Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Aim: N-Succinimidyl-4-[18F]fluorobenzoate [18F]SFB is a commonly used active ester suitable for the labeling of peptides and proteins. Radiosynthesis of [18F]SFB has been described by various methods, most often multi-step radiofluorination syntheses. Recently, the copper-mediated radiofluorination starting from boronic acid pinacol ester 1 [1] (Fig. 1) or the tributyl stannyl analog [2] in manual and automated radiosyntheses, respectively, were reported as one-step access to [18F]SFB. To substitute our automated three-step method starting from tert-butyl protected N,N,N-trimethylammoniobenzoic acid ester triflate, we attempted both approaches and detail results of optimization and automation starting from 1 herein.

Materials and methods: Organic syntheses comprised the synthesis of the stannyl-based precursor as described [2] as well as that of 1 starting from commercial 4-carboxy-phenyl boronic acid pinacol ester and N-hydroxysuccinimide using DCC as coupling reagent. Radiosyntheses were optimized regarding base (KHCO3/K3PO4) for QMA conditioning, pre-mix time (0-60 min), concentration (2.5-10 mM precursor and 10-40 mM [Cu(OTf)2(py)4]), reaction temperature (90, 110, 130°C), and solvent (DMF, DMA, DMI) using our recently described microliter-scale radiofluorination approach in HPLC vials [3]. Optimized reaction conditions were transferred to an automated radiosynthesizer (TracerlabFx2N) and purification was performed by semi-preparative HPLC and SPE to obtain [18F]SFB in high chemical and radiochemical purity for further conjugation chemistry.

Results: As a starting point, we envisaged the synthesis of the tributyl stannyl analog as precursor but failed to reproduce the reported synthesis starting from N-succinimidyl 4-iodobenzoate [2]. In comparison, the boronic acid pinacol ester was readily accessable from commercial starting materials in 84-89% yield. The optimized radiosynthesis sequence included elution of [18F]fluoride from a K3PO4-conditioned QMA cartridge with KOTf/K2CO3 in MeCN/H2O, evaporation at 130°C followed by radiofluorination using 10 mM of 1 and 40 mM of [Cu(OTf)2(py)4] in DMI at 90°C for 15 min. Automation furnished [18F]SFB in 13-20% isolated radiochemical yield after 68-83 min (n = 3).

Conclusion: Radiosynthesis of [18F]SFB starting from 1 was successfully optimized and transferred to an automated radiosynthesizer. The method provides the synthon in slightly lower RCY compared to our three-step method but preparation and the reaction sequence is considerable easier, allowing also to use the second reaction vessel of the module for conjugation chemistry which was not possible in the three-step two-pot approach applied before.

Due to the ongoing energy transition from fossil fuels to renewable energies, the topic of energy storage is more present than ever. Here, liquid metal batteries (LMBs) are one promising option for low-cost stationary storage of electrical energy. The working principle in general is quite simple – the system of liquid metal anode, molten salt electrolyte and liquid metal cathode self-assembles due to density differences and during operation electroactive species migrate from electrode to electrode through the electrolyte. The battery in the present study uses sodium as anode and zinc as cathode material as well
as a two layered molten salt mixture being separated by a diaphragm. Figure 1 shows this setup. Flow phenomena due to the liquid nature of the battery will arise during operation [1]. Most interestingly and very likely to occur in the electrolyte are thermal and solutal convection, which are consequences of unstable density distribution due to species transport and temperature differences. So far, those have mostly been investigated in the cathode of traditional LMBs only [2, 3]. Recently, mass transport in the electrolyte of a LiBi LMB was numerically investigated [4].
For NaZn cells, the electrolyte where two active species – Na + and Zn 2+ – are transported primarily is the most important region to consider. The consequences of the mentioned convection phenomena are improved mixing of the electrolyte and reduced concentration overpotentials, but also self-discharge is promoted by mass transfer. Thus, knowing and understanding the species transport in the electrolyte is a major step in improving cell
performance. Also, a charge-discharge asymmetry for solutal convection will be present during operation. Hence, solutal convection might evolve in the upper part of the electrolyte during charge and at discharge in the lower one. Additionally, the diaphragm influences the species transport and the evolving flow.
When operated above a critical current density, solutal convection can be observed in form of plumes evolving and sinking down/rising up, as it is exemplary shown in Fig. 1.

Ambipolar transistors facilitate concurrent transport of both positive (holes)
and negative (electrons) charge carriers in the semiconducting channel.
Effective manipulation of conduction symmetry and electrical characteristics in
ambipolar silicon junctionless nanowire transistors (Si-JNTs) is demonstrated
using gaseous nitrogen dioxide (NO2). This involves a dual reaction in both
p- and n-type conduction, resulting in a significant decrease in the current
in n-conduction mode and an increase in the p-conduction mode upon NO2
exposure. Various Si-JNT parameters, including “on”-current (Ion), threshold
voltage (Vth), and mobility (μ) exhibit dynamic changes in both the p- and
n-conduction modes of the ambipolar transistor upon interaction with NO2
(concentration between 2.5 – 50 ppm). Additionally, NO2 exposure to Si-JNTs
with different surface morphologies, that is, unpassivated Si-JNTs with a native
oxide or with a thermally grown oxide (10 nm), show distinct influences on Ion,
Vth, and μ, highlighting the effect of surface oxide on NO2-mediated charge
transfer. Interaction with NO2 alters the carrier concentration in the JNT
channel, with NO2 acting as an electron acceptor and inducing holes, as supported
by Density Functional Theory (DFT) calculations, providing a pathway
for charge transfer and “pseudo” molecular doping in ambipolar Si-JNTs.

Scientific Publishing has built the basis of knowledge exchange since the inception of the modern scientific method. Papers of last centuries contain uncountable experimental and theoretical findings. When exploring new materials or their facets, it becomes instrumental to extract these information from a myriad of papers. In this work, we present first attempts to extract viable physics information from existing publications using large language models. While the extraction of clearly defined terminology is straight forward, we showcase results with more vague information. We will compare our findings using different input formats and language models such as Mixtral 8x7B. We hope to start a conversation in the community how to bridge the paper-to-data-table gap in our community.

Although the reduction of Se(VI) to Se0 and FeSe2 by pyrite is thermodynamically favorable, well-crystallized natural pyrite remains chemically inert to aqueous Se(VI) under conventional conditions. In this study, the interaction of aqueous Se(VI) with natural arsenic-rich and arsenic-free pyrites was studied under gamma-irradiation at pH ∼4.0 to ∼9.0, mimicking the conditions near a nuclear waste repository. The results showed that gamma-irradiation significantly boosts the reductive precipitation of Se(VI) by arsenic-rich pyrite at pH ∼4.0 to ∼9.0. For arsenic-free pyrite, this enhancement was observed within a narrower pH range of ∼5.0 to ∼6.0, and a distinct red precipitate, indicative of Se0, formed during the reaction at pH ∼6.0 under an absorbed dose of 100 kGy at a dose rate of 100 Gy/min. The reduction process involving arsenic-rich pyrite is more sensitive to the absorbed dose rate, with a decrease in Se(VI) removal efficiency at higher dose rates. Conversely, both the absorbed dose and the dose rate have significant effects on the reactions involving the arsenic-free pyrite. Transmission electron microscopy and X-ray absorption spectroscopy analyses verified the occurrence of Se0 nanoparticles on pyrite surfaces via the intermediate product of Se(IV). It is suggested that the ·OH radical generated by water radiolysis can be scavenged by pyrite and/or its non-oxidative dissolved solutes such as Fe2+ and H3AsO3/AsO33− impurities, allowing the concurrent eaq− and ·H, primarily eaq−, to reduce Se(VI), thereby altering the reaction pathway between pyrite and aqueous Se(VI) under gamma-irradiation. This work offers important insights into the geochemical behavior of 79Se in the near-field of a nuclear waste repository.

Water electrolysis is a promising technology for large-scale green hydrogen production, but its efficiency is significantly affected by the formation and behavior of gas bubbles on the electrode surfaces. This talk will provide an overview of recent research on bubble dynamics during water electrolysis. Various measurement techniques, including electrochemical methods, optical analysis, and modeling, will be employed to explore the behavior of hydrogen and oxygen bubbles.

Recent decades have seen great progress in the experimental investigation of fundamental processes that are relevant to geophysical and astrophysical
fluid dynamics. For such studies, liquid metals have proven particularly suited, partly owing to their small Prandtl numbers which are comparable
to those in planetary cores and stellar convection zones, partly due to their high electrical conductivity which allows the study of various magnetohydyrodynamic phenomena. After summarizing some theoretical basics, we discuss the most important liquid-metal experiments on Rayleigh-Bénard-convection, Alfvén waves, the magnetorotational and Tayler instability, and the dynamo effect. We recapitulate what has been learned so far from those experiments, and what could be expected from future ones.

In the first part of the talk, we discuss a model of the solar dynamo that tries to explain its various periodicities on widely different time scales in a self-consistent manner. Starting with Rieger-type periods, we show that the two-planet spring-tides of Venus, Earth and Jupiter can excite magneto-Rossby waves in the solar tachocline with periods between 100 and 300 days and amplitudes of m/s or even more. We further show that the dynamo-relevant quadratic action of these waves contains a beat period of 11.07 years, and that its axisymmetric part might indeed be strong enough to synchronize the entire solar dynamo via parametric resonance. Then we argue that a second beat between the arising Hale cycle and the 19.86-year periodic motion of the Sun around the barycenter of the solar system may explain the longer-term Gleissberg and Suess-de Vries cycles. The spectrum emerging from this double-synchronized dynamo model shows amazing correspondence with climate-related data.

In the second part of the talk, we examine the present status of the DRESDYN precession-driven dynamo experiment. Its motivation stems, first, from the possible influence of the various Milankovic cycles on the geodynamo and, second, from the not yet fully understood spin-orbit coupling effects in our solar dynamo model. We discuss in some detail the combined numerical and experimental efforts to identify dynamo-optimizing precession ratios and
nutation angles, and illustrate the recent steps in finalizing the set-up of the machine.

Recent decades have seen great progress in the experimental investigation of fundamental processes that are relevant to geophysical and astrophysical
magnetohydrodynamics. After summarizing the results of the most important liquid-metal experiments on the dynamo effect, the magnetorotational instability, and Alfvén waves, we present some new results related to convection under the influence of steady magnetic fields or time-dependent electromagnetic forces. Special focus lies then on the DRESDYN precession experiment which is presently in the commissioning phase. Closely related to those experimental developments, we also discuss the potential role of various astronomical forcings in synchronizing the solar dynamo or triggering reversals of the geodynamo.

A magnetohydrodynamic dynamo process is supposed to take place in the
interior of the Sun or stars as well as in planets and smaller
celestial bodies like the ancient Moon or the asteroid Vesta, which
has motivated related studies in the laboratory. Currently, a new
dynamo experiment is under construction at Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), in which liquid sodium will be forced by a
precessing cylindrical container. In the present study, we conduct
related numerical simulations of dynamo action in order to examine the
interaction of flow and field and the associated transfer of kinetic
energy into magnetic energy. We compare self-consistent simulations of
the complete set of magnetohydrodynamic equations with a simplified
kinematic approach solely based on the magnetic induction equation
with a prescribed velocity field. In both cases, we observe an
optimal parameter range for the onset of dynamo action in a
transitional regime, within which the flow undergoes a radical change
from a large-scale to a smaller-scale turbulent behavior. In contrast
to the kinematic solution, the character of the dynamo is small-scale
in the MHD models, which in addition exhibit irregular magnetic bursts
with an increase in the magnetic energy by a factor of 3 to 5.
Nevertheless, the magnetic energy remains significantly lower than the
kinetic energy, so that the dynamo process is not particularly
efficient and there is nearly no noticeable feedback of the magnetic
field on the flow.

Inductive measurement techniques are extremely sensitive and thus offer high potential for monitoring flow processes in metallurgy, the chemical industry and process engineering. In particular, they are suitable for the characterisation of multiphase flows, e.g. in the detection of gas bubbles in electrically conductive fluids or the tracking of magnetic particles in flotation. The contactless inductive flow tomography (CIFT) is developed in our laboratory over the last 20 years to visualize three-dimensional velocity fields in liquid metals. The technique is based on precise measurements of small flow-induced perturbations of an applied magnetic field and the subsequent reconstruction of the flow field by solving the associated inverse problem. We will give an overview of diverse modifications of this technique employed for various measuring tasks in different processes specified below.
Foam processes are essential in many industrial applications e.g., in froth flotation for material separation. A detailed understanding of foam flows is vital for improvements in process efficiency. Magnetic particle tracking (MPT) is an attractive approach, that measures the trajectory of a small magnetic tracer particle inside the foam as a representation of its movement. Different magnetic field sensors can be applied to detect the magnetic tracer particle. We chose thin film sensors based on the planar Hall effect (PHE) due to their small size, high sensitivity, high signal-to-noise ratio and low cost.
A novel concept of a measurement technology for the localization and determination of the size of gas bubbles is presented, which is intended to contribute to a further understanding of the dynamics of efficiency-reducing gas bubbles in electrolyzers. A simplified proof-of-concept (POC) model is used to numerically simulate the electric current flow through materials with significant differences in electrical conductivity. Based on the measurable magnetic flux density, solving Biot-Savart’s law inversely is demonstrated and discussed with a model-based solution of an optimization problem, of which the gas bubble locations are derived.

Laser-structuring techniques like Direct Laser Interference Patterning show great potential for optimizing electrodes for water electrolysis. Therefore, a systematic experimental study based on statistical design of experiments is performed to analyze the influence of the spatial period and the aspect ratio between spatial period and structure depth on the electrode performance for pure Ni electrodes. The electrochemically active surface area could be increased by a factor of 12 compared to a non-structured electrode. For oxygen evolution reaction, a significantly lower onset potential and overpotential (≈ −164 mV at 100 mA cm−2) is found. This is explained by a lower number of active nucleation sites and, simultaneously, larger detached bubbles, resulting in reduced electrode blocking and thus, lower ohmic resistance. It is found that the spatial distance between the laser-structures is the decisive processing parameter for the improvement of the electrode performance.

All data that were used to generate the figures in the related publication are currently stored in the Springer Nature Figshare repository.

Background: Among the several inhomogeneities in the composition of globular cluster stars, an overabundance of 23Na is interpreted as the signature of the operation of the neon-sodium (NeNa) cycle. One of the hypothesis to explain the observed O-Na anticorrelation invokes massive asymptotic giant branch stars as the main agents. At temperatures relevant for nucleosynthesis in asymptotic giant branch stars the 22Ne(p ,γ )23Na reaction rate has been the most uncertain so far, giving rise to considerable experimental efforts in recent years. While overall there is a good agreement between reported cross section results, some tensions still remain on the branching ratios of resonance γ -ray modes and direct capture to excited sates.

Purpose: The present paper offers full details and a partial analysis of the high sensitivity study, of both direct capture and low-energy resonances in the 22Ne(p ,γ )23Na reaction, performed at LUNA, and whose results were previously published in abbreviated form [F. Ferraro et al., Phys. Rev. Lett. 121, 172701 (2018), 10.1103/PhysRevLett.121.172701].
Methods: During the LUNA measurement an intense proton beam was delivered to a 22Ne gas target. The γ rays from the 22Ne(p ,γ )23Na reaction were detected by a high efficiency 4 π , sixfold segmented bismuth germanate (BGO) detector. In the present paper the data from individual detector segments were combined with simulated detector responses to obtain cascade branching ratios.
Results: For the three resonances at Ep=156.2 and 259.7 keV new γ -decay branchings are provided. Moreover, partial cross sections for the direct capture to different states of 23Na are reported down to Ep=188 keV , the lowest energy measured to date.
Conclusions: A revised reaction rate has been calculated based on a new R -matrix fit of the recent 22Ne(p ,γ )23Na S -factor data and results for the resonances. The thermonuclear reaction rate is provided in tabular form to be used in stellar models.

Introduction to Laser-Driven Heavy Ion Acceleration

In machine learning, the ability to make reliable predictions is paramount. Yet, standard ML models and pipelines provide only point predictions without accounting for model confidence (or the lack thereof). Uncertainty in model outputs, especially when faced with out-of-distribution (OOD) data, is essential when deploying models in production. This talk serves as an introduction to the concepts and techniques for quantifying uncertainty in machine learning models. We will explore the different sources of uncertainty and cover various methods for estimating these uncertainties effectively. By understanding and addressing uncertainty, particularly in the context of OOD data, practitioners can enhance the robustness of their models and foster greater confidence in model predictions.

Radiobiological research with laser-driven ion sources

We carried out ultrasonic Doppler and power consumption measurements in a 1:6 downscaled water experiment to analyze the potential for dynamo action in a precession driven sodium experiment [1]. The experiments are embedded in the DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies) project devoted to a better understanding of the homogeneous dynamo effect in planets and stars.
First of all a non-axisymmetric Kelvin mode is growing with rising precession ratio, which alone is not suitable for dynamo action in the experiment. In a narrow region of the precession ratio a secondary axisymmetric mode arises. For even higher precession ratios, a strong shear appears at the outer rim of the cylinder and the flow in the bulk becomes completely turbulent. The appearance of the secondary axisymmetric mode promises dynamo action within the sodium experiment under construction [2].
The downscaled water experiment was operated in a wide range from Re=10000 to 1.6*10**6, showing a very good agreement with direct numerical simulations at their upper limit of Re=10000.
Furthermore, we give an overview of the present state and the commissioning of the DRESDYN facility which is still in progress.

Deep Ensembles \cite{lakshminarayanan_2017_SimpleScalablePredictive} remain a popular reference baseline and go-to method for neural network uncertainties (UC), despite the computational cost. The paper describes a method to construct calibrated uncertainties by explicit modeling of heteroscedastic noise to quantify the aleatoric uncertainty via a Gaussian Mixture Model of Mean Variance Estimation (MVE) networks~\cite{nix_1994_EstimatingMeanVariance} (MVE-GMM ensemble). Yet, in many practical applications a much simpler strategy, namely simple ensembling (SE), is performed, which gives access only to epistemic uncertainty~\cite{kendall_2017,gawlikowski_2022}. This affects calibration and, therefore, makes comparisons with other uncertainty methods difficult. Motivated by this observation, we empirically compare both uncertainty methods and assess their impact on the quality of the obtained uncertainty scores in practice.

The speed of sound c drops drastically when gas bubbles are dispersed in a liquid. This allows for access to supersonic flows at more easily achievable velocities. While the theory and simulations of the averaged properties in a bubbly fluid mixture are well developed and understood, any phenomena on the scale of the bubble size have not yet been investigated. Especially in applications, where microscopic bubble interactions are of interest, the large-scale averaged theories are insufficient and a more detailed understanding is required.

Flotation is used to separate particle intermixtures in many industrial applications, most notably in the mining industry for extracting valuable minerals from mined ores. During the flotation process, particles attach to air bubbles based on their hydrophobicity. More efficient recovery of fine and ultra-fine particles (smaller than 10 μm) benefits from highly turbulent flows and smaller bubble sizes.
We present results from a two-phase model experiment of a pressurized pneumatic floatation cell. The cell is constructed based on the physical principles of the Concorde Cell (Metso). In a vertical pipe, air bubbles are generated by a plunging jet: a water jet impinges on a free water surface, entrains the surrounding air and generates sub-millimeter-sized bubbles. These are transported downwards to the lower tip of the downcomer, where a nozzle accelerates the flow and ejects a bubbly jet into a water-filled cell. Due to the pressure drop over the tip nozzle, the air surrounding the plunging jet has to be pressurized. We investigate the properties of the bubble generation, their evolution along the downcomer length and the resulting bubbly jet. The bubble size and void fraction are recorded using optical shadowgraphy, along with pressure and electrical conductivity measurements. The bubble size is determined by using a machine learning algorithm to segment the bubbles in the shadowgraph and fitting ellipses to their contour. Control parameters of the process are the water and air fluxes, as well as the surfactant concentration in the water.

Laser plasma-based ion accelerators have not reached their full potential in producing high-radiation doses at high particle energies. The most stringent limitation is the lack of a suitable high-repetition rate target that also provides a high degree of control of the plasma conditions. For high-intensity laser-solid interactions, the absolute density and surface density gradients of the target at the arrival of the ultrarelativistic laser peak are critical parameters [1]. Accurate modeling of the leading edge-driven target preexpansion is required to strengthen the predictive power of associated computer simulations and thus to achieve higher beam energies with laser accelerators. This calls for plasma benchmark experiments to be carried out with well-defined laser and plasma conditions.
In this talk, we report on high repetition rate experiments in which a cryogenic hydrogen jet target is irradiated with an intense laser pulse, and show how such experiments open up new opportunities for understanding, improving and controlling the laser accelerator. The high-repetition rate is of interest not only for quasi-continuous acceleration, but also for addressing fundamental questions of the laser plasma interaction. This cryogenic jet platform allows to experimentally benchmark computer simulations due to the large number of shots resulting in a high statistic. As two examples, we consider studies on the transition from an initial solid state to a plasma state [2], i.e. to define the starting point of subsequent target preexpansion and thus for modeling, and on expanding plasma density distributions [3], i.e. to determine the plasma temperature evolution after laser irradiation as a comparison to simulations.

[1] M. Rehwald, et al. “Ultra-short pulse laser acceleration of protons to 80MeV from cryogenic hydrogen jets tailored to near-critical density”, Nature Communications 14, 4009 (2023)
[2] C. Bernert, et al. "Transient laserinduced breakdown of dielectrics in ultra-relativistic laser-solid interactions” Physical Review Applied 19, 014070 (2023)
[3] L. Yang, et al. Time-resolved optical shadowgraphy of solid hydrogen jets as a testbed to benchmark particle-in-cell simulations. Communications Physics 6, 368 (2023)

Metadata is a key element in data management when taking account of the F.A.I.R.(findable, accessible, interoperable and reusable) principles, answering the need for better data integration and enrichment. In the field of high-intensity laser-plasma physics, numerical simulations and experiments go hand in hand, complementing each other. While simulation codes are well documented and output files can follow some standards (like openPMD or Smilei/happi ), input files were often neglected. Experiment documentation is typically diverse, containing the description of manually executed setup steps (with photos or hand drawings), tabular data of experiment execution (parameters and observations) alongside with actual detector data. Often, data from the driving laser system is better organized but poorly connected to the experiment.
We will report on recent progress of data management in the field of high-intensity laser-plasma physics at HZDR by means of the center’s data strategy and external projects like “HELPMI” by HMC, “DAPHNE4DNFI” by NDFI and others.
HELPMI is an HMC project aiming towards a data standard for laser-plasma (LPA) experiment data, making data interoperable (I) and reusable (R). While openPMD is an open standard for simulations in that domain, NeXus is an open standard for experimental data in Photon and Neutron sciences. HELPMI has identified benefits and challenges when adopting NeXus for the LPA domain and extended openPMD for arbitrary data hierachies like NeXus. Alongside, a domain-specific glossary is being developed, where the community must be involved.
DAPHNE4DNFI supports metadata capture and data enrichment activities at HZDR. One major achievement is a web app for manual experiment logging, i.e. taking the above-mentioned tabular data of parameters and observations. This app is highly configurable, following the changes and improvements of experimental setup and techniques. It can connect to other electronic lab documentation resources (like the Mediawiki system deployed at HZDR) in order to directly re-use metadata. Data is stored in a central database instead of multiple spreadsheet files and can be directly plotted, also against historical data.
Another important outcome of DAPHNE4DNFI is metadata capturing and cataloging of simulation input data. This way, tables of simulation input data can be generated, allowing to re-use input files. Of course, output data and analysis scripts are also linked, thus the in-house re-use of data is strongly enhanced.
On top of that, but also as necessary tool, DAPHNE4DNFI has strongly promoted the use of metadata catalogues, in particular SciCAT. Even though daily usage is automated via scripts, a web interface to browse and search for data and metadata is extremely helpful. Such metadata catalogues complement data repositories by enabling the F (findable) but require a lot of effort in data enrichment.

This presentation summarizes activities at the high-intensity laser plasma group to imrove data and metadata handling, capture, storage and processing.

Flotation is used to separate particle intermixtures in many industrial applications, most notably in the mining industry for extracting valuable minerals from mined ores. During the flotation process, particles attach to air bubbles based on their hydrophobicity. More efficient recovery of fine and ultra-fine particles (smaller than 10 μm) benefits from highly turbulent flows and smaller bubble sizes.
We present results from a two-phase model experiment of a pressurized pneumatic floatation cell. The cell is constructed based on the principles of the Concorde Cell (Metso, see Jameson, Miner. Eng. 23, 835–841, 2010 and Yáñez et al., Miner. Eng. 206, 108538, 2024). In a vertical pipe, air bubbles are generated by a plunging jet: a water jet impinges on a free water surface, entrains the surrounding air and generates sub-millimeter sized bubbles. These are transported downwards to the lower tip of the pipe, where a nozzle accelerates the flow and ejects a bubbly jet into a water-filled cell. Due to the pressure drop over the tip nozzle, the air surrounding the plunging jet has to be pressurized. We investigate the properties of the bubble generation, their evolution along the downcomer length and the resulting bubbly jet. The bubble size and void fraction are recorded using optical shadowgraphy, along with pressure measurements. The bubble size is determined by using a machine learning algorithm to segment the bubbles in the shadowgraph and fitting ellipses to their contour. Control parameters of the process are the water and air fluxes, as well as the surfactant concentration in the water.

The following conlusions can be drawn: (i) The 2-step process by HPS controls the oxidation of Si substrate, (ii) Low contact resistivity was obtained with TiOx (40 mΩ∙cm2) and TiOx/a-Si:H (47 mΩ∙cm2), and (iii) TiOx/a-Si:H shows a lifetime of ~200 μs with a hotplate or flash lamp annealing (3 ms,
reached temperature: 550 °C).

Liquid metal batteries (LMBs) are a promising candidate for storing electrical energy at the grid scale. An LMB is a fully molten electrochemical cell in which two liquid metal electrodes are separated by a molten salt electrolyte. With its simple chemistry and geometry, fully liquid state, and the occurrence of multi-physics phenomena, the LMB has become an intriguing candidate for continuum mechanics studies. This presentation primarily focuses on mass transfer within a liquid metal electrode. There, concentration inhomogeneities degrade cell efficiency, and most significantly, the alloying and de-alloying processes are the ones responsible for energy storage. The geometry of these electrodes is simple : a liquid alloy is confined by a flat electrochemically active interface and inert walls. During operation, a mass flux is established across the interface. The liquid alloy experiences either an enrichment or depletion of the electroactive species. This alters the local density distribution and can either cause or inhibit convective flows. We demonstrate how this explains the disparity in cell efficiency seen during charge and discharge experiments. We then delve into the study of the solutal convective flow. We use spectral-element simulations to explore the dynamics over an extensive parameter space. We identify and map two regimes of convection, analyse their time evolution, and present robust scaling laws for onset time, steady-state velocity, and concentration differences. We conclude by examining the role of mechanical coupling with the molten salt layer.

Implementation of the SmART+ IB for small animal image-guided proton therapy

ABSTRACT. Parallel to the start of proton radiotherapy in 2013 preclinical experiments were established in the experimental area of the University Proton Therapy Dresden. Embedded in the OncoRay research building, experimenter’s of the proton area have access to cell laboratories and an animal facility including a preclinical imaging platform. First, a double-scattering setup was developed creating a 150 MeV spread-out Bragg peak (SOBP) for in-vitro studies within a homogeneous 10 x 10 cm² field (1). The inclusion of suitable collimators and range shifters in the beam path together with simple optical imaging and positioning enabled the irradiation of subcutaneous tumours on mice hind legs (2) and ears (3). In this process, a mouse bedding unit was developed allowing for CT and MRI imaging, photon and proton treatment without positional changes of the animal and preventing contamination at the same time (2). In a next step, a setup for partial brain irradiation of mice was developed making use of proton radiography for positioning at the beam – firstly by landmark-based co-registration of the bedding unit (4) and later on by target delineation directly on a proton radiography of the skull (5). A 90 MeV pristine proton beam was laterally collimated by 3 mm and 4 mm apertures and decelerated such that it stops in the middle of the mouse head. Irradiated mouse brains of two strains of differing radiosensitivity allowed insights into acute radiation damage, e.g. by double-strand break analysis (4), relative to photon irradiation. Moreover, late endpoints like radiation induced contrast enhancement were studied by regular MRI follow up over six months and subsequent histological analysis (6). The correlation of MRI imaging, spatial histology information and Monte Carlo dose- and LET-simulations provide further insights into the radiobiological response to proton irradiation. To develop this setup further a first prototype small animal irradiation device (SMART IB, Precision X-ray) was installed at the proton beam line. The device is currently commissioned and will allow on-site CT-based treatment planning and positioning as well as photon irradiation for reference. Lately, the Flash irradiation of mouse brains with protons was realized combining a dedicated 3D-range modulator (7) to produce an SOBP with one pencil beam and proton radiography for accurate mouse positioning. Conventional and Flash irradiation of six C57BL/6 each were performed and the animals were followed for 6 months; whereby analysis is still ongoing. To sum up, during the last years preclinical experiments with protons were developed starting from simple adaptations of an existing double-scattering setup to dedicated setups for partial brain irradiation with proton Flash. The integration of the small animal irradiation device will further enhance the experimental possibilities bringing the preclinical animal studies one-step closer to clinical-like treatment.

References: (1) Helmbrecht et al. (2016) J Instrum (2) Müller et al. (2020) Biomed Phys Eng Express (3) Kroll et al. (2022) Nat Phys (4) Suckert et al. (2020) Radiother Oncol (5) Schneider et al. (2022) Front Oncol (6) Suckert et al. (2021) Front Oncol (7) Horst et al. (2023) Front Phys

Preclinical studies on proton Flash-RT, Update from 2022

Zebrafish embryo studies of the role of oxygen in the FLASH effect

kein Abstrakt vorhanden

We present a synthetic Shadowgraphy Plugin for the particle-in-cell code PIConGPU. By time-integrating electric and magnetic fields and propagating them onto a screen in the far field with Fourier methods, shadowgram images equivalent to experimental measurements can be produced.

Our in-situ plugin now enables recording few-cycle probe pulses after they traverse plasma structures of e.g. laser-plasma accelerators with the PIC algorithm. The so generated images contain the full laser-plasma interactions in contrast to traditional post-processing approaches. By analyzing these shadowgrams alongside the 3D, time-resolved density distribution from the simulation, one can trace the origin of specific features.

We also show validation tests, that confirm the conservation of physical quantities and the plugin performing as expected. This allows to quantitatively predict and analyze shadowgrams.

Laser-plasma acceleration (LPA) sources exhibit extraordinary beam properties that create unique application opportunities but also pose challenges. LPA can generate energetic ions or electrons. The resulting bunches feature a high number of particles concentrated in temporally short bunches, making them capable of delivering ultra-high dose rates (UHDR), e.g., for radiobiological research. However, LPA sources suffer from unfavorable beam properties such as shot-to-shot fluctuation, high divergence, and a broad energy distribution.

The presentation focuses on results obtained at the Draco PW laser facility. Draco PW drives an LPA proton source that was stabilized by tuning the laser’s spectral phase. Pulsed high-field magnets efficiently tailor the beam to meet the demands of application experiments, here, the world’s first radiobiological animal studies with laser-accelerated particle beams (zebrafish embryos and tumors in a mouse model). The role of LPA particle sources in the context of UHDR radiobiology and FLASH radiotherapy – possibly the next breakthrough in the fight against cancer – will be discussed.

Beryllium is a chemotoxic, silver-gray, light-weight metal. Beryllium-bearing waste is present in the Aube Disposal Facility (CSA). This surface facility, managed by Andra since 1992, is specifically designed for low- and intermediate-level, short-lived radioactive waste. As for other chemo-toxic elements, the evaluation of Be release towards the biosphere is required for safety and environment impact assessment. This study aims a better characterization of Be migration in the sandy aquifers (Aptian sands) below the waste cells at CSA. Be(II) is characterized by a strong hydrolysis and the formation of sparingly soluble hydroxide phases. In the presence of carbonate, Be(II) forms stable binary/ternary complexes Be(II)-OH-CO3(aq), although the aqueous species prevailing in near-neutral to alkaline conditions remain ill-defined. Groundwater in Aptian sands is characterized by a near-neutral pH and carbonate concentrations ~ 1 mM. Be(II) uptake by Aptian sands has been quantified associated to the characterization of the aqueous speciation in carbonate-containing porewaters.

Metal aerogels are emerging porous materials composed entirely of nanostructured metals, which manifest broad prospects in diverse fields. Particularly, multimetallic aerogels (MMAs) receive increasing attention due to their widely tunable properties stimulated by the synergy of multiple metals. However, the investigation of multimetallic effects in MMAs is predominantly restricted to optimizing their application performances. Here, the untrivial multimetallic effects on the synthetic aspect are discovered, and the underlying mechanisms are unveiled, offering new perspectives for manipulating the sol-gel process and tuning the ligament size (d_L) of MMAs by designing the average bulk density (rho_ab) and atomic radius (r_a) mismatch. Moreover, a sedimentation-based non-destructive method is established, which solves the long-lasting challenge of preparing intact metal-gel-based electrocatalysts and yields record-high performances toward alcohol oxidation reactions.

Since its discovery, graphene has gained considerable interest from scientists all over the world. For more than one decade, the scientific community has been spending notable amounts of intellectual and financial resources to study its properties, which paves a way towards the commercialization of graphene, other 2D materials and a manifold of their derivatives. In this review, the spectroscopic properties of porphyrin-functionalized 2D materials are comprehensively discussed, followed by an extensive presentation of state-of-the-art achievements in photocatalysis based on such composite/hybrid materials. The primary focus is on the fundamental understanding of the structure–property–performance relationship as well as its importance in the future target-oriented design and fabrication of photocatalysts with tailored properties. After a short introduction, different design strategies for the fabrication of porphyrin (Por)-functionalized graphene-based materials (GBMs) (covalent vs. non-covalent assemblies) are systematically summarized. Then, the photocatalysis-relevant properties of the composites are thoroughly discussed based on the experimental results provided by steady-state absorption spectroscopy (ground-state properties) and time-resolved absorption and emission spectroscopies (excited-state properties). The importance of appropriate data analysis, with particular respect to the photoemission processes, is brought to attention. Subsequently, the photocatalytic behavior towards hydrogen generation, CO2 reduction and pollutant degradation of Por and GBM hybrids are comprehensively reported and fundamental mechanisms of light-driven catalytic processes in such systems, together with efficiency-limiting steps, are highlighted. The role of spectroscopy as a very powerful tool that enables the determination of key photophysical properties essential for light-driven catalysis is emphasized. Finally, recent advances with respect to 2D materials beyond graphene and their assembly with Por as promising photocatalysts are presented. We believe that this review, which comprehensively presents the knowledge gained to date regarding composites based on 2D materials with porphyrins as promising photocatalysts, will stimulate further efforts of researchers to tackle the remaining challenges and contribute to taking a decisive step towards the commercialization of these photocatalysts in the future.

Laser-Plasma Acceleration (LPA) is a highly non-linear process sensitively dependent on parameters of gas flow and laser which are hard to control or simultaneously measure in experiments. Understanding of such parameter dependencies can be driven by simulations which offer control and observability, but are more expensive the more physical details are included. In the case of LPA, full 3D particle-in-cell (PIC) simulations are far to expensive to allow detailed scans of the available parameter space. Deep-learning based surrogate models are promising for guiding parameter optimizations, enable fast result estimation or inversion and compile information about vast parameter spaces more effectively. In this talk we are going to review state-of-the-art approaches to surrogate modeling in plasma physics to show perspectives and challenges in leveraging approaches like neural operator and physically-informed neural networks (PINNs) to enhance simulation-driven progress in LPA.

ncreasing HPC cluster sizes and large-scale simulations that produce petabytes of data per run, create massive IO and storage challenges for analysis. Deep learning-based techniques, in particular, make use of these amounts of domain data to extract patterns that help build scientific understanding. Here, we demonstrate a streaming workflow in which simulation data is streamed directly to a machine-learning (ML) framework, circumventing the file system bottleneck. Data is transformed in transit, asynchronously to the simulation and the training of the model. With the presented workflow, data operations can be performed in common and easy-to-use programming languages, freeing the application user from adapting the application output routines. As a proof-of-concept we consider a GPU accelerated particle-in-cell (PIConGPU) simulation of the Kelvin- Helmholtz instability (KHI). We employ experience replay to avoid catastrophic forgetting in learning from this non-steady process in a continual manner. We detail challenges addressed while porting and scaling to Frontier exascale system.

Photonic integrated circuits (PICs) are crucial for advancing optical communications, promising substantial gains in data transmission speed, bandwidth, and energy efficiency compared to conventional electronics1. Telecom-wavelength photodetectors, operating near 1550 nm, are indispensable in PICs, where they enable the sensitive and low-noise conversion of optical signals to electrical signals for efficient data processing. While silicon is ideal for passive optical components, its limited absorption in the optical telecommunication range (1260-1625 nm) typically necessitates integrating an alternative material, such as germanium2, for photodetection — a process that introduces significant fabrication challenges3. Here, we present a highperformance, all-silicon photodetector, grating- and waveguide-coupled, which 1 operates at room temperature within the optical telecom C band. By introducing deep-level impurities into silicon at concentrations close to the solid-solubility limit, we enable efficient sub-bandgap absorption without compromising recombination carrier lifetimes and mobilities. This detector achieves a responsivity of 0.56 A/W, a quantum efficiency of 44.8%, a bandwidth of 5.9 GHz, and a noise-equivalent power of 4.2×10-10 W/Hz¹/² at 1550 nm, fulfilling requirements for telecom applications. Our approach provides a scalable and cost-effective solution for the monolithic integration of telecom-wavelength photodetectors into silicon-based PICs, advancing the development of compact photonic systems for modern communication infrastructures.

Melt flow is critical to microstructural evolution during various solidification processes, such as directional solidification and additive manufacturing. Applying an external magnetic field interacts with the intrinsic thermoelectric currents during solidification, generating a new flow field, due to thermoelectric magnetohydrodynamics (TEMHD). The introduction of TEMHD flow can disrupt the existing buoyancy-dominated flow and potentially tailor the microstructure. However, the physical mechanisms remain unclear, hindering its further application. Here, using in situ synchrotron X-ray imaging coupled with numerical simulation, we demonstrated that the macroscopic TEMHD flow ahead of the solidification front, along with the interstitial TEMHD flow arising within the mushy zone are the primary mechanisms controlling melt flow in the thin sample. Two thermoelectric regimes were revealed, each with distinctive mechanisms that control flow. Additionally, we developed a methodology on characterising melt pool in 3D during additive manufacturing process and demonstrated the significant TEMHD effect on the melt pool.

The current work presents an experimental study focusing on pulsed electromagnetic fields (PEMF) effects on dendrite microstructure and melt flow during the solidification of low-melting temperature Ga-In alloy. This alloy is solidified in a flat sample bottom-to-top applying a vertical temperature gradient [1-2]. The dendritic microstructure is visualized using synchrotron X-ray imaging at the Diamond Light Source. The magnetic system used generates field intensities of 8 - 11 mT and frequencies in the domain between 10 and 300 Hz, a duty cycle of 50%. The solidification under frequencies above 100 Hz leads to dendrite fragmentation and solute redistribution in the mushy zone. Moreover, direct observations show that large dendrite blocks (10 - 20 dendrites) can individually move or turn in the mushy zone leading to the formation of new sub-grain boundaries. We consider this phenomenon as an alternative mechanism of grain refinement. The next step is to validate a Cellular Automata Lattice Boltzmann-based numerical model [3-4] using the same set-up as the experiment and directly compare it with the synchrotron radiographic data.
References
[1]Shevchenko N., Boden S., Gerbeth G., Eckert S. Metall. Mater. Trans. A, 44: 3797-3808. 2013.
[2] Shevchenko N., Roshchupkina O., Sokolova O., Eckert S. Journal of Crystal Growth, 417: 1-8. 2015.
[3] Kao A., Shevchenko N., Alexandrakis M. et al. Phil. Trans. R. Soc. A, 377: 20180206. 2019.
[4] Kao A., Krastins I., Alexandrakis M. et al. JOM, 71: 48-58. 2019.

Melt flow is critical to microstructural evolution during various solidification processes, whether in directional solidification, or additive manufacturing. Applying an external magnetic field interacts with the intrinsic thermoelectric currents during solidification, generating a new flowfield, due to thermoelectric magnetohydrodynamics (TEMHD). The introduction of TEMHD flow can disrupt the existing buoyancy-dominated flow and potentially tailor the microstructure. However, the physical mechanisms remain unclear, hindering its further application. Here with a focus on directional solidification, using in situ synchrotron X-ray imaging coupled with numerical simulation, we demonstrated that the macroscopic TEMHD flow ahead of the solidification front, along with the microscopic TEMHD flow arising within the mushy zone are the primary mechanisms controlling melt flow. Two thermoelectric regimes were revealed, each with distinctive mechanisms that control flow. Further, we demonstrated how the TEMHD effect can also manipulate melt flow in a rapid solidification process, i.e., additive manufacturing.

The increasing use of lithium-containing materials highlights the urgent need for their recycling to preserve resources and protect the environment. Lithium-containing slags, produced during the pyrometallurgical process in lithium-ion battery recycling, represent an essential resource for lithium recovery efforts. While multiple methods for lithium recycling exist, it is crucial to emphasize environmentally sustainable approaches. This study employs dry forced triboelectrification (FTC) to recover valuable components from slag powder, commonly known as engineered artificial minerals (EnAMs). The FTC method is used to change the charge of the target material and achieve a neutral state while other materials remain charged. The downstream electrostatic separator enables the charged particles to be separated from the target material, which in this study is lithium aluminate. The results show that the method is effective, and lithium aluminate can be successfully enriched.

Modification of flow during solidification has been shown to have a large effect on the microstructural dendritic growth during directional solidification, causing changes to convective solute transport. In our previous reported study, we modified flow using the interaction of thermoelectric currents with static magnetic fields, employing the phenomenon known as Thermoelectric Magnetohydrodynamics (TEMHD). Our current work expands on this to look at the effect of pulsed magnetic fields and the interaction with the induced currents generated. Pulsed fields are known to influence microstructure evolution, and we hypothesise that this is also due to fluid flow. Modelling work of this process in thin Hele-Shaw quartz cells has been performed on both a micro and macro-scales, looking at both the gross flow patterns within the cells and the microstructural solidification and inter-dendritic flow. We compare our modelling work to experimental work in situ at Diamond Light Source.

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The circular economy holds significant potential as a resource for the sustainable management of plastic waste that cannot be mechanically recycled, offering a pathway for environmentally responsible practices. The pyrolysis of a 15 kg sample of an organic-rich fraction from the mechanical recycling of end-of-life refrigerators was carried out to provide an overall mass balance and a detailed breakdown of the composition of the resulting products. These include the organic condensate (pyrolysis oil) as the main product as well as gaseous and solid byproducts. Potential applications for the utilization of these pyrolysis products as petrochemical feedstocks are proposed highlighting the challenges associated with their utilization. Leveraging this potential is crucial for fostering a sustainable approach to plastic waste management, however remarkable improvement and product upgrading have to be established to uptake the pyrolysis products of real wastes as feedstock in the petrochemical industry.

Mn-doped UO2 is considered a potential advanced nuclear fuel due to ameliorated microstructural grain growth compared to non-doped variants. However, recent experimental investigations have highlighted limitations in grain growth apparently arising from misunderstandings of its redox-structural chemistry. To resolve this, we use synchrotron X-ray diffraction and spectroscopy measurements supported by ab initio calculations to cross-examine the redox and structural chemistry of Mn-doped UO2 single crystal grains and ceramic specimens. Measurements reveal Mn enters the UO2 matrix divalently as with the additional formation of fluorite Mn+2O in the bulk material. Extended X-ray absorption near edge structure measurements unveil that during sintering, the isostructural relationship between fluorite UO2 and Mn+2O results in inadvertent interaction and subsequent incorporation of diffusing U species within MnO, rather than neighbouring UO2 grains, inhibiting grain growth. The investigation consequently highlights the significance of considering total redox-structural chemistry of main and minor phases in advanced ceramic material design.

We present an entangling gate scheme for trapped-ion chains that achieves high-fidelity operations with excited motional states despite multiple error sources. Our approach incorporates all relevant motional modes and exhibits enhanced robustness against both motional heating effects and detuning errors, critical features for building robust and scalable trapped-ion quantum computers.

The surface code is a spin-1/2 lattice system that can exhibit non-trivial topological order when defects are punctured in the lattice and thus can be used as a stabiliser code. The protocols developed to create defects in the system have previously relied on adiabatic dynamics. In this work we use techniques of quantum optimal control to overcome the requirement for adiabaticity and achieve defect creation and implemention of other important operations required for quantum computation at much faster timescales.

Fluid-solid interactions drive changes in porosity and permeability. This has critical consequences for the evolution of the flow field in complex porous materials and thus controls the evolution of reactive transport processes. Important applications are in the vast field of reservoir and host rock alteration, e.g. by coupled dissolution and precipitation processes. While dissolution processes can cause local increases in pore space and permeability, they can also lead to pore throat blockage, which can cause formation damage due to precipitation reactions and particle retention in pore throats. Although these mechanisms are understood in principle, the direct changes in the flow field they cause are difficult or impossible to observe directly. Using positron emission tomography, we show how flow field heterogeneities are quantitatively affected by coupled dissolution reactions and pore throat blockage in a long-term experiment. Direct comparison of PET-derived flow field data reveals a pattern of flow field modification during this experiment. PET thus becomes a key analytical tool to localize and quantify pore-scale flow field changes, in addition to recent advances focused on the identification of flow channeling effects of advective flow and the heterogeneity of diffusive flux in low permeability rocks.

Quantum field theory predicts a nonlinear response of the vacuum to strong electromagnetic fields of macroscopic extent. This fundamental tenet has remained experimentally challenging and is yet to be tested in the laboratory. A particularly distinct signature of the resulting optical activity of the quantum vacuum is vacuum birefringence. This offers an excellent opportunity for a precision test of nonlinear quantum electrodynamics in an uncharted parameter regime. Recently, the operation of the high-intensity laser ReLaX provided by the Helmholtz International Beamline for Extreme Fields (HIBEF) has been inaugurated at the High Energy Density (HED) scientific instrument of the European XFEL. We make the case that this worldwide unique combination of an x-ray free-electron laser and an ultra-intense near-infrared laser together with recent advances in high-precision x-ray polarimetry, refinements of prospective discovery scenarios, and progress in their accurate theoretical modelling have set the stage for performing an actual discovery experiment of quantum vacuum nonlinearity.

In their +V and +VI oxidation states, actinide elements (U, Np, and Pu) are commonly encountered in characteristic linear dioxo structures, known as actinyl ions (AnO2n+; An = U, Np, Pu, n = 1, 2). A systematic understanding of the structural and redox behavior of AnVO2+/AnVIO22+ complexes is expected to provide valuable information for controlling the behavior of An elements in natural environments and in nuclear fuel cycles whilst enabling the development of spintronics and new reactivities that utilize the anisotropic spin of the 5f electrons. However, systematic trends in the behavior of AnVO2+/AnVIO22+ complexes remain poorly understood. The [AnV/VIO2(saldien)]−/0 complexes (saldien2− = N,N’-disalicylidenediethylenetriamine) studied here offer a promising avenue for advancing our understanding of this subject. The molecular structures of a series of [AnVIO2(saldien)] complexes were found to exhibit notable similarities through these An elements with minor, but still significant, contributions from the actinide contraction. The redox potentials of the [AnV/VIO2(saldien)]−/0 couples clearly increase from U to Np, followed by a subsequent decrease from Np to Pu (−1.667 V vs. Fc0/+ for [UV/VIO2(saldien)]−/0, −0.650 V for [NpV/VIO2(saldien)]−/0 and −0.698 V for [PuV/VIO2(saldien)]−/0). Such a difference can be explained in terms of the difference in character of the electronic configuration of the +VI oxidation state. A series of these redox trends was also successfully reproduced by DFT-based calculations. These findings provide valuable information for controlling the oxidation states of the An elements.

The mTeSS-X (Multi-tenanting TeSS eXchange) project aims to build upon the ELIXIR TeSS platform to address the fragmentation of training resources across
Research Infrastructures (RIs) and scientific domains. RIs and EOSC projects have limited training catalogue capability beyond sparse, outdated lists on web pages,
while cross-portal exchange has been discussed but not practised. Fragmentation of resources prevents the reuse of valuable training materials and limits the dissemination. By fostering the federation of interoperable training catalogues, mTeSS-X will significantly enhance the findability, accessibility, and reuse of high-quality training resources, improve the sustainability of training portals by reducing operational duplication and enabling resource-sharing across portals.

es hat kein aussagefähiges Abstract vorgelegen

es hat kein aussagefähiges Abstract vorgelegen

es hat kein aussagefähiges Abstract vorgelegen

In der Natur gehören chemische und biologische Prozesse untrennbar zusammen. Wie sehr sich diese Porzesse gegenseitig beeinflussen lässt sich am Beispiel des Verhaltens von Uran in der Umwelt und seiner Wechselwirkung mit verschiedenen biologischen Systemen sehr eindrücklich darlegen. Der Vortrag zeigt dies an einigen Beispielen auf und verdeutlicht damit die Verflechtung beider Fachdisziplinen.

The contrasting reactivity of hydrogen isotopes, including tritium, is of interest in several research areas, including nuclear fusion, pharmaceutical synthesis, and fundamental isotope separation research [1]. In our work on hydrogen isotope separation, we focus on approaches for gaseous isotopologue separation, other than the currently employed methods, e.g. cryogenic distillation. A promising approach is the selective ad- and desorption on nanoporous materials, i.e. MOFs (metal organic frameworks) and zeolites, in temperature-controlled environments. Previous work has shown positive results with respect to hydrogen and deuterium separation. [2, 3]

We investigated the separation efficiency of an Ag(I)-exchanged zeolite using thermal desorption spectroscopy (TDS). The zeolite was exposed to H2/T2 gas mixtures at low temperatures, obtained by liquid N2 cooling. The experimental approach with gaseous tritium requires a specific analytical strategy. Therefore, the desorbed tritium was collected after conversion to HTO and analyzed by liquid scintillation counting (LSC). This allowed us to safely handle and remove the tritium gas, while knowing exactly how much tritium was initially adsorbed. Using this analytical strategy, we exposed the sample to low gas pressures (10 mbar) in a temperature range from 80 K up to 100 K. We were able to achieve separation efficiencies of up to 6, for extremely asymmetric gas mixtures (approx. 0.5% T2).

References:

[1] L. Shere, A. K. Hill, T. J. Mays, R. Lawless, R. Brown, S. P. Perera Int. J. Hydrogen Energy 2024, 55, 319-338. [2] L. Zhang, T. Wulf, F. Baum, W. Schmidt, T. Heine, M Hirscher Inorg. Chem. 2022, 61, 25, 9413–9420. [3] J. Y. Kim, R. Balderas-Xicohténcatl, L. Zhang, S. G. Kang, M. Hirscher, H. Oh, H. R. Moon J. Am. Chem. Soc. 2017, 139, 42, 15135–15141.

The lecture described methods for analyzing uranium-containing samples and for determining dominant and relevant binding forms of uranium in complex environmental samples, and pointed out possible future development opportunities.

This lecture dealt with various interaction mechanisms between radionuclides and biosystems in general and with uranium in particular

Tritium has recently become a topic in numerous fundamental and applied research areas. This includes fields such as storage[1], fusion and isotope separation[2]. In our work, we specifically focus on investigating potential approaches on gaseous hydrogen isotopologue separation, which are supposed to yield a higher separation efficiency than currently employed methods. One approach is the selective permeation through a proton conducting polymer (i.e. Nafion) via electrochemical pumping. Combination with graphene, a monoatomic carbon material, is being explored to further increase the separation efficiency.[3, 4] This has already shown promising results for protium-deuterium mixtures.

One currently unanswered question is how the exposure to tritium as a beta emitter may modify the graphene structure, which could in turn affect the separation efficiency. To investigate this, graphene samples on SiO2/Si substrate were modified by either electron irradiation from an SEM electron beam or by direct exposure to tritium using a specific setup. A comparable electron dose was applied in both cases, but in contrast to the SEM electrons, the emitted beta particles are not focused and show a broad energy distribution. The samples were analyzed using a Raman spectroscope, including a pristine sample. From the spectra, the intensity ratios of the D- and the G-band were calculated as an indicator for the defect or modification density.
The results show just a very slight increase in the intensity ratio for the SEM irradiated sample, which could suggest minor changes in the structure. In comparison, the tritium exposed sample exhibits a much higher intensity ratio. This indicates not only a higher modification density but also structural changes, which cannot be solely contributed the electrons from the tritium decay. It appears likely that a tritiation reaction[1] occurs, facilitated by the beta emission.

Literature:

[1] Zeller, G. et al. Nanoscale Adv. 2024, 6, 2838.
[2] Shere, L. et al. Int. J. Hydrogen Energy 2024, 55, 319.
[3] Lozada-Hidalgo, M. et al. Science 2016, 351, 68.
[4] Lozada-Hidalgo, M. et al. Nat. Commun. 2017, 8, 15215.

Glacial fluctuations leave distinct imprints on the landscapes of mountain environments, such as
moraines and outwash terraces, that allow the reconstruction of past environmental changes. Unraveling the environmental history of the valleys of the Subtropical Andes of Argentina poses challenges due to the complex interplay of various surficial processes driven by both climatic and tectonic forces, which affects the preservation of glacial deposits. Consequently, there are few studies on past glaciations in this region compared to the rest of the Andes. This study focused on the lower section of the Blanco River Basin and the piedmont of the Frontal Cordillera in the south of San Juan Province, Argentina. A comprehensive geomorphological map of glacial landforms was created, along with sedimentological studies of outwash terraces. Additionally, numerical ages were obtained for both landforms using terrestrial cosmogenic nuclides for moraine boulders and luminescence dating for sandy layers in the outwash terraces. Our findings reveal at least two glacial advances since the Last Glacial Maximum (LGM), each associated with distinct outwash levels. The Río Blanco Advance occurred during the LGM, and the Laguna Advance is assigned to the late stages of the LGM, both with their corresponding outwash terraces. Additionally, the
Amarillo Advance is believed to have occurred during the Holocene period and an older Marine Istope Stage 5 d named Guanaquito Advance. The provided data add valuable numerical information about glacial fluctuations since the LGM and also reveal the impact of glacial downwasting on piedmont landforms.

In current electronic structure research endeavors such as warm dense matter or machine learning applications, efficient development necessitates non-monolithic software, providing an extendable and flexible interface. The open-source idea offers the advantage of having a source code base that can be reviewed and modified by the community. However, practical implementations can often diverge significantly from their theoretical counterpart. Leveraging the efforts of recent theoretical formulations and the features of Python, we try to mitigate these problems. We present eminus, an education- and development-friendly electronic structure package designed for convenient and customizable workflows, yet built with intelligible and modular implementations.

In order to assess the feasibility of bioremediation strategies, it is crucial to understand the interaction processes between the biosphere and the geosphere. In particular, this means understanding the specific mechanisms of fluid-solid interactions and their alteration by the biosphere. Soil fluids are chemically modified by biological activity and can potentially induce desorption reactions of contaminants from the solid soil components.
Positron emission tomography (PET), a method mainly employed in nuclear medicine, has been proven as a reliable tool for investigating a multitude of transport processes in natural[1] and technical materials. However, previous investigations focused on analyzing hydrodynamic parameters only. Because this tomographic method can quantitatively track radiotracers with high temporal and spatial resolution, it is well suited for analyzing the complex system created when plants are introduced into soil-like materials for phytoremediation purposes. As plants release chelating ligands into the rhizosphere via their root exudates, they induce highly localized changes in soil chemistry, which leads to changes in the mobility of metals and other nutrients. This affects not only the uptake of contaminants by plants, but also the overall mobility of metals in the soil. Reliable data on these effects are crucial for analyzing remediation processes for both nuclear and chemical waste.
To understand and quantify the effects of the interaction between the bio- and geosphere, PET techniques offer unique capabilities by providing in-situ volumetric radiotracer propagation and concentration data in with high temporal and spatial resolution, surpassing traditional flow and lysimeter experiments.
In this presentation, we discuss the possibilities of utilizing PET with various inert and reactive tracers in combination with µ-XRCT to assess the phytoremediation potential of contaminated soils by in-situ analysis of sorption and mobilization processes. Using both simplified substrates and complex soil systems, we demonstrate the impact of plants on the hydrodynamics and solute transport in complex materials such as soils and sediments.

Referenzen:

[1] T. Bollermann, T. Yuan, J. Kulenkampff, T. Stumpf, C. Fischer, Chemical Geology 2022, 606.

Remediation of former industrial or nuclear sites, as well as the evaluation of long-term storage strategies for nuclear and chemical waste, depends highly on a comprehensive understanding of contaminant mobility. This includes not only the hydrodynamics in the particular geomaterials, but also the kinetics of ion retention and mobilization. Although sorption coefficients are known for most materials, studying the in-situ behavior of solutes in natural materials under varying chemical conditions provides results that are crucial for predicting the feasibility of specific strategies for either decontamination or containment.
Utilizing radiotracers, positron emission tomography (PET) is capable of providing three-dimensional tracer concentration data with high temporal resolution. While previous studies using tomographic methods have focused on the acquisition of hydrodynamic parameters [1,2], the method also allows for the in situ monitoring of reactive transport experiments while providing spatially resolved data – enabling the possibility of extracting material-specific reactivities from complex natural and technical samples.

In this presentation, we discuss contaminant retention and subsequent mobilization in various materials, induced by changes in the chemical environment. Experiments using 86Y as a radiotracer analog for the lanthanide series, in conjunction with traditional hydrodynamic studies, allow the prediction of spatially resolved surface reactivities as well as gaining a holistic understanding into the transport of contaminants in subsurface environments.

[1] J.L. Pingel, J. Kulenkampff, D. Jara-Heredia, M. Stoll, W. Zhou, C. Fischer, T. Schäfer (2023), Geothermics 111, 102705.

[2] T. Bollermann, T. Yuan, J. Kulenkampff, T. Stumpf, C. Fischer (2022), Chemical Geology 606, 120997.

The formation of cyanopyridine (CN-py) adducts of silicon tetrahalides was investigated for 3- and 4-cyanopyridine in combination with SiF₄ and SiCl₄. Whereas bubbling of SiF₄ through toluene solutions of 3-CN-py and 4-CN-py afforded white precipitates, which should possess the respective composition SiF₄(CN-py)₂, addition of SiCl₄ did not cause any precipitation. Upon storage of the toluene solution of SiCl₄ and 4-CN-py at 6°C for several weeks, some crystals of the composition SiCl₄(4-CN-py)₂⋅2(4-CN-py)⋅(toluene) were obtained. The use of SiCl₄ as the solvent (i.e. SiCl₄ in large excess) and dissolving 4-CN-py therein gave access to a crystalline adduct of the composition SiCl₄(4-CN-py)₂⋅2(4-CN-py)⋅3-CN-py instead recrystallized from SiCl₄ without forming an adduct with the silane. Computational analyses (B2T-PLYP level) of the single-point energy differences between starting materials SiX₄ (X = F, Cl) and 'pyridine’ (‘pyridine’ = pyridine, 3-CN-py, 4-CN-py) and their adducts SiX₄(‘pyridine’)₂ revealed the tendencies toward adduct formation to decrease in the order SiF₄ > SiCl₄ as well as pyridine >> 4-CN-py > 3-CN-py. For SiCl₄ with 4- and 3-CN-py, the energy of adduct formation (−7.0 and−5.7 kcal mol⁻¹, respectively) is easily compensated by entropy effects at room temperature. Whereas the former explains as to why cyanopyridines and SiCl₄ may co-exist without noticeable adduct formation, the crystal structures of the adducts SiCl₄(4-CN-py)₄⋅2(4-CN-py)⋅(toluene) and SiCl₄(4-CN-py)₂⋅2(4-CN-py) reveal the additional stabilization of these solids by co-crystallization with 4-cyanopyridine, which eventually enabled the isolation of the SiCl₄(4-CN-py)₂ moiety in a solid. Partial decomposition (hydrolysis) during attempts of recrystallization of SiF₄(4-CN-py)₂ and SiF₄(3-CN-py)₂ afforded crystals of the ionic compounds [4-CN-PyH]⁺[SiF₅(4-CN-py)]⁻ and [3-CN-PyH]⁺₂[SiF₆]²⁻, respectively.

Predicting the migration behavior of dissolved contaminants in the pore space of rock and soil is crucial for assessing the feasibility of remediation and long term waste storage strategies.
Positron emission tomography (PET) using conservative radiotracers is an established and reliable method for investigating advective flow and diffusive flux in porous geomaterials and for validating transport models [1, 2]. However, solute transport is often significantly influenced by sorption effects. Reliable data concerning these effects are crucial for analyzing remediation processes as well as predicting desired immobilization in waste storage applications.
To understand and quantify the effects of solute-mineral surface interactions, analyses beyond breakthrough curve measurements are essential. PET techniques offer unique capabilities by providing in-situ tracer propagation and concentration data with high temporal and spatial resolution, surpassing traditional flow and lysimeter experiments.
For many materials, it is desirable to quantify both reactivity and hydrodynamic flow. The simultaneous quantification of both effects requires the use of a dual tracer system. In this presentation, we discuss the possibilities of utilizing a tracer pair consisting of
F as a reactive tracer and
Br as its conservative counterpart. This allows the prediction of spatially resolved surface reactivities as well as the evaluation of advective flow. Using different sandy sediments as model systems, we demonstrate the quantifiability of localized sorption effects as low as 10 pmol/mm³.

References
[1] J.L. Pingel, J. Kulenkampff, D. Jara-Heredia, M. Stoll, W. Zhou, C. Fischer, T. Schäfer, In-situ flow visualization with Geo-Positron-Emission-Tomography in a granite fracture from Soultz-sous-Forêts, France, Geothermics 111 (2023) 102705.
[2] T. Bollermann, T. Yuan, J. Kulenkampff, T. Stumpf, C. Fischer, Pore network and solute flux pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks, Chemical Geology 606 (2022) 120997.

This lecture provided the theoretical background of the bioleaching of uranium ores using microbiological processes, with a particular focus on microbiological, biochemical and technical aspects. This was supplemented by the identification of relevant influencing factors.

The experimental evaluation ofmany quantum mechanical quantities requires the estimation of several directly measurable observables, such as local observables. Due to the necessity to repeat experiments on individual quantum systems in order to estimate expectation values of observables, the question of how many repetitions to allocate to a given directly measurable observable arises. We show that an active learning scheme can help to improve such allocations, and the resultant decrease in experimental repetitions required to evaluate a quantity with the desired accuracy increases with the size of the underlying quantum mechanical system.

We review a scheme for the systematic design of quantum control protocols based on shortcuts to adiabaticity in few-level quantum systems. The adiabatic dynamics is accelerated by introducing high-frequency modulations in the control Hamiltonian, which mimic a timedependent counterdiabatic correction. We present a number of applications for the high-fidelity realization of quantum state transfers and quantum gates based on effective counterdiabatic driving, in platforms ranging from superconducting circuits to Rydberg atoms.

We experimentally investigate the viability of a variational quantum gate optimization protocol informed by the underlying physical Hamiltonian of fixed-frequency transmon qubits. Through the successful experimental optimization of two and three qubit quantum gates the utility of the scheme for obtaining gates based on static effective Hamiltonians is demonstrated. The limits of such a strategy are investigated through the optimization of a time-dependent, Floquet-engineered gate, however parameter drift is identified as a key limiting factor preventing the implementation of such a scheme which the variational optimization protocol is unable to overcome.

Uranium mining and milling activities contribute to the release of natural uranium and its decay products into the environment. This may lead to potential radiological risks. While U-238 and its decay products are routinely monitored, the behaviour of the U-235 decay products is either not considered, or only estimated based on the U-238 decay chain in radiological assessments [1].

Pa-231 is one of the few long-lived isotopes in the U-235 decay chain. It has a half-life of 3∙105 years and lacks analogues in the U-238 decay series. Hence, it is necessary to study Pa-231 to learn about the transport and possible accumulation of U-235 decay products in the environment that might differ from the U-238 decay series [2].

In this talk, I will present two different approaches to studying the behaviour of Pa-231 in the environment. First, we use the short-lived isotope Pa-233 (half-life 27 days) as an analogue to study the interaction of Pa with plants. Using gamma spectroscopy and autoradiography, we provide an insight into the translocation and accumulation patters of Pa in Sand Oat (Avena strigosa).

To check if the results from the Pa-233 experiments are transferable to real life environmental situations we are planning to measure Pa-231 in the environment using Accelerator Mass Spectrometry (AMS). This ultra-sensitive method is capable of measuring minute concentrations of long-lived radionuclides. Especially actinides can be measured to unparalleled sensitivity. The measurement of Pa-231 is not yet an established procedure at most AMS laboratories, but there are multiple ongoing efforts to develop such a procedure [2,3]. The main challenges are the complications in chemical sample preparation, particularly Pa losses due to sorption on lab equipment.

We have developed and adapted chemical sample preparation procedures for multiple environmental samples including water from a uranium mine, riverbank soil and plants. First, the Pa is leached from each environmental sample using a specific protocol. Then, Pa needs to be separated from the environmental matrix, where each sample material comes with its own challenges. I will give an overview of different leaching mechanisms and elemental separation methods we tested for separating Pa from environmental samples, focussing on where we lose Pa in the sample preparation and how to avoid these losses.

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[1] Beaugelin-Seiller, K., et al., J. Environ. Radioact., 2016, 151, 114-125.
[2] Medley, P., et al., Nucl. Instrum. Methods Phys. Res. B, 2019, 438, 66-69.
[3] Christl, M., et al., Nucl. Instrum. Methods Phys. Res. B, 2007, 262, 379-284.

Noise resilience of quantum information processing is a crucial precondition to reach the fault-tolerance threshold. While resilience to many types of noise can be achieved through suitable control schemes, resilience to amplitude noise seems to be elusive within the common harmonic approximation for the bus mode of trapped ions. We show that weak an-harmonicities admit control schemes that achieve amplitude noise-resilience consistent with state-of-the-art experimental requirements, and that the required an-harmonicities can be achieved with current standards of micro-structured traps or even the intrinsically an-harmonic Coulomb interaction.

We present photoconductive emitters for broadband THz emission based on Ge and GeSn. Ge is attractive for this purpose due to its high carrier mobility and because of the absence of infrared-active phonons that suppress the THz emission. Emitters based on Ge, with Au trapping centers for carrier lifetime reduction, excited with 11 fs near-infrared pulses emit gapless THz spectra extending up to 70 THz. For excitation at the telecom wavelength 1550 nm a slight reduction of the bandgap of Ge is desirable. We show that this can be achieved in layers of GeSn with 2 % of Sn, grown by molecular beam epitaxy on Si. THz devices on a silicon platform offer the perspective to develop CMOS compatible THz systems with photonic integration both for the near-infrared radiation and the broadband THz radiation.

We propose a new quantum simulation method for simulating N-body interactions, which are tensor products of N Pauli operators, in an analytically exact manner. This method iteratively attaches many two-body interactions on one two-body interaction to simulate an N-body interaction. Those controlled two-body interactions can be untunable and act only on neighboring spins. The strength difference between controlled and target Hamiltonians is normally not more than one order of magnitude. This simulation is theoretically error-free, and errors due to experimental imperfections are ignorable. A major obstacle to simulating the toric code model and modified toric codes used in topological quantum computation is to simulate N-body interactions. We employ the new quantum simulation method to solve this issue and thus simulate the toric code model and its modifications.

After providing a short overview of the activities of our activities in the spectroscopy department including materials and technology for THz generation [1] we focus on two topics regarding the excitation of low-dimensional semiconductor systems with intense THz radiation. Here, the free-electron laser FLEBE is used as a source of spectrally tunable, intense, narrowband radiation pulses [2]. In the first case, graphene discs featuring a plasmonic resonance in the THz frequency range are excited with circularly polarized THz radiation. The THz-induced current in the discs is accompanied by a rather strong transient magnetic fields of the order of 0.5 T perpendicular to the plane of the discs [3]. The second nanostructure under investigation is core-shell GaAs/InGaAs nanowires, a system that can reach high carrier mobilities via strain engineering [3]. THz-pump broadband mid-infrared-probe spectroscopy combined with near-field microscopy reveals the transient heating behavior and intervalley transfer of electrons in the single quantum wires. In summary we discuss the potential to study materials properties and discover new physical phenomena via the interaction with intense THz radiation.
[1] A. Singh, A. Pashkin, S. Winnerl, M. Welsch, C. Beckh, P. Sulzer, A. Leitenstorfer, M. Helm and H. Schneider, Light: Sci. and Appl. 9, 30 (2020).
[2] M. Helm, S. Winnerl, A. Pashkin, J. M. Klopf, J.-C. Deinert, S. Kovalev, P. Evtushenko, U. Lehnert, R. Xiang, A. Arnold, A. Wagner, S. M. Schmidt, U. Schramm, T. Cowan and P. Michel, Eur. Phys. J. Plus 138, 158 (2023).
[3] J.W. Han, P. Sai, D-B. But, E. Uykur, S. Winnerl, G. Kumar, M.L. Chin, R.L. Myers-Ward, M.T. Dejarld, K.M. Daniels, T.E. Murphy, W. Knap, M. Mittendorff: Strong transient magnetic fields induced by THz-driven plasmons in graphene disks, Nature Commun. 14, 7493 (2023).

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A protocol for the monazite (LREE,Y,Th,U,Si,Ca)PO4 in situ Th-U-Pb dating by electron
probe microanalyser (EPMA) involves a suitable reference monazite. Ages of several potential
reference monazites were determined by TIMS-U-Pb isotope analysis. The EPMA protocol is based
on calibration with REE-orthophosphates and a homogeneous Th-rich reference monazite at beam
conditions of 20 kV, 50 nA, and 5 μm for best possible matrix matches and avoidance of dead
time bias. EPMA measurement of samples and repeated analysis of the reference monazite are
performed at beam conditions of 20 kV, 100 nA, and 5 μm. Analysis of Pb and U on a PETL crystal
requires YLg-on-PbMa and ThMz-on-UMb interference corrections. Offline re-calibration of the
Th calibration on the Th-rich reference monazite, to match its nominal age, is an essential part of
the protocol. EPMA-Th-U-Pb data are checked in ThO2*-PbO coordinates for matching isochrones
along regressions forced through zero. Error calculations of monazite age populations are performed
by weighted average routines. Depending on the number of analyses and spread in ThO2*-PbO
coordinates, minimum errors <10 Ma are possible and realistic for Paleozoic monazite ages. A test of
the protocol was performed on two garnet metapelite samples from the Paleozoic metamorphic Zone
of Erbendorf-Vohenstrauß (NE-Bavaria, western Bohemian Massif).

Aerosol particle separation is essential in diverse industrial and medical applications. In the present context, the separation of particles in a rising Taylor bubble is investigated. The distinctive elongated shape, bullet-shaped nose, and flat tail of Taylor bubbles make their application particularly interesting for investigating interfacial effects. The aerosols present in the gas Taylor bubble migrate to the water, where they are eventually trapped. Experimental 8 mm circular test sections with constriction ratios ranging from 10 % to 30 % are used to induce flow and bubble interface perturbations. With a particle size ranging from about 1 to 5 μm, the separation takes place in the inertia-dominated regime, where the particle inertia is strongly dependent on the air flow. First, we show how the constriction affects the dynamics of the Taylor bubble as it moves through the constriction. Second, we investigate the particle separation results in tubes with and without constrictions.

Gain dynamics of graphene in the mid-infrared regime has attracted significant academic interest. Here, by utilizing a three-pulse pump-probe technique, we are able find evidence for transient gain and discuss relevant carrier relaxation channels.

Continuous Integration (CI) is an indispensable part of modern software development. All major providers of software development platforms now offer an integrated range of resources for Continuous Integration, some of which are free to use. This offer is not sufficient for the requirements and use cases of some scientific software projects. There are scientific software projects which would like to take advantage of a large software development platform such as GitHub for the development of an open source software project and at the same time have access to the CI resources provided locally at an institution. This use case was implemented as part of HIFIS at HZDR and combines the GitHub platform with the locally available GitLab CI resources.

The presentation shows how this integration was implemented, which hurdles could be overcome, and at the same time addresses which difficulties exist. To this end, the talk goes into a practical use case, the alpaka C++ library and their specific CI implementation. The alpaka library (https://github.com/alpaka-group/alpaka) is a C++ abstraction library for accelerator development. It allows to write code once and run it on different accelerators/processor types like CPUs, GPUs and FPGAs. Therefore, it supports a wide range of processor manufacturers, through various compilers and SDKs. This results in a large set of supported software combinations that cannot be executed on the publicly available CI resources. With smart measures, the team makes use of the CI resources that have been made available and implements measures to handle the complexity and available resources.

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es hat kein aussagefähiges Abstract vorgelegen

Ion irradiation is a powerful tool to tune the properties of two-dimensional (2D) materials by creating defects and introducing impurities. At the same time, efficient defect production and especially ion implantation into 2D materials require a careful choice of ion energies, as when energies are too low or too high, production of defects and implantation rate will be unsatisfactory low. As for the bulk systems, various approaches have been employed to predict optimum ion energies for specific tasks, but they not always can be directly applied to 2D materials. Here we carry out ab-initio molecular dynamics (MD) and analytical potential (AP) MD simulations and compare the results to those obtained with a simple binary collision approximation (BCA) model. We show that when chemical interactions between the ions and target atoms are essential, as in the case of B and N ion implantation into graphene, as compared to inert gas ions, the AP MD or the BCA model are inadequate. We further suggest a modified BCA approach with the corrected
displacement threshold energies, which account for chemical interactions between the ion and target atoms. The threshold energy can be obtained from first-principles calculations, and the modified BCA model gives qualitatively and for some ions even quantitatively correct results for the energies corresponding to the onset of defect production and substitution probabilities while being at same time many orders of magnitude computationally less expensive than the first-principles MD. We show that in any case the BCA and modified BCA calculations give the upper and lower bound on the optimum ion energy.

The Kupferschiefer ore deposits that occur along the southern margin of the Central European Permian
Basin constitute one of the largest and highest-grade sediment-hosted copper provinces in the world.
Mineralization formed when oxidizing and metal-rich basinal fluids interacted with a thin but laterally
persistent carbonaceous black shale/marl unit at the base of the Permian Zechstein succession. In addition
to copper, Kupferschiefer ores also contain elevated concentrations of silver, lead, zinc, cobalt, nickel,
rhenium, and gold. While some of these metals (especially Ag) already contribute as by-products to the
overall revenue generated, quantitative geometallurgical studies exploring the deportment and spatial
variability of all these metals are still lacking.
In this study, we investigate multi-metal deportment (i.e. Ag, Pb, Zn, Co, Ni, Re, Au) at the Spremberg-
Graustein-Schleife deposit, located in Lusatia in SE Germany. This investigation is carried out through a
comprehensive approach that integrates data from laser ablation ICP-MS (LA-ICP-MS), electron microprobe
analysis (EPMA) and mineral liberation analysis (MLA) on samples from the mineralized intervals of three
exploration drill-cores. The results illustrate that the deportment of Ag is particularly complex, as it occurs
as i) substitution in the crystal lattices of ore-forming Cu and Cu-Fe sulfides, ii) micro-inclusions within Cuenriched
zones in pyrite/marcasite, and iii) isolated grains of electrum. Galena and sphalerite are the main
hosts of Pb and Zn, respectively. Cobalt and Ni, in contrast, are found as Co-Ni-arsenides and sulfides, with
chalcopyrite and pyrite exhibiting enrichment in cobalt. Such quantitative information can not only
facilitate the integration of processing of the by-products into the geometallurgical models, but also
enables the prediction of the mineralogical distribution of these elements within drill-cores, using bulk
geochemical data.

The bulk of the known sediment-hosted stratabound copper (SSC) deposits of the Kupferschiefer are located near the southern margin of the Central European Basin. High-grade copper ores containing remarkable concentrations of Ag and other base metals, occur where metal-rich basinal brines intersected a carbonaceous and pyritiferous shale unit at the base of the Zechstein succession. Resultant fluid-rock interaction is expressed by a prominent redox front that intersects the carbonaceous shale unit, as well as underlying sandstones and overlying carbonate rocks. Although silver is the most important by-product, only a limited number of qualitative studies have investigated the distribution of Ag within the ore. In this contribution, we present the first quantitative silver deportment using ores from three exploration drill cores of the Spremberg-Graustein-Schleife deposit in Germany as example. To determine the deportment of Ag, ore mineralogy, mineral chemistry and bulk geochemistry were quantitatively constrained. Mineral Liberation Analysis, electron probe microanalysis and geochemical assay methods were used to generate the required data. Uncertainties were estimated using Monte Carlo simulation. The results illustrate that almost all of the Ag occurs as solid substitution in the crystal lattice of ore-forming Cu (chalcocite, covellite) and Cu-Fe (bornite) sulfides. Relative quantities and concentrations are rather variable. Actual Ag minerals are absent, with a few minute electrum grains identified in a single sample being a notable exception. The results obtained in this study are in good agreement with qualitative observations made, for example, in the Kupferschiefer deposits in Poland. They suggest that the efficient recovery of Cu- and Cu-Fe-sulfides as primary ore minerals from the Kupferschiefer-type ores will, by necessity, also result in high Ag recoveries.

The D⁡(p,γ)⁢³He reaction, where ‘D’ denotes ‘²H’, is of primary importance in cosmology and nuclear physics since it offers a unique opportunity to test predictions based on the description of nuclear interactions. We present a novel approach to extract the angular distribution of the photons emitted by the D⁡(p,γ)⁢³He reaction inferred from the shape of the experimental γ spectra. The measurement was performed in the Gran Sasso Laboratories by the LUNA collaboration. By using a HPGe detector faced to an extended deuterium gas target, it was possible to derive the angular distribution in the 30–280 keV kinetic energy range and to compare the results with recent ab initio predictions.

A regional tungsten anomaly was discovered and explored in the Lienzer Schlossberg area that is part of the crystalline
Austroalpine nappe complex of the Eastern Alps in the 1970/80-ties. Tungsten is present as scheelite, which occurs
in steeply SSW dipping WNW-ENE oriented quartz veinlets and joints within the porphyritic dioritic to tonalitic/granodioritic
host rocks of the Oligocene Lienz/Edenwald intrusion and in the exoskarn, which developed at the contact of
the intrusion with Ca-rich lithologies. The skarn system is characterised by two stages: (1) a primary high-temperature
calc-silicate stage characterised by grossular, diopside-hedenbergite, vesuvianite, wollastonite and Ca-plagioclase and
(2) a retrograde skarn stage including scheelite-bearing massive sulphide ores (pyrrhotite, chalcopyrite, tremolite-actinolite,
diopside-hedenbergite) and scheelite-rich fault rocks with calcite, sericite and chlorite. The two ore stages, the
mineral paragenesis and composition is like that of a reduced tungsten skarn; i.e., garnet is grossular-rich, clinopyroxene
is diopside-hedenbergite. Vesuvianite contains up to 1.8 mass % fluorine. Scheelite has been studied by cathodoluminescence
(CL), electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. Three types
of scheelite (Scheelite 1–3) are distinguished. In short-wave UV light, all types show blue fluorescence but CL revealed
internal micro-textures in scheelite grains which are dominated by oscillatory zoning. Prolonged hydrothermal activity is
indicated by dissolution-replacement and overgrowth textures affecting the primary zonation and trace element composition
of scheelite. The distribution of rare earth elements (REE) in Scheelite 1 in tonalite-hosted quartz veinlets shows
a convex (i.e., middle REE-enriched), heavy REE-depleted pattern with negative Eu anomalies (EuA). The evolution of REE
patterns from skarn-hosted Scheelite 2 and 3 illustrates a gradation of convex REE patterns with high ΣREE and distinct
negative Eu anomalies to relatively flat REE patterns with small to no EuA. Scheelite at Lienzer Schlossberg has one of the
highest ΣREE+Y contents of all scheelite-bearing ore settings in the Eastern Alps but incorporates minor Mo and the least
Sr. High Na and Nb contents together with the positive correlation of REE+Y vs. Na+Nb+Ta suggests that the main exchange
vectors for REE incorporation in scheelite is via a combined coupled substitution mechanism. Results of this study
confirm the genetic similarity with reduced tungsten skarns and highlight the tungsten potential of this area.