissner effect (PME). The magnitude of the PME increases when the field is augmented. This effect shows a strong paramagnetic relaxation, such that the paramagnetic moment increases as a function of the time. The pinning by the Y211 particles plays a crucial role in the explanation of this effect and our results suggest that the pinning capacity can produce a strong flux compression into the sample, originating the PME and the strong time dependence.

Keywords: Melt-textured YBaCuO; Paramagnetic Meissner effect; Time dependence

Permalink: https://www.hzdr.de/publications/Publ-19437
Publ.-Id: 19437


Determination of the intersublattice exchange interactions in GdCo12-xFexB6 (x= 0-3) intermetallic compounds by high field magnetization measurements

Diop, L. V. B.; Isnard, O.; Skourski, Y.; Ballon, G.

High field magnetization measurements up to 60 T on free powder samples from GdCo12-xFexB6 (x = 0-3) compounds are reported. The data were used to evaluate the microscopic exchange interaction integral, JGd-3d, between Gd and 3d (Co,Fe) spins. The systems are ferrimagnets; they order magnetically between TC = 95 K for x = 3 and TC = 165 K for x = 0. The low temperature magnetization curves as well as the temperature dependence of intrinsic magnetic parameters are determined by magnetic measurements in pulsed magnetic field. The average magnetic moment µCo+Fe per mean transition metal atom (Co + Fe) is small and increases with increasing Fe concentration from 0.44 µ B for x = 0 to 0.51 µB for x = 3 at T = 4 K. From high field magnetization curves, a value of JGd-3d/kB = -4.65 K is derived for x = 0, whereas mean field approximation yields a much larger 3d-3d exchange integral of JCo-Co/kB = 105 K. The obtained results reveal an increase of JGd-3d/kB with Fe concentration. For x = 0.5, the intersublattice coefficient nGd-3d is found to keep an almost constant value of 5.87 ± 0.13 T*f.u.*µB-1 whatever the temperature in the 2 to 60 K range.

Permalink: https://www.hzdr.de/publications/Publ-19436
Publ.-Id: 19436


Low-Temperature Softening Due to Vacancy Orbital with Γ8 Quartet Ground State in Boron-Doped Floating Zone Silicon

Baba, S.; Akatsu, M.; Mitsumoto, K.; Komatsu, S.; Horie, K.; Nemoto, Y.; Yamada-Kaneta, H.; Goto, T.

We have carried out low-temperature ultrasonic measurements using shear-mode ultrasound to clarify the quantum state of a vacancy orbital in boron-doped silicon grown by the floating zone (FZ) method. The elastic constants (C11 - C12)/2 and C44 of the transverse mode exhibit considerable softening below 2 and 5 K down to the base temperature of 30 mK, respectively. The elastic constant C44 measured by the three ultrasonic modes (kx, uy), (kz, ux), and (kx, uz) shows the different magnetic field dependences among the configurations under applied magnetic fields along the z-axis. The elastic softening and the magnetic field dependence of the elastic constants are accounted for by the quadrupole susceptibility based on the energy level scheme of the vacancy orbital with a Γ8 quartet ground state and Γ7 doublet excited state located at an energy of 1 K. The difference in C44 between the two ultrasonic modes (kz, ux) and (kx, uz) at fields along the z-axis indicates that the Γ8 quartet ground state is slightly split by local strain in the silicon sample. The quantum state of the vacancy orbital is expected to be sensitive to strain because of the extremely large quadrupole-strain coupling energy of gΓ ≈ 105 K due to the extensively spreading orbital radius of r ≈ 1 nm. The differences in variation of the low-temperature softening and magnetic field dependence among eight samples cut out from different locations of the present boron-doped FZ silicon ingot evidence the inhomogeneous distribution of the vacancy concentration.

Keywords: vacancy; boron-doped FZ silicon; ultrasound; quadrupole

Permalink: https://www.hzdr.de/publications/Publ-19435
Publ.-Id: 19435


Recycling von Gallium mit Dialyseverfahren

Zeidler, O.

Der Vortrag geht auf die Probleme des Ga-Recyclings aus Rückständen der GaAs-Wafererzeugung ein. Daraufhin werden ein gesamtheitliches Konzept für die Zusammenlegung der Abwässer sowie ein neu entwickeltes Dialyseverfahren zur weiteren Behandlung dieser vorgestellt. Aktuelle Ergebnisse zur dialytischen Trennung des Galliums von der Hauptverunreinigung Arsen werden ausführlich diskutiert und ein Ausblick auf weitere Untersuchungen gegeben.

  • Invited lecture (Conferences)
    Fachausschusses Sondermetalle der GDMB, 23.-24.10.2013, Reutte, Österreich

Permalink: https://www.hzdr.de/publications/Publ-19434
Publ.-Id: 19434


Current-driven flow instabilities in large-scale liquid metal batteries, and how to tame them

Weber, N.; Galindo, V.; Stefani, F.; Weier, T.

The use of liquid metal batteries is considered as one promising option for electric grid stabilisation. While large versions of such batteries are preferred in view of the economies of scale, they are susceptible to various magnetohydrodynamic instabilities which imply a risk of short-circuiting the battery due to the triggered fluid flow. Here we focus on the current driven Tayler instability and give critical electrical currents for its onset as well as numerical estimates for the appearing flow structures and speeds. Scaling laws for different materials, battery sizes and geometries are found. We further discuss and compare various means for preventing the instability.

Keywords: Tayler instability; liquid metal battery; simulation; OpenFOAM

Permalink: https://www.hzdr.de/publications/Publ-19433
Publ.-Id: 19433


Neogene to Quaternary ash deposits in the Coastal Cordillera in northern Chile: Distal ashes from supereruptions in the Central Andes

Breitkreuz, C.; de Silva, S. L.; Wilke, H. G.; Pfänder, J. A.; Renno, A. D.

Silicic volcanic ash deposits investigated at 14 localities between 22° and 25°S in the Chilean Coastal Cordillera are found to be the distal ash fall from supereruptions in the Central Andean cordillera several hundreds of kilometers to the east. Depositional textures, modal composition and granulometry of the ashes and tuffs (the latter lithified by halite and gypsum under ultra-arid conditions) allow for a distinction between primary fallout/aeolian deposits (mean 4 - 5 Φ, sorting 1.5 - 2Φ) and secondary deposits that formed by down wash from hill slopes during local rain fall. Primary volcanic components comprise two types of glass shards (with small stretched vesicles and coarse-walled with rounded to elliptic vesicles), and biotite. Previously published studies on ash deposits in the north Chilean Coastal Cordillera reported 14 40Ar/39Ar and K/Ar ages on biotite or sanidine ranging between 6.66 ± 0.13 and 0.6 ± 0.4 Ma. In this project, three 40Ar/39Ar ages on biotite have been determined for samples from the Cuenca del Tiburón, the northern margin of Salar de Navidad and from the Quebrada de la Chimba (3.9 ± 0.1 Ma, 4.1 ± 0.1 Ma, 6.0 ± 0.1 Ma, respectively). The range of the 17 ages coincides with the Late Miocene to Quaternary ages of the major ignimbrite-forming eruptions of the high Andes to the east such as the Altiplano Puna Volcanic Complex (APVC). Electron microprobe data of glass and biotite of the Coastal Cordillera ashes have been compared with data from major ignimbrites of the APVC, of other major Central Andean volcanic fields, and of marine ashes (ODP Leg 201). Additional new biotite microprobe data from three APVC ignimbrites (Pastos Grandes, Pujsa and Guacha) have been included in the present study. Biotite composition of the investigated Coastal Cordillera ashes is similar to those of ignimbrites from the APVC. In particular, based in Fe, Mg, Mn and Ti, distal equivalents of the 3.96 ± 0.08 Ma Atana and/or 4.09 ± 0.02 Ma Puripicar and of the 5.6 ± 0.2 Ma Pujsa and/or the 5.56 ± 0.01 Ma Guacha eruptions can be identified. In addition, based only on age relations, distal ash units of the Pastos Grandes, Tatio and Purico eruptions may be present in the Coastal Cordillera. Composition of glass is comparable to APVC ignimbrite matrix glass and to marine glass, however, significant alkali depletion and SiO2 enrichment is attributed to in situ alteration. The identification of these ashes demonstrates for the first time that the supereruptions in the southern Central Andes gave rise to voluminous ash clouds, most likely co-ignimbrite. The present outcrops represent ash dispersed by easterly winds, consistent with atmospheric models that show favorable westward-directed winds existing in the upper troposphere/stratosphere during the southern summer in the southern Central Andes. This requires that current volume estimates for the major eruptions to be considered minima with a significant augmentation likely.

Keywords: Supereruptions; Central Andes; co-ignimbrite ash clouds; 40Ar/39Ar ages; biotite composition; granulometry

Permalink: https://www.hzdr.de/publications/Publ-19432
Publ.-Id: 19432


Permanent magnet electron beam ion source/trap systems with bakeable magnets for improved operation conditions

Schmidt, M.; Zschornack, G.; Kentsch, U.; Ritter, E.

EBIS/T systems provide ions of intermediate up to the highest ion charge states via electron impact ionization by a dense electron beam. In order to produce highly charged ions in an EBIS/T high electron beam densities of several hundred A/cm2 are necessary to realize high ionization factors and compensate for charge destructive processes such as charge exchange etc. The required electron beam compression is realized via an axial magnetic field. Two different EBIS/T magnet design approaches have been established over the past decades: Superconducting magnets with high magnetic fields of several Tesla (significant initial and maintenance costs), Compact permanent magnets with magnetic fields of Sub-Tesla (low initial and maintenance costs). Comparing both solutions shows that the produced ion species and current output of the permanent magnet EBIS/T suits most of the user requirements.

  • Poster
    International Conference on Ion Sources 2013, 09.09.2013, Chiba, Japan
  • Review of Scientific Instruments 85(2014)2, 02B704
    DOI: 10.1063/1.4828723

Permalink: https://www.hzdr.de/publications/Publ-19430
Publ.-Id: 19430


A Compact, Versatile Low-Energy Electron Beam Ion Source

König, G.; Thorn, M.; Zschornack, J.; Schmidt, A.

Electron Beam Ion Sources (EBIS) were originally developed to produce highly charged ions (HCI) [1]. For this purpose, high density electron beams at electron beam energies higher than the ionization potential of the desired ion species are required leading to the development of high energy and high current devices working with superconducting magnet coils.
For applications with focus on low and intermediate charge states EBIS/T with high-energy density rare-earth permanent magnets are an economic and compact alternative [2-5]. EBIS/T setups for electron beam energies of 2 keV and below have become more interesting recently. They can be used as sources of electromagnetic radiation in the UV, EUV, and visible light region for calibration purposes, as reference source for emission and absorption spectroscopy with ions of intermediate charge states in astrophysical experiments, as ion sources for research in radiation biology and medicine, and for the diagnostics of plasmas in fusion devices in the low energy range.

  • Poster
    International Conference on Ion Sources 2013, 09.09.2013, Chiba, Japan
  • Review of Scientific Instruments 85(2014)2, 02B703
    DOI: 10.1063/1.4826687

Permalink: https://www.hzdr.de/publications/Publ-19429
Publ.-Id: 19429


Electron beam ion sources for use in second generation synchrotrons for medical particle therapy

Zschornack, G.; Ritter, E.; Schmidt, M.; Schwan, A.

Cyclotrons and first generation synchrotrons are the commonly applied accelerators in medical particle therapy nowadays. Next generation accelerators such as Rapid Cycling Medical Synchrotrons (RCMS), direct drive accelerators, or dielectric wall accelerators have the potential to improve the existing accelerator techniques in this field. Innovative accelerator concepts for medical particle therapy can benefit from ion sources which meet their special requirements. In the present paper we report on measurements with a superconducting Electron Beam Ion Source, the Dresden EBIS-SC, under the aspect of application in combination with RCMS as a well proven technology. The measurements indicate that this ion source can offer significant advantages for medical particle therapy. We show that a superconducting EBIS can deliver ion pulses of medically relevant ions such as protons, C4 + and C6 + ions with intensities and frequencies required for RCMS [S. Peggs and T. Satogata, “A survey of Hadron therapy accelerator technology,” in Proceedings of PAC07, BNL-79826- 2008-CP, Albuquerque, New Mexico, USA, 2007; A. Garonna, U. Amaldi et al., “Cyclinac medical accelerators using pulsed C6 +/ H+2 ion sources,” in Proceedings of EBIST 2010, Stockholm, Sweden, July 2010]. Ion extraction spectra as well as individual ion pulses have been measured. For example, we report on the generation of proton pulses with up to 3 × 109 protons per pulse and with frequencies of up to 1000 Hz at electron beam currents of 600 mA.

  • Poster
    International Conference on Ion Sources 2013, 09.09.2013, Chiba, Japan
  • Review of Scientific Instruments 85(2014)2, 02B702
    DOI: 10.1063/1.4827306

Permalink: https://www.hzdr.de/publications/Publ-19428
Publ.-Id: 19428


Charge Exchange and Energy Loss of Slow Highly Charged Ions in 1 nm Thick Carbon Nanomembranes

Wilhelm, R. A.; Gruber, E.; Ritter, R.; Heller, R.; Facsko, S.; Aumayr, F.

Experimental charge exchange and energy loss data for the transmission of slow highly charged Xe ions through ultra thin polymeric carbon membranes are presented. Surprisingly, two distinct exit charge state distributions accompanied by charge exchange dependent kinetic energy losses are observed. The energy loss for ions exhibiting large charge loss shows a quadratic dependency on the incident charge state, indicating that equilibrium stopping force values do not apply in this case. Additional angle resolved transmission measurements and reduction of the layer thickness due to a structural phase transition of the membrane lead to the conclusion that a charge state enhanced elastic scattering potential is the main reason for the increase in energy loss rather than charge state enhanced inelastic losses. Thus, the presented results connect scattering experiments of ions on gaseous and on solid targets.

Keywords: slow highly charged ion; HCI; carbon nanomembranes; CNM; stopping power; ion charge state; charge exchange

Permalink: https://www.hzdr.de/publications/Publ-19427
Publ.-Id: 19427


Bubbly flows with fixed polydispersity: validation of a baseline closure model

Rzehak, R.; Krepper, E.

For practical applications the Euler-Euler two-fluid model relies on suitable closure relations describing interfacial exchange processes. In dispersed gas-liquid multiphase flow, closures are needed for bubble forces, bubble-induced turbulence, as well as bubble-coalescence and -breakup. The quest for models with a broad range of applicability allowing predictive simulations is an ongoing venture. Reasonable success has been achieved so far for flows that are amenable to a monodisperse approximation for the bubble size which limits the latter to no more than a few mm.
In the present work we extend the validation to flow in which bubbles with a broad distribution of sizes up to ~10mm are present, but the shape of the distribution remains unchanged during the flow development. The existence of such conditions which we term “fixed polydispersity” is deduced from the experimental data. For this kind of situation the complexity of the closure problem is reduced since a balance between bubble-coalescence and -breakup prevails that allows to neglect these processes and simply impose a fixed bubble size distribution. Conclusions towards best practice guidelines for modeling bubbly flows are drawn and needs for further research identified.

Keywords: dispersed gas liquid multiphase flow; Euler Euler two fluid model; fixed polydispersity; closure relations; CFD simulation; model validation

Permalink: https://www.hzdr.de/publications/Publ-19425
Publ.-Id: 19425


Surface-Mediated Formation of Pu(IV) nanoparticles at the Muscovite-Electrolyte Interface

Schmidt, M.; Lee, S. S.; Wilson, R. E.; Knope, K. E.; Bellucci, F.; Eng, P. J.; Stubbs, J.; Soderholm, L.; Fenter, P.

The formation of Pu(IV)-oxo-nanoparticles from Pu(III) solutions by a surface- enhanced redox/polymerization reaction at the muscovite (001) basal plane is reported, with a continuous increase in plutonium coverage observed in situ over several hours. The sorbed Pu extends > 70 Å from the surface with a maximum concentration at 10.5 Å and a total coverage of >9 Pu atoms per unit cell area of muscovite (0.77 µg Pu/cm²) (determined independently by in situ resonant anomalous x-ray reflectivity and by ex situ alpha-spectrometry). The presence of discrete nanoparticles is confirmed by high resolution atomic force microscopy. We propose that the formation of these Pu(IV) nanoparticles from an otherwise stable Pu(III) solution can be explained by the combination of a highly concentrated interfacial Pu-ion species, the Pu(III) – Pu(IV) redox equilibrium, and the strong proclivity of tetravalent Pu to hydrolyze and form polymeric species. These results are the first direct observation of such behavior of plutonium on a naturally occurring mineral, providing insights into understanding the environmental transport of plutonium and other contaminants capable of similar redox/polymerization reactions.

Keywords: plutonium; colloids; nanoparticles; X-ray scattering; sorption; crystal truncation rods; resonant anomalous x-ray reflectivity

Permalink: https://www.hzdr.de/publications/Publ-19424
Publ.-Id: 19424


Die Versorgung mit wirtschaftskritischen Rohstoffen – Eine Ursachensuche und -analyse

Gutzmer, J.; Klossek, A.

Mineralische sowie insbesondere metallhaltige Rohstoffe sind für die Wertschöpfung aller hochentwickelten Volkswirtschaften von elementarer Bedeutung. Gleichzeitig entstammen diese Rohstoffe letztlich alle der Erdkruste – und damit einem Reservoir von endlicher Größe. Auch wenn die gesamte Größe dieses Reservoirs, auch Geopotenzial genannt, für keinen mineralischen oder metallhaltigen Rohstoff bisher ausgeschöpft wird, so werden die zur Verfügung stehenden Rohstoffkörper (Lagerstätten) zunehmend minderwertiger und teurer in ihrer Erschließung, ihrem Abbau und ihrer Verarbeitung.
Durch den technischen Fortschritt wird sich die Rohstoffabhängigkeit noch weiter verschärfen, wobei insbesondere der Bedarf an bislang technologisch wenig genutzten Metallen dramatisch steigen wird. Wurden in den 1980er-Jahren für die Herstellung eines Computerchips noch zwölf verschiedene Rohstoffe benötigt, sind es heute bis zu sechzig. Prognosen zufolge lassen technischer Wandel und Innovationen den Bedarf an Technologiemetallen wie Gallium (Ga), Neodym (Nd), Indium (In), Germanium (Ge), Scandium (Sc), Platin (Pt) oder Tantal (Ta) bis 2030 auf ein Vielfaches der heutigen Weltproduktionsmenge steigen (Angerer et al. 2009).
Nicht nur technischer Wandel und Innovationen katapultieren den internationalen Rohstoffbedarf nach oben. Auch die steigende Weltbevölkerung gerade in Entwicklungs- und Schwellenländern wie China und Indien oder die Wachstumssprünge in der Wirtschaftsleistung vieler dieser Länder beeinflussen den weltweiten Bedarf nach metallhaltigen Rohstoffen dramatisch. So ist schon jetzt klar, dass die Wirtschaftsmacht China ihren eigenen immens ansteigenden Rohstoffbedarf nicht nur aus eigenen, teilweise bereits heute schon nach außen hin reglementierten Rohstoffvorkommen decken kann, sondern bei weiter steigendem volkswirtschaftlichem Wachstum alle Kategorien mineralischer und metallischer Rohstoffe in zunehmendem Maße auch von außen zukaufen muss.
In letzter Instanz führen diese globalen Entwicklungen zu Lieferrestriktionen, sich verteuernden Rohstoffen und zu Rohstoffknappheit. Rohstoffe, deren Verfügbarkeit für Zukunftstechnologien gesichert werden muss, die eine große Hebelwirkung für die Wirtschaft haben und von denen bereits ein relativ geringer Mengeneinsatz damit zu einer hohen zusätzlichen Wertschöpfung in Hochtechnologiebereichen beiträgt, werden als „wirtschaftsstrategische“ Rohstoffe bezeichnet (BMBF 2012). Rohstoffe, deren Versorgungslage sich für die Wirtschaft mittel- bis langfristig als kritisch erweisen könnte, sind als „kritisch“ zu bezeichnen (ebd.), sodass die vorliegende Studie in Anlehnung an beide Definitionen von „wirtschaftskritischen Rohstoffen“ spricht. Was genau macht jedoch einige der bereits genannten Rohstoffe wirtschaftskritischer als andere, und wie kann auf unterschiedlichen gesellschaftlichen Ebenen mit dieser Rohstoffkritikalität umgegangen werden? Dieser Frage widmet sich die vorliegende Studie.

Keywords: criticality of mineral raw materials

  • Book chapter
    Kausch, P., Bertau, M., Gutzmer, J., Matschullat, J.: Strategische Rohstoffe — Risikovorsorge, Heidelberg: Springer Spektrum, 2014, 978-3-642-39704-2, 59-74

Permalink: https://www.hzdr.de/publications/Publ-19423
Publ.-Id: 19423


Sensitivity study on Xe depletion in the high burn-up structure of UO2

Holt, L.; Schubert, A.; van Uffelen, P.; Walker, C. T.; Fridman, E.; Sonoda, T.

Experimental results for the Xe depletion in high burn-up fuel are presented from the High Burnup Rim Project (HBRP). In this project a number of UO2 fuel discs with 235U enrichment of 25.8 wt% were irradiated. The Xe content of the fuel discs was analysed by means of electron probe microanalysis (EPMA) with respect to burn-up and temperature. The influence of the burn-up and temperature on Xe concentration was investigated using a multi-physics approach involving various simulation tools. The temperature influence was modelled by the means of the temperature dependent effective burn-up. Good agreement was found between the modelled temperature threshold of the effective burn-up and the experimental temperature threshold between un- and restructured fuel in the HBRP. However, a systematic difference is observed between the onset burn-up derived from the Xe measurements in highly enriched discs such as those of HBRP and the corresponding values derived from irradiated Light Water Reactor (LWR) fuel rods and reported in the open literature. A sensitivity study identified the neutron flux spectrum and the fission product yields as main reasons for the observed differences.

Permalink: https://www.hzdr.de/publications/Publ-19422
Publ.-Id: 19422


Calculation of effective point kinetics parameters in the Serpent 2 Monte Carlo code

Leppanen, J.; Aufiero, M.; Fridman, E.; Rachamin, R.; van der Marck, S.

This paper presents the methodology developed for the Serpent 2 Monte Carlo code for the calculation of adjoint-weighted reactor point kinetics parameters: effective generation time and delayed neutron fractions. The calculation routines were implemented at the Politecnico di Milano, and they are based on the iterated fission probability (IFP) method. The developed methodology is mainly intended for the modeling of small research reactor cores, and the results are validated by comparison to experimental data and MCNP5 calculations in 31 critical configurations.

Keywords: Serpent; Monte Carlo; adjoint-weighted time constants; effective generation time; effective delayed neutron fraction

Permalink: https://www.hzdr.de/publications/Publ-19421
Publ.-Id: 19421


Surface patterning of GaAs under irradiation with very heavy polyatomic Au ions

Bischoff, L.; Böttger, R.; Heinig, K.-H.; Facsko, S.; Pilz, W.

Self-organization of surface patterns on GaAs under irradiation with very heavy polyatomic Au ions has been found. The patterns depend on the ion mass, the substrate temperature as well as the incidence angle of the ions. At room temperature, under normal incidence the surface remains flat, whereas above 200 °C nanodroplets of Ga appear after irradiation with monatomic, biatomic as well as triatomic Au ions of kinetic energies in the range of 10 to 30 keV per atom. In the intermediate temperature range of 100 to 200 °C meander- and dot-like patterns form, which are not related to Ga excess. Under oblique ion incidence up to 45° from the surface normal, at room temperature the surface remains flat for mon- and polyatomic Au ions. For bi- and triatomic ions, in the range 60° ≤ a ≤ 70° ripple patterns have been found, which become shingle-like for a ≥ 80°, whereas the surface remains flat for monatomic ions.

Keywords: surface morphology; ripples; nanodots; FIB; polyatomic ions; GaAs; Au

Permalink: https://www.hzdr.de/publications/Publ-19420
Publ.-Id: 19420


Modelling of Nuclear Fuel under Accident Conditions by means of TRANSURANUS

van Uffelen, P.; van de Laar, J.; Schubert, A.; Di Marcello, V.; Vlahovic, L.; Holt, L.

The TRANSURANUS fuel performance code, which is developed at the JRC-ITU and in collaboration with many partner institutes since more than three decades, has been adapted in order to be able to simulate design basis accident (DBA) conditions.

In a first step, the developments and associated validation work will be summarised for LOCA conditions. This part includes modifications in the model for large strains, for the crystallographic phase transition in zircaloy, and for burst release and large cladding deformations.

In a second step, the ongoing work for simulations of RIA conditions will be outlined that include the model for the plenum temperature, along with the separate effect studies and detailed model developments made in parallel by means of multi-scale and multi-physics tools for the high burnup structure.

Finally, the perspectives of model developments and needs for further verification and validation in the frame of international benchmark exercises dedicated to DBA simulations and the first phase of a sever accident, i.e. when the cylindrical fuel rod geometry is preserved, will be presented for discussion.

  • Contribution to proceedings
    Technical meeting on modelling of water-cooled fuel including design basis and severe accidents, 28.10.-01.11.2013, Chengdu, China
    Proceedings of the technical meeting on modelling of water-cooled fuel including design basis and severe accidents
  • Lecture (Conference)
    Technical meeting on modelling of water-cooled fuel including design basis and severe accidents, 28.10.-01.11.2013, Chengdu, China

Permalink: https://www.hzdr.de/publications/Publ-19419
Publ.-Id: 19419


Inclined rotating fixed bed reactors as a new reactor concept for process intensification

Härting, H.-U.; Schubert, M.

After a short introduction about the research activities of the Experimental Thermal Fluid Dynamics Department the new reactor concept "inclined rotating fixed bed reactor" is presented.
The idea and the benefits as well as selected aspects of the design are explained in detail.
Selected results from hydrodynamic experiments coupled with tomographic imaging are presented.
Furthermore, the evaluation of the new reactor concept by gas-liquid mass transfer studies is presented.

Keywords: process intensification; fixed bed reactor; inclination; rotation; tomographic imgaging

  • Invited lecture (Conferences)
    Autumn Session PINNL 2013, 13.11.2013, Amersfoort, Nederland

Permalink: https://www.hzdr.de/publications/Publ-19418
Publ.-Id: 19418


Lambda hyperon production and polarization in collisions of p (3.5 GeV) + Nb

Agakishiev, G.; Arnold, O.; Balanda, A.; Belver, D.; Belyaev, A. V.; Berger-Chen, J. C.; Blanco, A.; Böhmer, M.; Boyard, J. L.; Cabanelas, P.; Chernenko, S.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O. V.; Finocchiaro, P.; Fonte, P.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzon, J. A.; Gernhäuser, R.; Göbe, K.; Golubeva, M.; Gonzalez-Diaz, D.; Guber, F.; Gumberidze, M.; Heinz, T.; Hennino, T.; Holzmann, R.; Ierusalimov, A.; Iori, I.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Koenig, I.; Koenig, W.; Kolb, B. W.; Kornakov, G.; Kotte, R.; Krasa, A.; Krizek, F.; Krücken, R.; Kuc, H.; Kühn, W.; Kugler, A.; Kurepin, A.; Ladygin, V.; Lalik, R.; Lang, S.; Lapidus, K.; Lebedev, A.; Liu, T.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michalska, B.; Michel, J.; Müntz, C.; Naumann, L.; Pachmayer, Y. C.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Schmah, A.; Schwab, E.; Siebenson, J.; Sobolev, Y. G.; Spataro, S.; Spruck, B.; Ströbele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Trebacz, R.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Weber, M.; Wendisch, C.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y. V.

Results on Lambda hyperon production are reported for collisions of p (3.5~GeV) + Nb, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18 at GSI Helmholtzzentrum for Heavy-Ion Research, Darmstadt. The transverse mass distributions in rapidity bins are well described by Boltzmann shapes with a maximum inverse slope parameter of about 90\,MeV at a rapidity of y=1.0, i.e. slightly below the center-of-mass rapidity for nucleon-nucleon collisions, y_{cm}=1.12. The rapidity density decreases monotonically with increasing rapidity within a rapidity window ranging from 0.3 to 1.3. The Lambda phase-space distribution is compared with results of other experiments and with predictions of two transport approaches which are available publicly. None of present versions of the employed models is able to fully reproduce the experimental distributions, i.e. in absolute yield and in shape. The present high-statistics data allow for a genuine two-dimensional investigation as a function of phase space of the self-analyzing Lambda polarization in the weak decay Lambda\rightarrow p pi^-. Finite negative values of the polarization in the order of 5-20 % are observed over the entire phase space studied. The magnitude of the polarization increases almost linearly with increasing transverse momentum, {\cal P}(p_t) = (-0.19 \pm 0.02)~(GeV/c)^{-1}p_t, and increases with decreasing rapidity for y < 0.8.

Permalink: https://www.hzdr.de/publications/Publ-19417
Publ.-Id: 19417


Laser cooling of stored relativistic C3+ ions at the ESR

Winters, D.; Clark, C.; Dimopoulou, C.; Giacomini, T.; Kozhuharov, C.; Kühl, T.; Litvinov, Y.; Lochmann, M.; Nörtershäuser, W.; Nolden, F.; Sanchez, R.; Sanjari, S.; Steck, M.; Stöhlker, T.; Ullmann, J.; Beck, T.; Birkl, G.; Rein, B.; Tichelmann, S.; Walther, T.; Ma, X.; Wen, W.; Yang, J.; Zhang, D.; Schramm, U.; Seltmann, M.; Siebold, M.; Bussmann, M.

After several years of planning, development, and tests, in August 2012 a new laser cooling experiment (E089) has been performed at the ESR. One essential goal of this beamtime was to demonstrate that the initially ‘hot’ ions can be collected inside the rf-bucket using just the laser, i.e. without changing the bucket frequency and without electron cooling. This scheme can namely be used to cool relativistic ion beams in future storage rings and synchrotrons, such as the HESR and SIS-100 at FAIR.

Keywords: laser cooling; esr; storage ring; ion beam; bunching; relativistic

  • Open Access Logo Contribution to external collection
    Katrin Große: GSI Scientific Report 2012 - GSI Report 2013-1, Darmstadt: GSI Helmholtzzentrum für Schwerionenforschung GmbH, 2013, 313

Permalink: https://www.hzdr.de/publications/Publ-19416
Publ.-Id: 19416


Vacuum birefringence – a feasibility study

Schlenvoigt, H.-P.; Cowan, T. E.; Heinzl, T.; Sauerbrey, R.; Schramm, U.; Schroer, C.; Uschmann, I.

We consider an experiment to test nonlinear QED by light-by-light-scattering: An intense optical laser pulse generates in a perfect vacuum a field which induces birefringence of the vacuum. That birefringence is measured with an XFEL beam and state-of-the-art X-ray polarimetry. We calculate for planned facilitites the phase shift, ellipticity and photon numbers per shot. In addition, we consider shot-to-shot fluctuations and beam-arrival-jitter, and derive required integration times.

  • Poster
    User workshop on High-Power Lasers, 01.-02.10.2013, Menlo Park, California, USA

Permalink: https://www.hzdr.de/publications/Publ-19415
Publ.-Id: 19415


Development of a PET-Tracer for Phoshodiesterase 10A

Wagner, S.; Scheunemann, M.; Brust, P.

Phosphodiesterases (PDEs) are a class of enzymes heavily involved in cellular signaling by inactivating the second messenger cAMP and cGMP. So far, 11 different PDE families are known, of which one, the dual substrate enzyme PDE10A is abundantly expressed in the striatum. Since this brain region is thought to be involved in the pathomechanism of schizophrenia, PDE10A inhibition represents an approach in the treatment of this disease. In-vivo imaging via positron emission tomography (PET) of PDE10A would allow investigating the enzyme and its expression in neuropathological processes. Therefore our group is focused on the development of a F18-labeled PET tracer for PDE10A. Recently reported 1-arylimidazoquinoxaline inhibitors have been chosen as lead structure.
Based on this scaffold we synthesized a series of new fluorinated compounds as possible PET tracer candidates for PDE10A. To enable an easy F-18 incorporation, fluorine was chosen to be in the 2-position of the pyridine ring. The key step to introduce these different 2-fluoropyridines is the Pd-catalyzed Suzuki-coupling. 2-Fluoropyridines can be localized in two different positions of the arylimidazoquinoxaline scaffold leading to three different types of inhibitors (type A, type B, type C). The inhibitory potency of these compounds was tested towards human, recombinant PDE10A and other PDE-families. All synthesized compounds showed a high inhibitory potency. The most selective inhibitor was chosen to be further developed as PET tracer for PDE10A.

  • Poster
    12th Leipzig Research Festival for Life Sciences 2013, 19.12.2013, Leipzig, Deutschland
  • Contribution to proceedings
    12th Leipzig Research Festival for Life Sciences 2013, 19.12.2013, Leipzig, Deutschland
    Leipzig Research Festival for Life Sciences 2013, Leipzig: Universität Leipzig, 978-3-9810760-9-7

Permalink: https://www.hzdr.de/publications/Publ-19414
Publ.-Id: 19414


Inelastic scattering of fast neutrons from excited states in 56Fe

Beyer, R.; Schwengner, R.; Hannaske, R.; Junghans, A.; Massarczyk, R.; Anders, M.; Bemmerer, D.; Ferrari, A.; Kögler, T.; Röder, M.; Schmidt, K.; Wagner, A.

We have studied the inelastic scattering of neutrons from 56Fe in the energy range from about 0.5 to 10 MeV at the photoneutron source nELBE. The neutron energies were determined on the basis of a time-of-flight measurement. Gamma-ray spectra were measured with an HPGe detector defining the energy resolution to about 10 ns. We deduced scattering cross sections for the 2+, 4+ and 6+ yrast states in 56Fe by applying feeding corrections. The gross features of the total scattering cross section can be described within the statistical code Talys, whereas the scattering cross sections of individual states represent new information that may be used to improve the description within statistical models.

Keywords: Inelastic neutron scattering; scattering cross sections; photoneutron source; gamma-ray spectra; HPGe detector; statistical models

Permalink: https://www.hzdr.de/publications/Publ-19413
Publ.-Id: 19413


Magnetization and spin dynamics of the spin S = ½ hourglass nanomagnet Cu5(OH)2(NIPA)4·10H2O

Nath, R.; Tsirlin, A. A.; Khuntia, P.; Janson, O.; Förster, T.; Padmanabhan, M.; Li, J.; Skourski, Y.; Baenitz, M.; Rosner, H.; Rousochatzakis, I.

We report a combined experimental and theoretical study of the spin S = ½ nanomagnet Cu5(OH)2(NIPA)4·10H2O (Cu5-NIPA). Using thermodynamic, electron spin resonance, and 1H nuclear magnetic resonance measurements on one hand, and ab initio density-functional band-structure calculations, exact diagonalizations, and a strong-coupling theory on the other, we derive amicroscopicmagnetic model of Cu5-NIPA and characterize the spin dynamics of this system. The elementary fivefold Cu2+ unit features an hourglass structure of two corner-sharing scalene triangles related by inversion symmetry. Our microscopic Heisenberg model comprises one ferromagnetic and two antiferromagnetic exchange couplings in each triangle, stabilizing a single spin S = ½ doublet ground state (GS), with an exactly vanishing zero-field splitting (by Kramers’ theorem), and a very large excitation gap of ∆ ≈ 68 K. Thus, Cu5-NIPA is a good candidate for achieving long electronic spin relaxation (T1) and coherence (T2) times at low temperatures, in analogy to other nanomagnets with low-spin GS’s. Of particular interest is the strongly inhomogeneous distribution of the GS magnetic moment over the five Cu2+ spins. This is a purely quantum-mechanical effect since, despite the nonfrustrated nature of the magnetic couplings, the GS is far from the classical collinear ferrimagnetic configuration. Finally, Cu5-NIPA is a rare example of a S = ½ nanomagnet showing an enhancement in the nuclear spin-lattice relaxation rate 1/T1 at intermediate temperatures.

Permalink: https://www.hzdr.de/publications/Publ-19412
Publ.-Id: 19412


Metamagnetic transition of martensitic type in electron-doped manganites Ca1-ΧCeΧMnO3 (Χ= 0.10, 0.12)

Loshkareva, N. N.; Gorbunov, D. I.; Andreev, A. V.; Mushnikov, N. V.; Skourski, Y.; Wolff-Fabris, F.

Magnetic and electrical properties of electron-doped manganites Ca0.88Ce0.12MnO3 and Ca0.90Ce0.10MnO3 were studied in pulsed magnetic fields up to 60 T in the temperature range T = 1.5–260 K. Metamagnetic transition caused by the melting of the charge/orbital ordering and martensitic structural transition in a magnetic field was revealed. The transition is accompanied by a change in electrical resistivity of the sample by three orders. A magnetic phase diagram in the plane of the H–T was constructed. Higher values of the critical transition fields for the system Ca1-ΧCeΧMnO3, compared to the known system Ca1-ΧSmΧMnO3 are explained by a narrower range of phase separation and a bigger difference between the Néel temperatures of the C and G-type antiferromagnetic phases, which originated from the difference between the valence of the Ce4+ and Sm3+ ions.

Permalink: https://www.hzdr.de/publications/Publ-19411
Publ.-Id: 19411


Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

Mallast, U.; Siebert, C.; Wagner, B.; Sauter, M.; Gloaguen, R.; Geyer, S.; Merz, R.

The semi-arid region of the Dead Sea heavily relies on groundwater resources. This dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management. Yet, information on groundwater discharge as one main component for a sustainable management varies significantly in this area. Moreover, discharge locations, volume and temporal variability are still only partly known. A multi-temporal thermal satellite approach is applied to localise and semi-quantitatively assess groundwater discharge along the entire coastline. The authors use 100 Landsat ETM + band 6.2 data, spanning the years between 2000 and 2011. In the first instance, raw data are transformed to sea surface temperature (SST). To account for groundwater intermittency and to provide a seasonally independent data set ∆T (maximum SST range) per-pixel within biennial periods is calculated subsequently. Groundwater affected areas (GAA) are characterised by ∆T < 8.5 °C. Unaffected areas exhibit values >10 °C. This allows the exact identification of 37 discharge locations (clusters) along the entire Dead Sea coast, which spatially correspond to available in situ discharge observations. Tracking the GAA extents as a direct indicator of groundwater discharge volume over time reveals (1) a temporal variability correspondence between GAA extents and recharge amounts, (2) the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge, (3) a certain variability in discharge locations as a consequence of the Dead Sea level drop, and finally (4) the assumed flushing effect of old Dead Sea brines from the sedimentary body to have occurred at least during the two series of 2000–2001 and 2010–2011.

Keywords: Landsat ETM+; Sea surface temperature; Submarine groundwater discharge; Groundwater resource

Permalink: https://www.hzdr.de/publications/Publ-19410
Publ.-Id: 19410


Onset of Magnetic Order in U2(Ni1−xFex)2Sn-H

Mašková, S.; Havela, L.; Kolomiets, A.; Miliyanchuk, K.; Andreev, A. V.; Nakotte, H.; Peterson, J.; Skourski, Y.; Yasin, S.; Zherlitsyn, S.; Wosnitza, J.

We present specific heat and magnetic studies as a function of temperature and magnetic field for U2(Ni1−xFex)2Sn alloys (x = 0.0, 0.05, 0.1, 0.15, 0.2, 0.4, 0.6 and 0.8) and their hydrides (absorption of ≈ 2 H/f.u.). For the parent alloys, antiferromagnetic order is rapidly suppressed with increasing Fe concentration and non-Fermi-liquid behavior was found for x = 0.2. Hydrogenation of the parent alloys causes a substantial increase of TN in Fe-low hydrides (x < 0.2), while Fe-rich hydrides show an unexpected appearance of ferromagnetism in the range 0.4 ≤ x ≤ 0.8. Some of the findings are compared with similar studies in U2Co2Sn and U2Co2InH1.9.

Permalink: https://www.hzdr.de/publications/Publ-19409
Publ.-Id: 19409


Upgrade of the Machine Interlock System for the ELBE Accelerator Facility

Justus, M.; Freitag, M.; Lange, B.; Michel, P.; Sorge, W.; Steinbrück, R.; Tietze, H.

The ELBE facility with its 40 MeV C.W. LINAC has recently received an upgrade in terms of new secondary radiation sources and beam lines, while advancing the accelerator infrastructure towards 1.6 mA C.W. operation (1.0 mA before). Therefore, the machine interlock system (MIS) was in parts redesigned to meet the new timing requirements resulting from the increased overall beam power. It comprises fast beam loss detection and a PLC based equipment protection system (EPS), tripping the key components of the electron sources. The former tripping system using PLC interrupts was replaced by an in-house developed staggered CPLD based system with optical transmission and a PROFINET IO interface for control system integration. The EPS is distributed on several PLCs and has been improved in terms of M2M communication. Further, the vacuum inrush protection was completely renewed using brought-in equipment.
This contribution depicts the technical features and performance of the MIS subsystems, as well as the challenges posed by the project track of the ELBE upgrade during implementation.

Keywords: ELBE; MIS; Conrol System

  • Poster
    IPAC 2014 - 5th International Particle Accelerator Conference, 15.-20.06.2014, Dresden, Deutschland
  • Open Access Logo Contribution to proceedings
    IPAC 2014 - 5th International Particle Accelerator Conference, 14.-20.06.2014, Dresden, Deutschland
    IPAC2014: Proceedings of the 5th International Particle Accelerator Conference, Geneva, Switzerland: JACoW, 978-3-95450-132-8, 469-471

Permalink: https://www.hzdr.de/publications/Publ-19408
Publ.-Id: 19408


Determining the Stability Domain of Perturbed Four-Dimensional Systems in 1:1 Resonance

Hoveijn, I.; Kirillov, O.

For a parametric family of four-dimensional linear dynamical systems determined by a matrix A(m) with A(0) in 1 : 1 semi-simple resonance, we have established that the central singularity on the stability boundary has codimension 8, ie the centralizer unfolding of the family needs 8 parameters. By recognizing equivalence classes in the centralizer unfolding we reduced the codimension to 5 and finally by using the homogeneity properties to 3. This allowed us to find explicitly the boundary of the stability domain and list all its singularities including six self-intersections and four ’Whitney umbrellas’. We have proposed an algorithm of approximation of the stability boundary near singularities and applied the results to the study of enhancement of the modulation instability with dissipation as well as to the study of stability of a nonconservative system of rotor dynamics.

Keywords: semi-simple resonance; dynamical systems; stability theory; modulational instability; differential equations; versal deformation

  • Book chapter
    Oleg N. Kirillov, Dmitry E. Pelinovsky: Nonlinear Physical Systems: Spectral Analysis, Stability and Bifurcations, London: Wiley-ISTE, 2013, 9781848214200, 155-175

Permalink: https://www.hzdr.de/publications/Publ-19407
Publ.-Id: 19407


Nonlinear Physical Systems: Spectral Analysis, Stability and Bifurcations

Kirillov, O.; Pelinovsky, D.; (Editors)

Bringing together 18 chapters written by leading experts in dynamical systems, operator theory, partial differential equations, and solid- and fluid mechanics, this book presents state-of-the-art approaches to a wide spectrum of new and challenging stability problems.

Nonlinear Physical Systems: Spectral Analysis, Stability & Bifurcations focuses on problems of spectral analysis, stability and bifurcations arising in the nonlinear partial differential equations of modern physics. Bifurcations and stability of solitary waves, geometrical optics stability analysis in hydro- and magnetohydrodynamics, and dissipation-induced instabilities are treated with the use of the theory of Krein and Pontryagin space, index theory, the theory of multi-parameter eigenvalue problems and modern asymptotic and perturbative approaches.

Each chapter contains mechanical and physical examples, and the combination of advanced material and more tutorial elements make this book attractive for both experts and non-specialists keen to expand their knowledge on modern methods and trends in stability theory.

List of authors

Anatoly Anikin, Davide Bigoni, Jean-Francois Bony, Radomir Bosak, Richard Cushman, Olivier Doare, Sergey Dobrokhotov, Nir Dror, Setsuro Fujiie, Yasuhide Fukumoto, George Hagstrom, Makoto Hirota, Igor Hoveijn, Oleg Kirillov, Richard Kollar, Paolo Luzzatto-Fegiz, Boris Malomed, Sherwin Maslowe, Philip Morrison, Youichi Mie, Diego Misseroni, Francis Nier, Giovanni Noselli, Michael Overton, Dmitry Pelinovsky, Thierry Ramond, Jonathan Robbins, Dmitrii Sadovskii, Emanuele Tassi, Cesare Tronci, Charles Williamson, Zensho Yoshida, Daniele Zaccaria, Mather Zerzeri

Keywords: Nonlinear dynamics; Stability theory; WKB approximation; solitary waves; vortex dynamics; material stability; index theorems; absolute and convective instabilities; dissipation-induced instabilities; Krein space; singularity theory; Hopf bifurcation; Hamiltonian system; Energy-Casimir method; root radius and abscissa; eigenvalue optimization; pseudospectra

  • Book (Editorship)
    London: Wiley-ISTE, 2013
    448 Seiten
    ISBN: 9781848214200

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-19406
Publ.-Id: 19406


Automation of the radiosynthesis and purification procedures for [18F]Fluspidine preparation, a new radiotracer for clinical investigations in PET imaging of σ1 receptors in brain.

Maisonial-Besset, A.; Funke, U.; Wenzel, B.; Fischer, S.; Holl, K.; Wünsch, B.; Steinbach, J.; Brust, P.

The radiosynthesis of [18F]Fluspidine, a potent σ1 receptor imaging probe for preclinical/clinical studies, was implemented on a TRACERlabTM FX F-N synthesizer. [18F]2 was synthesized in 15 min at 85 °C starting from its tosylate precursor. Purification via semipreparative RP-HPLC was investigated using different columns and eluent compositions and was most successful on a polar RP phase with acetonitrile/water buffered with NH4OAc.
After solid phase extraction, [18F]Fluspidine was formulated and produced within 59 ± 4 min with an overall radiochemical yield of 37 ± 8%, a radiochemical purity of 99.3 ± 0.5% and high specific activity (176.6 ± 52.0 GBq/μmol).1 receptor imaging probe for preclinical/clinical studies, was implemented on a TRACERlabTM FX F-N synthesizer. [18F]2 was synthesized in 15 min at 85 °C starting from its tosylate precursor. Purification via semipreparative RP-HPLC was investigated using different columns and eluent compositions and was most successful on a polar RP phase with acetonitrile/water buffered with NH4OAc.
After solid phase extraction, [18F]Fluspidine was formulated and produced within 59 ± 4 min with an overall radiochemical yield of 37 ± 8%, a radiochemical purity of 99.3 ± 0.5% and high specific activity (176.6 ± 52.0 GBq/μmol).

Keywords: [18F]Fluspidine; one-step automated radiosynthesis; positron emission tomography; σ1 receptors

Permalink: https://www.hzdr.de/publications/Publ-19405
Publ.-Id: 19405


Dialyseverfahren zum Recycling von Gallium

Zeidler, O.

Der Aufsatz beleuchtet die Anwendung von Dialyseverfahren am Beispiel eines Projektes zur Trennung von Gallium und Arsen aus verbrauchten Beizlösungen der GaAs-Waferproduktion. Der Einsatz von Diffusions- und Elektrodialyse kann durch geringere Chemikalienverbräuche sowie einen einfacheren Aufbau deutliche Vorteile gegenüber Fällungs- und Extraktionsverfahren besitzen und auf diese Weise bisher nicht ökonomisch schließbare Stoffstromketten schließen.
Während Dialyseverfahren zur Laugenregeneration, Metallrückgewinnung oder Säurerückgewinnung in der Galvanotechnik bereits seit Jahren etabliert sind und sich ständig weiter entwickeln [1], sind aus der Halbleiterindustrie kaum Anwendungsfälle bekannt. In Folge der Verknappung von Seltenen Metallen und der Debatte zur Ressourceneffizienz besteht hier ein Forschungs- und Handlungsbedarf.

  • Open Access Logo Contribution to proceedings
    46. Metallurgisches Seminar der GDMB: Herstellung und Recycling von Technologiemetallen, 10.-12.12.2013, Joachimsthal, Deutschland
  • World of Metallurgy - Erzmetall 67(2014)2, 5

Permalink: https://www.hzdr.de/publications/Publ-19404
Publ.-Id: 19404


Abtrennung von Zinn beim Recycling von Bleiakkumulatoren

Beimel, B.; Stelter, M.; Morgenstern, G.; Zeidler, O.

Der gegenwärtig anfallende Akkumulatorenschrott besitzt höhere Zinngehalte als die Bleilegierungen moderner Akkumulatoren. Dadurch fallen bei der Aufarbeitung des Akkuschrotts blei/zinnhaltige Raffinationsprodukte an, die nicht in den Wertstoffkreislauf zurückgeführt werden können. Es wird eine Möglichkeit zur Trennung dieser Produkte beschrieben. Damit hat der Recycler die Möglichkeit, die Wertstoffe Zinn und Blei der Wirtschaft wieder getrennt zur Verfügung zu stellen.

Keywords: Battery recycling; Lead; Separation of lead and tin; Tin

Permalink: https://www.hzdr.de/publications/Publ-19403
Publ.-Id: 19403


The Revival of Rare Metal Research in Freiberg/Germany - Continuation of a Success Story

in Russian

Zeidler, O.

The mining and smelting region of Freiberg is well-known for its Pb-Zn-Ag lodes. These have been mined for their high silver contents since 1180. From the 18th century on, Pb, Zn, Sn and Ni became increasingly important as by-products. But the hydrothermally formed deposit also contains rare metals as In and Ge at unusually high concentrations.
Although metal prices decreased at the end of the 19th century and the operation of mines and smelters was more and more dependent of federal subsidization, parts of the research and industrial landscape were preserved. With semiconductor industry, a second economic pillar was established. The recent rise of metal prices may give a further momentum for economic growth.

  • Open Access Logo Contribution to proceedings
    5th International Congress and Exhibition "Non-Ferrous Metals 2013", 04.-06.09.2013, Krasnoyarsk, Rossijskaja Federazija
    Proceedings of the 5th International Congress and Exhibition "Non-Ferrous Metals 2013", Krasnoyarsk: Legkie Metallie, 978-5-85981-344-5, 175-178
  • Invited lecture (Conferences)
    5th International Congress and Exhibition "Non-Ferrous Metals 2013", 04.-06.09.2013, Krasnoyarsk, Rossijskaja Federazija

Permalink: https://www.hzdr.de/publications/Publ-19402
Publ.-Id: 19402


Recycling von Gallium aus Prozessrückständen

Stelter, M.; Zeidler, O.

Bemühungen zur Rückgewinnung von seltenen Metallen beschränken sich derzeit meist auf die Verwertung von End-of-life Produkten. In Produktionsprozessen dagegen gehen oft erhebliche Mengen dieser Wertstoffe verloren, die aus technologischen oder wirtschaftlichen Gründen nicht zurück gewonnen werden. In dem vorliegenden Beitrag werden die Möglichkeiten der Rückgewinnung von Gallium, über den bisherigen Stand der Technik hinaus, in der Halbleiterindustrie dargestellt. Als Beispiel dient das Recycling von Gallium aus Ätzlösungen der GaAs-Wafer und -Chipproduktion. Die Galliumverluste über Abwasserbehandlung und Reststoffrecycling der Waferproduktion belaufen sich auf etwa 150 g Gallium pro kg im produzierten Wafer. Ein wesentlicher Grund sind die hohen Kosten für eine umfassende selektive Rückgewinnung des Galliums aus dem Abwasser. Die TU Bergakademie Freiberg, das Helmholtz-Institut Freiberg und die Freiberger Compound Materials GmbH forschen an einem neuartigen und kostengünstigen Abwasserbehandlungsverfahren mit geringem Chemikalienverbrauch, um die Recyclingrate für Gallium wesentlich zu erhöhen und dabei die Qualität des Abwassers weiter zu verbessern. Zum Einsatz kommen sollen dabei Membranverfahren wie Dialyse und Elektrodialyse.

  • Open Access Logo Contribution to proceedings
    Berliner Recycling- und Rohstoffkonferenz, 04.-05.03.2013, Berlin, Deutschland
    Recycling und Rohstoffe, Band 6, Neuruppin: TK Verlag Karl Thomé-Kozmiensky, 978-3-935317-97-9, 471-480
  • Lecture (Conference)
    Berliner Recycling- und Rohstoffkonferenz, 04.-05.03.2013, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19401
Publ.-Id: 19401


On the acceleration of the microstructure evolution detected by SANS in low-Cu RPV steels

Wagner, A.; Chaouadi, R.; Bergner, F.; Viehrig, H.-W.

Previous work on low-Cu RPV steels JPB and JPC irradiated at 255 °C indicated an acceleration of the increase of both yield stress and total SANS intensity as functions of neutron fluence. A new algorithm was used to analyze the original SANS data as well as SANS data obtained for new BR2-irradiations at 290 °C of the same materials. Both data sets are compared with one another and correlated with the respective mechanical test results. Additional evidence is provided on the basis of SANS experiments performed for the RPV steels irradiated at 255 °C and post-irradiation annealed at 290 °C.

  • Lecture (Conference)
    17th Meeting of the IGRDM, 19.-24.05.2013, Les Embiez, France

Permalink: https://www.hzdr.de/publications/Publ-19399
Publ.-Id: 19399


Cycloisomerization of 2-alkynylanilines to indoles catalyzed by carbon-supported gold nanoparticles and subsequent homocoupling to 3,3′-biindoles

Perea-Buceta, J. E.; Wirtanen, T.; Laukkanen, O.-V.; Mäkelä, M. K.; Nieger, M.; Melchionna, M.; Huittinen, N.; Lopez-Sanchez, J. A.; Helaja, J.

Elevated by the support: 2-Alkynyl aniline cycloisomerization to indole is catalyzed by cationic Au NPs on a carbon support. Electroneutral and rich 2-aryl indoles are further converted into 3,3′-biindoles by oxidative homocoupling that is readily catalyzed by the Au NPs on carbon, and exclusively but also somewhat sluggishly by the carbon support.

Keywords: biindoles; carbon supports; gold; heterogeneous catalysis; homocoupling

Permalink: https://www.hzdr.de/publications/Publ-19398
Publ.-Id: 19398


Supraleitende Schichten in Ga-implantiertem Si und Ge

Fiedler, J.

  • Lecture (Conference)
    34. Treffen der Nutzergruppe Heißprozesse und RTP, 06.11.2013, Frankfurt (Oder), Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19397
Publ.-Id: 19397


Visualizing the Radiation of the Kelvin-Helmholtz Instability

Huebl, A.; Pugmire, D.; Schmitt, F.; Pausch, R.; Bussmann, M.

Emerging new technologies in plasma simulations allow tracking billions of particles while computing their radiative spectra. We present a visualization of the relativistic Kelvin-Helmholtz Instability from a simulation performed with the fully relativistic particle-in-cell code PIConGPU powered by 18,000 GPUs on the USA’s fastest supercomputer Titan.

Keywords: Plasma stability; Simulation; Parallel machines; Particle tracking; Electromagnetic radiation; Visualization

Permalink: https://www.hzdr.de/publications/Publ-19396
Publ.-Id: 19396


Molecular Imaging of σ1 Receptors In Vivo: Current Status and Perspectives

Brust, P.; Deuther-Conrad, W.; Lehmkuhl, K.; Jia, H.; Wünsch, B.

Abstract: It is widely accepted that sigma (σ) receptors represent a new and different avenue in the possible pharmacological treatment of cancer and several brain-related disorders. Of the two different σ receptor types the σ11 receptors are assumed to be of major impact for brain diseases. Molecular imaging of brain σ1 receptors with positron emission tomography (PET) or single photon emission computed tomography (SPECT) may provide a significant contribution to the understanding of the cross-talk between σ1 receptors and inter- and intracellular signalling systems. New insights into These functional interrelationships will allow a better diagnosis of brain and cancerous diseases and direct a rational development of new therapeutic concepts.

Keywords: brain; chaperone; cancer; disease; fluspidine; molecular imaging; positron emission tomography; sigma receptor; signalling; single photon emission computed tomography; therapy

Permalink: https://www.hzdr.de/publications/Publ-19395
Publ.-Id: 19395


Geochemische Untersuchungen an Moränen des Inylchek-Gletschers im Tien Shan

Hahne, K.; Naumann, R.; Niedermann, S.; Wetzel, H.-U.; Merchel, S.; Rugel, G.

In this study, we present results of the chemical composition of the moraine cover from the Inylchek Glacier in Kyrgyzstan using observations from three field campaigns between 2010 and 2012. The sample locations were selected based on high-resolution remote sensing data. Sampling included the main profile from Lake Merzbacher to Station “Hochgebirgsobservatorium Gottfried Merzbacher”, which is about 8 km in length trending in N-S-direction. Chemical analyses of more than 60 elements, including Rare Earth Elements (an important tool for the discrimination and localisation of source areas of sediments, boulders and outcropping rocks) were carried out.
Based on these data different geochemical material streams have been identified. Generally, two chemical groups of sediments, the North Type/Lake Merzbacher and the South Type/Southern Inylchek can be distinguished. The Lake Merzbacher Type sediments are characterised by a uniform chemical composition, whereas the South Inylchek Type is geochemically more heterogeneous. Toxic elements in the sediments, such as Ni, As, Cd, Tl and U, are moderately enriched. The low sulphur concentration suggests that the main water transport is caused by suspended matter.
One erratic granite block was analysed for in situ cosmogenic 10Be for exposure age dating. The age of 330 ± 90 a is conform to a glacier high stand during the “Maunder“ minimum of the solar activity.

Keywords: AMS; cosmogenic exposure dating; moraine

Permalink: https://www.hzdr.de/publications/Publ-19394
Publ.-Id: 19394


Interaction of U(VI) with Schizophyllum commune studied by microscopic and spectroscopic methods

Günther, A.; Raff, J.; Merroun, M. L.; Roßberg, A.; Kothe, E.; Bernhard, G.

Biosorption of actinides like uranium by fungal cells can play an important role in the mobilization or immobilization of these elements in nature. Sorption experiments of U(VI) with Schizophyllum commune at different initial uranium concentrations and varying metal speciation showed high uranium sorption capacities in the pH range of 4 to 7. A combination of High Angle Annular Dark-Field (HAADF) and Scanning Transmission Electron Microscopy (STEM) analysis showed that living mycelium cells accumulate uranium at the cell wall and intracellular. For the first time the fluorescence properties of uranium accumulates were investigated by means of time-resolved laser-induced fluorescence spectroscopy (TRLFS) beside the determination of corresponding structural parameters using X-ray absorption fine structure spectroscopy (EXAFS). While the oxidation state of uranium remained unchanged during sorption, uranium speciation changed significantly. Extra and intracellular phosphate groups are mainly responsible for uranium binding. TRLFS spectra clearly show differences between the emission properties of dissolved species in the initial mineral medium and of uranium species on fungi. The latter were proved to be organic and inorganic uranyl phosphates formed depending on the uranyl initial concentration and in some cases on pH.

Keywords: Fungi; Uranium; HAADF/STEM; TRLFS; EXAFS

Permalink: https://www.hzdr.de/publications/Publ-19393
Publ.-Id: 19393


Size-dependent magnetism and exchange bias effect in Sm0.27Ca0.73MnO3nanoparticles

Markovich, V.; Puzniak, R.; Fita, I.; Mogilyansky, D.; Wisniewski, A.; Skourski, Y.; Jung, G.; Gorodetsky, G.

Magnetic properties of compacted Sm0.27Ca0.73MnO3 nanoparticles with average particle size ranging from 20 to 80 nm have been investigated in wide temperature and magnetic field range. It has been found that charge ordering transition gradually shifts to lower temperatures with decreasing particle size and almost disappears for 20 nm particles. At the same time, the relative volume of the ferromagnetic phase increases monotonously. Field-induced transition from antiferromagnetic to ferromagnetic state in 80 nmparticles appears at the same magnetic field as in the bulk. In small 20 nm particles, the transition is strongly suppressed by increasing surface spins disorder. Magnetic hysteresis loops show size-dependent exchange bias effect with exchange field, remanence asymmetry, and magnetic coercivity that depend on cooling magnetic field and temperature. Magnetic training effect has been observed in 20 nm particles and analyzed using a spin relaxation model. The thermoremanence and isothermoremanence curves have provided fingerprints of irreversible magnetization originating from the glassy component. Analysis of remanence curves has showed that the inner core of small 20 nm particles behaves as a two-dimensional diluted antiferromagnet.

Permalink: https://www.hzdr.de/publications/Publ-19392
Publ.-Id: 19392


Strong room-temperature easy-axis anisotropy in Tb2Fe17H3: An exception among R2Fe17 hydrides

Tereshina, E. A.; Drulis, H.; Skourski, Y.; Tereshina, I. S.

The iron-rich intermetallics R2Fe17 (where R is a rare-earth element) proved unamenable to anisotropy control via interstitial doping. There is only one precedent, Sm2Fe17N3−δ (Sm2Fe17C3−δ ), where interstitial modification has stabilized an easy-axis anisotropy at all temperatures up to TC. All previous attempts to prepare a usable easy-axisR2Fe17 hydride have failed. Now we have succeeded in preparing a high-quality single-phase Tb2Fe17H3 single crystal,which has the required easy-axis anisotropy between 0 K and TC =560 K. At T =300 K, Tb2Fe17H3 has the spontaneous magnetic moment Ms of 22.5 μB per formula unit and anisotropy field μ0Ha of 2.5 T. The main mechanism stabilizing the easy-axis anisotropy in hydrides is the same as in other similar compounds by way of boosting the leading crystal field parameter A20. Terbium is rather special in having the Stevens factors such that αJ < 0 and βJ > 0, which is why the easy-axis anisotropy in Tb2Fe17 hydrides is also assisted by the fourth-order parameter A40. This proves a decisive advantage over the compounds with R = Pr, Nd, Dy, or Ho where βJ < 0 and A40 is a hindrance.

Permalink: https://www.hzdr.de/publications/Publ-19391
Publ.-Id: 19391


Magnetic and magnetoelastic properties of UCo2Si2 as studied by high-field magnetization and ultrasound measurements

Andreev, A. V.; Yasin, S.; Skourski, Y.; Zvyagin, A. A.; Zherlitsyn, S.; Wosnitza, J.

We investigated an antiferromagnet UCo2Si2 by use of magnetization and ultrasound measurements in pulsed magnetic fields up to 60 T. It is found that the crystal UCo2Si2, which has the antiferromagnet type-I magnetic structure in zero field below TN = 83 K, undergoes the metamagnetic phase transition to ferrimagnetic structure ++− type similarly to the UNi2Si2 with substitution of 10%–15% Ni by Pd or UPd2Si2. Therefore, similar phase transitions take place in the compounds with expected essentially different strength of the 5 f -d electron hybridization. In UCo2Si2, the transition occurs when the magnetic field is applied along the c axis at 45 T (at 1.5 K). The transition is extremely sharp and exhibits a small but non-negligible hysteresis. With increasing temperature, it becomes broader and vanishes at TN. In our ultrasound measurements, the metamagnetic transition appears as anomalies in the sound velocity and attenuation. Our analysis suggests that the low-temperature changes in the sound velocity and attenuation predominantly are determined by an exchange renormalization caused by the sound waves.

Permalink: https://www.hzdr.de/publications/Publ-19390
Publ.-Id: 19390


Role of Hyperfine Coupling in Magnetic and Quadrupolar Ordering of Pr3Pd20Si6

Steinke, L.; Mitsumoto, K.; Miclea, C. F.; Weickert, F.; Dönni, A.; Akatsu, M.; Nemoto, Y.; Goto, T.; Kitazawa, H.; Thalmeier, P.; Brando, M.

We study the ternary clathrate Pr3Pd20Si6 in specific heat and ac susceptibility measurements on a highquality single crystal, distinguishing antiferromagnetic and antiferroquadrupolar ordering, as well as a hitherto unknown magnetic low-temperature transition. The specific heat shows the direct involvement of nuclear spin degrees of freedom in the antiferromagnetic ordering, which is well supported by our calculation of the hyperfine level scheme without adjustable parameters. Pr3Pd20Si6 is, therefore, one of the rare materials where the nuclear moments are involved in the formation of the magnetic ground state.

Permalink: https://www.hzdr.de/publications/Publ-19389
Publ.-Id: 19389


Magnetic, thermal, and transport properties of single-crystalline U3Fe4Ge4

Henriques, M. S.; Gorbunov, D. I.; Waerenborgh, J. C.; Havela, L.; Andreev, A. V.; Skourski, Y.; Gonçalves, A. P.

Magnetic, thermal, and transport properties of a U3Fe4Ge4 single crystal have been studied. The compound crystallizes in the orthorhombic Gd3Cu4Ge4 structure type. U3Fe4Ge4 displays ferromagnetic order below the Curie temperature TC = 18 K. The magnetism originates from the uranium sublattice, as iron atoms have no ordered magnetic moments. U3Fe4Ge4 exhibits a pronounced easy-axis anisotropy with the anisotropy field exceeding 60 T. The spontaneous magnetic moment is Ms = 1.2 µB/f.u. at T = 2 K. Magnetic contribution to specific heat shows a gap excitation behavior with D = 4 meV, which can be related to the magnon gap due to the anisotropy. The Sommerfeld coefficient of the electronic specific heat is \gamma = 57 mJ/(mol-U K2) in the ordered state, whereas it is much higher (145 mJ/(mol-U K2) if derived from the paramagnetic state. Electrical resistivity has very high values on the mΩ cm range.

Permalink: https://www.hzdr.de/publications/Publ-19388
Publ.-Id: 19388


High-field magnetization of a DyFe5Al7 single crystal

Gorbunov, D. I.; Andreev, A. V.; Skourski, Y.; Kuz’Min, M. D.

The magnetization of a DyFe5Al7 single crystal with the tetragonal ThMn12-type structure was measured in pulsed fields up to 60 T along the principal axes. The compound orders ferrimagnetically at TC = 231 K and exhibits a compensation of the Dy and Fe sublattices at Tcomp = 93 K. DyFe5Al7 displays a high magnetic anisotropy of the easy-plane type, the [100] axis is the easy magnetization direction with the spontaneous magnetic moment Ms = 2.1 µB/f.u. at T = 2 K. In a field applied along the easy axis, two field-induced hysteretic transitions are observed at 30 and 53 T at T = 2 K. The critical field H of the first transition depends strongly on temperature, whereas Hcr2 is practically temperature-independent. Above the transitions the magnetization continues to grow as a function of field, as the sublattice moments continue to rotate. To reach the full saturation (forced ferromagnetic state), fields of several Tesla higher than 60 T are required. The field dependence of magnetization along the easy [100] axis was analyzed within a model for a ferrimagnet with an anisotropic dominant sublattice. The model correctly reproduces the behavior of magnetization in a magnetic field. The intersublattice molecular field on Dy and the basal-plane anisotropy constant of the Dy sublattice have been determined.

Permalink: https://www.hzdr.de/publications/Publ-19387
Publ.-Id: 19387


Ionenstrahlverfahren für die Element- und Spurenanalytik in Festkörpern

von Borany, J.; Munnik, F.; Neelmeijer, C.; Renno, A.; Merchel, S.

Im Rahmen eines Workshops zur "Analyse von Spurenverunreinigungen auf Oberflächen und in Gasen" werden in einer Übersicht die ionenanalytischen Verfahren vorgestellt.

Keywords: Analytik; Spurenelemente; Ionen

  • Lecture (Conference)
    Workshop " Analyse von Spurenverunreinigungen auf Oberflächen und in Gasen", 03.12.2013, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19386
Publ.-Id: 19386


Field-induced magnetic ordering and single-ion anisotropy in the quasi-one-dimensional Haldane chain compound SrNi2V2O8: A single-crystal investigation

Bera, A. K.; Lake, B.; Islam, A. T. M. N.; Klemke, B.; Faulhaber, E.; Law, J. M.

Field-induced magnetic ordering in the Haldane chain compound SrNi2V2O8 and the effect of anisotropy have been investigated using single crystals. Static susceptibility, inelastic neutron scattering, high-field magnetization, and low-temperature heat-capacity studies confirm a nonmagnetic spin-singlet ground state and a gap between the singlet ground state and triplet excited states. The intrachain exchange interaction is estimated to be J ∼ 8.9 ± 0.1meV. Splitting of the dispersions into two modeswithminimum energies 1.57 and 2.58 meV confirms the existence of single-ion anisotropy D(Sz)2. The value of D is estimated to be −0.51 ± 0.01 meV and the easy axis is found to be along the crystallographic c axis. Field-induced magnetic ordering has been found with two critical fields (μ0Hc⊥c = 12.0 ± 0.2 T and μ0HcIIc = 20.8 ± 0.5 T at 4.2 K). Field-induced three-dimensional magnetic ordering above the critical fields is evident from the heat-capacity, susceptibility, and high-field magnetization study. The phase diagram in the H-T plane has been obtained from the high-field magnetization. The observed results are discussed in the light of theoretical predictions as well as earlier experimental reports on Haldane chain compounds.

Permalink: https://www.hzdr.de/publications/Publ-19385
Publ.-Id: 19385


Measurement of the dipole polarizability of the unstable neutron-rich nucleus 68Ni

Rossi, D. M.; Adrich, P.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Böhmer, M.; Boretzky, K.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Datta Pramanik, U.; Emling, H.; Ershova, O.; Fernandez-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H. T.; Junghans, A.; Kelic-Heil, A.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Krücken, R.; Kurz, N.; Labiche, M.; Le Bleis, T.; Lemmon, R.; Litvinov, Y. A.; Mahata, K.; Maierbeck, P.; Movsesyan, A.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Savran, D.; Scheit, H.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.

The E1 strength distribution in 68Ni has been investigated using Coulomb excitation in inverse kinematics at the R3B-LAND setup and by measuring the invariant mass in the one and two Neutron decay channels.The GDR and a low-lying peak (PDR) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic RPA calculations yielding a neutron-skin thickness of 0.175(21) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.

Keywords: strength distribution 68Ni Coulomb excitation; inverse kinematics invariant mass GDR PDR; dipole polarizability neutron skin

Permalink: https://www.hzdr.de/publications/Publ-19384
Publ.-Id: 19384


Re-examining the doping effect on the performance of quantum well infrared photodetectors

Hao, M. R.; Zhang, S.; Zhang, Y. H.; Shen, W. Z.; Schneider, H.; Liu, H. C.

This paper investigates the dependence of background limited performance (BLIP) temperature of quantum well infrared photodetectors (QWIPs) on doping density. In contrast to the generally accepted optimal doping condition EF = k_B TBLIP, our theoretical prediction shows that lower doping densities should slightly increase the BLIP temperature TBLIP taking into account the temperature dependence of the Fermi energy EF, a factor neglected in previous analyses. Numerical modeling results are used to reinterpret the reported TBLIP measurements for a series of QWIPs of typical design for 9 μm peak wavelength with different doping values. In addition, based on the same general expression for the Fermi energy, the optimized sheet doping concentration to achieve maximum detectivity is given by EF = 1.37 kBT, a revision to the previous EF = 2kBT condition.

Keywords: Quantum well infrared photodetector; QWIP; background limited performance; detectivity

Permalink: https://www.hzdr.de/publications/Publ-19383
Publ.-Id: 19383


Investigation of Structure, Adsorption Free Energy, and Overcharging Behavior of Trivalent Yttrium Adsorbed at the Muscovite (001)–Water Interface

Lee, S. S.; Schmidt, M.; Laanait, N.; Sturchio, N. C.; Fenter, P.

The speciation, coverage, and thermodynamics of trivalent Y3+ adsorbed at a negatively charged muscovite (001)–water interface were measured to investigate electrostatic ion–ion correlations in a strong coupling regime. In situ specular crystal truncation rod and resonant anomalous X-ray reflectivity data show that Y3+ adsorbs as three distinct species (inner-sphere, adsorbed outer-sphere, and extended outer-sphere) among which the fractional coverage of the inner-sphere species (10%) is the smallest. Uptake measurements show that the maximum Y3+ coverage is higher by 50% than the amount needed to satisfy the muscovite surface charge in the absence of background electrolyte, but this overcharging is largely suppressed in the presence of 0.1 m NaCl. The measured intrinsic standard-state Gibbs free energy for Y3+ adsorption (−36.9 ± 0.9 kJ/mol) is smaller than that expected solely on the basis of its charge, and this discrepancy can be partly explained by the difference in adsorbed cation speciation at the charged interface.

Permalink: https://www.hzdr.de/publications/Publ-19382
Publ.-Id: 19382


Interfacial Reactivity of Pu and Th at the Muscovite (001) Basal Plane

Schmidt, M.; Lee, S. S.; Knope, K. E.; Bellucci, F.; Soderholm, L.; Fenter, P.

The geochemistry of the actinides is of utmost importance in understanding and predicting their behavior in contaminated legacy sites as well as nuclear waste storage facilities. The unique chemistry of this group of elements including strong hydrolysis, complex redox chemistry, and the potential for polymerization reactions in combination with the actinides’ inherent radioactivity and toxicity makes studies challenging. However, especially for artificial elements like Pu and other transuranics, no natural analogues are available and homologues frequently fall short in accurately reproducing the actinides’ behavior.
We will present and discuss recent results from in situ resonant anomalous x-ray reflectivity (RAXR) and crystal truncation rod (CTR) experiments, shedding light on the inter-action of Th(IV) as well as Pu(III) and Pu(IV) with the negatively charged muscovite (001) basal plane. The example of Th(IV) demonstrates how the strong hydration of the highly charged cations prevents a close approach to the surface, instead favoring adsorption as a highly hydrated extended outer sphere complex. Subsequently, it will be shown how similar adsorption behavior in combination with the complex redox chemistry of plutonium, leads to a surface-enhanced formation of nanoparticles.
Results from surface x-ray scattering will be supplemented by ex situ alpha-spectrometry quantification and atomic force microscopy (AFM), to yield a more complete understanding of the interfacial structure.

Keywords: Plutonium; Sorption; RAXR; CTR; AFM

  • Invited lecture (Conferences)
    247th ACS National Meeting, 16.-20.03.2014, Dallas, Texas, USA

Permalink: https://www.hzdr.de/publications/Publ-19381
Publ.-Id: 19381


Exploiting Memristive BiFeO3 Bilayer Structures for Compact Sequential Logics

You, T.; Shuai, Y.; Luo, W.; Du, N.; Bürger, D.; Skorupa, I.; Hübner, R.; Henker, S.; Mayr, C.; Schüffny, R.; Mikolajick, T.; Schmidt, O. G.; Schmidt, H.

Abstract: Resistive switching devices are considered as one of the most promising candidates for the next generation memories and nonvolatile logic applications. In this paper, we present BiFeO3:Ti/BiFeO3 (BFTO/BFO) bilayer structures with optimized BFTO/BFO thickness ratio which show symmetric, bipolar, and nonvolatile resistive switching. The resistive switching mechanism is understood by a model of flexible top and bottom Schottky-like barrier heights in the BFTO/BFO bilayer structures. For the nonvolatile logic applications, the polarity of reading bias can be used as an additional logic variable, which makes it feasible to program and store all 16 Boolean logic functions into a single cell of a BFTO/BFO bilayer structure in three logic cycles. In comparison to standard logic hardware solutions, the proposed memristive bilayer structures allow for simplified parallel, sequential, and looped logical processing.

Keywords: memristor; resistive switching; BiFeO3; boolean logic functions; reconfigurable nonvolatile logics

Permalink: https://www.hzdr.de/publications/Publ-19380
Publ.-Id: 19380


Resonance THz spectroscopy in high magnetic fields

Barra, A.-L.; Goiran, M.; Sessoli, R.; Zvyagin, S. A.

The employment of the high-magnetic-field resonance spectroscopy to probe magnetic excitations in the THz frequency range is reported. To illustrate the great potential of this technique in solid state physics, we present results of recent electron spin resonance studies of the quantum-tunneling effect in the single-molecule magnet Mn12tba and of the soliton–magnon crossover in Cu-PM, a spin-1/2 Heisenberg chain system with a staggered transverse field. Among others, we report on the successful use of the THz-range timedomain and free electron laser spectroscopy to study magnetic excitation spectra in pulsed magnetic fields.

Permalink: https://www.hzdr.de/publications/Publ-19379
Publ.-Id: 19379


CFD for subcooled flow boiling: Analysis of DEBORA tests

Krepper, E.; Rzehak, R.

In this work we investigate the present capabilities of CFD for wall boiling. The computational model used combines the Euler / Euler two-phase flow description with heat flux partitioning. Very similar modelling was previously applied to boiling water under high pressure conditions relevant to nuclear power systems. Similar conditions in terms of the relevant non-dimensional numbers have been realized in the DEBORA tests using Dichlorodifluoromethane (R12) as the working fluid. This facilitated measurements of radial profiles for gas volume fraction, gas velocity, liquid temperature and bubble size.
Robust predictive capabilities of the modelling require that it is validated for a wide range of parameters. In previous studies (Krepper and Rzehak, 2011, 2013) it was shown that a careful calibration of correlations used in the wall boiling model is necessary to obtain agreement with the measured data. We here consider tests under a variety of conditions concerning liquid subcooling, flow rate and heat flux. It is investigated to which extent a set of calibrated model parameters suffices to cover at least a certain parameter range.
In the paper the potential of the application of a population balance model is demonstrated. The measured gas bubble size profiles show an increase of the bubble size with increased distance from the heated wall caused by bubble coalescence. Furthermore the model framework is shown to be able to describe a shift from wall peak to core peak in the radial gas volume fraction profiles with increasing inlet temperature respective decreasing subcooling temperature, which was observed in some test series.

Keywords: CFD; wall boiling; DEBORA tests; population balance model; model calibration; model validation

Permalink: https://www.hzdr.de/publications/Publ-19377
Publ.-Id: 19377


Development of fluorinated CB2 receptor agonists for PET studies

Lueg, C.; Schepmann, D.; Günther, R.; Brust, P.; Wünsch, B.

A convergent strategy was followed to modify systematically carbazole based CB2 receptor ligands. The length of the N-(fluoroalkyl) group (n in 7), the length of the alkanamide (m in 7) and the substitution pattern of the phenyl moiety (X and Y in 7) were varied systematically. The highest CB2 affinity was found for the 2-fluoroethyl substituted carbazole derivative 20a (Ki = 5.8 nM) containing the propionamide and the 2-bromo-4-fluorophenyl moiety. According to docking studies 20a fits nicely into the binding pocket of the CB2 receptor, but elongation of the fluoroethyl side chain leads to a different binding mode of the ligands. The high CB2 affinity together with the high selectivity over the CB2 subtype qualifies the fluoroethyl derivative 20a to be developed as a PET tracer.

Keywords: CB2 receptor ligands; Carbazole derivatives; Fluorinated ligands; Structure affinity relationships; PET; Docking

Permalink: https://www.hzdr.de/publications/Publ-19376
Publ.-Id: 19376


DREAMS: Die Zauberkugel für die Vergangenheit

Merchel, S.; Akhmadaliev, S.; Pavetich, S.; Rugel, G.; Ziegenrücker, R.

ohne Abstract, da eingeladener Vortrag

Keywords: AMS; cosmogenic radionuclides

  • Invited lecture (Conferences)
    WiN-Mitgliederversammlung (2. Runde WiN-Germany-Preis 2013), 22.11.2013, Kernkraftwerk Obrigheim, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19375
Publ.-Id: 19375


Super-radiant Linac-based THz Sources in 2013

Gensch, M.

These proceedings shall give an overview over the rapidly growing number of super-radiant linac-based THz sources which have been developed and designed over the past 13 years following the seminal pilot experiment at the Jefferson lab energy recovery linac in 2001 [1]. More than 20 super-radiant THz facilities already exist or are planned worldwide and are listed together with a set of fundamental parameters in the appendix of this paper.

[1] G.L. Carr et. al., “High power terahertz radiation from relativistic electrons” Nature 420 (2001), 153.

  • Open Access Logo Contribution to proceedings
    FEL13 - 35th International Free-Electron Laser Conference, 25.-30.08.2013, New York, USA
    Proceedings of FEL13

Permalink: https://www.hzdr.de/publications/Publ-19374
Publ.-Id: 19374


Magnetization dynamics in periodically modulated nanostructures

Lenz, K.

Periodical arrangements of magnetic nanostructures offer very exciting and new features that do not exist in thin films. They range from dipolar interactions leading to two-magnon scattering in periodically perturbed films to the opening of magnonic band gaps in a magnonic crystal acting as e.g. filters - analog to a photonic crystal.
I will present experimental data from ferromagnetic resonance (FMR) experiments of two types of periodic nanostructures, which depict the transition region from a thin film to an array of separated magnetic elements. The structures were created (i) by ion beam erosion in a self-organizing process or (ii) by local magnetic property patterning using ion beam implantation in conjunction with lithographic masks. Both methods allow for easy tailoring of the magnetic dimensions.
The FMR data shows a splitting of the uniform resonance mode into several modes due to the dipolar stray fields of the nanostructures, which can be imaged by transmission electron holography. The results are corroborated by an analytical perturbation theory of two-magnon scattering developed by P. Landeros and D.L. Mills. This extended model allows for calculating the resonance response function of 1D and 2D periodically perturbed ferromagnetic films in almost perfect agreement to the FMR experiments.

Keywords: ferromagnetic resonance; magnetism; dynamics; spinwaves; magnons

  • Lecture (others)
    Physikalisches Kolloquium, Technische Universität Chemnitz, 30.10.2013, Chemnitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19373
Publ.-Id: 19373


Channeling radiation with low-energy electron beams: Experimental plans & status at FERMILAB

Blomberg, B.; Brau, C. A.; Choi, B. K.; Gabella, W. E.; Ivanov, B.; Mendenhall, M.; Mihalcea, D.; Panuganti, H.; Piot, P.; Wagner, W.

Channeling radiation is an appealing radiation process to produce x-ray radiation with low-energy electron beams.
In this contribution we describe the anticipated performance and preliminary results from a channeling-radiation experiment
to produce ~1,2-keV radiation from a ~4-MeV electron beam at Fermilab’s high-brightness electron source lab (HBESL).
We also discuss plans to produce x-ray radiation ([10; 80]-keV photon energy) at Fermilab’s advanced superconducting
test accelerator (ASTA).

Keywords: channeling radiation; X-rays; electron beam

  • Open Access Logo Contribution to proceedings
    35th International Free-Electron-Laser Conference, 25.-30.08.2013, New York, USA
    Proceedings of FEL2013: www.jacow.org, MOPSO07

Permalink: https://www.hzdr.de/publications/Publ-19372
Publ.-Id: 19372


Accelerated simulations for plasma physics - Understanding and probing plasmas on the atomic scale

Bussmann, M.

Modern compute hardware allows for simulating laser plasma interaction interactively and for integrating physical effects that could not be accounted for previously. I will show how efficient plasma simulations may pave the way towards predictive simulations of laser matter interaction.

Keywords: simulation; plasma; x-ray; laser; ultrashort; dynamics

  • Invited lecture (Conferences)
    Seminar of the Shanghai Institute of Optics and Fine Mechanics (SIOM), 13.11.2013, Shanghai, China

Permalink: https://www.hzdr.de/publications/Publ-19371
Publ.-Id: 19371


Laser cooling of relativistic heavy ion beams at the ESR and CSRe

Wen, W.; Siebold, M.; Schramm, U.; Ma, X.; Bussmann, M.

We present results on laser cooling of heavy ion beams at ESR and discuss prospects for laser cooling at CSRe.

Keywords: laser; cooling; heavy; ion; beam; storage ring

  • Lecture (Conference)
    Chinese-German Workshop on "High Precision Experiments with Stored Exotic and Stable Ions", 06.-11.11.2013, Lanzhou, China

Permalink: https://www.hzdr.de/publications/Publ-19370
Publ.-Id: 19370


Laser cooling experiments in storage rings

Bussmann, M.; Siebold, M.; Schramm, U.

We present results on laser cooling of ion beams at storage rings and discuss their relevance for future facilities.

Keywords: laser; cooling; storage ring; ion; beam

  • Invited lecture (Conferences)
    Chinese-German Workshop on "High Precision Experiments with Stored Exotic and Stable Ions", 06.-11.11.2013, Lanzhou, China

Permalink: https://www.hzdr.de/publications/Publ-19369
Publ.-Id: 19369


Twinkle, Twinkle Little Star - Using 18.000 GPUs to Simulate Jets in the Cosmos

Bussmann, M.; Burau, H.; Cowan, T. E.; Debus, A.; Huebl, A.; Juckeland, G.; Kluge, T.; Nagel, W. E.; Pausch, R.; Schmitt, F.; Schramm, U.; Schuchart, J.; Widera, R.

In order to understand what happens when jets of hot, streaming gas are ejected at high speed into the cosmos, we are bound to rely on m easuring the radiation emitted by the particles in the jet. Astrophysical jets can originate from a variety of sources such as stars, black holes and even galaxies. In such jets, the plasma flow can become unstable, generating characteristic patterns of p article flows. Using our particle-in-cell code PIConGPU utilizing the complete TITAN supercomputer system at Oak Ridge National Laboratory, we were able, for the first time, to not only simulate the particle dynamics but also the radiation emitted during the formation of such an instability, the Kelvin-Helmholtz instability.

Keywords: kelvin-helmholtz-instability; plasma; simulation; jet; astrophysics; gpu; titan; ornl; picongpu; particle-in-cell; pic; simulation; khi

  • Invited lecture (Conferences)
    GPU Technology Theatre at the SC'13, The International Conference for High Performance Computing, Networking, Storage and Analysis, 17.-22.11.2013, Denver, CO, United States of America

Permalink: https://www.hzdr.de/publications/Publ-19368
Publ.-Id: 19368


Radiative Signatures of the Relativistic Kelvin-Helmholtz Instability

Bussmann, M.; Burau, H.; Cowan, T. E.; Debus, A.; Huebl, A.; Juckeland, G.; Kluge, T.; Nagel, W. E.; Pausch, R.; Schmitt, F.; Schramm, U.; Schuchart, J.; Widera, R.

We present a particle-in-cell simulation of the relativistic Kelvin-Helmholtz Instability (KHI) that for the first time delivers angularly resolved radiation spectra of the particle dynamics during the formation of the KHI. This enables studying the formation of the KHI with unprecedented spatial, angular and spectral resolution. Our results are of great importance for understanding astrophysical jet formation and comparable plasma phenomena by relating the particle motion observed in the KHI to its radiation signature. The innovative methods presented here on the implementation of the particle-in-cell algorithm on graphic processing units can be directly adapted to any many-core parallelization of the particle-mesh method. With these methods we see a peak performance of 7.176 PFLOP/s (double-precision) plus 1.449 PFLOP/s (single-precision), an efficiency of 96% when weakly scaling from 1 to 18432 nodes, an efficiency of 68.92% and a speed up of 794 (ideal: 1152) when strongly scaling from 16 to 18432 nodes.

Keywords: picongpu; titan; ornl; kelvin-helmholtz-instability; khi; pflop; gpu; simulation; plasma; performance; gordon bell prize

  • Invited lecture (Conferences)
    SC'13, The International Conference for High Performance Computing, Networking, Storage and Analysis, 17.-22.11.2013, Denver, CO, United States of America
  • Open Access Logo Contribution to proceedings
    SC13: International Conference for High Performance Computing, Networking, Storage and Analysis, 17.-22.11.2013, Denver, CO, United States of America
    Proceedings of SC13, New York, NY, USA: ACM, 978-1-4503-2378-9, 5-1
    DOI: 10.1145/2503210.2504564

Permalink: https://www.hzdr.de/publications/Publ-19367
Publ.-Id: 19367


Concurrent visualisation for PIC simulations on Titan

Bussmann, M.; Schneider, B.; Grottel, S.; Gumhold, S.

We present live visualization of large-scale plasma simulations with PIConGPU.

Keywords: visualization; in-situ; live; interactive; supercomputing; picongpu; gpu; simulation

  • Invited lecture (Conferences)
    HBP Workshop on Interactive Supercomputing, IASC 2013, 30.09.-01.10.2013, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19366
Publ.-Id: 19366


Playing with Petaflops - Interactive, large-scale Plasma Simulations with GPUs

Bussmann, M.

We present results of our PIConGPU KHI simulation on TITAN at ORNL.

Keywords: hpc; titan; khi; plasma; petaflop; gpu; picongpu; simulation

  • Invited lecture (Conferences)
    NVIDIA Application Lab at Jülich: 1st Annual Workshop, 08.-09.07.2013, Jülich, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19365
Publ.-Id: 19365


Laser cooling of relativistic ion beams with broad initial momentum spread

Bussmann, M.; Siebold, M.; Schramm, U.

One of the key requirements to using laser cooling at future high energy storage rings is to address the entire and initially broad spectrum of a bunched ion beam with a single cooling laser system.
Recent experiments at ESR have shown that this can indeed be realized by scanning the frequency of a single cw laser over a broad frequency range.
By this technique, each part of the phase space of the ions in the bucket potential can be subjected to the same cooling force, resulting in efficient cooling over the whole bucket acceptance.
Cooling times are thus limited prominently by the duration of the frequency scan and can be in the order of seconds.
In my talk I will present recent results from our experiments at ESR but will also give an outlook on what to do next - and how large-scale beam dynamics simulations can help in making the best use of laser cooling.

Keywords: laser; cooling; ion; beam; storage ring

  • Invited lecture (Conferences)
    GSI Atomphysikseminar, 02.07.2013, Darmstadt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19364
Publ.-Id: 19364


The future of Laser-Plasma-Simulations - A personal view

Bussmann, M.

Simulations of laser plasma interaction face several challenges. The most important one is having predictive capabilities. While qualitative agreement between experiments and simulations is frequently seen, quantitative agreement is scarce. Predictive capability requires defining your simulated system as accurately as possible and using numerical methods that do not alter your results in an unphysical manner. I'll present how these requirements influence your simulation codes and what role next-generation computers play in the game.

Keywords: picongpu; gpu; laser; plasma; acceleration; simulation; modeling

  • Invited lecture (Conferences)
    Institutsseminar Helmholtz-Institut Jena, 26.06.2013, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19363
Publ.-Id: 19363


Large-scale particle-in-cell simulations scaling up to 18432 GPUs on TITAN

Bussmann, M.

An overview of our Petaflop simulations on the ORNL TITAN HPC system.

Keywords: titan; pflop; picongpu; plasma; simulation; gpu

  • Invited lecture (Conferences)
    ISC'13, GPU Supercomputing for Physics & Astrophysics – a Road to Exascale, 16.-20.06.2013, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19362
Publ.-Id: 19362


Summary “Data Analysis and Simulations”

Bussmann, M.

A summary of data analysis and simulations with regard to the Helmholtz Beamline at XFEL

Keywords: xfel; hibef; data analysis; simulation

  • Lecture (Conference)
    Kick Off Meeting for the Helmholtz International Beamline for Extreme Fields, 02.-05.06.2013, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19361
Publ.-Id: 19361


Petaflop Plasma Physics: Pursuing Particle Paths

Bussmann, M.

We present first results on radiative signatures of the Kelvin-Helmholtz Instability in relativistic streams. Large-scale simulations enable us to follow particle trajectories through turbulent plasma flows by computing the radiation of the charged particles inside the plasma. This allows imaging the plasma particle flow with unprecedented resolution by detecting the far field radiation coming from the plasma. Our results bring forward the understanding of the complex dynamics of plasmas especially in situations where direct plasma probing is impossible.

Keywords: picongpu; petaflop; gpu; plasma; astrophysics

  • Invited lecture (Conferences)
    1st Dresden CCoE GPU Programming Workshop, 27.-29.05.2013, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19360
Publ.-Id: 19360


Towards Exascale Simulations of Laser-Driven Accelerators, Ultra-Short Solid Density Plasma Dynamics and Plasma Astrophysics

Bussmann, M.

With new compute hardware existing today, interactive simulations of large-scale plasma dynamics have become possible. Moreover, speed ups of two orders of magnitude allow to integrate new physics into our simulations. I will present recent advances in particle-in-cell codes running on GPUs and other hardware platforms and discuss applications in laser-driven particle acceleration, ultra-short plasma phenomena at solid density and astrophysics.
Following the lessons learned from these examples I will show how gaming and file sharing may pave a path towards Exascale simulations and what the Zebra fish might have to do with this.

Keywords: picongpu; gpu; plasma; astrophysics; laser; acceleration; simulation

  • Invited lecture (Conferences)
    Seminarreihe "Aktuelle Probleme der Beschleuniger-, Plasma- und Astrophysik", 24.05.2013, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-19359
Publ.-Id: 19359


Laser cooling of relativistic heavy ion beams at the CSRe and the ESR

Wen, W.; Siebold, M.; Schramm, U.; Zhang, D.; Ma, X.; Bussmann, M.

An overview of laser cooling experiments at ESR/GSI and CSRe/IMPCAS Lanzhou.

Keywords: laser; cooling; esr; csre; impcas; lanzhou; ion; beam; storage ring

  • Lecture (Conference)
    China-Germany Symposium for “Laser Cooling at Storage Rings”, 06.-10.05.2013, Lanzhou, China

Permalink: https://www.hzdr.de/publications/Publ-19358
Publ.-Id: 19358


Bringing Crystalline Ion Beams from PALLAS to FAIR

Bussmann, M.; Schramm, U.

An overview of our work on crystalline ion beams and how it applies to large-scale storage rings.

Keywords: crystalline; ion; beam; laser; cooling; storage ring

  • Invited lecture (Conferences)
    China-Germany Symposium for “Laser Cooling at Storage Rings”, 06.-10.05.2013, Lanzhou, China

Permalink: https://www.hzdr.de/publications/Publ-19357
Publ.-Id: 19357


Laser Cooling at current and future Storage Rings: From ESR to FAIR

Bussmann, M.; Siebold, M.; Schramm, U.

A history and outlook of laser cooling of relativistic ion beams

Keywords: ion; beam; laser; cooling; storage ring; relativistic

  • Invited lecture (Conferences)
    China-Germany Symposium for “Laser Cooling at Storage Rings”, 06.-10.05.2013, Lanzhou, China

Permalink: https://www.hzdr.de/publications/Publ-19356
Publ.-Id: 19356


Large-scale simulations of laser-plasma interaction: state of the art and next steps

Bussmann, M.; Burau, H.; Widera, R.; Hübl, A.; Pausch, R.; Debus, A.; Kluge, T.; Schramm, U.; Cowan, T. E.; Schmitt, F.; Juckeland, G.; Nagel, W. E.

We present new results on PIConGPU, a GPGPU implementation of a relativistic 3D3V particle-in-cell implementation. We show weak and strong scalings for PIConGPU on large GPU clusters and discuss the techniques used to achieve such scalability.
We furthermore introduce new physics and analysis modules added to PIConGPU that have previously not been seen in laser-plasma interaction simulations. The new analysis modules help to better conduct large parameter surveys and increase the usability of the code. One of the special features of these analysis models is that all of them are in-memory and thus allow for live generation of simulation videos at frames per second time step rates. The new physics modules focus on the generation of radiation during the laser-plasma interaction and the inter-particle interactions.
We finally discuss new techniques to scale PIConGPU and other particle-in-cell codes to Exaflop performance and the possible benefits of such extreme scaling performance.

Keywords: picongpu; particle-in-cell; simulation; laser-matter interaction; plasma

  • Invited lecture (Conferences)
    SPIE 2013 Optics+Optoelectronics, 15.-18.04.2013, Praha, Tschechische Republik

Permalink: https://www.hzdr.de/publications/Publ-19355
Publ.-Id: 19355


Aplicacion de la tecnica de espectrometria de masas con aceleradores en el estudio de la dinamica de sedimentos submarinos
Application of the accelerator mass spectrometry technique to the study of the marine sediments dynamic

Rodrigues, D.; Korschinek, G.; Merchel, S.; Rugel, G.; Arazi, A.; Marti, G. V.

Utilizando la técnica de Espectrometría de Masas con Aceleradores se ha determinado la relación entre el radionucleido 10Be (T½ = 1,39 Ma) y su isótopo estable 9Be en siete muestras de sedimentos submarinos. Estas muestras, con relaciones isotópicas 10Be/9Be del orden de 10-8, constituyen un primer perfil de 275 m de profundidad cercano al punto donde confluyen las placas tectónicas de Nazca, Antártica y Sudamericana. Debido a su decaimiento, la concentración del 10Be disminuye con la edad del sedimento, y esta última, se espera que se corresponda linealmente con la profundidad de los mismos. Sin embargo, en este trabajo se encontraron discontinuidades en la concentración de 10Be entre los 100 y 150 metros y entre los 200 y 250 metros de profundidad con un comportamiento opuesto al esperado. Este resultado es consistente con un perfil de sedimentos estratificado en capas de edades semejantes producido por un proceso de plegamiento.

Using the accelerator mass spectrometry technique, the ratio between the radionuclide 10Be (T½ = 1.39 Ma) and its stable isotope 9Be in seven submarine sediment samples has been determined. These samples, with 10Be/9Be isotopic ratios of the order of 10-8, constitute a first 275 m-deep profile near the point where Nazca, Antarctica and South American tectonic plates join each other. Due to the decay of 10Be, its concentration decreases with the age of the sediment, which is expected to vary linearly with the depth. However, in this study we found discontinuities in the 10Be concentration between 100 and 150 meters and between 200 and 250 meters of depth. This result is consistent with a stratified sediment profile in layers with similar ages produced by a plication process.

Keywords: AMS; sediments; geochronology; site 860 ODP; plication

  • ANALES AFA 25(2014), 51-55

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-19354
Publ.-Id: 19354


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