Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The application of electric currents during solidification can cause grain refinement in metallic alloys. However, the knowledge about the mechanisms underlying the decrease in grain size remains fragmentary. This study considers the solidification of Al-Si alloys under the influence of electric currents for the configuration of two parallel electrodes at the free surface. Solidification experiments were performed under the influence of both direct currents (DC) and rectangular electric current pulses (ECP). The interaction between the applied current and its own induced magnetic field causes a Lorentz force which produces an electro-vortex flow. Numerical simulations were conducted to calculate the Lorentz force, the Joule heating and the induced melt flow. The numerical predictions were confirmed by isothermal flow measurements in eutectic GaInSn. The results demonstrate that the grain refining effect observed in our experiments can be ascribed solely to the forced melt flow driven by the Lorentz force.

The solidification of Al - 7 wt. % Si alloys under the influence of electric current pulses (ECP) through two parallel electrodes at the melt surface is investigated. An effective grain refinement was found if the ECP is applied during the initial solidification period (nucleation and recalescence). The grain size can be gradually reduced, which is likely due to the remelting process of high-order dendrite arms in the mushy zone driven by solute fluctuation and promoted by thermal fluctuation. This fragmentation process is mainly driven by electromagnetically forced convection. The grain refinement does not require the formation of nuclei from a solidified shell near the electrodes, which would result in a grain rain inside the sample.

Multiphase flows are frequently applied in industrial processes as e.g. in chemical engineering, oil industries or power plants. Reliable predictions of the flow characteristics such as local concentration of species, interfacial area density or heat transfer in gas-liquid flows can contribute to an optimization of the design of corresponding apparatuses and processes. Computational Fluid Dynamics (CFD) in principle allows the simulation of such flows and provides local flow characteristics. While it is frequently used for industrial problems in case of single phase flows it is not yet mature for two-phase flows. The reason is the complex gas-liquid interface. For medium and large scale flow domains it is not feasible to resolve all details of this interface. Averaging procedures have to be applied and in most cases the so-called two- or multi-fluid approach is used. It assumes interpenetrating phases and the information on the interface gets lost by these averaging procedures. This information has to be added to the basic balance equations by so-called closure models. The development and validation of such models is done at Helmholtz-Zentrum Dresden – Rossendorf (HZDR) to obtain tools for reliable predictions of multiphase flow characteristics in medium and large industrial scales.
One difficulty for the model development and validation results from the fact that we still have a lack of knowledge on local phenomena which determine the two-phase flow characteristics and which should be considered in the closure models. Experimental data with high resolution in space and time are required. To get such information on the gas-liquid interface new innovative measuring techniques as wire-mesh sensors and ultrafast X-ray tomography were developed at Helmholtz-Zentrum Dresden – Rossendorf (HZDR) and extensively used to establish comprehensive databases. The corresponding experiments were conducted at the TOPFLOW-facility of HZDR. It can be operated for air-water and steam-water flows with a pressure up to 7 MPa and the corresponding saturation temperature of 286 °C. An electrical steam generator with a power of 4 MW is able provide up to 1.5 kg steam per second.
In this keynote lecture the strategy of the CFD-model development and validation for multiphase flows is presented. This includes the corresponding experimental work and development of innovative measuring techniques.

A clear progress was achieved during the last 20 years in the qualification of CFD-codes for problems of the nuclear safety research. Especially two-phase flows are important, e.g. for LOCA scenarios, but up to now the predictive capabilities of CFD-methods for such flows are limited. Two-phase flows are determined by complex interactions between the phases. Some of them are not yet well understood at the local scale and, therefore, CFD models are limited. This paper discusses such local phenomena and their reflection in presently available CFD-models. It turns out that most of the assumptions in the formulation of closure models for the multi-fluid approach reflect the real phenomena only in a coarse way. Possible uncertainties are listed. Nevertheless, the simulation results obtained by the HZDR baseline model for poly-disperse flows in which all models including model parameter are fixed show in general a rather good agreement with experimental data. One sensitive issue seems to be how to handle the bubble size. In case of poly-disperse flows the sub-division of the gas phase with respect to the bubble size is important and the exact choice of the limits for this division sensitively influences the simulation results.

In this talk an overview on the CFD activities at HZDR is given. The general strategy to qualify CFD for multiphase flows is presented. Examples for specific topics related to nuclear safety research are discussed.

Modifications of magnetic and magnetooptical properties of Pt/Co/Pt tri-layers upon irradiation with ion beam are investigated in this work. They are studied in detail as a function of the Co layer thickness, dCo (up to 5 nm), ion species (Ne+, Ar+, Ga+) the energy of ions, E (up to 30 keV) and ion fluence, F (range from 1013 to 3∙1016 ions/cm2). Modified magnetic properties are correlated with structural features of irradiated samples. Numerical simulations of in-depth atomic concentration profile and surface etching carried out by TRIDYN software complements explanation of the observed effects.
MBE grown Pt/Co/Pt tri-layers display a spin reorientation transition (SRT) at a well-defined Co thickness, dSRT from out-of-plane to in-plane magnetization alignment as dCo increases. Upon ion irradiation various processes undergo: degradation of chemically sharp interfaces, formation of Co-Pt alloys and lattice strain development [1, 2]. Spread interfaces reduce perpendicular anisotropy whereas formation of the ordered alloy may strength this property. Therefore a resulting magnetic state of the sample is a product of interplay of these two opposing trends in anisotropy evolution and the sample surface etching, particularly effective for highest fluences. It is very sensitive to dCo, ion species, their energy and the ion fluence.
Discussion is focused on results obtained with Ar+ ions irradiation, which is commonly used for technological processes especially for nanostructures sputtering. Set of (dCo, log F) diagrams of remanence, mr (Figure. 1), (normalized magnetization perpendicular component) measured by means of magnetooptical Kerr effect magnetometry in polar configuration (PMOKE) upon irradiation with Ar+ ions with different energies. Irradiation of the samples modifies magnetic properties in various manners depending on dCo, F and ion energy. The suppression of the dSRT with F in the range from 1013 to 1014 ions/cm2 and formation of branch(es) corresponding to strong perpendicular anisotropy (higher value of mr) are the most distinguished differences depending on the ion energy. As the ion energy increases a single branch with high mr (for 1.2 keV) begins to split into two parts for 5.0 keV, which are clearly separated for 30.0 keV. Qualitatively this evolution resembles that one already reported for Ga ions [1]. However, the mr modifications strength are weaker due to the lower mass of Ar atoms. Nevertheless, up to 5 transitions between various magnetic states are observed with F increase, e. g. for dCo = 1.6 nm and E = 30 keV. It is worth to notice that even the lowest applied energy of Ar+ ions induces visible modifications of magnetic properties. In the case of the lightest studied Ne ions modification of magnetic anisotropy is weaker than for Ar+ ions and the branches in a similar diagram are non-continuous.
TRIDYN software determined in-depth chemical profile (Figure 2) is helpful in identification of possible alloy composition being responsible for enhanced perpendicular magnetic anisotropy. Also the surface etching extent allows to estimate an amount of sputtered (also magnetic) material that may result in superparamagnetic state observed for the highest ion doses.
Structural properties of the irradiated samples are investigated by Rutherford backscattering (RBS). Evolution of the acquired chemical profiles is correlated with that simulated with TRIDYN software. Moreover, the etching efficiency is estimated from topography step profile between irradiated and non-irradiated areas of the sample investigated by means of profilometer and atomic force microscopy.
Discussed above abundance of magnetic investigated states in combination with controlled structural features developing upon ion irradiation enable a precise tuning of desired magnetic properties. In particular, such approach, exploiting a focused ion beam, might be of great importance in fabrication of magnonic crystals – a new type of metamaterial with reprogrammable band structure.

In this presentation the requirement to consolidate the CFD modelling for two-phase flows in frame of the Euler-Euler approach is discussed. To do that a baseline model strategy is proposed and illustrated by the HZDR baseline model for poly-dispersed bubbly flows.

Ion implantation of metal ions followed by annealing can be used for the formation of buried layers of metal nanoparticles in glasses with optical properties for perspective photonic materials. Results are presented from three samples of silica glasses implanted with Cu+, Ag+ or Au+ ions under the same conditions (energy 330 keV and fluence 1×10^16 ions/cm2) and three silica glass samples implanted with the same metals and conditions but coimplanted subsequently by oxygen into the same depth. All the implanted glasses were annealed at 600°C, which lead to forming of metal nanoparticles. The depth profiles measured by RBS and SIMS indicated that the sequential implantation of oxygen followed by post-annealing caused the shift of Cu, Ag and Au aggregated into nanoparticles deeper into the glass substrate. Both RBS and SIMS are shown to be valuable complementary techniques.

In 1974, Nelson, Kase, and Svenson published an experimental investigation on muon shielding using the SLAC high energy LINAC. They measured muon fluence and absorbed dose induced by a 18 GeV electron beam hitting a copper/water beamdump and attenuated in a thick steel shielding. In their paper, they compared the results with the theoretical models available at the time. In order to compare their experimental results with present model calculations, we use the modern transport Monte Carlo codes to model the experimental setup and run simulations. The results will then be compared between the codes, and with the SLAC data.

A very low background level is a key requirement for underground nuclear astrophysics experiments.
A detailed gamma-background study with two escape-suppressed HPGe detectors has been performed at a medium deep underground site, namely the Reiche Zeche mine (148m) in Freiberg, Germany [1]. The new data complement a data set with the same detector at other underground sites [2,3].
Now, detailed background data are available at the Earth’s surface and at underground sites with depths of 45m, 148m, 1400m from one and the same escape-suppressed HPGe detector. This allows to investigate the effect of the active and passive shielding on the high energy (E_g > 3 MeV) laboratory background.
A detailed interpretation of the behaviour of different background components as a function of the underground depth will be presented.

In addition to this work with gamma-ray detectors, the neutron background has been studied by 3He counters from the BELEN neutron detector, equipped with polyethylene moderators of various thicknesses in the Felsenkeller laboratory (45m). By mean of the varied moderation, spectral information of the neutron flux is derived. The same detectors and same method were used previously deep underground in Canfranc/Spain (850m) to measure the neutron flux and spectrum [4]. This allows a direct comparison of the two sites.

• Supported by the Helmholtz Association (HGF) through the Nuclear Astrophysics Virtual Institute (HGF VH-VI-417), and via the Helmholtz Young Investigators Group LISA (VH-NG 627).

[1] T. Szücs et al., Eur. Phys. J. A 51, (2015) 33
[2] T. Szücs et al., Eur. Phys. J. A 44, (2010) 513
[3] T. Szücs et al., Eur. Phys. J. A 48, (2012) 8
[4] D. Jordan et al., Astropart. Phys. 42, (2013) 1

In 1974, Nelson, Kase, and Svenson published an experimental investigation on muon shielding using the SLAC high energy LINAC. They measured muon fluence and absorbed dose induced by a 18 GeV electron beam hitting a copper/water beamdump and attenuated in a thick steel shielding. In their paper, they compared the results with the theoretical models available at the time. In order to compare their experimental results with present model calculations, we use the modern transport Monte Carlo codes to model the experimental setup and run simulations. The results will then be compared between the codes, and with the SLAC data.

Results on activation calculation for the CHANDA project are presented.

Single layer thin films have been exposed to low energy alpha particles (4keV). Implanted doses are equivalent to those accumulated in 1, 2, 4 and 6 years of ESA Solar Orbiter mission operation. Two ions fluences have been considered. In order to change the total dose accumulated, for each ion flux the time of exposure was varied. Reflectance in the visible spectral range has been measured prior and after implantation. Results show no significant change in performances in gold and palladium, while a small decrease in performances is observed in iridium. The implantation rate does not seem to affect the experiment.

Ultrafast X-ray electron beam computed tomography (CT) is an imaging technique, which has been developed for measuring phase distributions in multiphase flows. For example, two- and multiphase flow experiments in vertical pipes, conventional and slurry bubble columns, fluidized beds, monolithic structures and bundle geometries could be evaluated by this technique. With extending the measurement system towards dual-plane imaging, the option of velocity measurement has been created and applied for instance in two-phase vertical pipe flow.
In this study, we focus on measuring velocities in particulate systems. Some methods for velocity evaluation can be adapted from gas-liquid flows, such as the cross-correlation technique for determining the velocity of gas bubbles. Now, we present a technique, which allows velocity evaluation of the solid particles. This is achieved by adding marker particles with higher X-ray absorption to the particle phase and determining their velocities representatively.
In this paper, two different velocity evaluation techniques are described and selected results achieved by conducting experiments on a spout fluidized bed are presented. This combination of spouting and fluidized bed is a rather new type of particulate system, which combines the advantages of both, but whose dynamics is yet not fully understood. The capability of ultrafast X-ray CT to recover phase distributions as well as velocity information from particulate systems in order to better understand the dynamics of particulate systems is demonstrated with this exemplary experiment.

I. INTRODUCTION
Defect-induced ferromagnetism provides an alternative for organic and semiconductor spintronics. Though it is weak, it can be stable above room temperature. Till now it has been confirmed at least in oxides [1, 2] and carbon based materials [3, 4]. Interestingly, the relation between magnetism and defects in Silicon was demonstrated decades ago [5]. Since then, some progresses were made [6-9] and push forward the research of magnetic Mn doped Si a lot but it is drawn little attention itself. Here, with the latest growth purifying technique and sensitive measurements, we investigated the magnetism in Silicon after neutron irradiation and try to correlate the observed magnetism to particular defects in Si.

II. RESULTS
Commercially available p-type Si wafer (Hefei Ke Jing) is cut into pieces for performing neutron irradiations. The magnetic impurities are ruled out as they can not be detected by secondary ion mass spectroscopy. The concentration of the main impurity Boron is around 4 × 1014 cm-3. Pieces are irradiated for varying durations, corresponding doses in the ranges of 1.91 × 1017 - 2.29 × 1018 n/cm2. Each piece is irradiated only once and pristine pieces are kept for the purpose of comparison.
Raman spectra show the patterns of Si crystals irradiated similar to that of the pristine one. The relative intensity variation confirms the slight damage induced by irradiation. Positron annihilation lifetime spectroscopy is performed to investigate the defect types. All the measured spectra are fit into an exponential function of three components. The lifetime τ2, usually corresponding to defects, takes value of 375 ps, independent of irradiation dose. This positron trapping center is assigned to a kind of stable vacancy clusters of hexagonal rings (V6) [10]. The fraction of the longer lifetime (τ2) component I2 is closely correlated with irradiation dose, which means the concentration of V6 is enhanced by increasing neutron doses.
After irradiation, the samples still show strong diamagnetism. Only weak paramagnetism can be found in zero-field-cooled / field-cooled magnetization. The ferromagnetic signal in Silicon after irradiation enhances and then weakens with increasing irradiation doses as shown in Fig. 1. The saturation magnetization can reach 6 × 10-5 emu/g at 5 K. At room temperature it still remains as much as 5 × 10-5 emu/g. In such a transition metal free system, the ferromagnetism in neutron irradiated Si is closely associated with V6 defects. A Silicon 2 × 2 × 2 supercell with a defect of V6 is built to understand the magnetism in neutron irradiated Silicon. Unfortunately, the V6 shows no spin-polarized state. The change of charge state or Boron doping can not make it spin-polarized, either. At this end, more efforts are needed to comprehend this phenomenon.

REFERENCES
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NeuLAND (new Large-Area Neutron Detector) is the next-generation neutron detector integrated into the R3B experiment, and is a key instrument for a major part of the physics program. NeuLAND features a high detection effciency, a high resolution, and a large multi-neutronhit resolving power, achieved by a highly granular design with a total of 3000 plastic scintillator bars [1]. In January 2013 the Technical Design Report [2] has been approved by FAIR, following the recommendation by the Expert Committee Experiments (ECE) at its first meeting in November 2012.
Here we report about the progress of the NeuLAND project, which was dominated in 2012 by the transition from prototypes to mass production. During the previous year 200 NeuLAND modules and their readout were purchased and brought into operation.

Absorber layers consisting of nanostructured Si are candidates for next generation thin film Si solar cells. For this aim, Si-SiO2 nanocomposites with crystalline sponge-like Si are promising materials since their band gap is increased by quantum confinement and since they provide electrical interconnectivity. Such nanosilicon has recently been fabricated by annealing of non-reactively sputter deposited SiOx films (x< 1). It is formed by solid state phase separation into a percolated network of Si nanowires. The phase separation is usually accompanied by crystallization of Si. Here, SiOx layers have been grown by ion beam sputter (IBS) as well as by reactive magnetron sputter (RMS) deposition. Phase separation into Si-SiO2 nanocomposites has been achieved by scanning a diode laser line source with dwell times in the ms range and compared to a furnace treatment lasting ~106 times longer. Furnace annealing of IBS and RMS deposited layers result in sponge-like and filament-like silicon nanostructures, respectively. Laser processing of IBS layers leads to morphologies self-similar to furnace annealed samples, but scaled up by a factor of ~10. This indicates that the faster phase separation mechanism occurs in the liquid state. It is expected that laser processing of RMS layers will result in sponge-like morphologies too, and not filament like ones due to the liquid state phase separation.

Line-shaped light beams from diode laser arrays permit homogeneous and long-term stable processing of surface layers. Here we report on thermally activated decomposition of SiOx using a commercial diode laser of the LIMO GmbH, with cw-operation at a wavelength of 808nm, a maximum power density of 30 kW/cm², a minimum line focus < 100 µm, and a variable scan speed. Dwell times from < 1ms to 100ms can be realized by adjusting the scan speed and focus width, which allows very Rapid Thermal Processing (vRTP) of surfaces layers. SiOx layers of < 1µm thickness have been grown on quartz by sputter deposition. Two different modes of thermal treatment have been used: Furnace annealing at 950°C for 90 minutes and vRTP with 17ms dwell time. Energy-Filtered Transmission Electron Microscopy (EFTEM) reveals that in both cases the homogeneous SiOx has been transformed into a sponge-like Si-SiO2 nanocomposite. Raman spectroscopy shows that the crystallinity of spongy Si is higher for the laser treated sample. Whereas the characteristic structure size of the spongy Si of the furnace annealed sample amounts to a few nm only, it is a few tens of nm for vRTP. It will be shown that in the furnace the phase separation proceeds in the solid state, whereas the more complete phase separation by laser treatment can only be understood by liquid state processes. The laser-synthesized Si nanosponge can be applied as new material in next generation solar cells.

In the upcoming R3B-FAIR facility, to achieve the design goal for high resolution neutron time-of-flight [1,2], various types of prototypes have been explored at several places [3,4,5,6]. The possible candidates for active material of such a spectrometer can be either Multigap Resistive Plate Chamber (MRPC) or conventional plastic scintillators. At initial stage of NeuLAND development, at Saha Institute of Nuclear Physics, Kolkata, MRPC design feasibility was studied extensively[3,5].

Shielding and activation analysis status of the MYRRHA research reactor is presented.

NeuLAND, the successor of the LAND time-of-flight neutron spectrometer is planned to be constructed of 5 × 5 × 250 cm3 scintillator bars of RP-408 [1] or equivalent. Light readout will be performed by 1" photomultiplier tubes (PMTs). A demonstration prototype of the detector concept was recently tested at GSI [2]. During the operation of the complete detector with 6,000 channels a significant number of photomultiplier tubes may have to be replaced each year. Recent developments in the field of semiconductor based photon readout systems [2, e.g.] raise the possibility of using Silicon Photomultipliers (SiPMs) for this task.

Absorber layers consisting of nanostructured Si are candidates for next generation thin film Si solar cells. For this aim, Si-SiO2 nanocomposites with crystalline sponge-like Si are promising materials since their band gap is increased by quantum confinement and since they provide electrical interconnectivity. Such nanosilicon has recently been fabricated by annealing of non-reactively sputter deposited SiOx films (x< 1). It is formed by solid state phase separation into a percolated network of Si nanowires. The phase separation is usually accompanied by crystallization of Si. Here, SiOx layers have been grown by ion beam sputter (IBS) as well as by reactive magnetron sputter (RMS) deposition. Formation of sponge-like Si-SiO2 nanocomposites has been achieved for the IBS deposited layers by scanning with a diode laser line source (LIMO GmbH) and furnace treatment. Laser processing leads to morphologies self-similar to furnace annealed samples, but scaled up by a factor of ~10. Moreover, the laser process proceeds approximately 106 times faster. The larger mean structure size for the shorter process is explained by a phase separation in the liquid state in contrast to a solid state process which has been observed for furnace annealing. Furthermore, filament-like morphologies produced by RMS deposition and furnace annealing are compared to those of the IBS deposited layers.

It is investigated whether NeuLAND may be reinstrumented with semiconductor based photosensors. Tests with an 11cm long slab of RP-408 plastic scintillator and a PiLas 45 ps laser diode system show time resolutions of σ = 100 ps.
The NeuLAND time-of flight detector for 1GeV neutrons will consist in its final configuration of 30 double planes of 100 scintillator bars (RP-408) each. Each bar of 270×5×5cm3 must be read out at each end. Thus altogether 6000 timing photomultipliers of 1” diameter are needed [1]. In order to limit their cost impact, it is being investigated whether parts of NeuLAND may be (re-)instrumented with semiconductor-based photosensors, socalled Silicon Photomultipliers (SiPMs). Previous experiments using the one-electron-per-bunch mode of the superconducting electron accelerator ELBE have shown that nearly full efficiency can be reached even when instrumenting one NeuLAND bar with just one 3×3mm2 SiPM [2]. However, in those first tests the charge resolution did not allow to separate single photons, and the time resolution did not fulfill the required σ ≤ 150 ps.

Topographical features on the nanometer scale are known to influence cellular behavior. The response of specific cell types to various types of surface structures is currently still being investigated. Alumina ceramics play an important role as biomaterials, e.g., in medical and dental applications. In this study, we investigated the influence of nanoscale surface features with low aspect ratio (< 0.1) on the response of osteoblast-like MG-63 cells. To this end, low-energy ion irradiation was employed to produce shallow nanoscale ripple patterns on Al2O3(0001) surfaces with lateral periodicities of 24 nm and 179 nm and heights of only 0.7 and 11.5 nm, respectively. The nanopatterning was found to increase the proliferation of MG-63 cells and may lead to pseudopodia alignment along the ripples. Furthermore, focal adhesion behavior and cell morphology were analyzed. We found that MG-63 cells are able to recognize surface nanopatterns with extremely low vertical variations of less than 1 nm. In conclusion, it is shown that surface topography in the sub-nm range significantly influences the response of osteoblast-like cells.

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.

During 2013 the NeuLAND (new Large-Area Neutron Detector) project passed the important step from prototype tests to series production. Being one of the key instruments of the R3B experiment [1] the NeuLAND demonstrator will be utilized in the 2014 beam times together with demonstrators of other major R3B components. NeuLAND is a highly granular detector composed of 3000 scintillator bars with a total volume of 250x250x300 cm3. It enables the detection of fast neutrons with high efficiency, high time and spatial resolution and a high resolving power for multi-neutron events [2]. Despite the compact cubical arrangement of the NeuLAND components, the detector is built up from individual subgroups with an independent functionality, the so-called NeuLAND double-planes. This modular design facilitates maintenance and it allows upon experimental needs to split the detector in subdetectors being located at different positions with respect to the target area.

Objectives: Ligands based on 3,7-diazabicyclo[3.3.1]nonane (bispidine) form very stable coordination compounds, particularly with Cu^II. Due to the formation of thermodynamically and kinetically very stable ⁶⁴Cu^II complexes, pentadentate I, hexadentate II and macrocyclic bispidines III are well suited for in vivo application. The bispidine scaffold has a number of options for derivatization that permit the introduction of additional functions such as biological vectors and fluorescent molecules. This allows the adjustment of defined features of solubility and of selective binding properties for in vivo applications with controllable targeting.

Methods: Bispidine ligands I and II were synthesized by two consecutive Mannich reactions. The bispidine dioxotetraaza macrocycle III was synthesized by cyclization of 5,7-dimethyl-1,3-diazabicyclononane with the bis(α-chloroacetamide) of o-phenylendiamine. ⁶⁴Cu was produced following an established protocol with high specific activities of 150-250 GBq/µmol. ⁶⁴Cu-labeling of bispidine ligands and peptide conjugates were performed using [64Cu]CuCl2 dissolved in 0.05 M 2-[N-morpholino]ethansulfonic acid (MES)-NaOH buffer (pH 5.5, 6.0, and 6.5). The stability of the ⁶⁴Cu^II-labeled bispidine ligands I – III was studied in the presence of an excess of human superoxide dismutase (SOD) and human serum using standard gel electrophoresis techniques. Biodistribution and PET studies were conducted in male Wistar rats. Small animal PET studies were performed in tumor (PC3, MPC^#) bearing mice.

Results: Bispidine ligands I and II form highly stable metal complexes with ⁶⁴Cu^II under mild conditions (ambient temperature, aqueous solution). ⁶⁴Cu-labeling of bispidine dioxotetraaza macrocycles III shows relatively rapid complex formation at 50°C. Challenge experiments with SOD and human serum indicate a high in vitro stability of ⁶⁴Cu^II complexes with bispidine ligands I – III. Biodistribution studies, showing rapid blood and tissue clearance, support the high complex stability in vivo. ⁶⁴Cu-labeled bispidine bioconjugates, incorporating specific vector molecules, such as bombesin and TATE peptides, permit clear tumor visualization with high target-to-background ratio.
Conclusions: Bifunctional bispidine ligands I - III represent a versatile platform for the development of new copper radiopharmaceuticals. The bispidine scaffold holds promising potential to tune the charge and lipophilicity of the radiocopper complexes and consequently to influence the biodistribution and pharmacokinetic properties. Moreover, bispidine ligands can be readily modified with appropriate vector molecules and fluorescence tags.
Acknowledgements: Financial support by the Helmholtz Virtual Institute NanoTracking (Agreement Number VH-VI-421) is gratefully acknowledged.
References:
[1] Comba, P., et al. (2007) Progr. Inorg. Chem. 46, 458-464.
[2] Juran S., et al. (2009) Bioconjugate Chem. 20, 347-359.
[3] Comba P., et al. (2013) Inorg. Chem. 52, 8131-8143.
[4] Comba, P., et al. (2014) Inorg. Chem. 53, 6698-6707.
[5] Stephan, H., et al. (2014) Chem. Eur. J. 20, 17011-17018.
[6] Zarschler K., et al. (2013), RSC Adv. 4, 10157-10164.
[7] Thieme S., et al. (2012) Appl. Radiat. Isot. 70, 602-608.

Objectives: Pyridine containing bifunctional chelating agents (BFCA) based on 1, 4, 7 – triazacyclononane backbones (DMPTACN) are suitable platforms for copper (II) complexes. These ligands rapidly form highly stable, inert square pyramidal complexes that are resistant to metal leaching.¹ The ligand structure enables convenient introduction of additional conjugatable functional groups like -COOH end groups to allow a regioselective coupling to various biomolecules for e.g. bombesin.² Since Cu-64 is a highly useful PET (positron emission tomography) radioisotope because of its intermediate half-life (⁶⁴Cu, t_1/2 -12.7 h) and a high resolution image, these conjugatable DMPTACN chelators can be coupled with various vectors for e.g., proteins, dendritic polymers in order to understand their detailed in vivo pharmacokinetic properties with respect to their ADME behavior. The current objective of the work was to synthesize new maleimide and -SCN derivatives of DMPTACN ligands which could be employed to be conjugated to anti-inflammatory dendritic polyglcerol sulfate (dPGS) & neutral dPG derivatives under mild conditions in order to study the metabolic fate of these potentially therapeutic polymers using positron emission tomography.
Methods: DMPTACN was synthesized by a 10-step process using an established protocol.¹ Two coupling groups such as maleimide (1) or isothiocyanate (2) have been attached for further conjugation. These ligands were then conjugated to the thiolated dPGS via Michael addition of 1 and also via direct labeling of 2 to dPGS amine to yield highly stable conjugates. ⁶⁴Cu was produced following an already established protocol with high specific activities of 150-250 GBq/µmol.^{3 64}Cu-labeling of the conjugates were performed using [⁶⁴Cu]CuCl₂ at ambient temperature in aqueous buffer solution (0.1 M MES/NaOH) and resulted in a radiochemical purity of ≥99% within a few minutes. Challenge experiments were conducted in presence of EDTA or copper seeking superoxide dismutase (SOD) for evaluation of in vitro stability.⁴ Biodistribution and PET studies were conducted in male Wistar rats.
Results: DMPTACN-dPG/S conjugates form highly stable metal complexes with ⁶⁴Cu under mild conditions (ambient temperature, aqueous solution) showing resistance to demetalation in vitro and high in vivo stability. Biodistribution data and PET experiments show a charge dependant excretion of the dPGS and dPG macromolecules.
Conclusions: DMPTACN ligands are a versatile platform which can be applied for labeling small molecules, proteins as well as polymers for detailed insight on their biodistribution profiles using ⁶⁴Cu that allows studying relatively long biochemical processes and thus, prove to be an attractive candidate for PET imaging.
Acknowledgements: This study is part of a research initiative “Technologie und Medizin – Multimodale Bildgebung zur Aufklärung des in-vivo Verhaltens von polymeren Biomaterialien” of the Helmholtz-Portfoliothema.
References:
[1] Gasser G., et al. (2008) Bioconjugate Chem. 19, 719-730.
[2] Bergmann R., et al. (2013) Eur. J. Med. Chem. 70, 434-446.
[3] Thieme S., et al. (2012) Appl. Radiat. Isot. 70, 602-608.
[4] Zarschler K., et al. (2013) RSC Adv. 4, 10157-10164.

kein Abstract vorhanden

Introduction: The 15.9 kg main mass of the Twannberg meteorite has been found in 1984 in the Canton of Bern, Switzerland. Five additional masses were found until 2007 [1]. Since then, nearly 100 new finds brought the known mass to ~37 kg. The Twannberg meteorite belongs to the small IIG group (6 members), which is characterized by a low concentration of nickel and large inclusions of schreibersite.
Here we study the cosmic ray exposure (CRE) history of 17 individuals of Twannberg using cosmogenic radionuclides and noble gases. We are especially interested in the terrestrial age of Twannberg to better understand its relation with the associated glacial sediments.
Experimental Methods: Noble gas isotopes (He, Ne, and Ar) are analyzed by noble gas mass spectrometry at the University of Bern following procedure described earlier [2,3]. Analyses of the cosmogenic radionuclides (¹⁰Be, ²⁶Al, ³⁶Cl, and ⁴¹Ca) are performed at the DREsden Accelerator Mass Spectrometry facility (DREAMS, [4]) adapted from procedures described in [5].
Results: So far, 17 samples have been analyzed for the noble gas; 6 of them have also been investigated for their cosmogenic radionuclide contents. We observed a wide range of noble gas and radionuclide concentrations (more than one order of magnitude). The noble gas and radionuclide concentration correlate, indicating the reliability of the analysis despite low concentrations. Combining the data with model calculations indicate a preatmospheric radius in range of 1 to 10 meters. Considering an average density of about 8 g/cm³ and assuming a spherical object, the Twannberg preatmospheric mass was greater than at least 33 tons.
The CRE age has been determined using the ³⁶Cl-³⁶Ar method [6]. The average CRE age is 243±64 Ma, which is in the range of typical CRE ages for iron meteorites [7] and which is in good agreement with the adopted age of 230±50 Ma found previously [1]. The average terrestrial age based on the ³⁶Cl/¹⁰Be-¹⁰Be systematics is 88±38 ka, indicating that the meteorite fell during the last glaciation, the Würm event (~110-15 ka), but before the maximum glaciation at 24 ka. We expect ⁴¹Ca measurements soon, which will help to further pin down the terrestrial age of the Twannberg meteorite and bring the fall into context of glacial events, as suggested by geological indicators [1].
References: [1] Hofmann B. et al. 2009. Meteoritics and Planetary Science 44:187-199. [2] Ammon K. et al. 2008. Meteoritics and Planetary Science 43:685-699. [3] Ammon K. et al. 2011. Meteoritics and Planetary Science 46:785-792. [4] Akhmadaliev S. et al. 2013. Nuclear Instruments and Methods in Physic B 294:5-10. [5] Merchel S. and Herpers U. 1999. Radiochimica Acta 84:215-219. [6] Lavielle B. et al. 1999. Earth and Planetary Science Letters 170:93-104. [7] Eugster O. 2003. Chemie der Erde-Geochemistry 63:3-30.
Acknowledgments: This work is supported by the Swiss National Science Foundation. We thank all the ion beam center members in Dresden for their precious help. This study is heavily based on a close cooperation with enthusiastic meteorite hunters.

Objectives: The α₇nAChR is involved in cognition and a potential drug target for treatment of Alzheimer’s disease and schizophrenia. ¹⁸F-DBT-10 is a candidate radioligand for α₇nAChR imaging (Kranz et al. J Nucl Med 2014; 55 (Suppl. 1):1143). We performed PET experiments in rhesus monkeys to assess its kinetic and imaging characteristics.

Methods: ¹⁸F-DBT-10 was prepared from its nitrophenyl precursor by nucleophilic substitution. The affinity of DBT-10 on human nAChRs was determined by radioligand binding studies. Dynamic PET imaging of two monkeys (each control and blockade) was performed using a Focus-220 scanner. Brain and plasma metabolites were analysed by HPLC. Regional volumes of distribution (V_T) were estimated from brain and plasma time-activity data.

Results: DBT-10 has high binding affinity to α₇nAChR (K_i = 0.60 nM) and excellent selectivity over other nicotinic receptor subtypes. ¹⁸F-DBT-10 was prepared in 14.5±4.6% radiochemical yield and >99% radiochemical purity (n=5). Free plasma fraction of ¹⁸F-DBT-10 was 18±2 % (n=4). Plasma metabolism varied considerable between the two animals. Brain uptake was high and tissue kinetics fairly fast, with peak uptake at 10-50 min (Figure 1). No radioactive metabolites were found in brain tissue (thalamus, frontal cortex, hippocampus, and cerebellum) taken from one monkey at 120 min p.i. Time-activity curves were fitted well with the 2-tissue kinetic model. Mean V_T values were 58.0, 57.5, 54.9, 54.5, 52.0, 48.4, 39.9, and 34.8 cm³/mL, respectively, for the thalamus, insular, frontal and cingulate cortices, striatum, temporal cortex, hippocampus, occipital cortex, and cerebellum (n=2). Pre-treatment with the selective α₇ ligand ASEM (0.69 & 1.24 mg/kg) dose-dependently reduced binding of ¹⁸F-DBT-10 in all regions by 30% and 64%, respectively.

Conclusions: ¹⁸F-DBT-10 is a novel PET radiotracer with high affinity and selectivity for the α₇nAChR. In rhesus monkeys it displays high uptake, appropriate kinetics and high specific binding in brain and thus is a promising agent for PET imaging of α₇nAChR in humans.

Figure 1. MR and PET VT images (left) and tissue TACs (right) from a baseline scan with 18F-DBT-10.

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High-energy short-pulse lasers are pushing the limits of plasma-based particle acceleration, x-ray generation, and high-harmonic generation by creating strong electromagnetic fields at the laser focus where electrons are being accelerated to relativistic velocities. Understanding the relativistic electron dynamics is key for an accurate interpretation of measurements. We present a unified and self-consistent modeling approach in quantitative agreement with measurements and differing trends across multiple target types acquired from two separate laser systems, which differ only in their nano-second to picosecond-scale rising edge. Insights from high-fidelity modeling of laser-plasma interaction demonstrate that the ps-scale, orders of magnitude weaker rising edge of the main pulse measurably alters target evolution and relativistic electron generation compared to idealized pulse shapes. This can lead for instance to the experimentally observed difference between 45MeV and 75MeV maximum energy protons for two nominally identical laser shots, due to ps-scale prepulse variations. Our results show that the realistic inclusion of temporal laser pulse profiles in modeling efforts is required if predictive capability and extrapolation are sought for future target and laser designs or for other relativistic laser ion acceleration schemes.

After the Fukushima accident the spent fuel pool has got a stronger focus in nuclear safety research. The objective of the German national joint project SINABEL (Safety of wet storage facilities for spent fuel) is the experimental investigation and modelling of the thermal hydraulics of fuel elements (10 fuel rods in square, D = 10 mm, P/D = 1.24) in the pool dry-out phase. Key parameters for validation of the models are the steam temperatures and velocities in the subchannels. Due to the complex geometry and the thermal insulation of the test facility there is a strong limitation in the optical and mechanical accessibility for measurements. As a result there is a need of novel measurement techniques to provide spatially resolved gas phase temperatures and velocities.
Our approach is a modified wire-mesh sensor that is usually used for phase discrimination in two-phase flows via the measurement of conductivity or capacity in the crossing points of the wires. In the new sensor concept we integrate special miniaturized converters, which are resistance thermometers for the temperature and velocity measurement. The advantage of this technique is the possibility to overheat the sensor by increasing the current through the sensor. By controlling the sensor temperature the use of the thermal anemometry principle becomes possible.
The challenges in the development of this combining measurement system are the boundary conditions. The range of the steam velocity is down to 0.01 m/s. The temperature range is from the water boiling temperature of 100 °C up to 500 °C overheated steam. As a result of this there are high requirements in temperature compensation and the mechanical resistivity of the measurement setup.
In the contribution we will describe both the new sensor technology as well as its application in thermal hydraulic experiments for advanced analysis of safety issues for the spent fuel pool.

For quantification of the thermal hydraulics in a heated rod bundle assembly the gas phase temperature and velocity in the subchannels has to be measured. The accessibility for sensors is strongly restricted due to the test facility design. In this paper the selection process for a suitable measurement device is presented. The approach is the modification of a wire-mesh sensor by implementation of special converters into the crossing points of the grid. Using a sensor material with a high thermal coefficient of resistance, both the resistance thermometer principle and the thermal anemometry principle, can be applicate by modulation of the sensor current.

Al doped ZnO (ZnO:Al) and Al–N co-doped ZnO (ZnO:Al–N) films were synthesized based on plasma assisted reactive deposition of ZnO matrix and in-situ doping of Al or co-doping of Al and N. Similar with undoped ZnO, the synthesized ZnO:Al and ZnO:Al–N films are hexagonal wurtzite in structure and exhibit high optical transparency in a wide spectral region. Al doping and Al–N co-doping in ZnO result in a significant variation of the optical properties in the ultraviolet (UV) region and an UV extension of the transparent range. Compared with undoped ZnO, the doped films show blue-shifted absorption edge of 320 nm and widened band gap of 3.69 eV after annealing in H2/N2 mixed gas because of the incorporation of dopants and the improvement in the crystal structure. The ZnO:Al film exhibits declined transparency in the near infrared (IR) region, while the ZnO film co-doped with Al and N preserves high transparency from near UV to medium IR in addition to the UV extension of the transparent range. The annealed ZnO:Al and ZnO:Al–N films show better electrical properties than those of the undoped ZnO film and the as-deposited doped ZnO films.

Despite high uranium concentrations (up to 14 mg L-1) and low pH (2.5 - 3.0) a high biodiversity was detected by culture independent methods in the flooding water of the former uranium mine Königstein (Saxony, Germany). In this study culture dependent methods were used for the isolation of eukaryotic microorganisms from the flooding water. It was possible to isolate different eukaryotic fungi with a glucose riche medium. The results of uranium immobilization tests showed high immobilization rates of about 120 to 160 mg uranium per 1 g dry mass. Flow cytometry experiments with KS5 and DSM 10134 were performed in liquid medium to quantitatively determine the uranium tolerance. In comparison, the isolate KS5 showed a higher uranium tolerance than the reference culture of DSM 10134 on solid as well as in liquid medium. In conclusion, this study indicates that eukaryotic microorganisms within a uranium-contaminated environment could potentially play an important role in the bioremediation of uranium.

X-ray absorption contrast techniques are an effective tool for investigating solidification processes in opaque metallic alloys. This work is devoted to the in situ visualization of the dendritic growth during the bottom-up solidification of a Ga-25wt%In alloy under natural and forced convections. Many effects of melt flow on the mushy zone structure were observed by standard X-ray radiography with a spatial resolution of 5-10 microns [1, 2]. The flow-induced variations of the local solute concentration result in an unsteady development of the primary dendrites and trigger or inhibit the development of secondary and tertiary arms. Variations of the vertical and lateral temperature gradients induce modifications of the melt flow pattern, which lead to different segregation structures and dendrite morphology.
A more detailed analysis of the particular processes (a detachment of side branches and growth of a dendrite tip) were carried out using synchrotron X-ray radiography with a spatial resolution of less than 1 µm. The synchrotron experiments were performed at the ROBL beam line (BM20, European Synchrotron Radiation Facility, Grenoble) at an energy of 28.5 keV. The combination of synchrotron X-ray radiography and synchrotron X-ray diffraction shows a big potential for orientation analysis of the growing grains and a lattice parameter determination of the solid phase.

X-ray radioscopic methods enable the in-situ real-time observation of solidification processes in metal alloys with a spatial resolution of a few microns. Visualization of bottom up directional solidification of a Ga-25wt%In binary metal alloy contained in a capillary slit container was conducted. The solidification is obviously affected by natural thermo-solutal melt flow patterns. Externally forced melt convection was superimposed by means of a magnetic stirrer in form of a rotating wheel equipped with permanent magnets. The electromagnetic flow provokes a considerable redistribution of the solutal boundary layers around the solidifying dendrites, and influences therewith the formation of the microstructure.
The X-ray radioscopy delivers a two-dimensional projection of the local density in the slit container corresponding to the distribution of the relative brightness P in the acquired images. The relative brightness P allows for an assessment of the local constitution inside the liquid phase. Our analysis of the flow field in the present article follows the Optical Flow approach proposed by Horn and Schunck. [1] The applied algorithm to determine the optical flow from the X-ray images delivers reliable information concerning the velocity field in regions where sufficiently large brightness gradients occurs. The solidification process creates differences of the local composition within the melt leading to characteristic pattern of transmitted light intensity. The analysis of the flow field relies on the monitoring of the temporal variations of characteristic brightness patterns in the liquid phase.
Our results show that melt flow induces various effects on the grain morphology primarily caused by the convective transport of solute. Our observations show a facilitation of the growth of primary trunks or lateral branches, suppression of side branching, dendrite remelting and fragmentation. The manifestation of all phenomena depends on the dendrite orientation, local direction and intensity of the flow. The forced flow eliminates the solutal plumes and damps the local fluctuations of solute concentration. It provokes a preferential growth of the secondary arms at the upstream side of the primary dendrite arms, whereas the high solute concentration at the downstream side of the dendrites can inhibit the formation of secondary branches completely. Moreover, the flow changes the inclination angle of the dendrites and the angle between primary trunks and secondary arms.

In this paper, we present mobility investigations of strained nMOS and pMOS short-channel transistors with dimensions down to 30-nm gate length. Using the geometrical magnetoresistance (MR) effect, carrier mobility of electrons and holes in the inversion channel of a recent state-of-the-art CMOS technology is presented from linear to saturation operation conditions. The MR effect allows for a more direct access to the carrier mobility compared with the conventional current/voltage and capacitance/voltage mobility derivation methods, in which series resistance, inversion charge density, and effective channel length are necessary to extract the mobility values of the short-channel devices. In another way, the MR effect can help to disentangle the performance gain of the strained state-of-the art devices to changes in channel mobility or device connection, e.g., series resistance effects.

The directional solidification of Ga–25wt%In alloys within a Hele-Shaw cell was visualized by X-ray radioscopy. The investigations are focused on the impact of melt convection on the dendritic growth. Natural convection occurs during a bottom up solidification because lighter solute is rejected during crystallization. Forced convection was produced by a specific electromagnetic pump. The direction of forced melt flow is almost horizontal at the solidification front. Melt flow induces various effects on grain morphology primarily caused by convective transport of solute, such as a facilitation of the growth of primary trunks or lateral branches, dendrite remelting, fragmentation or freckle formation depending on the dendrite orientation, the flow direction and intensity. Forced flow eliminates solutal plumes and damps local fluctuations of solute. A preferential growth of the secondary arms occurs at the upstream side of the dendrites, whereas high solute concentration at the downstream side inhibits the formation of secondary branches.

The quality of continuous cast steel is significantly affected by the flow pattern in the mould and submerged entry nozzle (SEN). The flow in continuous casting machines is often a two-phase one because argon is injected to avoid clogging inside the casting nozzle. Moreover, the argon bubbles are supposed to drag alumina particles and transport them towards the slag layer at the free surface. On the other hand, the gas injection leads to highly turbulent and complex two-phase flows, which are difficult to predict by numerical simulations. The injected bubbles have a distinct influence on the flow pattern and may trigger instabilities in the mold, for instance, observations made on real casters showed correlations between gas pressure variations in the SEN and mould meniscus perturbations.

Despite of the considerable number of previous studies mainly performed as numerical simulations and water models the understanding of liquid metal two phase flows remains fragmentary. Many open questions require further investigations, as concerns the formation process of gas bubbles, their distribution and flow regime in the SEN, the size of bubbles entering the mould, the flotation of the gas in the mould, the gas entrapment in the solidifying strand, etc. This situation motivated us to construct a specific model experiment where liquid metal two-phase flows can be investigated under flow conditions which are similar to those in the real continuous casting process.

We present an experimental study in a mockup of the continuous casting process. The two-phase flows in the mould and the SEN were visualized by means of X-ray radioscopy. The argon gas is injected through the tip of the stopper rod into the liquid metal flow. The system operates continuously with the low melting, eutectic alloy GaInSn under isothermal conditions. Experimental results will be presented and discussed accompanied by statistical analysis.

During the directional solidification of Ga-In25%wt., density variations in the liquid cause plumes of solute to be ejected from the interface through natural convection. This can lead to the formation of chimneys during solidification and ultimately freckles. The application of external magnetic fields can be used to suppress these plumes. Two magnetic systems are considered. The first is a rotating magnetic wheel, which provides conditions analogous to forced convection at the solidification interface. The forced convection causes preferential growth of secondary branches and the plumes to be transported downstream and back into the bulk. The second is the application of a static magnetic field, which interacts with inherent thermoelectric currents, generating a Lorentz force that drives fluid flow within the inter-dendritic region. However, in the bulk, where there are no thermoelectric currents electromagnetic damping dominates and plumes are stunted.

Using a fully coupled transient numerical model a quantitative analysis of each of these systems has been investigated. Figure 1 shows numerical results of the velocity profiles and dendritic morphology for each of these cases. Comparisons to experiments are given for the cases of natural and forced convection. The experimental setup uses a Hele-Shaw cell with an electric heater and Peltier cooler allowing for control over the thermal gradient and cooling rate.

This paper focuses on generating accurate 1-g cross section values that are necessary for evaluation of nuclide densities as a function of burnup for coupled Monte Carlo codes. The proposed method is an alternative to the conventional direct reaction rate tally approach, which requires extensive computational efforts. The method presented here is based on the multi-group (MG) approach, in which pre-generated MG sets are collapsed with MC calculated flux. In our previous studies we showed that generating accurate 1-g cross sections requires their tabulation against the background cross-section (σ0) to account for the self-shielding effect. However, in previous studies, the model that was used to calculate σ0 was simplified by fixing Bell and Dancoff factors. This work demonstrates that 1-g values calculated under the previous simplified model may not agree with the tallied values. Therefore, the original background cross section model was extended by implicitly accounting for the Dancoff and Bell factors. The method developed here reconstructs the correct value of σ0 by utilizing statistical data generated within the MC transport calculation by default. The method does not carry any additional computational burden and it is universally applicable to the analysis of thermal as well as fast reactor systems.

Using a fully coupled transient 3-dimensional numerical model, the effects of convection on the microstructural evolution of a thin sample of Ga-In25%wt. was predicted. The effects of natural convection, forced convection and thermoelectric magnetohydrodynamics were investigated numerically. A comparison of the numerical results is made to experimental results for natural convection and forced convection. In the case of natural convection, density variations within the liquid cause plumes of solute to be ejected into the bulk. When forced convection is applied observed effects include the suppression of solute plumes, preferential secondary arm growth and an increase in primary arm spacing. These effects were observed both numerically and experimentally. By applying an external magnetic field inter-dendritic flow is generated by thermoelectrically induced Lorentz forces, while bulk flow experiences an electromagnetic damping force. The former causes preferential secondary growth, while the latter slows the formation of solute plumes. This work highlights that the application of external forces can be a valuable tool for tailoring the microstructure and ultimately the macroscopic material properties.

Simultaneous study of solidification phenomena on different length scales (e.g. µm-sized dendrite morphology and mm-sized flow structures) raises a serious problem. Since several years X-ray radioscopy has been proposed and successfully used as an effective tool for in situ real time observations of the dendrite growth, concentration field and flow patterns. The upward directional solidification of Ga-25wt%In alloy within a Hele-Shaw cell was studied by in situ X-ray radioscopy. This work is focused on the investigation of the influence of natural convection on the concentration profiles, dendrite morphology, growth velocities, freckle formation and fragmentation. Additionally, we use the Optical Flow approach proposed by Boden et al. [1] for the estimation of the melt flow ahead of the solidification front.
The ascending plumes and the downward flow of In-rich melt lead to an inhomogeneous horizontal concentration profile along the solidification front. Variations of the vertical and lateral temperature gradients induce modifications of the melt flow pattern, which lead to different segregation structures and dendrite morphology. The dendrite growth velocity is mainly determined by the dynamics of the solute plumes which cause significant fluctuations of solute concentration. Our in situ experiments provide quantitative data on concentration, flow fields, tip velocity, etc. for the verification of actual models of freckle formation [2].
The second part of the study is devoted to the visualization of the fragmentation process in the mushy zone. Numerous events of detachment of secondary arms from the primary trunks occur in the deeper mushy zone. These fragments remain within the inter-dendritic regions. Fragments originating in the upper mushy zone can ascend by convective transport in the plumes and arrive in undercooled regions ahead of the dendritic front. Future work is in progress in order to classify our experimental data with respect to the known fragmentation mechanisms.

The directional solidification of Ga–25wt%In alloys within a Hele-Shaw cell has been studied by X-ray radioscopy. The investigations have focused on the influence of melt convection on the dendritic growth. Natural convection occurs during a bottom up solidification because a lighter solute is rejected during crystallization. Forced convection has been produced by a specific electromagnetic pump. The direction of forced melt flow is almost horizontal at the solidification front. Melt flow induces various effects on grain morphology caused primarily by convective transport of solute, such as facilitation of the growth of primary trunks or lateral branches, dendrite remelting, fragmentation or freckle formation depending on the dendrite orientation, the flow direction and intensity. Forced flow eliminates solutal plumes and damps local fluctuations of solute. A preferential growth of the secondary arms occurs at the upstream side of the dendrites, whereas high solute concentration at the downstream side inhibits the formation of secondary branches.

Investigating the complex interaction of conductive fluids and magnetic fields is relevant for a variety of applications from basic research in magnetohydrodynamics (MHD) to modeling industrial processes involving metal melts, such as the crystal growth process in the photovoltaic industry. This enables targeted optimizations of the melt flow and allows to significantly increase the yield and energy effciency of industrial processes. However, experimental studies in this field are often limited by the performance of flow instrumentation for opaque liquids. We present an ultrasound array Doppler velocimeter (UADV) for flow mapping in opaque liquids at room temperature. It is modular and flexible regarding its measurement configuration, for instance it allows capturing two velocity components in two planes (2d - 2c). It uses up to 9 linear arrays with a total element count of 225, driven in a parallelized time division multiplex (TDM) scheme. A FPGA-based signal pre-processing allows to handle the massive data bandwidth of typ. 1.2 GB/s and enables a continuous and near-realtime operation of the measurement system. The capabilities of the UADV system are demonstrated in a basic MHD research experiment with a metal melt (GaInSn) in a cubic container of (67 mm)³. The flow induced by a rotating magnetic field is captured with a temporal resolution of 250 ms for the horizontal and vertical central cross-section of the cube.

Optical free-electron lasers (OFELs) from the EUV to X-ray range can be realized in Traveling-Wave Thomson-Scattering (TWTS)[1,2] by utilizing pulse-front tilted high-power laser pulses as optical undulators.
The interaction distances required to induce microbunching to the electron beam for coherent radiation emission are realized in TWTS with a combination of side-scattering and a tilt of the laser pulse-front, as depicted in fig. 1. In the side-scattering geometry the electron beam and laser pulse directions of motion enclose the interaction angle. The tilt of the laser pulse-front by half of the interaction angle then ensures continuous overlap of electrons and laser while both are propagating in different directions. In this way, the interaction distances realized in TWTS are only limited by the transverse size of the laser and thus by the available laser power and size of available optics.
Our fully analytic theory of TWTS OFELs provides scaling laws for the electron and laser pulse quality requirements for OFEL operation. We show that TWTS OFELs can be realized with state-of-the-art technology in electron accelerators and laser systems if the presented scheme for dispersion control is applied. Thereby the variability of TWTS with respect to the interaction angle is used to control the electron and laser beam quality requirements. Especially the sub-μm transv. emittance beams from laser wakefield accelerators with energy spreads in the percent level can be used for the realization of all-optical FELs with acceleration and interaction distances in the centimeter range. An outlook on 3D simulations of TWTS OFELs using the particle in cell code PIConGPU is given.

Optical free-electron lasers (OFELs) from the ultra violet to x-ray range can be realized with Traveling-Wave Thomson-Scattering (TWTS). This becomes possible in TWTS by increasing the photon scattering efficiency of standard Thomson scattering geometries more than one order of magnitude by changing the interaction geometry. In TWTS a side-scattering geometry is used where the laser and electron propagation directions enclose the interaction angle $\phi$. Together with a tilt of the laser pulse front the interaction distance is increased in TWTS beyond the limits of head-on Thomson scattering. TWTS implements dispersion control of the laser pulse to compensate for variations of the optical undulator period originating from the pulse-front tilt. Altogether, the combination of side-scattering, pulse-front tilt and dispersion control in TWTS allows for meter-scale interaction distances in which the electron beam becomes microbunched and OFEL operation is achieved. These TWTS OFELs provide transverse coherence as well as brilliances an order of magnitude enhanced over standard head-on Thomson scattering geometries.
We present the scaling laws of TWTS OFELs derived from a fully analytic theory of the electron laser interaction in TWTS scattering geometries. TWTS OFELs can be realized in an all-optical setup with a meter-scale footprint using laser wakefield accelerated electrons featuring both ultralow transverse emittances and large energy spreads.

In Traveling-Wave Thomson-Scattering (TWTS) a high-power laser pulse is scattered off a relativistic electron pulse to realize optical free-electron lasers (OFELs) with a wavelength range from ultraviolet to Angstrom. TWTS employs a side-scattering geometry where laser and electron beam propagation direction enclose an interaction angle to become independent of the Rayleigh length limit for the maximum interaction distance inherent to standard head-on Thomson scattering geometries. For optimum spatial overlap between electrons and laser pulse in TWTS geometries the laser pulse features a pulse-front tilt. In this way, the electrons interact with all parts of the laser pulse and the brilliance of a TWTS light source become by orders of magnitude larger than in standard head-on geometries where spatial overlap between electrons and laser pulse is lost due to defocusing of the laser pulse. OFELs can be operated with TWTS using multi-hundred to petawatt class laser systems with beam diameters in the centimeter range since the interaction distance in TWTS can be controlled with the laser beam diameter in the interaction plane.
We show that interaction distances achieved in TWTS are long enough for microbunching of the electron beam and coherent amplification of the radiation from our 1.5D FEL theory for the interaction of electrons with laser fields in side-scattering geometries.
We give the scaling laws for the design of TWTS OFELs derived from this 1.5D theory and present possible experimental setups for TWTS OFELs using electrons from conventional and laser wakefield accelerators. We put emphasize on how the ultra-low emittance of a laser wakefield accelerator can be exploited to compensate for the one percent level energy spread and how laser pulse dispersion introduced with the pulse-front tilt in TWTS setups can be compensated with an additional pair of gratings in the laser pulse path before the interaction.

Traveling-Wave Thomson-Scattering (TWTS) realizes optical free-electron lasers (OFEL) from the extreme ultraviolet to the X-ray range with existing electron accelerators and high-power laser systems. In TWTS ultrashort laser pulses and relativistic electron bunches are utilized in a side-scattering geometry where laser pulse and electron bunch direction of motion enclose an interaction angle. The laser electric field thereby is the undulator field in which the electrons oscillate and emit radiation during the interaction. When the electrons traverse the laser beam cross-section, TWTS provides continuous overlap of electron bunch and laser pulse by employing a laser pulse-front tilt which compensates the spatial separation of electrons and laser at the beginning and end of the interaction originating from their different propagation directions. The combination of laser pulse-front tilt and side-scattering in TWTS enables interaction lengths long enough to induce microbunching of the electron beam leading to coherent amplification of the emitted radiation and the realization of TWTS OFELs.
We present the scaling laws for the electron beam and laser pulse requirements to operate TWTS OFELs and show with example scenarios that TWTS OFELs can be realized with existing radio-frequency accelerated electrons such as ELBE at HZDR as well as laser-wakefield accelerated electrons. We detail the necessary equipment in a TWTS OFEL experiment and discuss how current experimental limitations affect the design of TWTS OFEL setups.

No abstract needed

Defect-induced magnetism is attracting intensive research interest. It not only challenges the traditional opinions about magnetism, but also has some potential applications in spin-electronics. SiC is a new candidate for the investigation of defect-induced ferromagnetism after graphitic materials and oxides due to its high material purity and crystalline quality [1, 2]. In this contribution, we made a comprehensive investigation on the structural and magnetic properties of ion implanted and neutron irradiated SiC sample. In combination with X-ray absorption spectroscopy and first-principles calculations, we try to understand the mechanism in a microscopic picture.
For neon or xenon ion implanted SiC, we identify a multi-magnetic-phase nature [3]. The magnetization of SiC can be decomposed into paramagnetic, superparamagnetic and ferromagnetic contributions. The ferromagnetic contribution persists well above room temperature and exhibits a pronounced magnetic anisotropy. By combining X-ray magnetic circular dichroism and first-principles calculations, we clarify that p-electrons of the nearest-neighbor carbon atoms around divacancies are mainly responsible for the long-range ferromagnetic coupling [4]. Thus, we provide a correlation between the collective magnetic phenomena and the specific electrons/orbitals.
With the aim to verify if a sample containing defects through its bulk volume can persist ferromagnetic coupling, we applied neutron irradiation to introduce defects into SiC [5]. Besides a weak ferromagnetic contribution, we observe a strong paramagnetism, scaling up with the neutron fluence. The ferromagnetic contribution only occurs in a narrow fluence window or after annealing. We speculate that defect-induced ferromagnetism rather locally appears in particular regions, like surface/interface/grain boundaries.
[1] L. Li, et al., Appl. Phys. Lett. 98, 222508 (2011). [2] Y. Wang, et al., Phys. Rev. B 90, 214435 (2014). [3] Y. Wang,et al., Phys. Rev. B 89, 014417 (2014). [4] Y. Wang, et al., Sci. Reports 5, 8999 (2015). [5] Y. Wang, et al., Phys. Rev. B, submitted (2015).

Ge-based diluted magnetic semiconductors have drawn extensive attention over the past decades due to their potential to be applied in spintronic devices and to be integrated with the mainstream Si microelectronics as well. The hole-mediated effect in diluted magnetic semiconductors provides the possibility to realize the control of magnetic properties by the electrical control of free carriers. In this contribution, we will present the magnetic properties and X-ray absorption spectroscopy of Mn implanted Ge annealed by flashlamp.

Ternary AlxGa1−xN films with different Al compositions were synthesized on sapphire and Si substrates by pulsed laser co-ablation of a polycrystalline GaAs target and a metallic Al target in nitrogen plasma generated by electron cyclotron resonance discharge of N2 gas. Spectroscopy was used to characterize the synthesis process for the mechanisms responsible for AlxGa1−xN synthesis and film deposition. The synthesized AlxGa1−xN films were evaluated using field emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Raman scattering spectroscopy, transmission electron microscopy and optical transmission measurements. The AlxGa1−xN films have hexagonal wurtzite structure, which degenerates as the Al composition increases, and show high optical transparency with the absorption edge blue shifted and the bandgap widened with the increasing Al composition. A comparison of the synthesized AlxGa1−xN films with the binary GaN and AlN films synthesized by a similar method reveals their similarity in the structure and the optical properties.

The integration of III-V compound semiconductors into existing semiconductor technology is a milestone in future development of micro- and opto-electronics. III-V compound semiconductor nanocrystals (NCs) were fabricated in Ge and Si substrates by high-fluence ion implantation and short-time flash lamp annealing (FLA). The III-V NC formation takes place after amorphization due to implantation, followed by recrystallization via millisecond liquid phase epitaxy. Using this approach, GaAs and InAs NCs were fabricated. Whereas this formation process was recently investigated for Si, the case of Ge has not been reported yet but shows remarkable differences. In order to get III-V/Ge and III-V/Si heterojunctions in the form of free-standing III-V NCs on Ge and Si nanocolumns an additional selective etching of Ge and Si was performed using H2O2 and KOH solution, respectively.
Raman spectroscopy measurements confirmed the formation of III-V NCs within the particular, recrystallized matrices. The microstructural properties of the III-V NCs and the distribution of implanted species were investigated by scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (TEM), and Auger electron spectroscopy (AES). SEM and TEM images show distinct, crystalline NCs. Conductive atomic force microscopy (c-AFM) was performed to investigate the electrical behavior of the fabricated heterojunctions.

In the talk, the most important results obtained in the project for the system radionuclide/clay organics/clay rock are presented. The influence of salinity and temperature on complexation, sorption as well as diffusion/transport of radionuclides is discussed.

Pipe organs with their unique sound and beautiful housing are important objects of the cultural heritage. The instrument consists of a number of pipes (flute and reed), which are prone to heavy corrosion attack, resulting in a loss of voice. The atmospheric corrosion of reed (CuZn alloys) and flute pipes (PbSn alloys) is strongly enhanced by traces of volatile organic compounds (VOCs) and the alloy’s instability.
Experiments have been undertaken to explore the improvement of an aqueous corrosion with the high acetic acid concentration (2–5 v/v%) of CuZn and PbSn alloys, by deposition of protective films (Al2O3 and Al) in nano scale using Pulsed laser deposition and Magnetron sputtering. Afterwards, the samples were implanted with N+ ions using plasma immersion ion implantation. Such coating is then able to withstand stresses and vibrations due to sound generation in organ pipes, and it produces a barrier to VOCs and water vapor. Furthermore, for the treatments of new or slightly corroded flute pipes, solution of 4% Paraloid B-72 in toluene has been applied as corrosion inhibitor. The complete and overall application of the PB-72 improved significantly the corrosion resistance of flute pipes. The laboratory corrosion tests were combined with field studies at affected church organs.

The alpha–particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, alpha–particles were produced in the scintillator via 12C(n,alpha)9Be reactions. In the second approach, the scintillator was loaded with 2% of natSm providing an alpha–emitter, 147Sm, as an internal source. In the third approach, a scintillator flask was deployed into the water–filled SNO+ detector and the radioactive contaminants 222Rn, 218Po and 214Po provided the alpha–particle signal. The behavior of the observed alpha–particle light outputs are in agreement with each case successfully described by Birks’ law. The resulting Birks parameter kB ranges from (0.0066 +- 0.0014) cm/MeV to (0.0076+-0.0003) cm/MeV. In the first approach, the alpha–particle light response was measured simultaneously with the light response of recoil protons produced via neutron–proton elastic scattering. This enabled a first time a direct comparison of kB describing the proton and the alpha–particle response of LAB based scintillator. The observed kB values describing the two light response functions deviate by more than 5 sigma. The presented results are valuable for all current and future detectors, using LAB based scintillator as target, since they depend on an accurate knowledge of the scintillator
response to different particles.

Structural or chemical defects in materials can have a tremendeous effect on their functunality, e.g. in magnetic data storage or sustainable energy materials. Ion beam techniques are ideal methods for a controlled induction of defects, e.g. in thin films since the defect production rate can be controlled by the ion flux whereas the depth of generated defects can be controlled by means of the ion energy. The analysis of the defects generated, on the other hand, can be performed by means of positron annihaltion spectroscopy, where the positrons are implanted either from a radioactive source or from a free electron laser induced nuclear reaction.
In this tutorial, basic concepts of ion implantation as well as positron annihilation spectroscopy at HZDR will be presented. In addition, the effect of ion irradiation, i.e. defect generation, on the magnetic properties of metal alloys will be explained. We will focus on the potential of ion beams for writing magnetic nano- and microstructures. Moreover, magnetic , defect and structural properties of materials for hydrogen processing will be presented.

A major weakness of ion beam therapy is the absence of applicable tools for verifying the particle range in clinical routine. The application of the Compton camera concept for the imaging of prompt gamma rays, a by-product of the irradiation correlated to the dose distribution, is a promising approach for range assessment and even two-dimensional in vivo dosimetry. Multiple position sensitive gamma ray detectors arranged in scatter and absorber planes, together with an imaging algorithm, are required to reconstruct the prompt gamma emission density map. Conventional block detectors deployed in Positron Emission Tomography (PET), which are based on Lu2SiO5:Ce (LSO) and Bi4Ge3O12 (BGO) scintillators, are suitable candidates for the Absorber of a Compton camera due to their high density and absorption efficiency even for the prompt Gamma energy range (several MeV). We compare experimentally LSO and BGO block detectors in clinical-like radiation fields in Terms of energy, spatial and time resolution. The high energy range compensates for the low light yield of the BGO material and boosts significantly its performance compared to the PET scenario. Notwithstanding the overall superiority of LSO, BGO catches up in the field of prompt gamma Imaging and can be considered as a competitive alternative to LSO for the absorber plane due to its lower price and the lack of intrinsic radioactivity.

Scanning electron microscope-based automated mineralogy such as the Mineral Liberation Analyser (MLA) allows several automated procedures based on backscattered electron (BSE) image acquisition and the collection of energy-dispersive X-ray spectra of particles with a specified contrast in the BSE image. The collected spectra are classified with a standard mineral spectra list which has been collected and specified for the samples. Samples should be solid with a polished surface. Different measurement modes are available on the MLA which can deliver extensive sets of information as modal mineralogy, particle- and grain size/shape distribution, liberation, mineral association or intergrowth. SEM-based automated mineralogy is a well-established tool in applied mineralogy and mineral- and metallurgic processing. The features of this method can also be applied in wide areas of research fields including material sciences, geology or environmental sciences.

The dynamics of liquid drainage in inclined packed beds was studied experimentally using electrical capacitance tomography. The evolution of textural flow regimes and liquid saturation profiles were monitored as a function of bed tilt angle and bed height. Film and droplet textural regimes were discriminated during bed drainage tests. They consisted of a rapid step discharging, virtually at constant flow rate, ca. 80% of the poral dynamic liquid followed by a slower step of partially-saturated pores discharging the remaining 20%. The drainage time was markedly reduced upon tilting the column resulting ultimately in virtually bed-length independent drainage times. Bed inclination reduced the droplet paths to the vessel wall, stimulating migration and coalescence of liquid droplets towards the lowermost area of the column cross-section. This ensured sufficient hydraulic pressure nearby the high-porosity wall area to maintain enhanced liquid outflows. As a prospective process intensification artifice, inclining packed beds way exhibit superior advantage in stimulating drainage of tall vessels especially if emergency circumstances arise.

We show how the non-collinear magnetic arrangement of ferromagnetic Janus particles enables the construction of a rich phase diagram via static self-assembly in two dimensions.
Branched clusters of staggered chains, compact clusters, linear chains and single particles can be formed and interconverted via constant and low-frequency external magnetic fields. The magnetic anisotropy of the presented particles fundamentally adds new possibilities to controlled self-assembly

For quick screening of material properties, it is important to provide simple experimental test techniques to address specific aspects of material properties. Within work package 2 of the Euratom FP7-MATTER project, a small punch test collective exercise was conducted to critically evaluate the potential of this technique for the characterisation of irradiation hardening and embrittlement. The ferritic-martensitic 9%Cr-steel T91 was used. Several data sets were produced for two major specimen geometries by different European laboratories. The reproducibility and scatter of results expressed by coefficient of variation for the total and plastic energy, the elastic-plastic transition load, the maximum load and the displacement at maximum load was analysed. The largest scatter was observed for the elastic-plastic transition load and for the plastic energy. Correlations for the estimation of tensile properties were shown to be device dependent.The estimations of the ductile-to-brittle transition temperatures are in a good agreement in cases of identical main geometrical parameters. The SP tests of neutron irradiated T91 (dose between 2.3 and 4 dpa) showed that the equivalent Charpy transition temperature shifts obtained from SP tests are in very good agreement with KLST based values. Thus the small punch test is an appropriate tool for the screening of the neutron irradiation induced embrittlement. We also observed a significant effect of irradiation on the recalculated yield stress and ultimate tensile strength. In comparison with tensile data, the irradiation induced hardening was underestimated. The small punch test is less appropriate for the screening of hardening (yield stress increase) than it is for embrittlement.

This paper summarizes long-term operation conditions in European nuclear power plants. Recommendations for monitoring the radiation embrittlement of reactor pressure vessels during life extension periods (to 60 or 80 years) are presented. The guidelines were developed in the EURATOM FP7 project LONGLIFE. The work performed responds to the need for guidance to treat long term irradiation effects within the ageing management of NPPs, since the standard RPV surveillance programmes were designed for a time period of 40 years. In particular the following issues are addressed: re-use of tested surveillance speciems, transferability of material test reactor results to reactor operation conditions, extension of reactor pressure vessel surveillance programmes, withdrawal schemes for lon-term operation surveillance programmes.

Interest in the long-lived radioisotope 236U (t1/2 = 23.4 million years) has significantly increased recently, due to the emergence of environmental and earth science applications. Presently, only a few (AMS) accelerator mass spectrometry instruments are suited for this measurement. One major limitation is the relatively low total detection efficiency (on the order of 10^4), which is partly caused by a low stripping yield of the positive ion charge state selected after the tandem accelerator. It has been shown that high yield can be achieved using helium as stripper gas for uranium ion energies below 0.35 MeV. Here we investigate the potential of He stripping of U at the 3-MV tandem accelerator VERA. Phenomenological charge state distributions for U and Th are presented for terminal voltages from 1.0 to 1.7 MV. These terminal voltages provide better background rejection than possible below 1 MeV, and are suited to the widely used 1–3 MV workhorses of many accelerator mass spectrometry laboratories. The methods can be applied to other actinides also.

Skepsis und die daraus resultierende Frage, ob ein Kunstobjekt vielleicht ergänzt, restauriert oder gar gefälscht ist, sind berechtigt und stellen sich nicht nur dem Kunsthistoriker aus Museen, Sammlern oder interessierten Laien. Die Protonenstrahl-Analyse unterstützt bei der Suche nach der richtigen Antwort. Im Visier: eine Meißener Vase und ihr Deckel. Sowohl die chemischen Zusammensetzungen von Porzellanmassen und Glasuren als auch die Analysen von Pigmenten der Dekore auf Vasenkörper und Deckel beweisen, dass der Deckel nicht original, sondern eine spätere Ergänzung ist.

Secondary raw materials (SRM) are becoming increasingly more important in ensuring the stability of critical metal supply. Like for natural raw materials, processing and metallurgical treatment demands a detailed and meticulous geometallurgical characterisation. Unlike municipal solid waste and Waste Electrical and Electronic Equipment (WEEE), ashes, slags, dusts and other industrial residues are "produced" centrally in large quantities. In light of these circumstances, the logistics of supply is simpler. This makes these types of SRM ideal candidates for the extraction of critical metals.
Precise and accurate chemical and mineralogical data, knowledge of distribution of valuable and deleterious elements in the single phases as well as information about homogeneity and grain size distribution of the minerals are crucial for the development of new extraction technologies. Gaining these essential information can be achieved by using SEM-based automated mineralogical analysis. However, the large particle size range, the dominance of very small grain sizes (< 5 µm) and the diversity of phases are challenging for the analysis. Furthermore, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. To overcome these challenges we used complementary analytical methods, like XRD and optical microscopy. Two of them, High-Speed PIXE and the “MEGA” instrument are still in the stage of development. Both instruments deliver additional information about trace element distribution.
Nevertheless, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. We present initial results of ash and slag samples, like residues of pyrometallurgical recycling of spent lead batteries.

Along the value chain (exploration, mining, processing, recycling) generally solid samples of complex matrix and non-stoichiometric composition need to be analysed. Besides spatially-resolved analytics applied to technology development, bulk analytics is mainly used for characterisation of value components.
In the search of the best-suited method, there are important questions to answer at first:
1. What is already known about the sample (matrix, stability, solubility, interferences)?
2. What data are needed (quantitative, semi-quantitative or qualitative)?
3. Are the concentrations of the elements of interest at a major, minor or trace level?
4. How urgently are the data needed and what are the financial restraints?
Here, two different projects are selected to demonstrate a typical search for fit-for-purpose analytics spanning from commonly available Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to more rarely applied Instrumental Neutron Activation Analysis (INAA). These are two examples of primary and secondary raw materials (intermediate goods and waste), which would open possibilities for side products of critical metals, e.g. REE, PGE, Re, Ga.
The first project deals with a natural mineral sample of molybdenite (MoS2) taken from an open pit mine in Kačaran (Armenia) in use for Mo and by-product Re mining. Rhenium is important for catalytic and petrochemical industry, metallurgy, and aviation, e.g. it is used for steel reinforcement in turbine blades for aircrafts [1,2].
The second project focus on secondary raw materials from the non-bauxitic production of aluminium and alumina in Siberia. The analysed materials were taken from different stages of the production process: The final product alumina (Al2O3), waste products like red mud (mainly calcium carbonate and SiO2), sodium salts (e.g. Na2SO4) and anode slag (carbon, Cu-Al alloy, Al) and by-products like wollastonite ceramics (CaSiO3) and soda-potash (K2CO3/Na2CO3).
Of course, there are pros and cons of every analytical method (Total Reflection X-ray Fluorescence (TXRF), ICP-MS, INAA) for different samples yielding to clear conclusions about the best-suited method for future analytical tasks. For example in the case of Re, INAA is identified as method of choice for such kind of analysis due to high sample throughput, an easy and quick sample preparation and a low detection limit (0.26 μg/g).

References:

[1] A. Brumby, M. Verhelst, D. Cheret, Catalysis today. 2005, 106, 166-169.
[2] C. Zhan-Fang, Z. Hong, Q. Zhao-hui, Hydrometallurgy. 2009, 97, 153-157.

Die Abteilung „Reaktiver Transport“ der Forschungsstelle Leipzig beschäftigt sich mit dem Migrations-/Sorptionsverhalten von (Schad)stoffen in geologischen Formationen. In aktuellen Projekten werden partikuläre, kolloidale, gelöste und komplexierte, toxische und radiotoxische Stoffe in Batch- und Säulenstudien sowie Extraktionsverfahren für seltene Metalle untersucht. Bei der eingesetzten Radiotracertechnik kommen kurzlebige, nicht kommerziell erhältliche Radionuklide zum Einsatz. Am Leipziger Zyklotron Cyclone^® 18/9 neu implementiert ist die ⁸⁸Y-Herstellung (T_1/2 = 106,6 d) durch Protonenbeschuss von Strontium mit natürlicher Isotopenzusammensetzung via ⁸⁸Sr(p,n)⁸⁸Y^[1-3]. Das Target wird durch Verpressen von ca. 30 mg Strontiumcarbonat in eine Aluminiumhalterung hergestellt. Die Bestrahlung erfolgt bei einem Protonenstrom von 3 µA, einer Strahlzeit von 2 Stunden und einer Projektilenergie von ca. 12 MeV. Die chemische Aufarbeitung des bestrahlten Strontiumcarbonats erfolgte erstmals durch Ionenchromatographie mit LN-Resin-A (TrisKem Int.) aus salpetersaurer Lösung^[4-5]. N.c.a. (no-carrier-added) ⁸⁸Y wird mit einer radiochemischen Ausbeute von 95 % ± 4 % erhalten. Der entwickelte Trennungsgang dient zur Vorbereitung für die Produktion und Aufarbeitung des kurzlebigen Radionuklids ⁸⁶Y (T_1/2 = 14,7 h; I_β+ = 31,9 %) für die Positronen-Emissions-Tomographie (PET) durch Bestrahlung von isotopenangereichertem ⁸⁶Sr.

Literatur:

[1] S. A. Kandil, B. Scholten, K. F. Hassan, H. A. Hanafi, S. M. Qaim, J. Radioanal. Nucl. Chem. 2009, 279, 823. [2] K. Kettern, K.-H. Linse, S. Spellerberg, H. H. Coenen, S. M. Qaim, Radiochim. Acta 2002, 90, 845. [3] N. P. van der Meulen, T. N. van der Walt, G. F. Steyn, F. Szelecsenyi, Z. Kovacs, C. M. Perrang, H. M. Raubenheimer, Appl. Radiat. Isot. 2009, 67, 1320. [4] E. P. Horwitz, C. A. A. Bloomquist, J. Inorg. Nucl. Chem. 1975, 37, 425. [5] C. Pin, J. F. S. Zalduegui, Anal. Chim. Acta 1997, 339, 79.

With growing importance of nano-patterned surfaces and nano-composite materials in many applications from energy technologies to nano-electronics, a thorough understanding of the self-organized evolution of nano-structures needs to be established. Modelling and simulations of such processes can help in this endeavor and provide predictions for the turnout of manufacturing processes.

In this talk GPGPU-enabled implementations of two stochastic lattice models will be discussed, shedding light on the complications which arise when simulations of stochastic processes are to make efficient use of massively parallel GPU architectures.
A single-GPU implementation of the (2+1)-dimensional Roof-Top-model allows very precise large-scale studies of surface growth processes in the Kardar-Parisi-Zhang universality class.[1] Furthermore a multi-GPU enabled version of the 3d kinetic Metropolis lattice Monte-Carlo method[2] provides the capability to study the evolution of nano-structures both towards and out-of-equilibrium at spatio-temporal scales of experiments using only small to medium-sized GPU clusters.

[1] J. Kelling, G. Ódor Extremely large-scale simulation of a Kardar-Parisi-Zhang model using graphics cards, Physical Review E 84, 061150 (2011)
[1] J. Kelling, G. Ódor, F. Nagy, H. Schulz, K. Heinig Comparison of different parallel implementations of the 2+1-dimensional KPZ model and the 3-dimensional KMC model, The European Physical Journal - Special Topics 210, 175-187 (2012)

The solidification microstructures and physical properties of Al-Cu-Co ternary eutectic alloy were studied in a rotating magnetic field (RMF). The RMF-driven flow was the key factor causing grain refinement and uniformity of solidification microstructures. The temperature distributions during solidification were recorded under the conditions with and without RMF. The dependence of the eutectic spacing (λ) the microhardness (HV), tensile strength (σt) and compressive strength (σc) on the RMF were investigated. Electrical resistivity (ρ) measurements of the studied alloy were also performed by using the four-point probe method and the dependence of the resistivity on temperature and RMF were determined. Besides, the enthalpy (ΔH) and the specific heat (Cp) values were determined by the DSC analysis. Important changes were found in the microstructure, microhardness, tensile strength, compressive strength and electrical resistivity of the studied alloy with increasing RMF.

We study the interaction between polarized terahertz (THz) radiation and micro-structured large-area graphene in transmission geometry. In order to efficiently couple the radiation into the two-dimensional material, a lateral periodic patterning of a closed graphene sheet by intercalation doping into stripes is chosen. We observe unequal transmittance of the radiation polarized parallel and perpendicular to the stripes. The relative contrast, partly enhanced by Fabry-Perot oscillations reaches 20 %. The effect even increases up to 50% when removing graphene stripes in analogy to a wire grid polarizer. The polarization dependence is analyzed in a large frequency range from <80 GHz to 3 THz, including the plasmon-polariton resonance. The results are in excellent agreement with theoretical calculations based on the electronic energy spectrum of graphene and the electrodynamics of the patterned structure.

The recombination times of photo-excited free charge carriers in heavily doped and highly compensated germanium are studied by a time-resolved pump-probe experiment at a frequency of 3THz. The dominant dopant in the germanium samples is either antimony (n-Ge:Ga:Sb) or gallium (p-Ge:Sb:Ga) with compensating doping levels close to 100%. The recombination time of the free charge carriers measured by our pump-probe technique varies between 30 and 300 ps. It decreases with increasing pump pulse energy and increasing compensation due to high concentrations of Coulomb recombination centers. The recombination times at low pump powers are up to ten times shorter than those previously obtained for low-compensated n-Ge:Sb and p-Ge:Ga. The photoconductive detector made from this material shows the response time is in the order of its recombination time.

During slicing silicon block casts to wafers, about 50 % of the valuable material is lost into saw dust. The objective of the EU project SIKELOR is to process such silicon waste in an industrially viable and resource-friendly manner. To be competitive to virgin feedstock, maximum cumulative recycling costs of 10 $/kg are imposed as the economic goal.

Much attention is paid to magnetic nanostructures due to their intrigiung properties and different applications. Appearance of perpendicular magnetic anisotropy (PMA) when a magnetic layer thickness is decreased and a giant magneto-resistance effect are the most interesting effects. Tuning the magnetic domain sizes in a broad range (several orders of magnitude) by changing PMA, the geometrical parameters of the nanostructure, as well as by an applied external magnetic field is observed, see the review [1]. Patterned nanostructures with PMA are prospective for e.g.: mass memories together with magnetic ratchet memories, magnetic field sensors, spin wave applications.
A decrease of PMA as a result of the ion irradiation of the metallic ultrathin films, has been usually reported [2]. However we have recently shown that, Ga+ ion irradiation drives creation of the out-of-plane magnetization states, dependent on the ion fluence [3,4]. Irradiation with Ga+, Ar+, He+ ions results in an increase of magnetooptical effects and changes the coercivity field. We have also found that femtosecond light pulses induce: (i) reversible PMA changes which can be used to trigger magnetization oscillations [4] and (ii) irreversible PMA modifications [5] due to creation of out-of-plane magnetization states for low and high light power densities, respectively. Ion/light irradiation affecting magnetic and magnetooptical properties of nanostructures is a promising approach for new patterning purposes. Such desired modifications can be realized with fluence/energy densities lower than that reqired for the nanostructure surface etching. Moreover, using e.g. focused ion beam technique, lateral patterning can be performed with a nanometer precision. New metamaterials such as magnonic and magnetophotonic crystals or controllable transport of magnetic beads can be created in this way.

Acknowledgements
This work was supported by: National Science Center in Poland under the project HARMONIA Nr 2012/06/M/ST3/00475 and Foundation for Polish Science under the SYMPHONY project (Polish Science Team Programme, European Regional Development Fund, OPIE 2007–2013.

References
[1] A. Maziewski, et al., Phys. Status Solidi A, 211, 1005 (2014).
[2] H. Bernas (Ed.), Materials Science with Ion Beams, Vol. 116 (Springer-Verlag, Berlin, Berlin, 2010).
[3] A. Maziewski, et al., Phys. Rev. B 85, 054427 (2012).
[4] M. Sakamaki et al., Phys. Rev. B 86, 024418 (2012).
[4] J. Kisielewski, et al., Phys. Rev. B 85 (2012) 184429.
[5] J. Kisielewski, et al., Journal of Applied Physics 115, 053906 (2014).

When decreasing ultrathin film thickness d, an increase of the perpendicular magnetic anisotropy (PMA) occurs, resulting in the magnetization reorientation phase transition (RPT) from the in-plane to out-of-plane magnetization state below the critical thickness dRPT. The results of combined experimental, analytical, and micromagnetic simulations studies on the evolution of magnetization states and processes in ultrathin films and multilayered systems [1] will be presented. Possibilities of tuning the magnetic domain sizes in a broad range (of several orders of magnitude) by changing the geometrical parameters of the nanostructure, as well as by an applied external magnetic field will be discussed. Transitions between two- and three-dimensional magnetization distributions will be shown.
As a result of the ion irradiation of the metallic ultrathin films, a decrease of PMA was usually reported [2]. Contrariwise, Ga+ ion irradiation driven creation of the out-of-plane magnetization states, dependent on ion fluence, have been found [3]. Similarly, femtosecond light pulses of high energy density may also induce irreversible enhancement of PMA [4], while low energy density pulses can be used to trigger the magnetization oscillations, via reversible thermal changes of the magnetic anisotropy [5].
1. A. Maziewski, J. Fassbender, J. Kisielewski, M. Kisielewski, Z. Kurant, P. Mazalski, F. Stobiecki, A. Stupakiewicz, I.Sveklo, M.Tekielak, A.Wawro, and V. Zablotskii, Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers, Phys. Status Solidi A, 211, 1005 (2014).
2. H. Bernas (Ed.), Materials Science with Ion Beams, Vol. 116 (Springer-Verlag, Berlin, Berlin, 2010).
3. A. Maziewski, P. Mazalski, Z. Kurant, M. O. Liedke, J. McCord, J. Fassbender, J. Ferré, A. Mougin, A. Wawro, L. T. Baczewski, A. Rogalev, F. Wilhelm, and T. Gemming, Tailoring of magnetism in Pt/Co/Pt ultrathin films by ion irradiation, Phys. Rev. B 85, 054427 (2012).
4. J. Kisielewski, W. Dobrogowski, Z. Kurant, A. Stupakiewicz, M. Tekielak, A. Kirilyuk, A. Kimel, Th. Rasing, L. T.Baczewski, A. Wawro, K. Balin, J. Szade, and A. Maziewski, Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses, Journal of Applied Physics 115, 053906 (2014),
5. J. Kisielewski, A. Kirilyuk, A. Stupakiewicz, A. Maziewski, A. Kimel, Th. Rasing, L. T. Baczewski, and A. Wawro, Laser-induced manipulation of magnetic anisotropy and magnetization precession in an ultrathin cobalt wedge, Phys. Rev. B 85 (2012) 184429.

Neurodegenerative Erkrankungen werden mit Veränderungen der Expressionsdichte α7 nikotinischer Acetylcholinrezeptoren in Verbindung gebracht. Dieser Rezeptor ist folglich ein interessantes Target für die molekulare Bildgebung mit Positronen-Emissions-Tomographie (PET). In der vorliegenden Arbeit werden die Synthese sowie eine Evaluierung von [¹⁸F]NS14490, ([¹⁸F]2-(1,4-Diazabicyclo[3.2.2]nonan-4-yl)-5-(1-(2-fluoroethyl)-1H-indol-6-yl)-1,3,4-oxadiazol) als neuer, potentieller Radioligand vorgestellt. Für die Radiosynthese wurden zwei Strategien verfolgt: Zum einen wurde Ethylenglykolditosylat mit [¹⁸F]Fluorethyltosylat umgesetzt und anschließend mit NS14540, einem am Indolstickstoffatom unsubstituierten Derivat zu [¹⁸F]NS14490 umgesetzt. Gleichzeitig wurden synthetisierte Präkursoren für eine direkte Radiofluorierung eingesetzt. Nach umfangreichen Arbeiten zur Isolierung und Reinigung des Radioliganden mit semipräparativer HPLC und Festphasenextraktion sowie der Formulierung folgten Untersuchungen zur Stabiltität des Radioliganden in Puffersystemem bei pH = 7 und in Schweineplasma, die Bestimmung der Lipophilie und erste Versuche zur Extraktion aus Schweineplasma.
Die In-vivo-Evaluierung des Radioliganden setzt sich aus der Bestimmung der Anreicherung des Radioliganden im Gehirn von Mäusen und Schweinen sowie der Metabolitenanalyse von Plasmaproben und Hirnhomogenaten (Maus) und in der Metabolitenanalyse von Plasmaproben (Schwein) während dynamischer PET-Aufnahmen zusammen. Der Radioligand hatte im Plasma in Mäusen eine höhere Stabilität als in Schweinen und lag im Mäusehirn nahezu unmetabolisiert vor.
Der 2. Teil dieser Arbeit beschäftigt sich mit der Aufbereitung von bestrahltem [¹⁸O]H₂O zur Wiederverwendung bei der Produktion von [¹⁸F]F⁻. 1 Liter bestrahltes [¹⁸O]H₂O wurde durch Oxidation organischer Lösungsmittel mit KMnO₄ und NaOH bei 50 °C oder durch Bestrahlung mit 254 nm sowie anschließender Tieftemperatur-Vakuumdestillation zur Abtrennung von Rückständen aufbereitet. Die Charakterisierung des [¹⁸O]Wassers zeigte nur geringe Restkontaminationen durch Ionen (unterer mg-l⁻¹-Bereich) und eine nahezu abreicherungsfreie Aufbereitung. Die Durchführung von Modellexperimenten mit künstlich kontaminierten [¹⁶O]H₂O gab Hinweise auf eine fast quantitative Rückgewinnung des Wassers.
Die Bestrahlung von aufbereitetem [¹⁸O]H₂O und der Vergleich der Produktionsaktivitäten mit (verdünntem) [¹⁸O]Originalwasser sowie der unproblematische Einsatz des [¹⁸F]F⁻ in radiochemischen Synthesen unterstreichen die Qualität des Aufbereitungsprozesses.

An experimental study to assess the accuracy of wire-mesh sensors in dependence of bubble sizes and flow rates has been performed in a 50 mm x 50 mm transparent rectangular channel. The liquid superficial velocities were ranging from 0 m/s up to 0.62 m/s with the obtained bubble size ranging from 3 mm to 7 mm. A single wire-mesh sensor with 16 x 16 electrode wires was used with a temporal and spatial resolution of 10 kHz and 3.1 mm (lateral distance between two wires), respectively. Single bubbles with known bubble size, subsequently called reference bubble size, was injected into the test section via bubble injector approx. 25 cm upstream of the wire-mesh sensor. The bubble size measurement by using wire-mesh sensor cannot be obtained directly since it requires the information of bubble velocity which is not available only by installing a single sensor. Therefore, a stereoscopic observation was conducted to obtain the bubble velocity by tracking the successive frames as well as to study the intrusiveness of the sensor. This configuration gave an advantage that the registered bubble will be assigned with its real approach velocity and a better agreement is expected. As the result, a direct comparison of all individual bubbles with the reference bubble size showed an agreement within ±10%. However, a deceleration effect was found for low superficial and observed to disappear as the liquid superficial velocity increased then vanish at observed JL = 0.62 m/s.

RFe₅Al₇ (R – Gd, Tb, Dy, Ho, Er and Tm) single crystals have been studied by measurements of magnetization, sound propagation (in static and pulsed magnetic fields up to 60 T) and specific heat. Fundamental magnetic properties have been determined and compared for all these materials. RFe₅Al₇ are highly anisotropic ferrimagnets. Spontaneous and field-induced magnetic phase transitions of anisotropic and exchange nature have been observed in RFe₅Al₇. Strong magnetoelastic interactions are manifested by pronounced acoustic anomalies at the phase transformations. The detected magnetization jumps provide important information on the R–Fe inter-sublattice exchange interactions.

The present pulsed high-magnetic-field study on Ni₅₀Mn₃₅In₁₅ gives an extra insight into the thermodynamics of the martensitic transformation in Heusler shape-memory alloys. The transformation-entropy change, ΔS, was estimated from field-dependent magnetization experiments in pulsed high magnetic fields and by heat-capacity measurements in static fields. We found a decrease of ΔS with decreasing temperature. This behavior can be understood by considering the different signs of the lattice and magnetic contributions to the total entropy. Our results further imply that the magnetocaloric effect will decrease with decreasing temperature and, furthermore, the martensitic transition is not induced anymore by changing the temperature in high magnetic fields.

Wire mesh sensors (WMS) are state of the art devices that allow high resolution (in space and time) measurement of 2D void fraction distribution in any two-phase flow regime. Data using WMS have been recorded at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Lucas et al., 2010; Beyer et al., 2008; Prasser et al., 2003) for a wide combination of superficial gas and liquid velocities, providing an excellent database for advances in two-phase flow modeling.
In two-phase flow, the interfacial area plays an integral role in coupling the mass, momentum and energy transport equations of the liquid and gas phase. While current models used in best-estimate thermal-hydraulic codes (e.g. RELAP5, TRACE, TRACG, etc.) are still based on algebraic correlations for the estimation of the interfacial area in different flow regimes, interfacial area transport equations (IATE) have been proposed to predict the dynamic propagation in space and time of interfacial area (Ishii 2010). IATE models are still under development and the HZDR WMS experimental data provide an excellent basis for the validation and further advance of these models. The current paper is focused on the uncertainty analysis of algorithms used to reconstruct interfacial area densities from the void-fraction voxel data measured using WMS and their application towards validation efforts of two-group IATE models.
In previous research efforts, a surface triangularization algorithm has been developed in order to estimate the surface area of individual bubbles recorded with the WMS, and estimate the interfacial area in the given flow condition. In the present paper, synthetically generated bubbles are used to assess the algorithm’s accuracy. As the interfacial area of the synthetic bubbles are defined by user inputs, the error introduced by the algorithm can be quantitatively obtained. The accuracy of interfacial area measurements is characterized for different bubbles sizes and shapes, and for different WMS acquisition frequencies. It is found that while convex shapes are successfully analyzed by the reconstruction algorithm, some difficulties are faced with bubbles presenting internal cavities.
Utilizing the experimental HZDR database, the performance of the current two-group IATE model is evaluated. While the qualitative propagation of interfacial area is predicted sufficiently well, there is a discrepancy in magnitude between the model’s prediction and the experimental results. Overall, the study suggests that differences exist in the incidence of interaction mechanisms between small and large diameter pipes and further efforts are needed in order to extend the range of validity of current IATE models.

An enhanced probability for low-energy -emission (upbend, E < 3 MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the γ-decay probability for low-energy γ-rays (E < 2­ - 3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. The experimental and theoretical status of the upbend is discussed, and preliminary calculations of (n,γ) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.

Various flow measurement and visualization techniques are based on optical and laser-based methods. However, in many multiphase flow situations, e.g. at higher interfacial density or in flows with internals, the optical access is no longer given. Radiation based methods are in principle able to penetrate most of these systems, but are normally too slow to capture the dynamics of the flow. With ultrafast X-ray tomography a flow visualization and measurement technique has been developed, which is able to recover the dynamic phase distributions in various multiphase flow scenarios. The high imaging rate is achieved by deflecting an electron beam along a circular target, where a moving X-ray spot is generated. Tomographic projections are gathered simultaneously by a static detector ring with fast read-out. Thus, no components of the X-ray tomography system have to be rotated mechanically. The reconstructed tomography slices represent the non-superimposed phase distribution within a cross-section as a function of time. Up to 8,000 fps can be achieved in single plane mode. For velocity measurements, a second set of X-ray target and detector ring arranged at a small axial distance can be included to form the so-called dual plane mode. Although the alternating scanning of both planes reduces the frame rate by a factor of two, the benefit of combining the information from both planes to retrieve velocity information arises directly. There are different ways to extract velocity information from the two stacks of slice image data. Cross-correlation techniques offer the opportunity to retrieve time averaged as well as time resolved local or global velocities of the disperse phase. Some systems also allow the determination of single bubble or particle velocities, provided that they can be identified as the same object in both planes.

The Strange Lake pluton is situated on the northern border between Québec and Labrador in northeastern Canada. The ore-body, located within a complex peralkaline granite-hosted system of pegmatites and aplites, contains elevated concentrations of both LREE and the highly coveted HREE, as well as other HFSE (high field strength elements, such as Zr, Nb, Y, Ti, and Th). The REE mineralization, however, is extremely complex and the elements of interest are variably distributed between various “exotic” minerals from different mineral classes that may also contain considerable amounts of unwanted impurities such as thorium, uranium and beryllium. Naturally occurring radioactive materials (NORM) like Th may be concentrated during beneficiation, thus constituting a serious hazard to the workers and the environment. In order to limit transportation and storage of hazardous material during production, it is of the company’s interest to separate these deleterious constituents early in or at best in advance to the extraction process. This study focuses on the characterization of the mineral phases that primarily host thorium for early recognition. Combined chemical and structural analyses indicate that there is one particular mineral phase in which Th is present in highly elevated concentrations. This mineral is best described as a metamict Th-silicate occurring in isolated, rounded grains enclosed in quartz. Further studies are required to indicate if this mineral can be separated early during minerals processing from the ore without considerable loss of valuable REE.

The efficacy of external beam radiotherapy (EBRT) is dose dependent, but the dose that can be applied to solid tumour lesions is limited by the sensitivity of the surrounding tissue. The combination of EBRT with systemically applied radioimmunotherapy (RIT) is a promising approach to increase efficacy of radiotherapy. Toxicities of both treatment modalities of this combination of internal and external radiotherapy (CIERT) are not additive, as different organs at risk are in target. However, advantages of both single treatments are combined, for example, precise high dose delivery to the bulk tumour via standard EBRT, which can be increased by addition of RIT, and potential targeting of micrometastases by RIT. Eventually, theragnostic radionuclide pairs can be used to predict uptake of the radiotherapeutic drug prior to and during therapy and find individual patients who may benefit from this treatment. This review aims to highlight the outcome of pre-clinical studies on CIERT and resultant questions for translation into the clinic. Few clinical data are available until now and reasons as well as challenges for clinical implementation are discussed.

The production of non-commercially available ¹³⁵La by proton irradiation of an isotopically enriched [¹³⁵Ba]BaCO₃ target at a cyclotron is described. The purification of the radionuclide was performed by a La-selective resin. ¹³⁵La was separated in no-carrier-added (n.c.a) form in a nitric acid solution with a radiochemical yield of 83% ± 5% and a total activity per batch of 43 MBq ± 3 MBq. The enriched [¹³⁵Ba]Ba was recycled to the carbonate form with a recovery of 90% ± 3%. On the basis of a detection limit of 1 Bq/ml, solutions of n.c.a. ¹³⁵La could be measured down to the 10^-15 mol/l concentration range.

Spintronics appears to be a new and exciting field of technology, but there is still a lag of suitable materials. In principle magnetic semiconductors (DMS) would be an excellent choice, but even their highest reached Curie temperature (Tc) in GaMnAs is still too low for practical usage. Ferromagnetism in DMS is suggested to be holes according to the Zener-Model. Therefore, it is expected to increase Tc by adding additional holes, e.g. co-doping. But there is a high risk to induce more defects, especially interstitial Mn atoms. Indeed, previous investigation revealed a lower Tc in carbon codoped GaMnAs [1]. Ion Implantation followed by laser annealing might overcome this problem. We choose ferromagnetic GaMnP since it shows insulating behavior [2]. Co-doping with shallow acceptors may lead to a more pronounced change in the conductivity of GaMnP. The samples were investigated with SQUID-VSM and Hall-Effect measurement. First results do not show an increase in Tc. Structural analysis is in progress to check if more defects appear upon carbon codoping.
[1] G. M. Schott, et al., Appl. Phys. Lett. 85, 4678 (2004).
[2] M. A. Scarpulla, et al., Phys. Rev. Lett., 95, 207204 (2005).

Defect induced ferromagnetism has been reported in wide-bandgap semiconductors as well as in carbon-based materials, when defects are introduced in an appropriate way. It is desirable to establish a direct relation between such ferromagnetism and defects. Here, we succeed to reveal the origin of defect-induced ferromagnetism using SiC by X-ray magnetic circular dichroism (XMCD). In addition, the theoretical model is calculated by first-principles theory. We show that the long-range ferromagnetic coupling is due to the p electrons of the nearest-neighbor carbon atoms around VSiVC divacancies. Thus, the ferromagnetism is traced down to its microscopic, electronic origin.

The first cluster of the constructed PARIS calorimeter was assembled and tested at the ELBE facility at HZDR, Dresden, Germany. The experiment was aimed at the evaluation of the performance of each detector separately as well as the whole PARIS cluster with discrete gamma-ray energies seen by the PARIS ranging up to 8.9 MeV. As the detectors use phoswich configuration, with 2'' x 2'' x 2'' LaBr3 (Ce) crystal coupled to 2'' x 2'' x 6'' NaI(Tl) one, great care must be taken during the data analysis process to obtain the best possible values for energy resolution. Two algorithms for data transformation from matrices created with slow vs fast pulse shaping to energy spectra were tested from which one was chosen for further analysis. An algorithm for adding back energies of -rays scattered inside the cluster was prepared, as well. Energy resolution for gamma-rays in 2­8 MeV range was estimated and is presented in this paper.

Sorption of uranium(VI) onto orthoclase and muscovite, representing feldspars and micas as important components of the earth crust, was investigated in presence and absence of calcium under aerobic conditions. Batch experiments accompanied by time-resolved laser-induced fluorescence spectroscopy (TRLFS) were performed. A reduction of the U(VI) sorption by calcium at pH ≥ 8 due to the formation of the Ca2UO2(CO3)3 complex was observed. An evaluation of the spectroscopic results by PARAFAC indicates the formation of three surface species ≡SiO2UO20, ≡SiO2UO2OH– and ≡SiO2UO2OHCO33–. The results improve the basis for a mechanistic modeling of the sorption onto orthoclase and muscovite, which is important for long-term safety analysis of waste repositories.

Dendritic polyglycerol sulfate (dPGS) is a biocompatible, bioactive polymer which exhibits anti-inflammatory activity in vivo and thus represents a promising candidate for therapeutic and diagnostic applications. To investigate the in vivo pharmacokinetics in detail, dPGS with a molecular weight of ca. 10 kDa was radiolabeled with ³H and ⁶⁴Cu, and evaluated by performing biodistribution studies and small animal positron emission tomography (PET). ³H-labeling was accomplished by an oxidation-reduction process with sodium periodate and [³H]-borohydride. ⁶⁴Cu-labeling was achieved by conjugation of isothiocyanate- or maleimide-functionalized copper(II)-chelating ligands based on 1,4-bis(2-pyridinylmethyl)-1,4,7-triazacyclononane (DMPTACN) to an amino functionalized dPGS scaffold, followed by reaction with an aqueous solution containing ⁶⁴CuCl₂. Independent biodistribution by radioimaging and PET imaging studies with healthy mice and rats showed that the neutral dPG was quantitatively renally eliminated, whereas the polysulfated analogs accumulated mainly in the liver and spleen. Small amounts of the dPGS derivatives were slowly excreted via the kidneys. The degree of uptake by the reticuloendothelial system (RES) was similar for dPGS with 40% or 85% sulfation, and surface modification of the scaffold with the DMPTACN chelator did not appear to significantly affect the biodistribution profile. On the basis of our data, the applicability of bioactive dPGS as a therapeutic agent might be limited due to organ accumulation even after 3 weeks. The inert characteristics and clearance of the neutral polymer, however, underlines the potential of dPG as a multifunctional scaffold for various nanomedical applications.

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Results on the K*(892)⁺ production in proton-proton collisions at a beam energy of E = 3.5 GeV, which is hitherto the lowest energy at which this mesonic resonance has been observed in nucleon-nucleon reactions, are presented. The data are interpreted with a two-channel model that includes the 3-body production of K*(892)⁺ associated with the Λ- or Σ-hyperon. The relative contributions of both channels are estimated. Besides the total cross section σ(p + p -> K*(892)⁺ + X) = 9.5 +- 0.9 ^+1.1 _-0.9 +- 0.7 μb, that adds a new data point to the excitation function of the K*(892)⁺ production in the region of the low excess energy, transverse momenta and angular spectra are extracted and compared with the predictions of the two-channel model. The spin characteristics of K*(892)⁺ are discussed as well in terms of the spin-alignment.

The inclined rotating tubular fixed bed reactor has been introduced recently as a novel reactor concept for multiphase processes, especially for heterogeneously catalyzed gas–liquid reactions with a mass transfer limitation of the gas phase (Härting et al., 2015; DOI: http://dx.doi.org/10.1016/j.ces.2015.02.008). It is based on the adjustment of a beneficial gas–liquid distribution in the cross section of the fixed bed that allows for complete utilization of the fixed bed accompanied by periodic wetting and draining of the catalyst.
The hydrodynamics in gas–liquid co-current downflow are studied by applying a compact gamma-ray computed tomography system for different organic liquids and gas phase properties as well as various fixed bed packing materials. Four different flow regimes with stratified, sickle, annular and dispersed flow patterns are identified. Pressure drop and liquid saturation are presented as a function of reactor inclination and rotation.
Inclination of the reactor is applied to force phase separation and the superimposed rotation of the clamped fixed bed results in a favorable wetting intermittency via periodic catalyst immersion. A significant rate enhancement of the hydrogenation of alpha-methylstyrene to cumene under severe limitations of the mass transfer of the gas phase is observed in the novel reactor concept at separated flow conditions. In addition, the potential for an efficient quenching of hotspots for exothermic reactions is demonstrated.

In the framework of the project DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies) a next generation dynamo experiment is under construction at the Helmholtz-Zentrum Dresden-Rossendorf. In this experiment a fluid flow of liquid sodium in a cylindrical container, solely driven by precession, is considered as a possible source for magnetic field generation.

Precession has long been discussed as a complementary energy source for driving the geodynamo, and dynamo action generated by precession driven flows has been found in various numerical simulations in a sphere, ellipsoid, cube and cylinder. In the current study we perform hydrodynamic simulations of the three-dimensional non-linear Navier-Stokes equation in cylindrical geometry including weakly precessional forcing. The main focus is put on the development of the non-axisymmetric time-dependent instabilities that could be responsible for dynamo action like triadic resonances.

Our simulations reveal clear triads at aspect ratios and frequencies close to predictions from the linear inviscid theory with an amplitude below the forced m=1 mode so that most of the flow energy remains in the fundamental forced mode. Next step will be kinematic simulations in order to test the ability of the triades to provide for dynamo action.

We demonstrate that a low-remanent sample magnetization M_R is crucial for all-optical magnetic switching (AOS) in ferrimagnets and ferrimagnet heterostructures. M_R may be devised by the composition of the material. However, it can also be controlled in situ by changing the sample temperature because it affects MR. We show that increasing the lattice temperature by laser pulses or a simple heating resistor enables AOS in a ferrimagnetic Tb-Fe film, which does not exhibit AOS at room temperature. We reconcile earlier contradicting results for AOS in heated and cooled magnetic films by applying the low-remanence criterion. It also applies to other existing rare-earth transition-metal (RE-TM) alloys, such as GdFeCo or Tb-Co, to ferrimagnet heterostructures, and to RE-free synthetic ferrimagnets.