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< Seite 1 von 194 >   Gesamtzahl lt. Auswahl: 19372 Title records (100 Title records je Seite)
23839 Publications
Kompromissbereite Supraleitung
Zwicknagl, G.; Wosnitza, J.
Abstract: Hohe Magnetfelder und Supraleitung vertragen sich üblicherweise nicht: Das Magnetfeld favorisiert parallel ausgerichtete Elektronenspins, während die Supraleitung Cooper-Paare mit antiparallelen Spins voraussetzt. Daher sollte bei ausreichend großen Feldern die Supraleitung zusammenbrechen. Wie Fulde und Ferrell sowie Larkin und Ovchinnikov bereits 1964 vorhergesagt haben, können räumlich getrennte supraleitende sowie magnetisch geordnete Bereiche aber auch bei noch höheren Magnetfeldern koexistieren.
  • Physik Journal 14(2015)3, 31-36
Registration No. 21748

Novel phase transition and metastable regions in the frustrated magnet CdCr2O4
Zherlitsyn, S.; Tsurkan, V.; Zvyagin, A. A.; Yasin, S.; Erfanifam, S.; Beyer, R.; Naumann, M.; Green, E.; Wosnitza, J.; Loidl, A.
Abstract: A new magnetic phase transition, which we assign to the separation of two different spiral phases, has been observed by ultrasound studies below the Néel temperature (TN = 7.8 K) in the frustrated antiferromagnet CdCr2O4. This transition renormalizes the velocity and amplitude of the transverse acoustic mode cT whereas the longitudinal mode cL is not affected. The specific heat does not show any significant change in the entropy at this transition. Furthermore, in an applied magnetic field, the mode cT exhibits extended metastable magnetostructural states neighboring the one-half magnetization plateau in CdCr2O4. By applying an exchange-striction model we can quantitatively describe the field dependence of the sound velocity below and above the one-half magnetization plateau. Registration No. 21747

Direct measurements of the magnetocaloric effect in pulsed magnetic fields: The example of the Heusler alloy Ni50Mn35In15
Ghorbani Zavareh, M.; Salazar Mejia, C.; Najak, A. K.; Skourski, Y.; Wosnitza, J.; Felser, C.; Nicklas, M.
Abstract: We have studied the magnetocaloric effect (MCE) in the shape-memory Heusler alloy Ni50Mn35In15 by direct measurements in pulsed magnetic fields up to 6 and 20 T. The results in 6 T are compared with data obtained from heat-capacity experiments. We find a saturation of the inverse MCE, related to the first-order martensitic transition, with a maximum adiabatic temperature change of ΔTad= - 7 at 250 K and a conventional field-dependent MCE near the second-order ferromagnetic transition in the austenitic phase. The pulsed magnetic field data allow for an analysis of the temperature response of the sample to the magnetic field on a time scale of 10 to 100 ms, which is on the order of typical operation frequencies (10–100 Hz) of magnetocaloric cooling devices. Our results disclose that in shape-memory alloys, the different contributions to the MCE and Hysteresis effects around the martensitic transition have to be carefully considered for future cooling applications. Registration No. 21746

In situ spectroscopic identification of neptunium(V) inner-sphere complexes on the hematite-water interface
Müller, K.; Gröschel, A.; Rossberg, A.; Bok, F.; Franzen, C.; Brendler, V.; Foerstendorf, H.
Abstract: Hematite plays a decisive role in regulating the mobility of contaminants in rocks and soils. The Np(V) reactions at the hematite−water interface were comprehensively investigated by a combined approach of in situ vibrational spectroscopy, X-ray absorption spectroscopy and surface complexation modeling. A variety of sorption parameters such as Np(V) concentration, pH, ionic strength, and the presence of bicarbonate was considered. Time-resolved IR spectroscopic sorption experiments at the iron oxide−water interface evidenced the formation of a single monomer Np(V) inner-sphere sorption complex. EXAFS provided complementary information on bidentate edge-sharing coordination. In the presence of atmospherically derived bicarbonate the formation of the bis-carbonato inner-sphere complex was confirmed supporting previous EXAFS findings.1 The obtained molecular structure allows more reliable surface complexation modeling of recent and future macroscopic data. Such confident modeling is mandatory for evaluating water contamination and for predicting the fate and migration of radioactive contaminants in the subsurface environment as it might occur in the vicinity of a radioactive waste repository or a reprocessing plant.
Keywords: iron oxides, Fe2O3, neptunyl, actinides, ATR FT-IR spectroscopy, x-ray absorption, EXAFS, surface complexation Registration No. 21722

Electromagnetic Dipole Strength in 124,128,134Xe
Massarczyk, R.; Schwengner, R.; Junghans, A. R.
Abstract: The electromagnetic dipole strength in several even nuclei in the chain of Xenon isotopes has been investigated at the bremsstrahlung facility of the ELBE accelerator in Dresden, Germany and at the HIγS facility in Durham, USA. The goal of these measurements is to extend the knowledge about the general behavior of the dipole strength in the energy region below the neutron separation energy under the aspect of neutron excess and nuclear deformation. Registration No. 21709

Charged defects and defect-induced processes in nitrogen films
Savchenko, E.; Khyzhniy, I.; Uyutnov, S.; Barabashov, A.; Gumenchuk, G.; Ponomaryov, A.; Bondybey, V.
Abstract: Radiation effects in solid nitrogen irradiated with an electron beam were studied with emphasis on the role of charged centers in radiation-induced phenomena. The experiments were performed employing luminescence method and activation spectroscopy techniques - spectrally resolved thermally stimulated luminescence TSL and thermally stimulated exoelectron emission. Samples were probed in depth by varying electron energy, thus discriminating radiation-induced processes in the bulk and at the surface. Spectroscopic evidence of the excited N2 * (C3Πu) molecule desorption was obtained for the first time and mechanism of the phenomenon based on recombination of electron with intrinsic charged center N4 + was proposed. The key role of N3 + center dissociative recombination in generation of N radicals is suggested. Registration No. 21701

Low-dimensional compounds containing cyanido groups. XXVIII. Crystal structure, spectroscopic and magnetic properties of two copper(II) tetracyanidoplatinate complexes with 1,2-diaminopropane
Vavra, M.; Potočňák, I.; Dušek, M.; Čižmár, E.; Ozerov, M.; Zvyagin, S. A.
Abstract: Violet crystals of {[Cu(pn)2]2[Pt(CN)4]}[Pt(CN)4]·2H2O (1, pn=1,2-diaminopropane) and blue crystals of [Cu(pn)Pt(CN)4]n·nH2O (2) were prepared under hydrothermal conditions and characterized using elemental analysis, IR and UV–vis spectroscopy and by X-ray crystal structure analysis. Different number of ν(C≡N) absorption bands of these two compounds reflects their different structures. An X-ray crystal structure analysis has shown that complex 1 is of ionic character and is formed from trinuclear [Cu(pn)2–Pt(CN)4–Cu(pn)2]2+ complex cation and discrete [Pt(CN)4]2– anion together with two molecules of crystal water. On the other hand, complex 2 is of polymeric character and is formed by 2D networks of [Cu(pn)Pt(CN)4]n composition and completed by n molecules of crystal water. Magnetic measurements show the presence of a weak antiferromagnetic exchange interaction in complex 1 (Θ = –0.2 K), while the magnetic susceptibility of complex 2 is well described by the model of uniform S = 1/2 spin chain with exchange interaction J/kB = –1.64 K. Registration No. 21696

Laser Fluoride Nanoceramic And Method For Production Thereof / Lasertechnische, fluoridische Nanokeramika und Methode zur Herstellung
in Russian
Siebold, M.; Schramm, U.; Garibin, E. A.; Gusev, P. E.; Krutov, M. A.; Mironov, I. A.; Osiko, V. V.; Smirnov, A. N.; Tchernova, Y. V.; Hein, J.; Nietzold, D.; Pohl, H.-J.
Abstract: (EN) FIELD: chemistry. SUBSTANCE: fluoride nanoceramic is obtained by thermomechanical treatment of the starting crystalline material made from CaF2-YbF3, at plastic deformation temperature to obtain a workpiece in form of a polycrystalline microstructured substance, which is characterised by crystal grain size of 3-100 mcm and a nanostructure inside the grains, by annealing on air at temperature of not less than 0.5 of the melting point with compaction of the obtained workpiece in a vacuum at pressure of 1-3 tf/cm2 until the end of the deformation process, followed by annealing in an active medium of carbon tetrafluoride at pressure of 800-1200 mmHg. The starting crystalline material used can be a fine powder which has been subjected to heat treatment in carbon tetrafluoride, or a moulded workpiece of crystalline material made from the powder and heat treated in carbon tetrafluoride. EFFECT: invention enables to obtain a fluoride nanoceramic with high degree of purity and high uniformity of the structure of said optical material. 4 cl, 3 ex

(RU) Изобретение относится к технологии получения оптических поликристаллических материалов, а именно фторидной керамики, имеющей наноразмерную структуру и усовершенствованные оптические, лазерные и генерационные характеристики. Фторидную нанокерамику получают термомеханической обработкой исходного кристаллического материала, выполненного из CaF2-YbF3, при температуре пластической деформации до получения заготовки в виде поликристаллического микроструктурированного вещества, характеризующегося размером зерен кристаллов 3-100 мкм и наноструктурой внутри зерен, путем отжига на воздухе при температуре не менее 0,5 от температуры плавления с уплотнением полученной заготовки в вакууме при давлении 1-3 тс/см2 до окончания процесса деформации, после чего отжигают в активной среде тетрафторида углерода при давлении 800-1200 мм рт.ст. В качестве исходного кристаллического материала могут быть использованы мелкодисперсный порошок, прошедший термообработку в тетрафториде углерода, или отформованная заготовку кристаллического материала, полученная из порошка и термообработанная в тетрафториде углерода. Изобретение позволяет получать фторидную нанокерамику высокой степени чистоты с повышенной однородностью структуры данного оптического материала. 2 н. и 2 з.п. ф-лы, 3 пр., 1 табл.
  • Patent
    RU2484187 - Erteilung 08.12.2013
Registration No. 21695

Partikeltherapie-PET – Optimierung der Datenverarbeitung für die klinische Anwendung
Helmbrecht, S.
Abstract: Die Strahlentherapie ist einer der drei Partner im interdisziplinären Feld der Onkologie. In Europa, Asien und den USA besteht zunehmend die Möglichkeit einer Therapie mit Strahlen aus geladenen Ionen anstelle von Photonen. Eine Anlage in Dresden befindet sich in der Kommissionierungsphase.
Die Ionenstrahltherapie bietet den Vorteil einer sehr konformalen Behandlung des Tumorvolumens durch die endliche Reichweite der Strahlen und ein ausgeprägtes Dosismaximum kurz vor dem Ende des Strahlpfades. Da eine Therapie in der Regel über bis zu 30 Sitzungen an verschiedenen Tagen durchgeführt wird und der Strahlweg stark von dem durchdrungenen Gewebe beeinflusst wird, sind Verfahren für eine in vivo Verifikation der Strahlapplikation wünschenswert. Eine dieser Methoden ist die Partikeltherapie–Positronen-Emissions-Tomografie (PT-PET). Sie beruht auf der Messung der vom Therapiestrahl erzeugten β+-Aktivitätsverteilung. Da eine direkte Berechnung der Dosis aus der Aktivität in lebendem Gewebe nicht möglich ist, wird die gemessene Aktivitätsverteilung mit einer berechneten Vorhersage verglichen und anschließend entschieden, ob die nächste Therapiesitzung wie geplant erfolgen kann oder Anpassungen notwendig sind. Die vorliegende Arbeit beschäftigt sich mit drei Themen aus dem Bereich der Datenverarbeitung für die PT-PET.
Im ersten Teil wird ein Algorithmus zur Bestimmung von Reichweitendifferenzen aus zwei β+- Aktivitätsverteilungen adaptiert und evaluiert. Dies geschieht zunächst anhand einer Simulationsstudie mit realen Patientendaten. Ein Ansatz für eine automatisierte Analyse der Daten lieferte keine zufriedenstellenden Ergebnisse. Daher wird ein Software-Prototyp für eine semiautomatische, assistierte Datenanalyse entwickelt. Die Evaluierung erfolgt durch Experimente mit Phantomen am 12C-Strahl.
Die erzeugte Aktivitätsverteilung wird von physiologischen Prozessen im Organismus beeinflusst.
Dies führt zu einer Entfernung von Emittern vom Ort ihrer Erzeugung und damit zu einer Verringerung der diagnostischen Wertigkeit der erfassten Verteilung. Zur Quantifizierung dieses als Washout bezeichneten Effektes existiert ein am Tierexperiment gewonnenes Modell. Dieses Modell wird im zweiten Teil der Arbeit auf reale Patientendaten angewendet. Es konnte gezeigt werden, dass das Modell grundsätzlich anwendbar ist und für die betrachtete Tumorlokalisation Schädelbasis ein Washout mit einer Halbwertszeit von (155,7±4,6) s existiert.
Die Berechnung der Vorhersage der β+-Aktivitätsverteilung kann durch übliche Monte-Carlo-Verfahren erfolgen. Dabei werden die Wechselwirkungsquerschnitte zahlreicher Reaktionskanäle benötigt. Als alternatives Verfahren wurde die Verwendung gemessener Ausbeuten (Yields) radioaktiver Nuklide in verschiedenen Referenzmaterialien vorgeschlagen. Auf Basis einer vorhandenen Datenbank dieser Yields und einer existierenden Condensed-History-Monte-Carlo-Simulation wird ein Programm zur Berechnung von Aktivitätsverteilungen auf Yieldbasis entwickelt. Mit der Methode kann die β+-Aktivitätsverteilung in Phantomen und Patienten zufriedenstellend vorhergesagt werden.
Die entwickelten Verfahren sollen einen Einsatz der PT-PET im klinischen Umfeld erleichtern und damit einen breiten Einsatz ermöglichen, um das volle Potential der Ionenstrahltherapie nutzbar zu machen.
  • Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-058 2015

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Registration No. 21693

Improving material properties and performance of nuclear targets for transmutation-relevant experiments
Vascon, A.; Wiehl, N.; Runke, J.; Drebert, J.; Reich, T.; Trautmann, N.; Cremer, B.; Kögler, T.; Beyer, R.; Junghans, A. R.; Eberhardt, K.; Düllmann, Ch. E.
Abstract: To improve the properties and performance of thin layers produced by molecular plating as targets for nuclear experiments investigations with lanthanide elements (i.e., natural Nd and 147Sm-enriched Sm) were carried out. Plating parameters like roughness of the deposition substrate, plating solvent, electrolyte concentration, and applied current density were varied. The influence of each parameter on the properties of the layers was studied by characterizing the deposits. The characterizations showed that nuclear targets perform differently depending on their layer properties. The results obtained from the investigations were applied for the quantitative preparation of homogeneous large-area (i.e., 42 cm2) 242Pu targets to be used for transmutation-relevant experiments.
Keywords: Molecular plating Improved layer properties α-Particle spectroscopy 242Pu Transmutation Registration No. 21691

Magnetfelder für die Forschung
Wosnitza, J.
Abstract: Magnetfelder wirken auf bewegliche Ladungsträger und die magnetischen Freiheitsgrade eines Materials. Sie können somit das Verhalten von Materialien ebenso vielfältig beeinflussen wie z. B. Temperatur und Druck. Hohe Magnetfelder erlauben deshalb in der Physik und vielen anderen Forschungsdisziplinen grundlegende Untersuchungen der elektronischen und magnetischen Eigenschaften der Materie. So sind mehr als 15 Nobelpreise in Physik, Chemie und Medizin eng mit der Forschung in Magnetfeldern verknüpft. Nicht nur deshalb wächst die wissenschaftliche Nachfrage nach Forschungsanlagen, in denen Experimente in hohen Magnetfeldern möglich sind. Registration No. 21690

Positron studies of interaction between yttrium atoms and vacancies in bcc iron with relevance for ODS nanoparticles formation
He, C. W.; Barthe, M. F.; Desgardin, P.; Akhmadaliev, S.; Behar, M.; Jomard, F.
Abstract: The very high calculated binding energy of vacancy (V)-Y-sub (1.45 eV) in Fe makes it be one possible earliest formation stage of (Y, Ti, O) nanoclusters in ODS alloy. Our direct slow positrons annihilation observations are used to valid the interaction between V and Y. The pure bcc iron samples have been implanted by 1.2 MeV Y ions at three fluences from 1 x 10(14) to 3 x 10(15) cm(-2). Vacancy clusters are observed for all these three fluences. Their size and concentration decrease with Y concentration measured by using SIMS. Two hypotheses are proposed to explain the results, including the formation of complexes V-m-Y-n, and/or of precipitates Y-m-X-n (X = Y, O, etc.). In addition, vacancy clusters are detected deeper than predicted by SRIM calculation due to, at least for a part, channelling which is confirmed by Marlowe calculation and SIMS measurements.
Keywords: Nanostructured ferritic alloys, Dispersion, Metals, FE Registration No. 21686

New RP-CVD grown ultra-high performance selectively B-doped pure-Ge 20 nm QWs on (100)Si as basis material for post-Si CMOS technology
Mironov, O. A.; Hassan, A. H. A.; Uhlarz, M.; Kiatgamolchai, S.; Dobbie, A.; Morris, R. J. H.; Halpin, J. E.; Rhead, S. D.; Allred, P.; Myronov, M.; Gabani, S.; Berkutov, I. B.; Leadley, D. R.
Abstract: Magnetotransport studies at low and room temperature are presented for two-dimensional hole gases (2DHG) formed in fully strained germanium (sGe) quantum wells (QW). Two designs of modulation doped heterostructure grown by reduced pressure chemical vapour deposition (RP-CVD) were used and included a normal structure (doping above the Ge channel and inverted structure (doping beneath the Ge channel). The mobility (μH) for the normal structure was measured to be 1.34×106 cm2/Vs with a sheet density (ps) of 2.9×1011 cm-2 at 1.5 K, and μH = 3970 cm2/Vs and ps ~1×1011 cm-2 for room temperature, determined from simulation using the Maximum Entropy- Mobility Spectrum Analysis (ME-MSA) method.
For the inverted structure a μH of 4.96×105 cm2/Vs and ps of 5.25×1011 cm-2 was measured at 90 mK. From the temperature dependent amplitude of Shubnikov de Haas oscillations, the normal structure was found to have a very low effective mass (m*) value of 0.063 m0 and a ratio of transport to quantum lifetime (α) of ~78. This extremely high α is indicative of the carrier transport being dominated by small angle scattering from remote impurities i.e. a sample having an extremely low background impurity level and very smooth hetero-interfaces. The inverted structure had an m* of 0.069 m0 and α ~29, which also indicates exceedingly high quality material.

Keywords: pure strained Ge channel, ultra-high mobility, SdH oscillation, impurity scattering Registration No. 21685

Bi2Se3Q-switched Nd:YAG ceramic waveguide laser
Tan, Y.; Zhang, H.; Zhao, C.; Akhmadaliev, Sh.; Zhou, S.; Chen, F.
Abstract: Using a topological insulator (TI) Bi2Se3 as a saturable absorber, highly stable Q-switched laser pulses were realized in an Nd:YAG ceramic waveguide fabricated by carbon ion irradiation. The laser operation was at a wavelength of 1064 nm, with a repetition rate ranging from 2.7 to 4.7 MHz. The minimum pulsed duration was 46 ns. The maximum output power was up to 168.6 mW corresponding to the pulse energy of 31.3 nJ. This work opens up a practical way for implementation of TI modulated pulsed laser devices in dielectric waveguide platforms.
Keywords: Integrated optics, Lasers, Q-switched, Waveguides, Ion irradiation Registration No. 21684

SRF Gun – A Candidate for Future CW Linear Accelerators
Arnold, A.
Abstract: The success future continuous wave (CW) linear accelerators (LINAC) depend strongly on the development of appropriate sources. Thus, high brightness electron injectors for CW operation with megahertz pulse repetition rates and high bunch charges up to 1 nC are a hot topic of contemporary accelerator research and development. Present state-of-the-art CW photo electron sources are limited to a medium acceleration field; DC guns because of high-voltage discharge and normal conducting RF (NCRF) guns because of the dissipated power that scales with the square of the surface magnetic field (P~H²). Thus, in both cases the beam quality as well as the maximum extractable bunch charge is limited.
To get rid of these limitations the SRF gun concept is merging the well-established NCRF gun technology with the superconductivity. The resulting saving on dissipated power allows comparable high acceleration fields in continuous wave operation and thus high brightness and high average current at the same time. The talk will concentrate on the most advance electron source of this kind, the ELBE 3.5 cell SRF gun of Helmholtz-Zentrum Dresden-Rossendorf. Beside a historical classification and an overview on different design concepts, recent results as well as future challenges are discussed.
  • Lecture (others)
    Beschleunigerseminar am Institut für Kernphysik, 28.01.2015, Mainz, Deutschland
Registration No. 21678

Felsenkeller shallow-underground accelerator laboratory for nuclear astrophysics
Bemmerer, D.; Akhmadaliev, S.; Cowan, T. E.; Gohl, St.; Grieger, M.; Ilgner, C.; Junghans, A. R.; Müller, S. E.; Reinhardt, T. P.; Rimarzig, B.; Reinicke, S.; Röder, M.; Schmidt, K.; Schwengner, R.; Stöckel, K.; Szücs, T.; Takács, M. P.; Wagner, A.; Wagner, L.; Zuber, K.
Abstract: Underground, low-background accelerator-based experiments are an important tool to study nu- clear reactions directly at energies relevant for astrophysical processes. This technique has been developed and proven at the 0.4 MV LUNA accelerator in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400 m of rock. However, the nuclear reactions of helium and car- bon burning and the neutron source reactions for the astrophysical s-process require higher beam energies. The same is true for the study of solar fusion reactions. Therefore, the NuPECC long range plan for nuclear physics in Europe strongly recommends the installation of one or more higher-energy underground accelerators.
Detailed background studies have shown that the Felsenkeller shallow-underground laboratory in Dresden, with a rock overburden of 45 m, has very low background in γ -ray detectors typical for nuclear astrophysics experiments when an additional active shield is used to veto the remaining muon flux.
A used 5 MV pelletron tandem with 250 μ A upcharge current and external sputter ion source is currently being refurbished for installation in Felsenkeller. Work on an additional radio-frequency ion source on the high voltage terminal is underway. The project is fully funded, and the installa- tion of the accelerator in the Felsenkeller laboratory is expected for the near future.

Keywords: Felsenkeller Nuclear Astrophysics Low-background techniques Solar fusion
  • Contribution to proceedings
    Nuclei in the Cosmos XIII, 07.-11.07.2014, Debrecen, Ungarn
    Proceedings of Science 044

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Registration No. 21674

Development and application of computational fluid dynamics approaches within the European project THINS for the simulation of next generation nuclear power systems
Papukchiev, A.; Roelofs, F.; Shams, A.; Lecrivain, G.; Ambrosini, W.
Abstract: Today computational fluid dynamics (CFD) is widely used in industrial companies, research institutes and technical safety organizations to supplement the design and analysis of diverse technical components and large systems. Such numerical programs are applied to better understand complex fluid flow and heat transfer phenomena. In the last decades there is an increasing interest in the nuclear community to utilize such advanced programs for the evaluation of different nuclear reactor safety issues, where traditional analysis tools show deficiencies. Within the FP7 European project THINS (Thermal Hydraulics of Innovative Nuclear Systems), CFD and coupled 1D-3D thermal–hydraulic simulations are being carried out. These are dedicated to the analysis of the thermal–hydraulics of gas, liquid metal and supercritical water cooled reactors. Such concepts utilize innovative fluids, which have different properties from the ones used in the current nuclear reactors. In order to improve the thermal–hydraulic predictions of their behavior, CFD development, application and validation activities are performed within THINS. This overview paper highlights some of the CFD related work within the European project. Registration No. 21673

Non-Thermal Induction of Conforamtional Rearrangment in Proteins by Far-Infrared Excitation
Lörincz, I. Z.; Schay, G.; Rauscher, A. A.; Kellermayer, M. S. Z.; Gensch, M.; Malnasi-Csizmadia, A.
Abstract: How does a protein respond to infrared excitation? Our aim was to induce a specific non-thermal conformational change of a protein by infrared laser excitation. The fluorescence intensity of an intrinsically fluorescent protein, LSS-mOrange was monitored upon irradiation with a free electron laser at two of its IR absorption peaks (11.36/9.56 microns) and at a wavelength (9.06 microns) where the protein has no absorption. The irradiation at the absorption peaks caused a reversible fluorescence intensity increase on the sec-min timescale. Registration No. 21666

Bruchmechanische Prüfung von “Alten“ Konstruktionsstählen
Viehrig, H.-W.; Houska, M.; Stroetmann, R.; Sieber, L.; Vetter, B.; Schubert, V.
Abstract: In the framework of a research project concerning the brittle fracture resistance of “old” civil steel structures, mechanical and fracture mechanics parameters are determined on specimens from such structural steels. The specimens were sampled from steel structures erected between the years 1904 and 1930. The main focus was on fracture toughness testing according to the Master Curve (MC) approach according to the test standard ASTM E1921. Except one steel all fracture toughness values followed the Master Curve description and gave valid T0 values. The dataset was characterised as inhomogeneous and the MC based evaluation approaches of the SINTAP procedure characterising the brittle fraction of a dataset had to be applied.
Keywords: brittle fracture, impact energy, fracture toughness, Master Curve
  • Contribution to proceedings
    47. Tagung DVM Arbeitskreis Bruchvorgänge und Bauteilsicherheit: Bruchmechanische Werkstoff- und Bauteilbewertung: Beanspruchungsanalyse, Prüfmethoden und Anwendungen, 10.-11.02.2015, Freiberg, Deutschland
    Proceedings der 47. Tagung DVM Arbeitskreis Bruchvorgänge und Bauteilsicherheit: Bruchmechanische Werkstoff- und Bauteilbewertung: Beanspruchungsanalyse, Prüfmethoden und Anwendungen, Berlin: DVM
Registration No. 21665

Geometallurgy of iron ores
Gutzmer, J.
Abstract: Geometallurgy is an emerging field of research that has the aim to quantify compositional variability of ores contained in a deposit. Relevant parameter spaces to be considered include geochemistry, mineralogy, metal deportment and microfabric. These quantitative parameters need to be integrated with macroscopic geological and technical characteristics to define so-called geometallurgical domains, i.e., portions of an ore body that will exhibit similar beneficiation characteristics. This knowledge may then be used to optimize mining schedules and beneficiation routes, to optimize resource and energy efficiency, to maximize product quality and to minimize environmental impact. The value of developing a geometallurgical model is obvious for ore bodies that are either complex and/or of low grade. Important examples include PGE and Au deposits as well polymetallic base metal deposits. In accordance there are a number of case studies for such ore deposit types readily available in literature.

Iron ore deposits are, at least at first sight, not at all complex. In the last four decades very few deposit types have dominated the global supply of iron ore. High-grade iron ore deposits hosted by Precambrian iron formations clearly dominate, as these are often able to produce a direct shipping lump ore (DSO with > 60 wt%) Fe by simple crushing, screening and desliming. In fact, these deposits form the world’s largest virtually monomineralic ore bodies, not uncommonly reaching billions of tons of ore in size. Other deposit types that contribute significantly to the worlds iron ore supply are metamorphosed iron formation deposits (often referred to as taconites), Kiruna-type magnetite-apatite deposits and Robe River-type deposits. Magnetite deposits hosted by mafic/ultramafic intrusive complexes are increasingly gaining economic significance. Common to these deposit types are high concentrations of iron (≥ 50 wt.% Fe, but note that taconite only contains about 35 wt. % Fe) and uniform ore mineralogy, with only hematite, magnetite, and goethite of any significance.

The question thus arises what value geometallurgy may add to the utilization of iron ore deposits. In fact, a number of tangible benefits are being realized by taking this approach. Ore bodies that do not produce DSO require grinding followed by magnetic separation and/or flotation. Pellets need to be produced from the concentrate in order to have a saleable product. To assure that stringent quality requirements by the customer steel mills are being met consistently requires detailed knowledge of ore and gangue mineralogy – and its spatial variability across the ore body. Variations in gangue mineralogy, in particular, will determine concentrations of deleterious elements (Si, Ti, Al, P, S and alkali elments), whereas ore mineralogy will determine the suitability of beneficiation unit operations. Even if mineral assemblages remain uniform, relative proportions and microfabric relations (e.g., mineral grain sizes, intergrowth) will determine comminution and liberation characteristics, thus determining comminution energy requirements.

Keywords: geometallurgy, iron ores
  • Contribution to proceedings
    The Arctic Conference Days 2014, 02.-06.06.2014, Tromso, Norway
    Abstracts and Proceedings of the Geological Survey of Norway, Trondheim: Norsk Geologisk Forening, 72-73
Registration No. 21663

Optical imaging of COX-2: Studies on an autofluorescent 2,3-diaryl-substituted indole-based cyclooxygenase-2 inhibitor.
Tondera, C.; Ullm, S.; Laube, M.; Meister, S.; Neuber, C.; Mosch, B.; Kniess, T.; Pietzsch, J.
Abstract: This study aimed at in vivo visualization of cyclooxygenase-2 (COX-2) by optical imaging using a representative compound of a class of autofluorescent 2,3-diaryl-substituted indole-based selective COX-2 inhibitors (2,3-diaryl-indole coxibs). COX-2 was successfully visualized in mice models with phorbol myristate ester (TPA)-induced inflammation or bearing xenografted human melanoma cells by 2-[4-(aminosulfonyl)phenyl]-3-(4-methoxyphenyl)-1H-indole (C1). COX-2 protein expression in both TPA-induced inflammatory sites and human melanoma xenografts was confirmed by immunoblotting. Control experiments using surrogate markers, sham injections, and non-COX-2 expressing melanoma cells further confirmed specificity of tissue association of C1. The merging of therapeutic and diagnostic properties of 2,3-diaryl-indole coxibs may widen the range of applications of COX-2-targeted treatment, e.g., for in situ-guided surgery and ex vivo diagnostics.
Keywords: Fluorescence; Luminescence; Melanoma-associated inflammation; Phorbol myristate ester-induced COX-2 expression; Rodent melanoma xenograft model Registration No. 21656

Absolute value determination of vacancy concentration in silicon crystals using low-temperature ultrasonic measurements
Yamada-Kaneta, H.; Okabe, K.; Akatsu, M.; Baba, S.; Mitsumoto, K.; Nemoto, Y.; Goto, T.; Saito, H.; Kashima, K.; Saito, Y.
Abstract: For the samples taken from the void region of the CZ silicon crystal grown with the same solidification condition and different thermal histories after the solidification, we measure the magnitude S of the elastic softening which is proportional to the concentration of the single vacancies [V], For these samples, we also measure the size distribution of the void density by using the infrared lightscattering tomography, to evaluate the concentration [Vc] of the vacancies consumed for the void formation. From these two experiments, we find a sum rale [Vc] + a S= C, where C depends only on the solidification condition and is independent of the thermal history after the solidification. This enables us to find the conservation rale of the vacancies [Vc] + [V] = C. The value of the proportionality constant a in the relation [V] = a S is determined. Demonstration of determining the absolute values of [V] from the measured S is given. An estimate is made for the value of the quadrupole-strain coupling constant.
Keywords: Coupling constants; Different thermal history; Elastic softening; Light-scattering tomography; Low temperatures; Single vacancies; Solidification condition; Vacancy concentration Registration No. 21653

Production and Diagnostics of Dense Matter
Brambrink, E.; Amadou, N.; Benuzzi-Mounaix, A.; Geissel, M.; Harmand, M.; Pelka, A.; Vinci, T.; Koenig, M.
Abstract: High energy lasers are a unique tool to create high pressure states above 10 Mbar at ns time scales, which allow to study material properties under these extreme conditions. These conditions are, for example, comparable with planetary cores, where material properties play an important role for the properties and evolution of a planet. The rapid compression allows also to study dynamic effects of phase transitions as compression times are comparable to relaxation times. We will present recent results of laser compression of iron reaching conditions of so called “super-Earth” cores. A description of the compression schemes as well as present and future diagnostics is presented. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Keywords: Warm dense matter;high energy density physics;ramp compression Registration No. 21652

Evaluation of the cone-shaped pickup performance for low charge sub-10 fs arrival-time measurements at free electron laser facilities
Angelovski, A.; Kuntzsch, M.; Czwalinna, M. K.; Penirschke, A.; Hansli, M.; Sydlo, C.; Arsov, V.; Hunziker, S.; Schlarb, H.; Gensch, M.; Schlott, V.; Weiland, T.; Jakoby, R.
Abstract: An evaluation of the cone-shaped pickup performance as a part of the high bandwidth bunch arrival-time monitors (BAMs) for a low charge sub-10 fs arrival-time measurements is presented. Three sets of pickups are installed at the free electron laser FLASH at Deutsches Elektronen-Synchrotron, the quasi-cw SRF accelerator ELBE at the Helmholtz-Zentrum Dresden-Rossendorf and the SwissFEL injector test facility at Paul Scherrer Institute. Measurements and simulations are in good agreement and the pickups fulfill the design specifications. Utilizing the high bandwidth BAM with the cone-shaped pickups, an improvement of the signal slope by a factor of 10 is demonstrated at ELBE compared to the BAM with a low bandwidth.
Keywords: BAM ELBE FLASH Arrival-Time Diagnostic Registration No. 21651

Synthetic Scattering Images from Laser-Plasma Interaction - Heating and Ionization
Huang, L. G.; Bussmann, M.; Chung, H. K.; Zacharias, M.; Cowan, T. E.; Kluge, T.
Abstract: We present the dynamics of bulk electron heating and ionization in ultra-short relativistic laser plasmas interactions. In order to connect the plasma dynamics seen in simulations with experiments we also discuss the role of in-situ synthetic Scattering Images that mimic experimental diagnostics.
Keywords: Heating,Ionization,Laser-Plasma interaction,Synthetic Scattering
  • Poster
    European XFEL Users' Meeting 2015, DESY Photon Science Users' Meeting 2015, 28.-30.01.2015, Hamburg, Germany
Registration No. 21650

Photophysical Property of Catena-Bis(thiocyanato)aurate(I) Complexes in Ionic Liquids
Aoyagi, N.; Shinha, Y.; Ikeda-Ohno, A.; Haga, Y.; Shimojo, K.; Brooks, N. R.; Izuoka, A.; Naganawa, H.; Kimura, T.; Binnemans, K.
Abstract: The photochemistry of a gold(I) thiocyanate complex has been investigated to determine the coordination structure in both the solid and liquid states. The coordination geometries of the supramolecular [Au(SCN)2]n complex and the concomitant exciplex have mainly been analyzed by crystallographic analysis and X-ray absorption spectroscopy. The Au-S bond distance and Au···Au separation of the compound in the S0 ground state and in the T1 phosphorescent excited state (λex = 340 nm) were compared. Upon irradiation with UV light, the excimeric interactions were enhanced, resulting in a contraction of the AuI···AuI aurophilic distance by 0.0113(4) Å. A broad luminescence spectrum was observed for the one-dimensional chain suprastructure. The time-resolved luminescence spectra indicated the entity of several oligomeric species in the crude liquid without neutral solvent molecules. In addition, EXAFS spectroscopy exhibited a slight change in the nearest Au-S distance due to the photo-switched transformation. The deformation of the (Au---Au)* exciplexes was not apparently promoted in the liquid state with the asymmetrical imidazoium cations having a non-local charge distribution in the present observation.
Keywords: Gold, Au(I), thiocyanate, aurophilic interaction, ionic liquids, exciplex, XAS, TRLFS, polymers Registration No. 21649

Coordination chemistry for separation of nuclear-related metals
Ikeda, A.
Abstract: In order to understand the separation mechanism of metals in chemical processes, the chemical species formed in the processes should be characterised particularly on a molecular level. Structural characterisation is of particular importance to understand the interaction between the metal of interest and separating reagents (i.e. ligands), which would be also beneficial to further improve the efficiency of separation processes and/or to develop new separation ligands. This talk will cover the application of X-ray-based characterisation techniques (single-crystal X-ray diffraction (SC-XRD) and X-ray absorption spectroscopy (XAS)) to the separation chemistry of nuclear-related elements, such as actinides (An) or strontium (Sr).
Keywords: actinides, lanthanides, f-elements, nuclear-related elements, X-ray technique, synchrotron, XAS, XRD, coordination chemistry, separation
  • Invited lecture (Conferences)
    LEPMI-CNRS internal seminar, 13.02.2015, Grenoble, France
Registration No. 21648

Floating-zone single crystal growth of intermetallic compounds using a two-phase RF inductor
Hermann, R.; Priede, J.; Gerbeth, G.
Abstract: In this chapter the favorable applicability of the crucible-free floating zone method will be shown for the growth of single crystal intermetallic compounds
  • Book chapter
    P. Rudolph: Handbook of Crystal Growth, Vol. 2A, Amsterdam: Elsevier, 2014, 9780444633033, 313-329
Registration No. 21647

Carbide formation and optical properties in carbon:transition metal nanocomposite films
Heras, I.; Guillén, E.; Abrasonis, G.; Krause, M.; Pardo, A.; Endrino, J. L.
Abstract: The physical vapour deposition of transition metals with carbon leads to the formation of metal nano-clusters or nanocrystalline metallic carbides embedded in a carbon matrix. Interstitial carbides are very stable at high temperature, have high melting points and possess a high reflectivity. In contrast, carbon: transition metal nanocomposites can show optical selective properties such as good absorptance in the visible with high reflectance in the infrared. These properties make them very attractive for applications were high temperature resistant materials with selective optical properties are required.
In this study, Carbon: transition metal nanocomposites were grown using a physical vapour deposition system incorporating two pulsed filtered cathodic arc sources, one provided with a graphite cathode and the other with a metal cathode (Zr, V and Mo). The metal content in the composite was controlled by adjusting the ICarbon/IMetal pulse ration between the two sources, and determined by Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA). Comprehensive structure characterization was carried out using a combination of X-ray diffraction (XRD), Raman spectroscopy and high resolution transmission electron microscopy (HRTEM). Optical characterization has been done using both with ellipsometry and spectrophotometer measurements in order to obtain the optical constants and the reflectance spectra of the samples.
Together with experimental characterization, the computer program CODE is used to simulate the reflectance spectra of different carbon: transition metal films. Bruggeman effective medium theory was used to average the dielectric functions of the two components which compose the film. According to our simulations, the resulting reflectance of the nanocomposite films is strongly affected by the same metal content, independently if it results in metallic nano-clusters or nanocrystalline metallic carbides. Simulated spectra were compared with the measured reflectance of the deposited films obtaining good agreement between simulations and experimental results.
  • Lecture (Conference)
    International Conference on Nanotechnology, Nanomaterials & Thin Films for Energy Applications (Nanoenergy), 19.-21.02.2014, London, Großbritannien
Registration No. 21646

Comprehensive environmental testing of optical properties in thin films
Heras, I.; Guillén, E.; Krause, M.; Wenisch, R.; Escobar-Galindoa, R.; Endrino, J. L.
Abstract: Environmental characterization of optical and structural properties of thin films continues to be a challenging task. To understand the failure mechanism in high temperature thin film applications, it is crucial to understand how material properties change with temperature. An accurate knowledge of the variation of the dielectric function of thin films and its relation to compositional and microstructural changes could help to prevent failures. This article presents an environmental in-situ characterization methodology that combines the study of the optical constants in an environmental chamber by spectroscopic ellipsometry, with compositional depth profile analysis using ion beam analysis techniques and a structure analysis by Raman spectroscopy. The main novelty of this methodology is that all analytical techniques are carried out sequentially in a multi-chamber cluster tool without sample exposure to undefined atmospheres. Carbon-titanium metal thin film had been studied following the described characterization methodology.
Keywords: Thin films; optical constants; cluster tool; high temperature applications; thermal degradation; real time spectroscopic ellipsometry; ion beam analysis; Raman spectroscopy
  • Contribution to proceedings
    3rd International Conference on Through-life Engineering Services, 04.-05.11.2014, Cranfield, Großbritannien
    Procedia CIRP 22 ( 2014 ), 271-276
  • Lecture (Conference)
    3rd International through – life engineering services conference, 04.11.2014, Cranfield, United Kingdom
Registration No. 21645

Magnetic characterization of curved thin [Co/Pd]-multilayers and Py films
Steinbach, G.; Göhler, F.; Wolf, D.; Sluka, V.; Lindner, J.; Gemming, S.; Albrecht, M.; Erbe, A.
Abstract: In the last decades thin film technology has led to a vast increase in the variety of fabricated magnetic nano- and microstructures with desired shape, size and properties. Usually flat substrates are used to grow structures. Recently, a study on magnetic thin films with perpendicular anisotropy on curved substrates, for instance on silica spheres [1], has shown that the film curvature enormously influences the magnetic properties. In contrast to structures on flat substrates those so-called magnetic caps exhibit a spatial change of the magnetic easy axis and a film thickness variation across the cap. These features extend the possibilities in tailoring the magnetic specifications such as the magnetic anisotropy [2,3] and coercivity [1,4] or magnetization reversal process [1,2,5]. This complex structure geometry, however, leads to difficulties in characterizing the magnetic properties of the caps using standard techniques: In the case of micrometer-sized structures magnetic imaging methods suffer, for example, from beam deflection or the huge structure height due to the surface curvature.
We will present our results on 4.5µm and 0.33µm sized magnetic caps consisting of [Co(0.28nm)/Pd(0.9nm)]x8-multilayers with perpendicular magnetic anisotropy. First, we concentrate on the interior materials’ properties by studying the magnetic switching process of the cap in external fields and the spin dynamics. Second, the stray field is investigated, which determines the cap’s interaction with the environment.
The magnetization reversal in micron-sized caps has been studied by both, superconducting quantum interference device and magnetic force microscopy, for two distinct directions of an externally applied magnetic field: normal and parallel to the substrate surface. We observe clear deviations from curves measured for the flat film: The caps also show a hysteretic behavior with a very small coercivity of 150Oe in the field parallel to the substrate surface. In the normal field there is no abrupt switching as known from the flat film, but a continuous, two-step like reversal. The origin of the switching features is investigated with in-field and remanent MFM. We will present the magnetic reversal as a multi-step process across the different regions of the cap. In the parallel field two different nucleation processes during the magnetization switching have been observed: a ring nucleation, which is also mentioned in [2], and isolated domain nucleation.
The dynamic properties of the [Co/Pd]-caps have been investigated with ferromagnetic resonance. Due to the small particle size the use of conventional FMR setups does not allow single particle detection. Therefore we prepared micron sized resonators using electron beam lithography [6]. The angular dependence of the FMR modes is investigated. The results are compared with FMR measurements on geometrically similar permalloy caps with in-plane magnetic anisotropy.
The curvature-induced spatial modulation of the magnetic anisotropy further leads to a complicated stray field around the cap. So far, micromagnetic simulations [2] have been carried out to calculate the spin distribution giving rise to the stray field. Here we experimentally visualize the magnetic stray field of 0.33 µm particles by off-axis electron holography (figure 2, left). This technique provides access to the projected in-plane component of the magnetic induction by reconstructing the phase shift of the electron wave when passing through the magnetic stray field of the sample [7]. The projected stray field can be obtained by the gradual rotation of the cap. In contrast to standard measurements on flat samples, for magnetic caps the interpretation of the electron holograms is not straightforward since the stray field is not constant along the electron path. Therefore, we compare the experimentally obtained results with the outcome of micromagnetic simulations performed with the finite element based simulation software SpinFlow 3D (figure 2, right). The qualitative agreement proves the reliability of the simulation.
  • Poster
    IEEE International Magnetics Conference, INTERMAG Europe 2014, 05.05.2014, Dresden, Deutschland
Registration No. 21644

Crystallization of quasiantiferromagnetic colloids
Steinbach, G.; Gemming, S.; Erbe, A.
Abstract: The microscopic interactions between atomic magnetic moments determine the macroscopic magnetic properties of matter. For strongly correlated magnetic systems the local spin configuration plays a key role. High relaxation times, however, make direct investigations of dynamic processes such as crystallization very difficult. Here, we present an artificial spin system of magnetic colloids, which are often discussed as potential mesoscopic model systems for condensed matter. The very low relaxation rates of interacting colloids enable the visualization of phase transitions or crystallization processes by video microscopy. The used colloids have a predened net magnetic moment, as analogue to the atomic spin. These micromagnets show a quasiantiferromagnetic interaction. They form two-dimensional hexagonal clusters with a spin configuration similar to the 120° antiferromagnetic Neel state in the cluster center and strong deviations along the edges. The cluster size emerged as critical parameter for the occurrence of spin defects. Dur-ing the cluster growth the total magnetization of the system increased in discrete steps. Further we obtained a linear increase of the inverse spin pair correlation for particles in the center. The influence of an external constant or uctuating magnetic field is investigated as control tool for cluster growth and defect formation.
  • Lecture (Conference)
    DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM), 30.03.-04.04.2014, Dresden, Deutschland
Registration No. 21643

Cluster-Tool zur In situ Modifizierung und Analyse von Werkstoffen unter extremen Bedingungen am 6 MV Ionenbeschleuniger des HZDR
Wenisch, R.; Schumann, E.; Lungwitz, F.; Hanf, D.; Heller, R.; Gemming, S.; Krause, M.
Abstract: Moderne Werkstoffe sind bei vielen Anwendungen extremenUmgebungsbedingungen ausgesetzt. Dazu zählen hohe und tiefe Temperaturen bzw. große Temperaturschwankungen, die teilweise in Verbindung mit korrosiven oder reaktiven Atmosphären oder hohen mechanischen Belastungen auftreten. Sie stellen hohe Anforderungen an die Beständigkeit und Stabilität der verwendeten Werkstoffe. Als Beispiele seien solarselektive Absorber, Komponenten des Antriebsstranges von Verbrennungsmotoren und Rotoren von Turboladern und Turbinen genannt. Die Gewährleistung der Werkstofffunktionalität über die gesamte Lebensdauer erfordert neue Konzepte der Analyse und Prüfung. Dazu wurde am 6MV Ionenbeschleuniger des HZDR mit Fördermitteln des Impuls- und Vernetzungsfonds des Präsidenten der HGF sowie des KFSI ein Cluster-Tool zur in situ Modifizierung und Analyse von Werkstoffen bei Temperaturen von bis zu 1000°C, unter korrosiven Atmosphären und mechanischem Verschleiß aufgebaut.
Kernbestandteil des Cluster-Tools ist eine zentrale Hochvakuum (HV)-Probenaufnahme- und Transferkammer. Diese ist mit weiteren HV-Kammern verbunden, in denen die sequentielle Probensynthese und -modifizierung, die Element- und Strukturanalytik und die optische Charakterisierung erfolgt, ohne das Vakuum zu brechen und die Werkstoffe undefinierten Umgebungsbedingungen auszusetzen. In allen Kammern besteht die Möglichkeit, in situ Heizexperimente bei Temperaturen von bis zu 1000°C durchzuführen. Die mit dem 6MV Tandem-Ionenbeschleuniger verbundene Kammer zur Ionenstrahlanalytik ermöglicht die Untersuchung der Elementzusammensetzung durch Rutherford Rückstreuung und Nuklearer Reaktionsanalyse. Die Schichtzusammensetzung kann bis in eine Tiefe von ca. 1μm auf bis zu 10 nm genau bestimmt werden. Bei Hochtemperaturuntersuchungen reduziert sich die Tiefenauflösung auf etwa 25 nm. Zur strukturellen Charakterisierung der Proben dient ein fasergekoppeltes Ramanspektrometer an der Analysenkammer des Cluster-Tools, dessen Probenkopf über eine Kamera auch die visuelle Beurteilung der Proben ermöglicht. Die Untersuchung der optischen Eigenschaften und deren Abhängigkeit von Temperatur und Atmosphäre erfolgt durch spektroskopische Ellipsometrie in einer Umweltkammer, in der korrosive Umgebungen simuliert werden können. Für 2015 ist die Installation eines in situ Tribometers in Vorbereitung, mit dem das Reib- und Verschleißverhalten von Werkstoffen unter definierten Atmosphären untersucht werden kann.
Zusammengefasst entsteht mit dem Cluster-Tool am 6 MV Ionenbeschleuniger des HZDR ein Messplatz zur umfassenden in situ Modifizierung und Analyse von Werkstoffen, mit Hilfe dessen komplexe Probenbehandlungsprotokolle unter extremen Umgebungsbedingungen bearbeitet werden können.
  • Poster
    Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten 2014, 21.-23.09.2014, Bonn, Deutschland
Registration No. 21642

Nanostructuring CaF2 surfaces with slow highly charged ions
El-Said, A. S.; Wilhelm, R. A.; Heller, R.; Ritter, R.; Wachter, G.; Facsko, S.; Lemell, C.; Burgdörfer, J.; Aumayr, F.
Abstract: In recent years the potential of slow highly charged ions (HCI) as tools for nanostructuring purposes has received considerable attention and a wide range of material classes, from insulating ionic crystals, polymers and ultrathin films, to semiconducting and conducting substrates have been investigated regarding their response to individual HCI impact. For the majority of investigated materials, however, consistent theoretical modeling to supplement with experimental evidence and to satisfactorily explain the complete physical process from ion approach and impact to the formation of an individual nanostructure is still lacking. CaF2, from both an experimental and theoretical point of view, might be considered the most thoroughly investigated material. Combining results from numerous studies has allowed for the generation of a "phase diagram" for nanostructuring of CaF2 in dependence of ion beam parameters. This paves the way for a first unified picture, as implications from this phase diagram should be applicable to similar materials as well. Registration No. 21640

AIDA - Apparatus for In-situ Defect Analysis: Investigations on Fe60Al40
Trinh, T.; Wagner, A.; Liedke, M. O.; Anwand, W.; Butterling, M.; Potzger, K.
Abstract: We performed in-situ annealing investigations of 250 nm Fe60Al40 thin films. The magnetic properties of disorderd Fe60Al40 thin films change from the ferromagnetic to paramagnetic state du to annealing. No conclusive discussion of that phase transtion as a function of the open volume defects exists in the literature. First results on the Fe60Al40 annealing driven magnetic phase transition between the ferromagnetic A1 phase and the paramagnetic B2 phase as a function of the open volume defects will be shown. The magnetization of the film after each annealing step indicates its progress reflecting chemical ordering of the alloy and dinishing of ferromagnetism [1]. Fig. 1 shows the temperature dependence of the positron annihilation spectorscopy (PAS) S-parameter indicating the open volume defects evolution during annealing. The defects are very stable with respect to annealing and do not directly relate to the change of magnetic properties. Our results indicate that Fe60Al40 could be a promising candidate for Hydrogen storage due to a large amount of stable defects. Through hybridisation the electronic structure can be modified, combined with a local lattice distortion. Hydrogen can therefore be viewed as a tool to modify the electronic structure, allowing tuning of the magnetic properties as a consequence.
For the in-situ annealing we have utilized a unique high vacuum system combining material evaporation and ion beam modification with positron annihilation spectroscopy. The system has been developed and installed in the Helmholtz-Zentrum Dresden-Rossendorf. The system is capable to perform Doppler broadening spectroscopy as well as resistometry and provides a monoenergetic positron beam pre-accelerated in the range of 80 eV to 35 keV thus enabling sample depth profiling.

Keywords: Positron anihilation, In-situ, Apparatus, Defects, Spectroscopy
  • Poster
    14th International Symposium Metal Hydride Systems, 20.-25.07.2014, Manchester, United Kingdom
Registration No. 21638

Apparatus for In-situ Defect Analysis (AIDA)
Liedke, M. O.; Anwand, W.; Butterling, M.; Potzger, K.; Heidarian, A.; Bali, R.; Wagner, A.
Abstract: A unique high vacuum system combining material evaporation and ion beam modication with positron annihilation spectroscopy (PAS) has been developed and installed in the Helmholtz-Zentrum Dresden-Rossendorf. The in-situ system is capable to perform Doppler broadening spectroscopy as well as resistometry (4 point probe). It is an end station of the Slow-Positron System of Rossendorf (SPONSOR) that provides a mono-energetic positron beam pre-accelerated in the range of 80 eV to 35 keV thus enabling sample depth proling. The main focus of studies is the in-situ modication (during growth, ion irradiation, cooling/annealing) and the analysis of open volume defects and the chemical environment in thin lms of, e.g., memristive oxides or metal alloys. First results on the FeAl ion irradiation/annealing driven magnetic phase transition between the paramagnetic and ferromagnetic state as a function of the open volume defects will be shown. The project is nanced by the Impuls- und Vernetzungsfonds of the Helmholtz Association (code VH-VI-442).
Keywords: MBE, ion irradiation, evaporation, annealing, FeAl, transition metals, sheet resistance
  • Lecture (Conference)
    DPG-Frühjahrstagung (DPG Spring Meeting) 2014, 30.03.-04.04.2014, Dresden, Deutschland
Registration No. 21637

Apparatus for In-situ Defect Analysis (AIDA)
Liedke, M. O.; Anwand, W.; Potzger, K.; Wagner, A.
Abstract: A unique high vacuum system combining material evaporation and ion beam modication with positron annihilation spectroscopy (PAS) has been developed and installed in the Helmholtz-Zentrum Dresden-Rossendorf. The in-situ system is capable to perform Doppler broadening spectroscopy as well as resistometry (4 point probe). It is an end station of the Slow-Positron System of Rossendorf (SPONSOR) that provides a mono-energetic positron beam pre-accelerated in the range of 80 eV to 35 keV thus enabling sample depth proling. The main focus of studies is the in-situ modication (during growth, ion irradiation, cooling/annealing) and the analysis of open volume defects and the chemical environment in thin lms of, e.g., memristive oxides or metal alloys. First results on the FeAl ion irradiation/annealing driven magnetic phase transition between the paramagnetic and ferromagnetic state as a function of the open volume defects will be shown. The project is nanced by the Impuls- und Vernetzungsfonds of the Helmholtz Association (code VH-VI-442).
Keywords: MBE, ion irradiation, evaporation, annealing, FeAl, transition metals
  • Lecture (Conference)
    Treffen Deutscher Positronengruppen Kiel 2014, 25.-27.02.2014, Kiel, Deutschland
Registration No. 21636

Development of a Laser wakefield acceleration source as a secondary radiation driver
Couperus, J. P.; Jochmann, A.; Köhler, A.; Messmer, M.; Zarini, O.; Debus, A.; Hübl, A.; Widera, R.; Bussmann, M.; Sauerbrey, R.; Cowan, T.; Schramm, U.; Irman, A.
Abstract: In laser wakefield electron acceleration a high intensity ultrashort laser pulse drives plasma density waves, inducing a high accelerating field gradient (~GV/m) which can accelerate electrons to high energies within a very short distance.
For the development of secondary radiation sources, the maximization of the bunch charge is important. For this reason we investigate the beam-loading effect at the self-injected highly nonlinear regime. Beam-loading deteriorates the accelerating field structure and limits the maximum bunch charge.
Supported by intensive Particle-in-Cell code simulations run on a GPU-cluster (using the PIConGPU code), we aim on developing a stable high peak current (hundreds of kA) electron source.

Keywords: laser wakefield electron acceleration LWFA plasma PIConGPU
  • Poster
    Advanced School on Laser Applications at Accelerator, 29.09.-03.10.2014, Salamanca, Spain
Registration No. 21632

Investigation of the beam loading effect in laser wakefield acceleration
Couperus, J. P.; Jochmann, A.; Köhler, A.; Messmer, M.; Zarini, O.; Debus, A.; Hübl, A.; Widera, R.; Bussmann, M.; Sauerbrey, R.; Cowan, T.; Schramm, U.; Irman, A.
Abstract: In laser wakefield electron acceleration a high intensity ultrashort laser pulse drives plasma density waves, inducing a high accelerating field gradient (~GV/m) which can accelerate electrons to high energies within a very short distance.
For the development of secondary radiation sources, the maximization of the bunch charge is important. For this reason we investigate the beam-loading effect at the self-injected highly nonlinear regime. Beam-loading deteriorates the accelerating field structure and limits the maximum bunch charge.

Keywords: laser plasma electron acceleration LWFA wakefield gas-jet PIConGPU
  • Poster
    International Particle Accelerator Conference, 15.-20.06.2014, Dresden, Deutschland
Registration No. 21630

Energy-Angle Characteristic of an ICS source
Jochmann, A.
Abstract: A tunable source of intense ultra-short hard X ray pulses represents a novel tool for the structural analysis of complex systems with unprecedented temporal and spatial resolution. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR) we demonstrated the principle of such a light source (PHOENIX – Photon Electron collider for Narrow bandwidth Intense X-Rays) by colliding picosecond electron bunches from the ELBE linear accelerator with counter-propagating femtosecond laser pulses from the 150 TW Draco Ti:Sapphire laser system. The generated narrowband X rays are highly collimated and can be reliably adjusted by tuning the electron energy. A complete spectral characterization of this source is performed with high angular and energy resolution. These intensive studies provide predictive capability for the future high brightness hard X ray source PHOENIX and potential gamma-ray sources suited to an application.
Keywords: Laser Compton Scattering X-ray pulsed source femtosecond intense backscattering inverse
  • Lecture (Conference)
    LA3NET 3rd Topical Workshop on Novel Acceleration Techniques, 28.04.2014, Dresden, Deutschland
Registration No. 21628

Effect of a superimposed DC magnetic field on an AC induction semi-levitated molten copper droplet
Bojarevics, A.; Beinerts, T.; Grants, I.; Kaldre, I.; Sivars, A.; Gerbeth, G.; Gelfgats, J.
Abstract: While a piece of pure Copper on a ceramic substrate was inductively melted by 9 to 18 kHz AC magnetic field with axial magnetic DC field superimposed, the liquid metal stably semi-levitated in the expected “conical” free surface shape. The diameter of the liquid metal at the basis was 30 mm, the volume – more than 20 cm3. Replacing the ceramic substrate with a Glassy Carbon, which was not wetted by the molten Copper, caused instability of the semi-levitated Copper droplet. In the absence of the DC field severe chaotic instabilities of the liquid metal shape occurred, causing splashes and uncontrolled contact with crucible walls. When axial DC magnetic field with induction 0.35 T was superimposed the liquid metal droplet exhibited harmonic azimuthal wave deformation of the free surface. Higher frequencies lead to smaller characteristic wavelength. Transverse DC magnetic field direction suppressed the travelling wave deformations of the droplet shape. Stabilizing effect of the DC magnetic field during induction melting has been shown for axial, transverse and 45 degree direction magnetic field. These results experimentally demonstrate the possibilities to improve the stability of levitated metal volumes by superimposed DC magnetic field.
Keywords: -
  • Lecture (Conference)
    9th PAMIR conference on Fundamental and Applied MHD, 16.-20.06.2014, Riga, Lettland
  • Contribution to proceedings
    9th PAMIR conference on Fundamental and Applied MHD,, 16.-20.06.2014, Riga, Lettland
    Proceedings of the 9th PAMIR conference on Fundamental and Applied MHD, Vol 2, 125-129
Registration No. 21627

Experimental modelling using liquid metals
Gerbeth, G.; Eckert, S.
Abstract: An overview on liquid metal modelling experiments is presented for the steel casting process. Particular attention is given to the recent developments on measuring techniques for liquid metal flows, including the perspectives for measurements in real steel melts.
Keywords: -
  • Invited lecture (Conferences)
    VDEh Steel Academy Workshop „Computational Fluid Dynamics in Metallurgy“, 01.-03.12.2014, Mönchengladbach, Deutschland
Registration No. 21626

Recent results on flow measurements and magnetic control
Gerbeth, G.; Eckert, S.
Abstract: A brief summary is given on measurements in metal melts developed at HZDR. Melt velocities can be measured by local electromagnetic probes, ultrasonic Doppler velocimetry and by the Contactless Inductive Flow Tomography (CIFT). The latter is fully contactless and offers a possibility for an online monitoring of the melt flow. We report on first test measurements with CIFT at Czochralski facilities for Si growth. Regarding the details of solidification and the occurrence of inclusions, we present results on X-ray visualizations of alloy solidification. They allowed to demonstrate for metal alloys the formation of freckles driven by the mesoscopic melt convection ahead of the solidification front. For the magnetic melt control we present results of model experiments on the reduction of buoyant temperature oscillations using a rotating magnetic field. Related studies were performed for cylindrical melt volumes and a Cz-like configuration. The melt flow in the float-zone process can be efficiently influenced by a so-called magnetic two-phase stirrer. Its principle and related growth results for intermetallic compounds will be presented.
Keywords: -
  • Lecture (others)
    DGKK-Tagung, 12.-13.03.2014, Halle, Deutschland
Registration No. 21625

Towards laser wakefield acceleration with external injection at HZDR
Irman, A.
Abstract: Progress towards laser wakefield acceleration with external injection is presented.
  • Invited lecture (Conferences)
    Novel acceleration techniques ANAC2/EUCARD2 JRA meeting, 30.04.2014, HZDR, Germany
Registration No. 21624

High Resolution Energy-angle Correlation Measurement of Hard X rays from Laser Thomson Backscattering
Irman, A.; Bussmann, M. H.; Couperus, J. P.; Debus, A. D.; Jochmann, A.; Pausch, R. G.; Schlenvoigt, H. P.; Schramm, U.; Steiniger, K.; Cowan, T. E.; Kuntzsch, M.; Lehnert, U.; Sauerbrey, R.; Seipt, D.; Wagner, A.; Ledingham, K.; Stöhlker, T.; Thorn, D. B.; Trotsenko, S.
Abstract: A tunable source of intense ultra-short hard X ray pulses represents a novel tool for the structural analysis of complex systems with unprecedented temporal and spatial resolution. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR) we demonstrated the principle of such a light source (PHOENIX – Photon Electron collider for Narrow bandwidth Intense X-Rays) by colliding picosecond electron bunches from the ELBE linear accelerator with counter-propagating femtosecond laser pulses from the 150 TW Draco Ti:Sapphire laser system. The generated narrowband X rays are highly collimated and can be reliably adjusted by tuning the electron energy. A complete spectral characterization of this source is performed with high angular and energy resolution. These intensive studies provide predictive capability for the future high brightness hard X ray source PHOENIX and potential gamma-ray sources suited to an application.
Keywords: Laser Compton Scattering X-ray pulsed source femtosecond intense backscattering inverse
  • Poster
    IPAC’14 - 5th International Particle Accelerator Conference, 18.06.2014, Dresden, Deutschland
Registration No. 21623

Fluid dynamics research at HZDR Dresden
Gerbeth, G.
Abstract: An overview on fluid dynamics research activities is given, including multiphase and magnetohydrodynamic flows and the related computational fluid dynamics.
Keywords: -
  • Invited lecture (Conferences)
    Shandong Universität, 11.05.2014, Jinan, China
Registration No. 21622

Laser-plasma based electron acceleration
Irman, A.
Abstract: The concept of laser-driven plasma-based electron acceleration is reviewed. This lecture will be started by description of plasmas and its characteristics then follows with electron injection and acceleration. In the end, recent progress in the field will be highlighted.
Keywords: laser wakefield acceleration
  • Invited lecture (Conferences)
    LA3NET Advanced School on Laser Applications at Accelerators, 28.09.-03.10.2014, Salamanca, Spain
Registration No. 21621

Research on crystal growth problems at Institute of Fluid Dynamics of HZDR
Gerbeth, G.
Abstract: Research activities at HZDR on the measurement and magnetic field control of melt flows in crystal growth processes are summarized. Examples are given for the tailored control by magnetic fields of Czochralski, Vertical-Gradient-Freeze as well as Float-Zone growth processes.
Keywords: -
  • Invited lecture (Conferences)
    SICC Science & Technology, Ltd., 12.05.2014, Jinan, China
Registration No. 21620

Tornado-like flows driven by magnetic body forces
Gerbeth, G.; Grants, I.; Vogt, T.; Eckert, S.
Abstract: Alternating magnetic fields produce well-defined flow-independent body forces in electrically conducting media. This property is used to construct a laboratory analogue of the Fiedler chamber with a room-temperature liquid metal as working fluid. A continuously applied rotating magnetic field (RMF) provides the source of the angular momentum. A pulse of a much stronger travelling magnetic field drives a converging flow at the metal surface, which focuses this angular momentum towards the axis of the container. The resulting vortex is studied experimentally and numerically. In a certain range of the ratio of both driving actions the axial velocity changes its direction in the vortex core, resembling the subsidence in an eye of a tropical cyclone or a large tornado. During the initial deterministic spin-up stage (T. Vogt et al., JFM 736, 2013, pp. 641) the vortex is well described by axisymmetric direct numerical simulation. Being strong enough the flow develops a funnel-shaped surface depression that enables visual observation of the vortex structure. As the RMF strength is increased the eyewall diameter grows until it breaks down to multiple vortices. A number of further observed similarities to tornado-like vortices will be discussed.
Keywords: -
  • Invited lecture (Conferences)
    APS-DFD 2014 meeting, 23.-25.11.2014, San Francisco, USA
  • Abstract in refereed journal
    Bulletin of the American Physical Society 59(2014), 20
Registration No. 21619

Correlation of electron and laser beam parameters to the spectral shape and bandwidth of laser-Thomson backscattering x-ray beams
Irman, A.; Jochmann, A.; Debus, A.; Couperus, J. P.; Trotsenko, S.; Kuntzsch, M.; Lehnert, U.; Wagner, A.; Schlenvoigt, H.-P.; Bussmann, M.; Sthöhlker, Th.; Seipt, D.; Thorn, D. B.; Ledingham, K. D.; Cowan, T.; Sauerbrey, R.; Schramm, U.
Abstract: Development of advanced x-ray sources based on laser-Thomson scattering mechanism is becoming important pushed by a strong demand for ultrashort hard x-ray pulses, which can serve as a novel tool for structural analysis of complex systems with unprecendented temporal and spatial resolution. The spectral shape and bandwidth of this x-ray beam is the result from the interplay between interacting electron and laser beam parameters. We present high resolution angle and energy resolved measurements on the x-ray photon distribution generated by colliding picosecond electron bunches from the ELBE linear accelerator with counter-propagating laser pulses from the 150 TW DRACO Ti:Sapphire laser system. The measured data and an ab-initio comparison with the 3D radiation code CLARA enable us to reveal parameter influences and correlation of both interacting beams. We conclude that in the low laser intensity interaction regime the electron angular distribution and the laser bandwidth, as in the case of ultrashort laser pulses, give a strong influence to the x-ray spectral shape and bandwidth. We also show the x-ray spectral broadening as the laser intensity increases indicating nonlinear interaction on the scattering process. Controlling these parameters is necessary for designing future Thomson x-ray sources with a specific bandwidth suited to an application.
Keywords: laser-Thomson backscattering x-ray, ELBE electron beam, ultrashort x-ray, high power laser
  • Invited lecture (Conferences)
    16th Advanced Accelerator Concepts Workshop (AAC 2014), 13.-18.07.2014, San Jose, United States
Registration No. 21618

LIMTECH A5: Liquid metal two-phase flows
Strumpf, E.; Eckert, S.; Richter, T.; Gerbeth, G.
Abstract: Measurements for rising single bubbles were performed in a cuboid benchmark experiment filled with the liquid metal GaInSn. Data was acquired by two different ultrasound techniques simultaneously, which are Ultrasound Doppler Velocimetry (UDV) and Ultrasound Transit Time Technique (UTTT). The focus was on the influence of a horizontal magnetic field on the bubble behavior.
Keywords: liquid metal, two-phase, single bubble, horizontal magnetic field, UDV, UTTT
  • Poster
    LIMTECH annual meeting 2014, 10.-11.11.2014, Ilmenau, Deutschland
Registration No. 21617

Approaches to the Simulation of Compositional Data: A Nickel-Laterite comparative case study
Mueller, U.; Tolosana-Delgado, R.; van den Boogaart, K. G.
Abstract: An accurate prediction of benefit for some types of ore may require not just the ore grade, but a whole compositional characterization of the estimates, that is, its full mineral composition, including waste composition and nuisance elements. An example is Nickel laterite ores, where Ni/Co content must be complemented by estimates of many other elements, as these might have a notable impact on ore processing.
Estimates are often obtained with (co)kriging or co-simulation. However, geostatistics applied to compositional data may yield spurious and inconsistent results because of the constant sum constraint. The log-ratio approach avoids such problems. Like anamorphosis, it proposes a three-step procedure: (1) data are mapped to a set of log ratios of components, for example the additive log-ratio transformation (alr); (2) transformed scores are modelled with an appropriate fully multivariate geostatistical toolbox (e.g. direct/cross-variograms and cokriging or co-simulation); and (3) results are back-transformed to the original units. Some practical aspects may make the application of this technique difficult: the assumption of Gaussianity and the high dimensionality of the compositions combined with the need for using multivariate methods. This contribution compares several ways of treating compositional data (combining anamorphosisnormal score transformation, logratio transformations, and minimum maximummax autocorrelation decomposition) with respect to their ability to generate sensible simulations. The various approaches considered are illustrated with a Nickel laterite data set for which 10 variables are available. Both theoretical considerations and illustration results suggest that the best combination is (log)ratio-anamorphosisnormal score transform-MAF, in this order. The factors so obtained are closer to Gaussian, approximately spatially decorrelated and can be simulated independently. Simulations can later be recombined to alr-simulations, which in turn may be converted back to point compositions. The resulting simulated compositions are compared with a full Gaussian co-simulation of the raw data. The logratio methodsy show a reasonable to good reproduction of mean values and distribution of the data set and by construction honour the total sum constraint, in contrast to the simulations based on the raw data for which the total sums fluctuate strongly.
  • Contribution to proceedings
    SMP 2014, Ore body Modelling and Strategic Mine Planning Symposium 2014, 24.-26.11.2014, Perth, Australia
    Orebody Modelling and Strategic Mine Planning, SMP 2014, Integrated mineral investment and supply chain optimisation, Cartlon Victoria, Australia: Australasian Institute of Mining and Metallurgy, 987-1-925100-19-8, 61-72
Registration No. 21615

A comprehensive study of the magnetic, structural, and transport properties of the III-V ferromagnetic semiconductor InMnP
Khalid, M.; Gao, K.; Weschke, E.; Hübner, R.; Baehtz, C.; Gordan, O.; Salvan, G.; Zahn, D. R. T.; Skorupa, W.; Helm, M.; Zhou, S.
Abstract: The manganese induced magnetic, electrical, and structural modification in InMnP epilayers, prepared by Mn ion implantation and pulsed laser annealing, are investigated in the following work. All samples exhibit clear hysteresis loops and strong spin polarization at the Fermi level. The degree of magnetization, the Curie temperature, and the spin polarization depend on the Mn concentration. The bright-field transmission electron micrographs show that InP samples become almost amorphous after Mn implantation but recrystallize after pulsed laser annealing. We did not observe an insulator-metal transition in InMnP up to a Mn concentration of 5 at. %. Instead all InMnP samples show insulating characteristics up to the lowest measured temperature. Magnetoresistance results obtained at low temperatures support the hopping conduction mechanism in InMnP. We find that the Mn impurity band remains detached from the valence band in InMnP up to 5 at. % Mn doping. Our findings indicate that the local environment of Mn ions in InP is similar to GaMnAs, GaMnP, and InMnAs; however, the electrical properties of these Mn implanted III-V compounds are different. This is one of the consequences of the different Mn binding energy in these compounds.
Keywords: III-V magnetic semiconductors Registration No. 21614

The Tayler instability at low magnetic Prandtl numbers
Stefani, F.; Barry, L.; Gundrum, T.; Kirillov, O.; Seilmayer, M.; Weber, N.; Gellert, M.; Rüdiger, G.
Abstract: The Tayler instability is a kink type instability which appears when an axial current in a cylinder crosses a certain critical value. It has been discussed as a main ingredient of the Tayler-Spruit stellar dynamo model, but may also play a role as a size-limiting factor in large-scale liquid metal batteries. We discuss several theoretical aspects and the first experimental evidence of the Tayler instability in liquid metals.
  • Lecture (Conference)
    European GdR Dynamo Meeting, 01.-04.09.2014, Cambridge, England
Registration No. 21613

The present status of the DRESDYN project
Stefani, F.
Abstract: The DRESDYN project at Helmholtz-Zentrum Dresden-Rossendorf is intended as a platform for large-scale liquid sodium experiments on dynamo action and magnetically triggered flow instabilities. We report on the progress of the building construction, and on the design status of the precession driven dynamo experiment. Special focus is laid on new theoretical and experimental results on the magnetorotational and Tayler instability, and on the consequences for the planned liquid sodium experiment for the combined study of those instabilities. Some very recent results of a small-scale spherical Couette experiment with an applied axial magnetic field are also discussed.
  • Invited lecture (Conferences)
    Grands séminaires ISTerre, 13.11.2014, Grenoble, France
Registration No. 21612

The present status of the DRESDYN project
Stefani, F.
Abstract: The DRESDYN project is new platform for a variety of liquid sodium experiments, comprising a large-scale precession driven dynamo experiment and a combined set-up for investigating different versions of the magnetorotational instability and the Tayler instability. We sketch the history of previous liquid metal experiments on cosmic magnetic field, and outline the status of preparations for the various facilities planned in the framework of DRESDYN.
  • Invited lecture (Conferences)
    MHD-Days 2014, 02.-03.12.2014, Potsdam, Germany
Registration No. 21611

The new IR FEL Facility at the Fritz-Haber-Institut in Berlin
Schöllkopf, W.; Gewinner, S.; Erlebach, W.; Junkes, H.; Liedke, A.; Meijer, G.; Paarmann, A.; von Helden, G.; Bluem, H.; Dowell, D.; Lange, R.; Rathke, J.; Todd, Alan M. M.; Young, Lloyd M.; Lehnert, U.; Michel, P.; Seidel, W.; Wünsch, R.; Gottschalk, S. C.
Abstract: A mid-infrared oscillator FEL has been commissioned at the Fritz-Haber-Institut. The accelerator consists of a thermionic gridded gun, a subharmonic buncher and two S-band standing-wave copper structures. It provides a final electron energy adjustable from 15 to 50 MeV, low longitudinal (<50 keV-ps) and transverse emittance (<20 PI mm-mrad), at more than 200 pC bunch charge with a micro-pulse repetition rate of 1 GHz and a macro-pulse length of up to 15 µs. Pulsed radiation with up to 50 mJ macro-pulse energy at about 0.5% FWHM bandwidth is routinely produced in the wavelength range from 4 to 48 µm. Regular user operation started in Nov. 2013 with 6 user stations. These include, for instance, spectroscopy of bio-molecules (peptides and small proteins), which are conformer selected or embedded in superfluid helium nano-droplets at 0.4 K, as well as vibrational spectroscopy of mass-selected metal-oxide clusters and protonated water clusters in the gas phase.
  • Poster
    36th International Free Electron Laser Conference 2014, 25.-29.08.2014, Basel, Schweiz
Registration No. 21610

The new ELBE Center for High Power Radiation Sources at HZDR: Status and Opportunities
Seidel, W.
Abstract: The ELBE user facility located at the Helmhotz-Zentrum Dresden-Rossendorf operates a superconducting electron linear accelerator , which provides short (picosecond) electron bunches with energies up to 35 MeV at a 13 MHz repetition rate. Here we discuss the basic parameters of the ELBE Center and the experimental opportunities at the facility.
  • Invited lecture (Conferences)
    Turkish-German Workshop on Particle Accelerators and Light Sources, 09.-10.07.2014, Istanbul, Turkey
Registration No. 21609

Theranostic mercury: 197(m)Hg with high specific activity for imaging and therapy
Walther, M.; Preusche, S.; Bartel, S.; Wunderlich, G.; Freudenberg, R.; Steinbach, J.; Pietzsch, H.-J.
Abstract: The no carrier added (NCA) radionuclide 197(m)Hg is accessible through proton induced nuclear reactions on gold.The decay properties of both simultaneous produced nuclea risomers 197mHg and 197Hg like convenient half life, low energy gamma radiations for imaging, Auger and conversion electrons for therapy are combined with unique chemical and physical properties of mercury and its compounds. Gold as a monoisotopic element has a natural abundance of 100% 197Au superseding expensive enrichment for the target material. Additionally, the high thermal conductivity of gold enables high beam current irradiations. For separation of target material a liquid–liquid extraction method was applied.
Keywords: 197Hg; Theranostics; Dosimetry; 177Lu; Auger and conversion electrons Registration No. 21607

Wissens- und Innovationsgemeinschaften (KIC) am Beispiel des KIC Rohstoffe - nachhaltige Erkundung, Gewinnung, Verarbeitung, Verwertung und Substitution
Dirlich, S.; Klossek, A.
Abstract: Der Vortrag erläutert anhand von drei Leitfragen (Ziele von KIC, Synergien zur nationalen Forschung und aktuelle Entwicklungen) Wissens- und Innovationsgemeinschaften im Allgemeinen und geht im Besondere auf das geplante KIC Rohstoffe ein. Mit dem KIC Rohstoffe sollen die Ziele "vom Labor in den Markt", "vom Studenten zum Unternehmer" und "von der Idee zum Produkt" auf den Rohstoffsektor übertragen werden. Dabei wird die gesamte Kette von der Erkundung bis zum Recycling berücksichtigt. Für deutsche Wissenschaftler gibt es zahlreiche Synergiemöglichkeiten angesichts eines europäischen Netzwerks aus fast 120 Partnern aus den Bereichen Forschung, Bildung und Industrie. Das KIC beschäftigt sich insbesondere mit der Rohstoffverfügbarkeit in Europa, der Substitution kritischer Rohstoffe und der Nachhaltigkeit in der gesamten Kette der Rohstoffindustrie.
Keywords: raw materials, resources supply, innovation, knowledge, KIC
  • Invited lecture (Conferences)
    11. Fona-Forum, 29.09.2014, Berlin, Deutschland
Registration No. 21606

Attachment of solid elongated particles on the surface of a stationary gas bubble
Lecrivain, G.; Petrucci, G.; Rudolph, M.; Hampel, U.; Yamamoto, R.
Abstract: Froth flotation is a separation process which plays a major role in the mining industry. It is essentially employed to recover a vast array of different valuable commodities such as rare earth minerals essential to the manufacture of high-tech products. Owing to its simplicity, the process is also widely used for the de-inking of recycled paper fibres and for the removal of pollutants from waste water. The flotation process essentially relies on the attachment of solid particles on the surface of gas bubbles immersed in water. The present study seeks to investigate the effect of the particle shape on the attachment mechanism. Using an in-house optical micro-bubble sensor the approach, the sliding and the adhesion of micron milled glass fibres on the surface of a stationary air bubble immersed in stagnant water is thoroughly investigated. The translational and rotational velocities were measured for fibres of various aspect ratios. The results are compared with a theoretical model and with experimental data obtained with spherical glass beads. It is found that the fibre orientation during the sliding motion largely depends on the collision area. Upon collision near the upstream pole of the gas bubble the major axis of the fibre aligns with the local bubble surface (tangential fibre alignment). If collision occurs at least 30° further downstream only head of the fibre is in contact with the gas–liquid interface (radial fibre alignment).
Keywords: Froth flotation; Three-phase system; Solid elongated particles; Particle attachment; Gas-liquid interface Registration No. 21605

NeuLAND time of flight detector for 200-1000 MeV neutrons read out by fast photosensors
Bemmerer, D.
Abstract: A new setup for kinematically complete reaction experiments for beams of radioactive nuclei far from the valley of stability is under construction at FAIR Darmstadt, Germany. NeuLAND, a highly efficient (>90%) neutron time of flight detector made of fast plastic scintillators is included in the setup. In order to reach proper resolution in the reconstructed energy spectrum, a time resolution of sigma < 150 ps is required. Using the ELBE picosecond electron beam as a time reference, it is currently being studied whether semiconductor-based photosensors (SiPMs) can be used for the readout of the NeuLAND scintillator bars.
  • Lecture (Conference)
    WINS 2014 Workshop on Elastic and Inelastic Neutron Scattering, 03.-05.12.2014, Dresden, Deutschland
Registration No. 21604

Experimental investigations of a magnetically driven Tornado-like vortex by means of Ultrasound-Doppler Velocimetry
Vogt, T.; Grants, I.; Eckert, S.; Gerbeth, G.
Abstract: The spin-up of a concentrated vortex in a liquid metal cylinder with a free surface is considered experimentally. The vortex is driven by two flow independent magnetic body forces. A continuously applied rotating magnetic field provides the source of the angular momentum. A pulse of about one order of magnitude stronger travelling magnetic field drives a converging flow that temporarily focuses this angular momentum towards the axis of the container. A highly concentrated vortex forms that produces a funnel-shaped surface depression. In this study we have used some modified settings for the UDV device in order to detect the vertical position of the free surface along the beam line. The main modification was a reduction of the echo detection sensitivity. In this way the echo from microscopic particles was blinded out. Instead, only the position of the strong echo from the free surface was detected and recorded. We explore experimentally the duration, the depth and the conditions of formation of this funnel.
Keywords: gas entrainment, bubble detection
  • Lecture (Conference)
    9th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 26.-29.08.2014, Strasbourg, Frankreich
  • Contribution to proceedings
    9th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 26.-29.08.2014, Strasbourg, Frankreich
    Proceedings of the 9th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering
Registration No. 21603

Using XFELs to probe the interaction dynamics of ultra-intense lasers with solid-density matter
Cowan, T. E.; Kluge, T.; Huang, L.; Gutt, C.; Pelka, A.; Bussmann, M.
Abstract: The advent of intense coherent hard x-ray sources based on free electron lasers have opened a new era of ultrafast science. Facilities such as FLASH, LCLS, SACLA, and the under-construction European XFEL, will enable time and spatially resolved probing of atomic, molecular, chemical, biological and plasma dynamics, on the scale of fs and nm. Here we present theoretical concepts to make use of coherent x-ray scattering to probe ultra-intense laser-driven plasmas. In addition, status of the HIBEF User Consortium at the European XFEL will be presented.
Keywords: X-rays, XFEL, ultrafast science, relativistic plasmas
  • Invited lecture (Conferences)
    Graduate School of Engineering Seminar, Osaka University, 07.01.2014, Osaka, Japan
Registration No. 21602

The 22Ne(p,gamma)23Na reaction studied at LUNA: results from the germanium detector based part of the experiment
Bemmerer, D.
Abstract: The 22Ne(p,γ)23Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the 22Ne(p,γ)23Na cross section directly at the astrophysically relevant energies are needed.
The seminar talk will report on the recently concluded first phase of the 22Ne(p,γ)23Na experiment at LUNA. Using a windowless, isotopically enriched 22Ne gas target and two high-purity germanium detectors, selected, previously unobserved low-energy resonances were studied. The preliminary results will be summarized, and an outlook on the second phase of the experiment with a 4pi summing detector will be given.
  • Invited lecture (Conferences)
    INFN Laboratori Nazionali del Gran Sasso Seminar, 10.12.2014, Assergi, Italien
Registration No. 21601

Separation of ultrafine particles by two-liquid flotation: Selectivity and process behavior analysis
Rudolph, M.; Peuker, Urs A.
Abstract: It is well known, that for conventional froth flotation techniques the processing of ultrafine mineral particles is generally inefficient and results in rather low-grade concentrates and relatively high losses of valuable minerals. Therefore, the investigation of other possible methods, which can selectively separate such fine particle systems effectively, is of considerable interest.
In this study, the application of two-liquid flotation, a flotation-related process using oil droplets instead of air bubbles, is investigated as a possible processing strategy for the separation of ultrafine particle systems. The investigation involves the testing of the two-liquid flotation technique as simple laboratory-scale batch trials and moreover, the up-scaling to a semi-continuous process by using a modified lab scale flotation column. Magnetite and quartz particles, with particle sizes below 10 μm respectively, as academic mineral mixture and iso-octane and water as the two immiscible liquid phases are chosen for the experiments. To manipulate the wettability of the magnetite particles as well as the interfacial tension of the oil/water interfaces, surface active reagents of fatty acid basis are introduced in the system. The selectivity of the process is characterized by determining the removal of magnetite particles from the aqueous suspension through selective accumulation at the oil/water interface or extraction into the oil phase, respectively. Operational parameters including pH of the aqueous suspension, additional electrolyte addition and surfactant type as well as dosage are varied in order to maximize the efficiency and stability of the process.

Keywords: ultra fine particle prossessing, flotation methods, two-liquid flotation
  • Lecture (Conference)
    XXVII International Mineral Processing Congress, 20.-24.10.2014, Santiago de Chile, Chile
Registration No. 21600

Mineralization derived from felsic magma? A case study on Zr-Nb-REE deposits in Western Mongolia
Kempe, U.; Möckel, R.
Abstract: The genesis of unconvential Zr-Nb-REE deposits is still under discussion. The mineralization of the Khalzan Buregte and surrounding massifs in western Mongolia is introduced as a case study. We present data showing that the enrichment of valuable elements is mainly due to multistage metasomatic alteration, although the primary contents are quite high as well. The theory of secondary enrichment is also widened on other deposits in the Erzgebirge mountains, Saxony/Germany for comparison.
Keywords: rare earth elements REE, Khalzan Buregte, Mongolia
  • Invited lecture (Conferences)
    13th Freiberg Short Course in Economic Geology - Rare earth element deposits, 08.-12.12.2014, Freiberg, Deutschland
Registration No. 21598

Background intercomparison with an active shielded HPGe detector extended to Freiberg mine in Germany
Szücs, T.; Bemmerer, D.; Reinhardt, T. P.; Schmidt, K.; Takács, M. P.; Wagner, L.
Abstract: A key requirement for underground nuclear astrophysics experiments is the very low background level in germanium detectors. The reference for these purposes is the world’s so far only underground accelerator laboratory for nuclear astrophysics, LUNA. LUNA is located deep underground in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400m of rock. The background at LUNA was studied in detail using an escape-suppressed Clover-type HPGe detector [1]. Exactly the same detector was subsequently transported to the Felsenkeller underground laboratory in Dresden, shielded by 45m of rock, and the background was shown to be only a factor of three higher than at LUNA when comparing the escape-suppressed spectra, with interesting consequences for underground nuclear astrophysics [2]. As the next step of a systematic study of the effects of a combination of active and passive shielding on the cosmic ray induced background, this detector has recently been brought to the "Reiche Zeche" mine in Freiberg, Germany, shielded by 150m of rock.
The data available with one and the same actively shielded HPGe detector at the Earth's surface and below 45, 150, and 1400m of rock allow getting a general understanding of the effects of active shielding with depth.
– Supported by the Helmholtz Association (HGF) through the Nuclear Astrophysics Virtual Institute (HGF VH-VI-417).

[1] T. Szücs et al., Eur. Phys. J. A 44, 513 (2010).
[2] T. Szücs et al., Eur. Phys. J. A 48, 8 (2012).

Keywords: underground, nuclear astropysics, gamma background
  • Poster
    13th international symposium on Nuclei in the Cosmos (NIC-XIII), 07.-11.07.2014, Debrecen, Hungary
Registration No. 21597

Determination of level widths in 15N using nuclear resonance fluorescence
Szücs, T.; Bemmerer, D.; Caciolli, A.; Fülöp, Zs.; Massarczyk, R.; Michelagnoli, C.; Reinhardt, T. P.; Schwengner, R.; Takács, M. P.; Ur, C. A.; Wagner, A.; Wagner, L.
Abstract: The stable nucleus 15N is the mirror of the astrophysically important 15O, the product of the slowest reaction in the hydrogen burning CNO cycle, which therefore determine the production rate of the cycle.
Most of the 15N level widths below the nucleon emission thresholds are known from just one nuclear resonance fluorescence (NRF) measurement published more than 30 years ago, with limited precision in some cases [1]. A recent experiment with the AGATA demonstrator array aimed to determine level widths using the Doppler Shift Attenuation Method (DSAM) in 15O and 15N populated in the 14N + 2H reaction. In order to set a benchmark value for the upcoming AGATA demonstrator data, the widths of several 15N levels have been studied with high precision using the bremsstrahlung facility gELBE [2] at the electron accelerator of Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The precision of our new dataset are on a 10% level for the weak transitions, which have 60% and 100% error bars in the old dataset. The preliminary data seem to confirm the earlier NRF data.
- Supported by the Helmholtz Association (HGF) through the Nuclear Astrophysics Virtual Institute (HGF VH-VI-417).

[1] R. Moreh et al., Phys. Rev. C 23, 988 (1981).
[2] R. Schwengner et al., Nucl. Inst. Meth. A 555, 211 (2005).

Keywords: Level widths, nuclear astrophysics, bremsstrahlung
  • Poster
    13th international symposium on Nuclei in the Cosmos (NIC-XIII), 07.-11.07.2014, Debrecen, Hungary
  • Poster
    Fifteenth International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics (CGS15), 25.-29.08.2014, Dresden, Germany
Registration No. 21596

Background intercomparison with escape-suppressed germanium detectors in underground mines
Szücs, T.; Bemmerer, D.
Abstract: A key requirement for underground nuclear astrophysics experiments is the very low background level in germanium detectors underground. The reference for these purposes is the world’s so far only underground accelerator laboratory for nuclear astrophysics, LUNA. LUNA is located deep underground in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400 m of rock. The background at LUNA was studied in detail using an escape-suppressed Clover-type HPGe detector [1]. Exactly the same detector was subsequently transported to the Felsenkeller underground laboratory in Dresden, shielded by 45 m of rock, and the background was shown to be only a factor of three higher than at LUNA when comparing the escape-suppressed spectra, with interesting consequences for underground nuclear astrophysics [2]. As the next step of a systematic study of the effects of a combination of active and passive shielding on the cosmic ray induced background, this detector is now being brought to the "Reiche Zeche" mine in Freiberg/Sachsen, shielded by 150 m of rock. The data from the Freiberg measurement will be shown and discussed. – Supported by the Helmholtz Association (HGF) through the Nuclear Astrophysics Virtual Institute (HGF VH-VI-417).

[1] T. Szücs et al., Eur. Phys. J. A 44, 513 (2010)
[2] T. Szücs et al., Eur. Phys. J. A 48, 8 (2012)

Keywords: Underground, nuclear astrophysics, low background
  • Lecture (Conference)
    DPG Frühjahrstagung, Fachgruppe Hadronen und Kerne, 21.03.2014, Frankfurt, Germany
Registration No. 21595

Gamma-ray width measurements in 15N at the ELBE nuclear resonance fluorescence setup
Szücs, T.; Bemmerer, D.; Massarczyk, R.; Schwengner, R.; Takács, M.; Wagner, L.
Abstract: The stable nucleus 15N is the mirror of the astrophysically important 15O, compound nucleus of the leading reaction of the Bethe-Weizsäcker cycle of hydrogen burning. Most of the 15N level widths below the neutron and proton emission thresholds are known from just one nuclear resonance fluorescence (NRF) measurement published more than 30 years ago, with unsatisfactory precision on some cases [1]. A recent experiment with the AGATA demonstrator array aimed to determine level widths with the Doppler Shift Attenuation Method (DSAM) in 15O and 15N populated in 14N + 2H reaction. In order to set a benchmark value for the upcoming AGATA demonstrator data, the widths of several 15N levels are being studied using the bremsstrahlung facility γELBE at the electron accelerator of Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The γELBE experiment and its preliminary results will be presented. – Supported by the Helmholtz Association (HGF) through the Nuclear Astrophysics Virtual Institute (HGF VH-VI-417).

[1] R. Moreh et al., Physical Review C 23, 988 (1981)

Keywords: Nuclear astrophysiscs, level widths, gamma scattering, bremsstrahlung
  • Lecture (Conference)
    DPG Frühjahrstagung, Fachgruppe Hadronen und Kerne, 20.03.2014, Frankfurt, Germany
Registration No. 21594

Underground nuclear astrophysics (Dubna lecture)
Szücs, T.
Abstract: The very low background level is a key requirement for underground nuclear astrophysics experiments. The reference for these purposes is the world’s so far only underground accelerator laboratory for nuclear astrophysics, LUNA. LUNA is located deep underground in the Gran Sasso laboratory in Italy, shielded from cosmic rays by 1400m of rock.
This talk presents the need and the advantages of an underground setting. It covers also new findings, regarding active shielding at underground settings, leading to have the possibility to perform nuclear astrophysics experiments with sufficient precision also at shallow underground.
Finally the recent nuclear astrophysics related experiments performed at the surface, at LUNA, and at different underground depths will be presented.

Keywords: Underground, Nuclear Astropysics, low background
  • Invited lecture (Conferences)
    Helmholtz International Summer School "NUCLEAR THEORY AND ASTROPHYSICAL APPLICATIONS", 29.07.2014, Dubna, Russia
Registration No. 21593

Strategische Metalle und Mineralien - die BMBF Fördermaßnahme r³
Anke Dürkoop, G. G.
Abstract: Übersicht zur r³ Fördermaßnahme (Präsentation auf PIUS Länderkonferenz)
  • Invited lecture (Conferences)
    PIUS Länderkonferenz 2014, 02.07.2014, Frankfurt am Main, Deutschland
Registration No. 21588

Trace elements - small concentrations, great importance!
Frenzel, M.
Abstract: A lecture was given to school students (~ ages 16 - 18) about the industrial importance of certain trace elements occurring in different raw materials, and the methods used to study their behaviour in the related geological systems.
Keywords: Trace elements, geology, analytics
  • Lecture (others)
    Akademische Woche 2014, 13.02.2014, Meißen, Germany
Registration No. 21584

Trace elements - small concentrations, great importance
Frenzel, M.
Abstract: A presentation was given to school students (~ ages 16 - 18) on some aspects of trace elements occurring in different kinds of raw materials, their industrial importance, the uncertainties about their geological behaviour, and the methods used to study their occurrence and distribution in geological systems.
Keywords: Trace elements, Analytical techniques
  • Lecture (others)
    Akademische Woche, 13.02.2014, Meißen, Germany
Registration No. 21582

Selektive Trennung feinstdisperser Partikelsysteme mit Hilfe von Flotationstechniken
Schützenmeister, L.
Abstract: Deutschland ist eine der am höchsten technologisierten Industrienationen der Welt und liegt mit einem Rohstoffverbrauch von 200 kg pro Kopf und Tag ebenfalls mit an der Spitze [1]. Das Umweltbundesamt hat jedoch aus diesem Grund im Jahr 2012 nicht nur auf die damit verbundenen Umweltschäden hingewiesen sondern nachdrücklich fest-gestellt, dass Deutschland in der Zukunft sparsamer mit seinen Ressourcen umgehen muss. Anderenfalls wird es in der Zukunft aufgrund wachsender Rohstoffpreise seine weltweite Führungsrolle verlieren [1]. Die modernen High-Tech-Produkte wie Smart-phones, Tablet-PCs und LEDs aber insbesondere auch „grüne“ Technologien wie So-larzellen, Elektromotoren und Windkraftanlagen sind alle eng mit dem Verbrauch selte-ner Metalle wie Gallium, Germanium und Indium sowie den sogenannten seltenen Er-den verknüpft [2,3]. Im Zuge des wirtschaftlichen Aufschwungs der Schwellenländer nimmt jedoch der Rohstoffbedarf weltweit rasant zu. Eine herausragende Rolle spielt dabei China, da sich dort über 97 % der weltweiten Förderstätten für seltene Erden befinden [1]. Aufgrund des wachsenden Eigenbedarfs hat China jedoch den Export seltener Erden bereits zwischen 2009 und 2012 um 38 % reduziert, Tendenz steigend [seltene Erden]. Gleichzeitig wird prognostiziert, dass sich der weltweite Bedarf bspw. an Neodym und Dysprosium in den nächsten 25 Jahren um ca. 700 und 2600 % stei-gern wird [4]. Dabei ist der Preis für eine Tonne Neodym, wie sie bspw. für die Herstel-lung des Elektromagneten eines leistungsstarken, getriebelosen Offshore-Windrades benötigt wird, zwischen 2005 und 2012 bereits von 25.000 auf rund 700.000 US-Dollar gestiegen [3]. Zwar werden auch heute noch neue, reichhaltige Lagerstätten entdeckt, wie zum Beispiel durch japanische Forscher im Pazifik im Jahre 2013, jedoch ist die Gewinnung speziell in großen Tiefen auf offenem Meer mit großen Problemen verbun-den [3].
Diese Faktoren haben in den letzten Jahren zu einem Umdenken in der Ressourcen-politik geführt. So wurde von der Bundesregierung im Jahre 2011 das Helmholtz-Institut für Ressourcentechnologie in Freiberg gegründet, mit dem Ziel neue Technolo-gien zu entwickeln, welche eine effizientere Bereitstellung und Nutzung mineralischer und metallischer Rohstoffe ermöglichen [2]. Das Hauptziel der Forschung liegt sowohl in der Nutzbarmachung komplexer Erze, wie sie auch in Deutschland lagern, deren Aufbereitung mit bisherigen Technologien jedoch nicht wirtschaftlich ist, als auch in der Entwicklung effizienter Recyclingmethoden für verbrauchte Rohstoffe [2]. Eine bedeu-tende Rolle nimmt dabei die Weiterentwicklung von Flotationstechniken, speziell auch der Kolonnenflotation, ein.
Seit Beginn der achtziger Jahre wurden insbesondere zur Nachanreicherung zuneh-mend Flotationskolonnen anstelle von Flotationszellen eingesetzt [5]. Diese zeichnen sich durch ein verbessertes Wertstoffausbringen und Anreicherungsvermögen, niedri-gere Anschaffungs- und Betriebskosten, geringeren Verschleiß und geminderten Platzbedarf aus [6].
Die heute geforderten Aufbereitungsziele erfordern in der Regel eine Zerkleinerung des Materials in den Feinstkornbereich. Klassische Schaumflotation versagt jedoch ab Korngrößen von x < 20 zunehmend [7]. Eine Lösung dieses Problems kann in der Anwendung der sogenannten Flüssig-Flüssig-Flotation in Flotationskolonnen liegen. Dabei wird anstelle von Luft eine organische Phase zur Flotation eingesetzt.
Die vorliegende Arbeit befasst sich daher mit der Konzeptionierung, dem Bau und dem Einfahren einer Versuchsanlage für Schaum- und Flüssig-Flüssig-Flotation. Weiterhin werden Grundlagenuntersuchungen, welche für einführende Flotationstests an der neuen Kolonne benötigt wurden, beschrieben.

Keywords: Flotation, extraction, particles, disperse systems
  • Bachelor thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Tom Leistner, Dr. Martin Rudolph
    77 Seiten
Registration No. 21581

Flüssig-Flüssig Flotation in einer Tropfensäule – Tropfendispersitätsanalyse und Selektivität im System Magnetit-Quarz
Müller, M.
Abstract: Die selektive Extraktion von hydrophobisierten Partikeln in einer Tropfensäule ist eine Heterokoagulationstrennung, wie die Flotation. Dieser neuartige Prozess soll als Erweiterung der Flotation, insbesondere für Partikel kleiner 10 µm dienen.
In dieser Masterarbeit ist die bestehende Tropfensäule am Institut für Mechanische Verfahrenstechnik und Aufbereitungstechnik der TU Bergakademie Freiberg zu erweitern, sodass die Tropfen mit einer kamerabasierten Methode im einfachen und doppelten Kreislauf als Funktion der Zeit und unter Berücksichtigung von grenzflächenaktiven Substanzen quantifiziert werden können. Hierfür wird ein Messfenster konzipiert und in die bestehende Anlage integriert. Es soll gezeigt werden, wie die Prozessregime die Tropfendispersität über der Zeit beeinflussen.
Des Weiteren wird die selektive Trennung von Magnetit und Quarz als akademisches Stoffsystem im Scheidetrichter untersucht. Hierfür sind die natürlichen Minerale auf eine mittlere Partikelgröße von 10 µm zu konfektionieren. Als Ergebnis der Trennung im Scheidetrichter unter Variation der hydrophobisierenden Substanzen (Fettsäuren für Magnetit, bzw. Amine für Quarz), sowie von Reglern (pH Wert ändernd) wird das erfolgreichste Reagenzregime auf erste Versuche für Trennungen in der Tropfensäule zum Ende der Arbeit übernommen und untersucht. Zudem wird das natürliche Magnetit in separaten Versuchen ersetzt mit synthetischen gefällten Magnetit Nanopartikeln.
Die Untersuchungen erfolgen am Institut MVTAT in Kooperation mit dem Helmholtz-Institut Freiberg für Ressourcentechnologie des Helmholtz-Zentrums Dresden-Rossendorf.

Keywords: flotation, extraction, drop formation, magnetite, quartz
  • Master thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Tom Leistner, Dr. Martin Rudolph
    86 Seiten
Registration No. 21579

Flotation eines Seltene-Erden-Erzes mit dem Wertmineral Eudialyt
Ludwig, K.
Abstract: Bei der Herstellung moderner elektronischer Produkte sind Erze mit Seltenen Erden unverzichtbar. Ein Beispiel hierfür ist eudialythaltiges Erz, welches das chemische Element Yttrium beinhaltet. Yttrium wird z.B bei der Produktion von Leuchtstoffen, Laserkristallen, Keramiken für Zündkerzen und Lambda-Sonden verwendet. Daneben wird es zur Steigerung der Festigkeit in einigen Legierungen genutzt. Der Anteil an Yttrium im Eudialyt-Mineral ist sehr gering. Eudialyt selbst ist außerdem stark in anderen silikatischen Mineralen verwachsen. Zudem ähneln diese silikatischen Minerale aufgrund ihrer chemischen Struktur dem Eudialyt. Die Gewinnung und Anreicherung dieses Wertstoffes aus dem Erz ist daher eine Herausforderung für die Aufbereitungsindustrie. Eine Dichtesortierung ist aufgrund der ähnlichen Dichten der einzelnen Minerale nicht möglich. Zurzeit untersucht man zwei Trennverfahren hinsichtlich ihrer Brauchbarkeit: Magnetscheidung und Flotation. Bei der Flotation spielen die Wechselwirkungen zwischen den einzelnen Mineralen und den zugesetzten Reagenzien eine entscheidende Rolle. Letztere bieten Ansatzmöglichkeiten für eine Steuerung der Flotation. Daher werden auch gegenwärtig immer wieder neue Reagenzien entwickelt und damit neue flotative Verfahren geschaffen. Im Rahmen dieser Arbeit ist die Aufbereitung eines eudialythaltigen Erzes aus Norra Kärr in Schweden mit Hilfe der Flotation zu untersuchen. Dabei wird der Einfluss von verschiedenen Reagenzien, der sogenannten Sammler und Drücker, auf die Anreicherung der einzelnen Bestandteile des Aufgabegutes analysiert.Weiterhin werden die Flotationsergebnisse von entschlammten und nicht entschlammten Proben verglichen. Die Versuche finden sowohl in saurem als auch in basischem Milieu statt. Die Zusammensetzung des Aufgabegutes und der Konzentrate wird mit Hilfe der
Röntgendiffraktometrie ermittelt.

Keywords: eudialyte, rare earth elements, Flotation, aegirine, collector, hydroxamate, oleate
  • Bachelor thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Dr. Martin Rudolph
    84 Seiten
Registration No. 21578

Charakterisierung partikelhaltiger Öl/Wasser-Emulsionen - Phasenzusammensetzung und Stabilitätsbetrachtung
Landgraf, K.
Abstract: Seit Jahrzehnten steigt die Nachfrage nach Rohstoffen und die Anforderung aus diesen einen Wertstoff möglichst rein anzureichern. Durch die zunehmende Rohstoffknappheit werden längst sekundäre Rohstoffquellen genutzt, aber auch primäre Quellen, in welchen der Wertstoff nur zu geringen Anteilen und in sehr hohen Verwachsungsgraden vorkommt. Für den Aufbereitungsprozess ist es von Nöten den Rohstoff so weit aufzuschließen, dass der Wertstoff getrennt von dem Bergematerial vorliegt. Bei einem stark verwachsenen Material entsteht dadurch ein hoher Anteil an Feingut, welches in nachgeschalteten Sortierprozessen Probleme bereitet.
Etabliert zur Feinstgutaufbereitung sind die Verfahren der Heterokoagulationstrennung, in denen Berge- und Wertstoffmaterial auf Grund verschiedener physikalischer Eigenschaften sortiert werden [1], [2], [3].
Die Schaumflotation ist der am häufigsten angewandte Prozess, wobei Partikel mit einem Durchmesser zwischen 5 und 5000 mm flotiert werden können [4]. Am effizientesten werden Partikel im Größenbereich zwischen 10 mm und 100 mm [5], [6], [7] erfasst. Damit kann in diesem Größenbereich eine hohe Produktqualität erzielt werden.
Partikel, die kleiner als 10 mm sind, bereiten im Flotationsprozess Probleme und wurden darum meist vor der Flotation abgetrennt. Der darin enthaltene Wertstoff kann somit nicht gewonnen werden.
Um auch die im Feinstanteil vorkommenden Rohstoffe nutzbar zu machen, wurde für einige Anwendungen der Schaumflotationsprozess modifiziert.
Beispielsweise wurde die Flüssig-Flüssig-Flotation entwickelt, bei der die feinen Feststoffpartikel anstatt mit Luftblasen, mit einer zweiten fluiden, mit Wasser nicht mischbare Phase koagulieren. Dies kann den Trennerfolg im Aufbereitungsprozess verbessern.
Noch setzten sich diese Prozesse in der großtechnischen Aufbereitung nicht durch, unter anderem da sie kostenintensiv sind und der Einsatz von Öl umweltproblematisch ist. Des Weiteren entsteht im Verlauf der Flüssig-Flüssig-Flotation eine Emulsion, die durch die feinen Partikel stabilisiert wird. Ein Sortierprozess ist erfolgreich, wenn es gelingt die Feststoffpartikel selektiv auszutragen und die entstehende Emulsion zu brechen. Erst dann liegen die Wertstoffpartikel getrennt von den fluiden Phasen und dem Bergematerial vor.
Um weiterhin den Rohstoffbedarf decken zu können, sollten sich Bemühungen darauf richten, diese Verfahren zu optimieren, um sie in der Aufbereitung hoch aufgeschlossener Rohstoffe einsetzen zu können.
Diese Arbeit handelt von partikelstabilisierten Emulsionen, die in einem Flüssig-Flüssig-Flotationsprozess entstehen. Mineralisches Magnetit und Quarz mit einer Partikelgröße dP,80 < 10 mm [8] werden eingesetzt und lagern sich im Versuchsverlauf an Öltropfen, die in Wasser dispergiert sind und stabilisieren diese. Die so entstehenden Emulsionen werden von der wässrigen Phase getrennt und Untersuchungen zu Phasenzusammensetzung sowie Stabilität der Emulsionen durchgeführt.
Dies soll dazu beitragen, Erkenntnisse zu deren Handhabung und Destabilisierung zu erhalten und somit auf lange Sicht die Anwendbarkeit der ölbasierten Flotationsprozesse zu ermöglichen [2], [3], [6], [8], [9].

Keywords: Flotation, extraction, Emulsion, colloidal stability
  • Bachelor thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Tom Leistner, Dr. Martin Rudolph
    119 Seiten
Registration No. 21577

Oberflächenladungseigenschaften von synthetischen Selten-Erden Karbonaten und Selten-Erden Phosphaten und Wirkung von Sammlern und Drückern
Kratzsch, R.
Abstract: Das Helmholtz-Institut Freiberg für Ressourcentechnologie wurde im August 2011 als Institut des Helmholtz-Zentrum Dresden-Rossendorf gegründet um sich ressourcentechnologischen Fragestellungen für primäre und sekundäre Rohstoffe mit strategischen Metallen zu widmen. Die Abteilung Aufbereitung befasst sich insbesondere mit der Trennung von feinen Partikeln basierend auf unterschiedlichen Benetzungseigenschaften der Oberflächen, wie dem Prozess der Flotation. Im Fokus bzgl. Wertstoffen liegen insbesondere die Metalle der Seltenen-Erden, welche wichtig sind für High-Tech Anwendungen und somit essentiell für die deutsche Industrie.
In dieser studentischen Arbeit sollen die Oberflächenladungseigenschaften von synthetischen Selten-Erden Karbonaten (SEE-CO3) und Selten-Erden Phosphaten (SEE-PO4) im Vergleich zu Calciumcarbonat und Bariumcarbonat systematisch untersucht werden. Die physikochemischen Eigenschaften sind über den pH-Wert zu variieren. Die Wirkung von Fettsäuren als Sammler, sowie von Ligninsulfonat als Drücker sind zu untersuchen. Die Partikel sind granulometrisch zu beschreiben.
Die Untersuchungsmethoden umfassen hierbei:
- Mikroflotationsuntersuchungen in einer Hallimondröhre
- Zeta-Potential Bestimmung mit Zetasizer Nano ZS
- Partikelgrößenmessung mit Laserbeugung
- Bestimmung der spezifischen Oberfläche mit der BET-Methode
- Dichtebestimmung mit Pyknometer
- Schwingungsspektroskopie mit ATR-FTIR
- Adsorptionsuntersuchungen unter Verwendung von UV/VIS
Die Arbeit umfasst zudem eine begleitende Literaturrecherche unter Berücksichtigung aktuellster wissenschaftlicher Erkenntnisse zum Thema.

Keywords: Flotation, rare earth elements, collector, depressant, zeta potential
  • Bachelor thesis
    TU Bergakademie Freiberg, 2013
    Mentor: Dr. Martin Rudolph
    53 Seiten
Registration No. 21576

Vergleich von Carbonsäuren, Alkylhydroxamaten und Sarkosinaten als Sammler für die Apatitflotation
Klöpfel, K.
Abstract: Am Helmholtz-Institut Freiberg für Ressourcentechnologie werden Technologien entwickelt, um die Verfügbarkeit wirtschaftskritischer mineralischer Rohstoffe für die deutsche und europäische Industrie zu sichern. Ein wichtiges Wertmineral ist Apatit, aus dem Phosphor, sowie in Spuren Seltene Erden Metalle gewonnen werden kann. Die Flotation spielt hierbei eine wichtige Rolle, um Silikate und Carbonate als Gangminerale abzutrennen. Üblicherweise kommen Carbonsäuresalze als Sammler für die direkte Flotation zum Einsatz, wobei deren Selektivität besonders gegenüber den Carbonaten gering ist. Es existieren mit den Sarkosinaten und Hydroxamaten molekular ähnliche Substanzen, die in dieser Arbeit bzgl. Ihres Flotierbarkeitsverhalten zu Apatit untersucht werden sollen. Die Wirkung der zu vergleichenden Sammler wird in dieser Arbeit mit Hilfe von Oberflächenspannungsmessungen, Zeta-Potential-Bestimmungen sowie Mikroflotationsuntersuchungen an der reinen Mineralphase des Fluor-Apatits untersucht.
Es ist zudem die aktuelle Literatur zum Thema zu recherchieren und zusammenzutragen.

Keywords: flotation, apatite, collector, sodium oleate, sodium sarcosinate, potassium octyl hydroxamate, zeta potential
  • Bachelor thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Dr. Martin Rudolph
    72 Seiten
Registration No. 21575

Partikelsonden Rasterkraftmikroskopie - Untersuchung der hydrophoben Eigenschaften von Mineraloberflächen im Kontext der Flotation
Kaminsky, P.
Abstract: Das Helmholtz-Institut Freiberg für Ressourcentechnologie führt Grundlagenforschungen zur flotativen Aufbereitung von Erzen durch. Ein wichtiger Aspekt der Flotation ist die selektive Hydrophobisierung von Mineralen des Erzes. Der attraktive hydrophobe Effekt ist hierbei verantwortlich für die Anhaftung von selektiven Mineralen an Gasblasen und somit der Abtrennung dieser Mineralphasen aus einer gemahlenen Erzsuspension. Es wird eine Messmethode entwickelt, die es erlauben soll auf Mineralschliffen eines Erzes hydrophobe Eigenschaften ortsaufgelöst zu bestimmen. Grundbestandteil ist dabei die Partikelsonden-Rasterkraftmikroskopie (CP-AFM).
Diese Masterarbeit soll die CP-AFM Methode an grobkristallinen Magnetit- und Quarzproben unter Verwendung selektiver Sammler untersuchen. Die Ergebnisse dieser Hydrophobizitätsmessung sollen im Kontext gesetzt werden zu Mikroflotationsuntersuchungen der Stoffsysteme. Es soll die CP-AFM Methode kritisch analysiert werden. Neben den genannten Methoden sind die Stoffsysteme bzgl. der Sammlerwechselwirkung und der Benetzung näher zu untersuchen. Der aktuelle Stand der Forschung soll ebenfalls in einer Literaturrecherche erfasst und zusammengefasst werden.

Keywords: AFM, hydrophic interactions, Magnetite, quartz, Flotation, zeta potential, collector
  • Master thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Dr. Martin Rudolph
    120 Seiten
Registration No. 21574

Structural changes in amorphous GexSiOy on the way to nanocrystal formation
Nyrow, A.; Sternemann, C.; Sahle, Ch J.; Hohl, A.; Zschintzsch-Dias, M.; Schwamberger, A.; Mende, K.; Brinkmann, I.; Sala, M. Moretti; Wagner, R.; Meier, A.; Voelklein, F.; Tolan, M.
Abstract: Temperature induced changes of the local chemical structure of bulk amorphous GexSiOy are studied by Ge K-edge x-ray absorption near-edge spectroscopy and Si L-2/3-edge x-ray Raman scattering spectroscopy. Different processes are revealed which lead to formation of Ge regions embedded in a Si oxide matrix due to different initial structures of as-prepared samples, depending on their Ge/Si/O ratio and temperature treatment, eventually resulting in the occurrence of nanocrystals. Here, disproportionation of GeOx and SiOx regions and/or reduction of Ge oxides by pure Si or by a surrounding Si sub-oxide matrix can be employed to tune the size of Ge nanocrystals along with the chemical composition of the embedding matrix. This is important for the optimization of the electronic and luminescent properties of the material.
Keywords: KeyWords Plus:VISIBLE PHOTOLUMINESCENCE; GE NANOCRYSTALS; ALLOY-FILMS; SILICON NANOCRYSTALS; THIN-FILMS; MICROCRYSTALS; MEMORY; LUMINESCENCE; EXCITATIONS; DEFECTS Registration No. 21573

Investigation of the surface free energy of several minerals by iGC (inverse gas chromatography) and correlation with floatability
Hartmann, R.
Abstract: It is well known that the flotation process separates particles with different wettability dispersed in water. The fundamental physical-chemical property therefore is the specific surface free energy of the mineral surface which together with the specific surface free energy of water causes wettability phenomena besides the surface morphology (e.g. roughness). Inverse Gas Chromatography is a tool which enables determination of the specific surface free energy of powders. There are a few reports on the correlation of flotation response and surface free energy, however the crucial problem is that the flotability is determined in water and the surface free energy is evaluated in the dried powder phase. To determine the effect flotation chemicals have on the specific surface free energy of minerals it is important to investigate the preparation of the dried powder after conditioning with the chemicals in water.
In this Master thesis different minerals (quartz, apatite and magnetite) and ionic collectors (sodium oleate and dodecyl ammonium acetate) with crucially different surfactant adsorption mechanisms will be used to determine floatability and specific surface free energy with different steps of preparation, i.e. washing with mother liquid only or further with solvents with another polarity. The flotation response and the specific surface free energy shall be put in context. It is important to find the proper presentation of the surface free energy components and define a quantitative description of hydrophobicity. It should finally, based on the results, be described in which way flotation samples should be treated for iGC measurements.
The literature is to be researched and summarized for the latest information on the topic.

Keywords: inverse gas chromatography, flotation, surface free energy, wettability, hydrophobicity
  • Master thesis
    TU Bergakademie Freiberg, 2014
    Mentor: Dr. Martin Rudolph
    113 Seiten
Registration No. 21572

Charge trapping of Ge-nanocrystals embedded in TaZrOx dielectric films
Lehninger, D.; Seidel, P.; Geyer, M.; Schneider, F.; Klemm, V.; Rafaja, D.; von Borany, J.; Heitmann, J.
Abstract: Ge-nanocrystals (NCs) were synthesized in amorphous TaZrOx by thermal annealing of co-sputtered Ge-TaZrOx layers. Formation of spherical shaped Ge-NCs with small variation of size, areal density, and depth distribution was confirmed by high-resolution transmission electron microscopy. The charge storage characteristics of the Ge-NCs were investigated by capacitance-voltage and constant-capacity measurements using metal-insulator-semiconductor structures. Samples with Ge-NCs exhibit a maximum memory window of 5 V by sweeping the bias voltage from −7 V to 7 V and back. Below this maximum, the width of the memory window can be controlled by the bias voltage. The fitted slope of the memory window versus bias voltage characteristics is very close to 1 for samples with one layer Ge-NCs. A second layer Ge-NCs does not result in a second flat stair in the memory window characteristics. Constant-capacity measurements indicate charge storage in trapping centers at the interfaces between the Ge-NCs and the surrounding materials (amorphous matrix/tunneling oxide). Charge loss occurs by thermal detrapping and subsequent band-to-band tunneling. Reference samples without Ge-NCs do not show any memory window Registration No. 21569

Towards a novel THz-based monitor for sub picosecond electron bunches working at MHz repetition rates and low bunch charges
Kovalev, S.; Green, B.; Golz, T.; Kuntzsch, M.; Fisher, A.; Stojanovic, N.; Gensch, M.
Abstract: Femtosecond level diagnostic and control of sub-picosecond electron bunches is an important topic in modern accelerator research. At the same time new quasi-cw linear electron accelerators are the drivers of many future 4th Generation lightsources such as X-ray free electron lasers. A high duty cycle, high stability and online pulse to pulse diagnostic of these new accelerators are crucial ingredients to the success of these large scale facilities. A novel THz based online monitor concept is presented that has the potential to give access to pulse to pulse information on bunch form, arrival time and energy at high repetition rate and down to sub pC charges. It has been shown experimentally that pulse to pulse arrival time measurements can be used to perform high temporal resolution and dynamic range experiments, removing the influence of synchronization problems between the accelerator and external laser systems.
  • Poster
    4th workshop on longitudinal instrumentation for future accelerators, 15.-16.01.2015, Villigen, Switzerland
Registration No. 21567

Re-Green Indicator System
Dirlich, S.
Abstract: The presentation deals with the development of an indicator system for the sustainability assessment of green policies dedicated to retrofitting of buildings, urban districts, and entire cities.
Based on existing building sustainability assessment schemes a specific indicator system is developed meeting the requirements of the Re-Green project.
The flexible and modular structure of the system allows an adaptation of the sustainability assessment to the particular circumstances and conditions of the region/city to be evaluated.

Keywords: sustainability assessment; green building; retrofit
  • Invited lecture (Conferences)
    FutureBuild 2014, 05.-06.11.2014, Sheffield, Großbritannien
Registration No. 21566

High magnetic field study of the Dy2Fe17Hx compounds with x = 0-3.8
Isnard, O.; Andreev, A. V.; Heczko, O.; Skourski, Y.
Abstract: The Dy2Fe17Hx compounds crystallizing in a hexagonal Th2Ni17-like structure are studied on aligned powder by magnetization measurements carried out in steady (up to 5 T) and pulsed (60 T) magnetic fields at 4.2-300 K. Dy2Fe17 is a ferrimagnet with TC = 375 K and a spontaneous moment of 16.5 μB/f.u. Magnetization curves recorded for two different crystal orientations for Dy2Fe17Hx polycrystalline oriented samples show that the insertion of hydrogen in the Dy2Fe17 crystal lattice significantly modifies the magnetization, Curie temperature and intersublattice exchange interactions of the Dy2Fe17 phase. The high-field behavior of Dy2Fe17 is compared with that of its hydrides derivatives. Despite different types of magnetic anisotropy, the high-field behavior of the hydrides and the parent compound is qualitatively similar. Depending upon the composition, they can exhibit easy plane or else conical type anisotropy as for x = 0 and 3, respectively. The low temperature spontaneous magnetization exhibits a moderate composition dependence, it first decreases continuously upon increasing the hydrogen composition up to x = 3 then slightly increases for x = 3.8 reflecting the Fe sublattice evolution. A mean Fe moment of about 2.1 μB is derived for Dy2Fe17H3.8 composition, this magnetization value is close to that of the original Dy2Fe17 compound. It is found that the intersublattice coupling between the Fe and Dy sublattices is reduced as illustrated by the decrease of the nDy-T coefficient from about 3.3 down to 2.82 T f.u./μB for Dy2Fe17 and Dy2Fe17H3.8, respectively. Registration No. 21563

Highly transparent and conductive Al-doped ZnO films synthesized by pulsed laser co-ablation of Zn and Al targets assisted by oxygen plasma
You, Q.; Cai, H.; Gao, K.; Hu, Z.; Guo, S.; Liang, P.; Sun, J.; Xu, N.; Wu, J.
Abstract: Highly optically transparent and electrically conductive Al-doped ZnO (AZO) thin films were deposited by pulsed laser co-ablation of a Zn target and an Al target in an oxygen plasma. Zn ablation resulted in the reactive deposition of ZnO films assisted by the plasma, while Al ablation provided the growing ZnO films with Al dopants. The morphology, composition and structure as well as the optical and electrical properties were characterized and the effects of Al doping and annealing treatment were investigated. The deposited AZO films have a hexagonal wurtzite structure with deteriorated crystal quality which can be improved by annealing. The AZO films are highly transparent from ultraviolet up to 1450 nm and present an obvious blue shift in absorption edge and a widening of band gap compared with undoped ZnO. The electrical properties were also improved after annealing with the resistivity decreasing by over two orders of magnitude because of the increase of free carrier concentration. The variation in the carrier concentration also affects the absorption edge and the band gap of the films as well as the transparency in the infrared region. Meanwhile, this method offers an approach for in-situ doping preparation of other doped compound films with different dopant concentrations.
Keywords: Al-doped ZnO; Co-ablation deposition; Electrical properties; In-situ doping; Optical properties; Thin films Registration No. 21561

Study of the p\vec{d}→n{pp}s charge-exchange reaction using a polarised deuterium target
Gou, B.; Mchedlishvili, D.; Bagdasarian, Z.; Barsov, S.; Garbonell, J.; Chiladze, D.; Dymov, S.; Engels, R.; Gaisser, M.; Gebel, R.; Grigoryev, K.; Hartmann, M.; Kacharava, A.; Khoukaz, A.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Li, Z.; Lomidze, N.; Lorentz, B.; Macharashvili, G.; Merzliakov, S.; Mielke, M.; Mikirtychyants, M.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Shmakova, V.; Ströher, H.; Tabidze, M.; Trusov, S.; Tsirkov, D.; Uzikov, Y.; Valdau, Yu.; Wang, T.; Weidemann, C.; Wilkin, C.; Yuan, X.
Abstract: The vector and tensor analysing powers, Ayand Ayy, of the p d→n{pp}scharge-exchange reaction have been measured at a beam energy of 600MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3MeV on the diproton excitation energy ensured that the two protons were dominantly in the 1S0state, here denoted by {pp}s. The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥160MeV/c. These data provide a good continuation of the earlier results at q ≤140MeV/cobtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam. Registration No. 21560

Subthreshold Xi- Production 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.; Göbel, 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, Yu. G.; Spataro, S.; Spruck, B.; Ströbele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Trebacz, R.; Tsertos, H.; Vasiliev, V.; Wagner, T.; Weber, M.; Wendisch, C.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y. V.
Abstract: Results on the production of the double-strange cascade hyperon Ξ 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. For the first time, subthreshold Ξ production is observed in proton-nucleus interactions. Assuming a Ξ phase-space distribution similar to that of Λ hyperons, the production probability amounts to PΞ−=(2.0±0.4(stat)±0.3(norm)±0.6(syst))×10−4 resulting in a Ξ/(Λ+Σ0) ratio of PΞ−/ PΛ+Σ0=(1.2±0.3(stat)±0.4(syst))×10−2. Available model predictions are significantly lower than the estimated Ξ yield. Registration No. 21556

(V,Nb):TiO2 - a transparent conductor and ferromagnetic semiconductor !?
Cornelius, S.
Abstract: Both the property combinations a) transparent conductivity and b) diluted magnetic semiconductivity are based on the concept of dispersed substitutional doping of a suitable semiconductor with dopants that provide free electrons and/or carry a magnetic moment. The implications of current point defect theory with respect to defect formation enthalpies in anatase TiO2 are discussed in context with experimental results on electrical, optical and magnetic properties of V and Nb doped TiO2 thin films prepared by reactive magnetron sputtering. While transparent conductivity could be achieved via Nb doping, V doped films remain paramagnetic (in contrast to theoretical predictions).
Keywords: anatase, titanium oxide, magnetron sputtering, transparent conductive oxide, doping, magnetic semiconductor
  • Lecture (Conference)
    Deti.2 project meeting, 22.10.2014, Dresden, Deutschland
Registration No. 21553

Dopant activation and charge transport limits in transparent conductive (Al,Ga):ZnO and Nb:TiO2
Cornelius, S.
Abstract: Transparent conductive oxides (TCOs) are a class of wide bandgap metal oxides in which high densities of free charge carriers can be induced in such a way, that a unique combination of high optical transmittance in the visible spectral range and metal-like electrical conductivity is achieved. The influence of the oxygen partial pressure, substrate temperature, dopant concentration and substrate type on the properties (Al,Ga) doped ZnO and Nb doped TiO2 thin films has been studied systematically. The correlations between electrical, structural and optical properties as well as the elemental composition of the films have been characterized by a combination of Hall-effect, XRD, spectroscopic ellipsometry, spectral photometry, RBS and PIXE techniques including complementary XANES and TEM studies. The results are discussed with a focus on understanding the dopant incorporation into the ZnO and TiO2 host materials as well as finding physical limits for the resistivity based on charge transport models for degenerate polar semiconductors.
Keywords: transparent conductive oxide, zinc oxide, doping, titanium oxide, anatase, electron mobility, reactive sputtering, magnetron sputtering
  • Invited lecture (Conferences)
    Institutsseminar, Institut für experimentelle Physik II, Universität Leipzig, 26.11.2014, Leipzig, Deutschland
Registration No. 21552

Formation and propagation of laser-driven plasma jets in an ambient medium studied with X-ray radiography and optical diagnostics
Diziere, A.; Pelka, A.; Ravasio, A.; Loupias, B.; Falize, E.; Kuramitsu, Y.; Sakawa, Y.; Morita, T.; Pikuz, S.; Yurchak, R.; Koenig, M.
Abstract: In this paper, we present experimental results obtained on the LULI2000 laser facility regarding structure and dynamics of astrophysical jets propagating in interstellar medium. The jets, generated by using a cone-shaped target, propagate in a nitrogen gas that mimics the interstellar medium. X-ray radiography as well as optical diagnostics were used to probe both high and low density regions. In this paper, we show how collimation of the jets evolves with the gas density. Registration No. 21551

Investigation of ionoluminescence of semiconductor materials using helium ion microscopy
Veligura, V.; Hlawacek, G.; van Gastel, R.; Zandvliet, H. J. W.; Poelsema, B.
Abstract: Helium ion microscopy has been employed to investigate the ionoluminescence of various semiconduc- tors. We have verified the possibility of application of this technique for high-resolution ionolumines- cence analysis of this kind of materials. In this work the ionoluminescence signal was induced by a sub- nanometer Heþ beam with an energy of 35 keV. Several types of semiconductor samples were investigated: bulk materials, nanowires and quantum dots. All samples were found to exhibit ionoluminescence. However, the ionoluminescence signal rapidly degrades under the ion irradiation. The signal degradation was found to depend not only on the sample's composition, but also on its size. The ionoluminescence emission spectra were recorded and emission peaks identified.
Keywords: Ionoluminescence Helium ion microscopy Semiconductors Nanowires Quatum dots Registration No. 21549

Hyperdoping silicon with selenium: solid vs. liquid phase epitaxy
Zhou, S.; Liu, F.; Prucnal, S.; Gao, K.; Khalid, M.; Baehtz, C.; Posselt, M.; Skorupa, W.; Helm, M.
Abstract: Chalcogen-hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of chalcogen elements in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. The high energy density deposited on the silicon surface leads to a liquid phase and the fast recrystallization velocity allows trapping of chalcogen into the silicon matrix. However, this method encounters the problem of surface segregation. In this paper, we propose a solid phase processing by flash-lamp annealing in the millisecond range, which is in between the conventional rapid thermal annealing and pulsed laser annealing. Flash lamp annealed selenium-implanted silicon shows a substitutional fraction of ≈ 70% with an implanted concentration up to 2.3%. The resistivity is lower and the carrier mobility is higher than those of nanosecond pulsed laser annealed samples. Our results show that flash-lamp annealing is superior to laser annealing in preventing surface segregation and in allowing scalability.
Keywords: Ion implantation, Solid phase epitaxy, Deep level impurity, Si Registration No. 21546

Ion irradiation and nanoindentation as a screening test for irradiation effects on neutron-irradiated ferritic/martensitic high-Cr steels
Heintze, C.; Akhmadaliev, S.; Altstadt, E.; Bergner, F.
Abstract: A combined approach based on ion irradiation and nanoindentation as a screening test procedure for the irradiation response of structural materials foreseen for components exposed to heavy neutron irradiation has been selected and specified in detail. Important constituents of the approach are:
• Design of the ion irradiation experiments using the MD code SRIM and taking into account recommendations according to [1], detailed documentation of the irradiation experiments and the SRIM calculations,
• Nanoindentation testing over a large range of indentation depths (from about 5% to 100% of the thickness of the ion-irradiated layer) to gain information on the indentation size effect and the substrate effect, analysis according to the Oliver-Pharr method [2,3],
• Elimination of the indentation size effect (ISE) based on an unirradiated reference sample of the same material using a suitable model (e.g. [4]), elimination of the substrate effect.

A version of the approach specified above was applied to unirradiated, ion-irradiated and neutron-irradiated 9%Cr F/M steel T91 (MATTER reference material). The findings indicate that the approach based on ion irradiation and nanoindentation is suitable as a screening test for F/M steels exposed to neutron irradiation.

References
[1] R. E. Stoller, M. B. Toloczko, G. S. Was, A. G. Certain, S. Dwaraknath, F. A. Garner, Nucl. Instrum. Methods Phys. Res. B 310 (2013) 75–80.
[2] W. C. Oliver, G. M. Pharr, J. Mater. Res., 7 (1992) 1564–1583.
[3] W. C. Oliver, G. M. Pharr, J. Mater. Res., 19 (2004) 3–20.
[4] W. D. Nix, H. Gao, J. Mech. Phys. Solids, 46 (1998) 411–425.

Keywords: ion irradiation, neutron irradiation, nanoindentation, irradiation hardening, ferritic/martensitic steels, T91
  • Lecture (Conference)
    MATTER - “MATerials TEsting and Rules“ Project Final Workshop, 20.-22.10.2014, Rom, Italy
Registration No. 21544

The Zn-vacancy related green luminescence and donor-acceptor pair emission in ZnO grown by pulsed laser deposition
Wang, Z.; Su, S. C.; Younas, M.; Ling, F. C. C.; Anwand, W.; Wagner, A.
Abstract: Low temperature (10 K) photoluminescence study shows that green luminescence (GL) peaked at 2.47 eV and near band edge (NBE) emission at 3.23 eV are introduced in undopd ZnO grown by pulsed laser deposition (PLD) after the 900°C annealing. The NBE emission exhibiting blue shift with increasing temperature is assigned to the transitions of donor-acceptor-pair (DAP)/free-electron-to-acceptor (FA). Positron annihilation spectroscopy (PAS) study shows that the introduction of the GL is correlated with the formation of the Zn vacancy-related defect (VZn). Comparing the transition energies of VZn obtained by the previous first principle calculation [Janotti and Van de Walle, Phys. Rev. B 76, 165202 (2007)], the GL is associated with the transition from the conduction band to the ε(-/2-) state of VZn and the DAP/FA emission involves the acceptor level ε(0/-) of VZn.
Keywords: ZnO, green luminescence, Zn vacancy, Registration No. 21543

Influence of the discharge regime on Ti thin films growth and properties in dc, single pulsed and chopped high power impulse magnetron sputtering
Meško, M.; Heller, R.; Hübner, R.; Krause, M.
Abstract: High power impulse magnetron sputtering (HiPIMS) has been becoming an appealing deposition process for synthesis of high quality coatings over the last decade. It utilizes average power similar to the dc magnetron sputtering (DCMS) applied on magnetron target, which is however concentrated in short pulses. This ensures generation of dense plasmas with high fraction of ionized film forming species. Control over the energy and trajectory of ionized sputtered species can lead to the formation of coatings with improved properties. Despite of certain advantages the HiPIMS process has often a lower deposition rate compared to DCMS. This is one reason which hinders the HiPIMS process from further exploration in industrial applications. However more recently it has been shown that deposition rates of Ti thin films can be significantly increased by so called chopped-HiPIMS (c-HiPIMS) technique [1]. In this case a single HiPIMS pulse is decomposed into several individual pulses with microsecond pulse off-times. C-HiPIMS can be especially effective in suppression of thermal spikes on the target. The effect of thermal spikes is most pronounced during long single HiPIMS pulses. It negatively influences mobility of arriving ad-atoms leading to the formation of larger grains and rougher surface of Ti thin films [2]. In present work we compare the density, crystallinity, roughness, and microstructure of Ti thin films prepared by dc, single pulsed, and c-HiPIMS. Much attention has been paid on role of microsecond pulse off-times on Ti thin films properties. Plasma parameters have been measured to supplement our investigations.
References:
[1] P. M. Barker, E. Lewin, and J. Patscheider “Modified high power impulse magnetron sputtering process for increased deposition rate of titanium” J. Vac. Sci. Technol. A 31 (2013) 0606041
[2] F. J. Jing, T. L. Yin, K. Yukimura, H. Sun, Y. X. Leng, and N. Huang “Titanium film deposition by high-power impulse magnetron sputtering: Influence of pulse duration” Vacuum 86 (2012) 2114

Keywords: HiPIMS, Ti thin film, microstructure, plasma parameters
  • Poster
    14th International Conference on Plasma Surface Engineering, 15.-19.09.2014, Garmisch-Partenkirchen, Deutschland
Registration No. 21542

The effect of He on irradiation hardening of Fe-9Cr-based non-ODS and ODS alloys at 300°C
Heintze, C.; Kögler, R.; Bergner, F.; Hernández Mayoral, M.
Abstract: The influence of helium on the irradiation hardening and embrittlement of reduced-activation ferritic/martensitic Cr-steels and their oxide dispersion strengthened variants under fusion-relevant irradiation conditions is still a concern. While the fact that He can influence the mechanical properties is well established [1,2], the underlying mechanisms are not fully understood [1,2]. In this work the effect of He and displacements per atom (dpa) on the irradiation-induced hardening of an Fe-9at%Cr alloy, Eurofer97 and an oxide dispersion strengthened variant of Eurofer (ODS-Eurofer) at 300°C was studied. Self-ion irradiation was applied to simulate the neutron-irradiation-induced damage. To separate the effect of helium different irradiation modes were applied. Apart from single-beam irradiations with He or self-ions, only, Helium was implanted prior to (pre-implantation), simultaneously (dual-beam irradiation) or following the (post-implantation) self-ion irradiation. The ion irradiated layer was characterized by means of nanoindentation. We conclude, that:
• there is a significant interaction between dpa and He
• pre-implantation of He followed by self-ion irradiation is not suitable to replace simultaneous irradiations or to simulate neutron irradiation induced damage
• nano-oxides in ODS-Eurofer mitigate the effect of helium on irradiation hardening

[1] H. Trinkaus, B.N. Singh, J. Nucl. Mater. 323 (2003) 229
[2] R. Schäublin, Y.L. Chiu, J. Nucl. Mater. 362 (2007) 152

Keywords: irradiation hardening, ODS, dual-beam, ion irradiation, nanoindentation
  • Poster
    2nd International Workshop on ODS Materials, 26.-27.06.2014, Dresden, Deutschland
Registration No. 21541
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