Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41397 Publications

A convolutional neural network for automated delineation and classification of metabolic tumor volume in head and neck cancer

Nikulin, P.; Hofheinz, F.; Maus, J.; Cegła, P.; Furth, C.; Kaźmierska, J.; Rogasch, J.; Hajiyianni, M.; Kotzerke, J.; Zschaeck, S.; van den Hoff, J.

Deep Learning based approaches for automated analysis of tomographic image data are drawing ever increasing attention in Radiology and Nuclear Medicine. With the advent of the new generation of PET scanners with massively enlarged axial field of view (“total body PET”) the importance of integrating such approaches into clinical workflows will further increase. In the present study we report on our application of a convolutional neural network (CNN) for automated survival analysis in head and neck cancer (HNC): PET parameters such as metabolic tumor volume (MTV), total lesion glycolysis, and asphericity of the primary tumor are known to be prognostic of clinical outcome in HNC patients. Additionally including evaluation of lymph node metastases further increases the prognostic value of PET. However, accurate manual delineation and classification of all lesions is time consuming and incompatible with clinical routine. Our goal, therefore, was development and evaluation of an automated tool for MTV delineation/classification of primary tumor and lymph node metastases in HNC in PET.

Automated delineation of the HNC cancer lesions was per- formed with a residual 3D U-Net convolutional neural network (CNN). 698 FDG PET/CT scans from 3 different sites and 4 public databases were used for network training and testing. In these data, primary tumor and metastases were manually delineated (with assistance of semi-automatic tools) and accordingly labeled by an experienced physician. Performance of the trained network models was assessed by 5-fold cross validation using the Dice similarity coefficient for individual delineation tasks.

Additionally, survival analysis using univariate Cox regression was performed. Delineation of all malignant lesions with the trained U-Net model achieves a Dice coefficient of 0.866 when not dis-
criminating between primary tumor and lymph nodes. Treating primary tumor and lymph node metastases as distinct classes yields Dice coefficients of 0.835 and 0.757 for the respective delin-
eations. The univariate Cox analysis reveals that, both, manually as well as automatically derived total MTVs are highly prognostic with similar hazard ratios (HR) with respect to overall survival
(HR=1.8; P<0.001 and HR=1.7; P<0.001, respectively). To the best of our knowledge, our work represents the first CNN model for successful MTV delineation and lesion classification in HNC. The network quickly performs usually satisfactory delineation and classification of primary tumor and lymph node metastases in HNC using FDG-PET data alone with only minimal sporadic manual corrections required. It is able to massively facilitate study data evaluation in large patient groups and also does have clear potential for clinical application.

  • Poster
    9th Conference on PET/MR and SPECT/MR & Total-Body PET Workshop, 28.05.-01.06.2022, Isola d'Elba, Italia

Permalink: https://www.hzdr.de/publications/Publ-36040
Publ.-Id: 36040


Experimental and Theoretical Analyses of Adiabatic Two-phase Flows in Horizontal Feed Pipes

Döß, A.

The majority of technical separation processes for fluid mixtures utilize the principle of rectification. If a two-phase mixture is fed into the column, possibly undesirable flow morphologies or severe droplet carry-over may occur, which detrimentally affect separation efficiency and equipment integrity. Currently, the two-phase flow behavior in feed pipes is hardly predicable and mostly based on empirical or heuristic methods, which do not properly account for a broad range of possible fluid properties and plant dimensions. As a consequence, costly safety margins are applied. Feed pipes to separation columns are often characterized by horizontal inlet nozzles, small length-to-diameter ratios and complex routing, involving elbows or bends. The pipe lengths are too short to enable the two-phase flow to fully develop, which thus, enters the column with unknown flow morphology. Since developing flows have rarely been studied, today’s engineering practice relies on existing predictive methods for fully developed two-phase flows. Graphical methods can hardly represent gradual transitions between flow regimes. Analytical models provide only simplified flow representations of the two-phase flow that have not yet been qualified for developing pipe flow. In this work, a comprehensive experimental database of horizontal water-air flows in two test sections with nominal pipe diameters of D = 50 mm and D = 200 mm and feed pipe lengths in the range 10 < L/D < 75 was established. This way, the data cover developing pipe flows with entrance lengths typical for two-phase feeds of separation columns and more developed flows that are comparable with the extensively studied reference system water-air. A particular focus was put on the effect of pipe bends on the flow morphology up- and downstream. The flow morphology was captured using imaging wire-mesh sensors. A 4D fuzzy algorithm was applied to objectively identify the flow two-phase morphologies. Based on their fuzzy representation, the flow morphologies were classified and a novel 2D visualization technique is proposed to discuss the flow development along the feed pipes. Undesired flow morphologies (intermittent flow and entrainment) during the operation of two-phase feeds are hardly predictable by conventional design tools. The inception of intermittent flows was analyzed using the experimental data. Consequently, the inception criteria based on the required liquid levels for fully developed intermittent flows were adapted for short entrance lengths. The characteristic dynamics of flow morphologies that are known to cause the onset of entrainment were analyzed. Based on wave frequencies, a predictive criterion for the susceptibility of wavy flows for the onset of entrainment is introduced and applied to straight feed pipes and horizontal 90° bends. Among the dozens available, 66 reduced-order models for the prediction of the void fraction were tested for straight feed pipes and horizontal 90° pipe bends. Thereof, the ones most suitable for variable operating conditions and pipe geometries were identified and adapted. Complementary 3D simulations were performed to verify the applicability of numerical codes (VoF, AIAD) for flows with free interfaces. The flow morphologies were successfully reproduced at macroscopic scale, however, the simulation results rank behind reduced-order models considering their quantitative predicting capabilities.

Keywords: Distillation; Two-phase feed; Flow morphology; Horizontal two-phase flow

  • Doctoral thesis
    TU Dresden, 2022
    PURL: https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa2-827786

Permalink: https://www.hzdr.de/publications/Publ-36039
Publ.-Id: 36039


Structural stability of transparent conductive oxide tantalum doped tin oxide during high-temperature treatment

Krause, M.; Hoppe, M.; Mendez, A.; Munnik, F.; Rodriguez Garcia, J.; Lungwitz, F.; Gemming, S.; Rafaja, D.; Escobar-Galindo, R.

The transparent conductive tantalum doped tin oxide is a potential candidate for applications in concentrated solar power technology, dye-sensitized solar cells and dynamic random access memories [1], [2], [3]. In all these fields, high-temperature stability in air is mandatory to preserve its functionality. In this work we demonstrate the compositional and structural in-air-stability of SnO2:Ta thin films at 650 °C and 800 °C for 12 hours. While the element composition and optical spectra were unchanged and the X-ray diffractograms revealed the conservation of a single-phase rutile-type crystal structure, some strong Raman lines of SnO2:Ta underwent substantial changes upon tempering. Quantum ab initio calculations of pristine and Ta-doped SnO2 with systematically varied point defects indicated that preferentially Sn vacancies and excess O atoms are responsible for these strong and unexpected Raman signatures. These defects are partially healed during high-temperature exposure, but that does not affect the functionality of SnO2:Ta as transparent conductor under these harsh conditions. This study provides a comprehensive understanding of crystal and defect structure of Ta-doped SnO2 prior to and after high temperature treatment in air for the first time and encourages its application in different fields where high-T stability, transparency and conductivity are required.
[1] F. Lungwitz et al., Transparent conductive tantalum doped tin oxide as selectively solar-transmitting coating for high temperature solar thermal applications, Solar Energy Mater. Solar Cells 199, 84 (2019), doi: 10.1016/j.solmat.2019.03.012
[2] R. Ramarajan, et al. Large-area spray deposited Ta-doped SnO2 thin film electrode for DSSC application, Solar Energy 211, 547-559 (2020), doi:10.1016/j.solener.2020.09.042.
[3] C. J. Cho, et al. Ta-Doped SnO2 as a reduction-resistant oxide electrode for DRAM capacitors, Journal of Materials Chemistry C 5, 9405-9411 (2017), doi:10.1039/c7tc03467a
Financial support by the EU, grant No. 645725, project FRIENDS2, is gratefully acknowledged.

Keywords: high-temperature materials; in-air stability; transparent conductive oxide; Ta-doped tin oxide; Raman signatures; point defects

Related publications

  • Lecture (Conference)
    PSE 2022 - 18th International Conference on Plasma Surface Engineering, 12.-15.09.2022, Erfurt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36038
Publ.-Id: 36038


A convolutional neural network for automated delineation and classification of metabolic tumor volume in head and neck cancer in FDG-PET/CT

Nikulin, P.; Hofheinz, F.; Maus, J.; Cegła, P.; Furth, C.; Kaźmierska, J.; Rogasch, J.; Kotzerke, J.; Zschaeck, S.; van den Hoff, J.

Aim: Image derived PET parameters such as metabolic tumor volume (MTV), total lesion glycolysis, and tumor asphericity of the primary tumor have been shown to be prognostic of clinical outcome of patients with head and neck cancer (HNC). Evaluation of lymph node metastases in addition to the primary tumor further increases the prognostic value of PET. Such analysis requires, however, accurate delineation and classification of all lesions which is very time-consuming when performed manually. The goal of this study is development of an automated tool for MTV delineation of primary tumor and lymph node metastases in HNC in PET/CT.

Methods: Automated delineation of the HNC cancer lesions was performed with a residual 3D U-Net convolutional neural network (CNN). 698 FDG PET/CT scans from 3 different sites and 4 public databases were used for network training (N=558) and testing (N=140). In these data, primary tumor and metastases were manually delineated and accordingly labeled by an experienced physician. This manual delineation served as the ground truth for network training. Performance of the trained network model was assessed in the test data using the Dice similarity coefficient for primary tumor, metastases, and the union of all lesions, respectively.

Results: The derived U-Net model is capable of accurate delineation of malignant lesions achieving a Dice coefficient of 0.847 for indiscriminative segmentation. Treating primary tumor and lymph node metastases as distinct classes yields Dice coefficients of 0.840 and 0.714 for the respective delineations.

Conclusions: In this work, we present the first CNN model for MTV delineation and classification in HNC. The developed network model allows to quickly perform satisfactory delineation of (and discrimination between) primary tumor and lymph node metastases in HNC with only minimal manual corrections possibly required. It thus is able to improve and to accelerate study data evaluation in quantitative PET and does also have potential for clinical application.

  • Lecture (Conference)
    NuklearMedizin 2022, 27.-30.04.2022, Leipzig, Deutschland
  • Contribution to proceedings
    NuklearMedizin 2022, 27.-30.04.2022, Leipzig, Deutschland
    A convolutional neural network for automated delineation and classification of metabolic tumor volume in head and neck cancer in FDG-PET/CT: Thieme
    DOI: 10.1055/s-0042-1745945

Permalink: https://www.hzdr.de/publications/Publ-36037
Publ.-Id: 36037


Advantages of Using Triboscopic Imaging: Case Studies on Carbon Coatings in Non-Lubricated Friction Conditions

Lorenz, L.; Makowski, S.; Weihnacht, V.; Krause, M.; Lasagni, A. F.

Triboscopy focuses on the analysis of the temporal evolution of a tribological system, combining local and time-resolved information, most commonly the evolution of friction. In this work, this technique is applied on measurements, which were carried out with a custom-built ultrahigh vacuum tribometer in ball-on-disc configuration. Based on these experiments, an extended classification to distinguish different triboscopic features is suggested, depending on the persistence in both track position and time: UNIFORM, GLOBAL, LOCAL, and SPORADIC. Further, a filter technique for quantifying triboscopic data regarding this classification is introduced. The new and improved triboscopic techniques are applied to various dry friction measurements of hydrogen-free carbon coatings under varying humidity and pressure. The resulting specific triboscopic features are correlated to wear phenomena, such as counter body coating abrasion, inhomogeneities in the wear track, non-uniform track wear, stick-slip and debris in the contact area, demonstrating the increased analysis and monitoring capabilities when compared to conventional friction curves and wear track images.

Keywords: DLC; ta-C; a-C; friction; wear

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36035
Publ.-Id: 36035


Low-Friction of ta-C Coatings Paired with Brass and Other Materials under Vacuum and Atmospheric Conditions

Härtwig, F.; Lorenz, L.; Makowski, S.; Krause, M.; Habenicht, C.; Lasagni, A. F.

Vacuum environments provide challenging conditions for tribological systems. MoS2 is one of the materials commonly known to provide low friction for both ambient and vacuum conditions. However, it also exhibits poor wear resistance and low ability to withstand higher contact pressures. In search of wear-resistant alternatives, superhard hydrogen-free tetrahedral amorphous carbon coatings (ta-C) are explored in this study. Although known to have excellent friction and wear properties in ambient atmospheres, their vacuum performance is limited when self-paired and with steel. In this study, the influence of the paired material on the friction behavior of ta-C is studied using counterbodies made from brass, bronze, copper, silicon carbide, and aluminum oxide, as well as from steel and ta-C coatings as reference materials. Brass was found to be the most promising counterbody material and was further tested in direct comparison to steel, as well as in long-term performance experiments. It was shown that the brass/ta-C friction pair exhibits low friction (µ < 0.1) and high wear in the short term, irrespective of ambient pressure, whereas in the long term, the friction coefficient increases due to a change in the wear mechanism. Al2O3 was identified as another promising sliding partner against ta-C, with a higher friction coefficient than that of brass (µ = 0.3), but considerably lower wear. All other pairings exhibited high friction, high wear, or both.

Keywords: diamond-like coatings; wear; tribology; carbon; films

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36034
Publ.-Id: 36034


Phase Transformation Induced by High Pressure Torsion in the High-Entropy Alloy CrMnFeCoNi

Chulist, R.; Pukenas, A.; Chekhonin, P.; Hohenwarter, A.; Pippan, R.; Schell, N.; Skrotzki, W.

The forward and reverse phase transformation from face-centered cubic (fcc) to hexagonal
close-packed (hcp) in the equiatomic high-entropy alloy (HEA) CrMnFeCoNi has been investigated
with diffraction of high-energy synchrotron radiation. The forward transformation has been induced
by high pressure torsion at room and liquid nitrogen temperature by applying different hydrostatic
pressures and large shear strains. The volume fraction of hcp phase has been determined by Rietveld
analysis after pressure release and heating-up to room temperature as a function of hydrostatic
pressure. It increases with pressure and decreasing temperature. Depending on temperature, a
certain pressure is necessary to induce the phase transformation. In addition, the onset pressure
depends on hydrostaticity; it is lowered by shear stresses. The reverse transformation evolves over
a long period of time at ambient conditions due to the destabilization of the hcp phase. The effect
of the phase transformation on the microstructure and texture development and corresponding
microhardness of the HEA at room temperature is demonstrated. The phase transformation leads
to an inhomogeneous microstructure, weakening of the shear texture, and a surprising hardness
anomaly. Reasons for the hardness anomaly are discussed in detail.

Keywords: high-entropy alloy; high-entropy alloy; high pressure torsion; microstructure; texture; phase transformation; strength

Permalink: https://www.hzdr.de/publications/Publ-36033
Publ.-Id: 36033


Generating synthetic shadowgrams with an in-situ plugin in PIConGPU

Carstens, F.-O.; Steiniger, K.; Pausch, R.; Schöbel, S.; Chang, Y.-Y.; Irman, A.; Schramm, U.; Debus, A.

Few-cycle shadowgraphy is a valuable diagnostic for laser-plasma accelerators for obtaining insight into the $\mu$m- and fs-scale relativistic plasma dynamics. To enhance the understanding of experimental shadowgrams, we developed a synthetic shadowgram diagnostic within the fully relativistic particle-in-cell code PIConGPU.
In the shadowgraphy diagnostic, the probe laser is propagated through the plasma using PIConGPU, and then extracted and propagated onto a virtual CCD using an in-situ plugin for PIConGPU based on Fourier optics. The in-situ approach circumvents performance limitations of a post-processing workflow, like storing and loading large output files that result from large-scale laser-plasma simulations.
This poster presents the in-situ plugin and first synthetic shadowgrams from laser wakefield accelerator simulations that are generated by the plugin.

Keywords: Shadowgraphy; Synthetic Diagnostics; In-Situ Plugin; PIConGPU; Laser-Electron Acceleration

  • Poster
    8. Annual MT Meeting, 26.-27.09.2022, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36032
Publ.-Id: 36032


Curvilinear magnetism: from fundamentals to applications

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review current application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions [4] and enables fundamentally new non-local chiral symmetry breaking effect [5]. Application potential of geometrically curved magnetic architectures is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics relying on thin films [6,7] as well as printed magnetic composites [8,9].

[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
[5] D. D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020).
[6] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[7] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[8] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[9] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: curvature effects in magnetism; curvilinear magnetism; printed electronics; human-machine interfaces

Related publications

  • Lecture (others)
    Seminar at the University of Kiel, 25.01.2023, Kiel, Germany

Permalink: https://www.hzdr.de/publications/Publ-36031
Publ.-Id: 36031


Pattering data from NPVE software for Helium Ion Microscopy (HIM) irradiation data

Hlawacek, G.; Fowley, C.; Kuria, J.
Project Member: Fowley, Ciaran; Project Member: Kurian, Jinu; Project Leader: Doudin, Bernard

Pattering data from NPVE software for Helium Ion Microscopy (HIM) irradiation data

Keywords: focused ion beam; helium ion microscopy; nanopatterning; magnetic

Related publications

Downloads

Permalink: https://www.hzdr.de/publications/Publ-36030
Publ.-Id: 36030


Fungal bioleaching of metals from industrial wastes

Chakankar, M. V.

Industrial wastes and wastewaters are important secondary sources for many metals. Recovering these metals from such waste streams helps in resource recycling and reduce the environmental burden. Microbial technology offers an economical alternative to traditional metal recovery. Several bacterial and fungal species are reported for metal bioleaching from different industrial wastes. Use of fungi in bioleaching process offers a variety of advantages. The present study provides an overview of fundamental mechanisms of fungal bioleaching and methods used for the same. The case study of two different industrial wastes is also provided.

  • Invited lecture (Conferences) (Online presentation)
    Fungal Diversity and its novel applications, 09.04.2022, Pune, India

Permalink: https://www.hzdr.de/publications/Publ-36029
Publ.-Id: 36029


Metal recovery by bioionflotation using biosurfactants

Chakankar, M. V.; Pollmann, K.; Rudolph, M.

Metal recovery by bioionflotation using biosurfactants

  • Lecture (others) (Online presentation)
    UGC STRIDE Lecture Series- Advances in Life Science Research, 10.02.2022, Kolhapur, India

Permalink: https://www.hzdr.de/publications/Publ-36028
Publ.-Id: 36028


Curvilinear micromagnetism: from fundamentals to applications

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and discuss realizations of curved low-dimensional architectures and their characterization, which among others resulted in the experimental confirmation of exchange-driven chiral effects [4]. Geometrically curved architectures can support a new chiral symmetry breaking effect: it is essentially non-local and manifests itself even in static spin textures living in curvilinear magnetic nanoshells [5]. The field of curvilinear magnetism was extended towards curvilinear antiferromagnets, offering a novel material science platform for antiferromagnetic spinorbitronics. It was demonstrated that intrinsically achiral 1D curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [6]. Application potential of geometrically curved magnetic thin films is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics [7,8].

References:

[1] P. Gentile et al., Electronic materials with nanoscale curved geometries, Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures, Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022). https://link.springer.com/book/10.1007/978-3-031-09086-8
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism, Physical Review Letters 123, 077201 (2019).
[5] D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells, Communications Physics 3, 128 (2020).
[6] O. Pylypovskyi et al., Curvilinear One-Dimensional Antiferromagnets, Nano Letters 20, 8157 (2020).
[7] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time, Nature Communications 10, 4405 (2019).
[8] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics, Nature Electronics 1, 589 (2018).

Keywords: curvature effects in magnetism; curvilinear magnetism

Related publications

  • Invited lecture (Conferences) (Online presentation)
    8th Quantum Oxide Research Online Meeting (QUOROM-8), 16.02.2023, London, UK

Permalink: https://www.hzdr.de/publications/Publ-36027
Publ.-Id: 36027


Geometrically curved, skin-conformal and self-healable magnetoelectronics

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2,3]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [3]. In this talk, we will address fundamentals of curvature-induced effects and discuss experimental realisations of geometrically curved low-dimensional architectures and their characterization, which among others resulted in the experimental confirmation of the exchange-driven chiral effects [4]. Geometrically curved magnetic thin films are interesting not only fundamentally. They are the key component of mechanically flexible magnetic field sensors. We will briefly outline activities on shapeable magnetoelectronics [5,6], which includes flexible, stretchable and printable magnetic field sensors for the realisation of human-machine interfaces [7,8], interactive electronics for virtual [9] and augmented [10] reality applications and soft robotics [11] to mention just a few. Very recently, self-healable magnetic field sensors for interactive printed electronics were reported [12]. The presence of the geometrical curvature in a magnetic thin film influences pinning of magnetic domain walls and in this respect it affects the sensitivity of mechanically flexible magnetic field sensors. This is an intimate link between the fundamental topic of curvilinear magnetism and application-oriented activities on shapeable magnetoelectronics. This link will be discussed in the presentation as well.

References
1. P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
2. D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications. (Springer, Zurich (2022)). https://link.springer.com/book/10.1007/978-3-031-09086-8
3. D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
4. O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
5. D. Makarov et al., Shapeable Magnetoelectronics. Appl. Phys. Rev. 3, 011101 (2016).
6. G. S. Canon Bermudez et al., Magnetosensitive e-skins for interactive devices. Advanced Functional Materials (Review) 31, 2007788 (2021).
7. P. Makushko et al., Flexible Magnetoreceptor with Tunable Intrinsic Logic for On-Skin Skin Touchless Human-Machine Interfaces. Adv. Funct. Mater. 31, 2101089 (2021).
8. J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
9. G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
10. G. S. Canon Bermudez et al., Magnetosensitive e-skins with directional perception for augmented reality. Science Advances 4, eaao2623 (2018).
11. M. Ha et al., Reconfigurable Magnetic Origami Actuators with On-Board Sensing for Guided Assembly. Advanced Materials 33, 2008751 (2021).
12. R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: curvature effects in magnetism; flexible electronics; printed electronics; human-machine interfaces

Related publications

  • Invited lecture (Conferences)
    8th International Conference on Superconductivity and Magnetism (ICSM2023), 04.-11.05.2023, Fethiye-Oludeniz, Turkey

Permalink: https://www.hzdr.de/publications/Publ-36026
Publ.-Id: 36026


Curvilinear magnetism: fundamentals and applications

Makarov, D.

In this tutorial, we will review recent activities in the field of curvilinear magnetism. In particular, fundamental aspects on controling anisotropy and chiral responses via geometrical curvature will be discussed. Furthermore, activities on the realization and application scenarios of flexible, stretchable and printed magnetic field sensors will be presented.

Keywords: curvature effects in magnetism; curvilinear magnetism; printed electronics; human-machine interfaces; flexible magnetoelectronics

Related publications

  • Invited lecture (Conferences)
    IEEE Advances in Magnetics conference (AIM2023), 15.-18.01.2023, Moena, Italy

Permalink: https://www.hzdr.de/publications/Publ-36025
Publ.-Id: 36025


Small Molecule Radiotracers for PET Imaging of PD-L1 with Copper-64

Krutzek, F.; Donat, C.; Ullrich, M.; Kopka, K.; Stadlbauer, S.

The programmed cell death ligand (PD-L1) is expressed on a number of different tumor entities and inhibits the immune response through binding to PD-1 on T-cells. Immune checkpoint inhibitors (ICI) prevent this blockade and thus can reactivate an immune response. However, only about 30% of the patients respond to an ICI monotherapy. Therefore, clinicians are in need for a non-invasive PET/SPECT radioligand for patient stratification and therapy monitoring.

Based on the structures of non-peptidic PD-L1 inhibitors, six different radiotracers were synthesized and radiolabelled with [64Cu]Cu2+ (HZDR, 30 MeV TR-FLEX cyclotron). Binding affinities were determined on PC3 cells stably overexpressing hPD-L1. For in vivo studies, qualitative PET/CT imaging experiments (nanoSCAN PET/CT, Mediso) were performed in NMRI-FoxN1-nude mice bearing PC3-hPD-L1 and mock xenograted tumors.

Two PD-L1 inhibitors were modified with strongly water-soluble acid groups, hydrophilic linker units and a NODAGA-chelator resulting in six different radioligands. The log(D) values of the copper-64 labelled radiotracers were between –3.17 and –4.15 and binding affinities ranged between 80.5 and 533 nM. Depending on the number and the pattern of sulfonate and phosphonate groups, in vivo experiments showed drastically different pharmacokinetic profiles. The radiotracer with one sulfonate and phosphonate group and the most hydrophobic linker exhibited a short circulation time, renal clearance, good tumor uptake (SUVmax = 3.5) and a distinct contrast between the hPD-L1 and the mock tumor.

In conclusion one PD-L1 radiotracer showed a promising pharmacokinetic profile, which is currently further modified to improve the binding affinity and tumor uptake.

  • Lecture (Conference) (Online presentation)
    The 8th International Electronic Conference on Medicinal Chemistry, 01.-30.11.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36024
Publ.-Id: 36024


Synthesis and Biological Evaluation of Chelator-Based Small Molecule PET-Radiotracers for Imaging of PD-L1

Krutzek, F.; Donat, C.; Ullrich, M.; Kopka, K.; Stadlbauer, S.

Aim:

The programmed cell death ligand 1 (PD-L1) is overexpressed by various cancers, resulting in a downregulation of the local immune response and therefore enabling further tumor growth.[1] Immune checkpoint inhibitors (ICIs) can reactivate the immune system, however, only 30% of the patients respond to an ICI monotherapy.[2] Since PD-L1 is heterogeneously expressed within and across tumor sites, there is an urgent clinical need for non-invasive diagnostic tools to support the therapeutic decision process. Small molecule-based radiotracers for noninvasive molecular PD-L1 imaging offer improved tissue penetration, fast blood clearance and low immunogenicity over radiolabeled antibodies.

Methods:

Based on a published small molecule PD-L1 inhibitor, 10 different radioligands were synthesized and radiolabeled with copper-64 (HZDR, 30 MeV TR-FLEX cyclotron). Binding affinities were determined on PC3 cells stably overexpressing human PD-L1. For in vivo evaluation, qualitative PET/CT imaging (nanoSCAN PET/CT, Mediso) was performed in NMRI-FoxN1-nude mice bearing PC3-hPD-L1 xenografted tumors.

Results:

Modification of the PD-L1 binding motif with strongly water-solubilizing sulfonate and phosphonate groups, different linker units and a NODAGA-chelator in 21-25 organic synthesis steps (12-13 longest linear sequence) yielded 10 different ligands [3]. The 64Cu-labelled radiotracers exhibited logD values between -3.17 and -4.15 for six ligands of the first series, with dissociation constants (Kd) between 80.5 and 532.8 nM, as determined by saturation binding assays. Depending on the number and pattern of sulfonate and phosphonate groups, the in vivo experiments showed drastically different pharmacokinetic profiles: Compounds bearing a less hydrophilic linker showed improved tumor uptake. Three sulfonates resulted in increased blood circulation times of up to 24 h due to albumin binding increased renal clearance but also low tumor uptake (SUVmax = 1.4). Substitution of one sulfonate with a phosphonate reduced the circulation time to two hours, however, accompanied by mainly hepatobiliary clearance. To achieve predominant renal clearance, a second series of four compounds bearing two phosphonate and one sulfonate groups in the solubilizer unit and larger halogens at the central aryl core for improved tumor uptake were synthesized and are currently tested in vivo.

Conclusion:

Sulfonate groups in the PD-L1 tracers increased circulation times along with renal clearance, while tracers with one phosphonate group reduced the blood circulation time but lead to a more hepatobiliary clearance. Structural modifications to increase the binding affinity and improve tumor uptake are currently ongoing.

References:

[1] M. A. Postow, M. K. Callahan, J. D. Wolchok, J. Clin. Oncol. 2015, 33, 1974-1982.
[2] S. L. Topalian, C. G. Drake, D. M. Pardoll, Cancer Cell 2015, 27, 450-461.
[3] Stadlbauer S., Krutzek F., Kopka K. EP21212444.0, December 6th 2021.

  • Lecture (Conference)
    20th European Symposium on Radiopharmacy and Radiopharmaceuticals, 24.-27.11.2022, Verona, Italia

Permalink: https://www.hzdr.de/publications/Publ-36023
Publ.-Id: 36023


Small Molecule-Based Radiotracers for PET Imaging of PD-L1 With Copper-64

Krutzek, F.; Donat, C.; Ullrich, M.; Kopka, K.; Stadlbauer, S.

Aim/Introduction
The programmed cell death ligand 1 (PD-L1) is expressed by several cancer types and leads to a downregulation of the local immune response, therefore enabling tumour cells to evade the immune response.[1] So-called immune checkpoint inhibitors (ICI) are able to reactivate the immune system, however, only 30% of the patients respond to an ICI monotherapy.[2] Since PD-L1 is heterogeneously expressed within and across tumour sites, there is an urgent clinical need for a diagnostic, non-invasive imaging probe to support therapy decision. Small molecule-based radiotracers for PD-L1 PET or SPECT imaging fulfil these requirements due to their fast clearance, low risk of side effects and highly sensitive imaging at the molecular level.[3]

Materials & Methods
Based on a published small molecule PD-L1 inhibitor, six different radioligands were synthesized and radiolabelled with copper-64 (HZDR, 30 MeV TR-FLEX cyclotron). Binding affinities were determined on PC3 cells stably overexpressing human PD-L1 which were kindly provided by the Department of Radioimmunology. For in vivo evaluation, qualitative PET/CT imaging experiments (nanoSCAN PET/CT scanner, Mediso) were performed in NMRI-FoxN1-nude mice bearing PC3-hPD-L1 xenografted tumours.

Results
We designed six radioligands by modifying the PD-L1 binding motif with strongly water-solubilizing sulfonate and phosphonate groups, hydrophilic linker units and a NODAGA-chelator in 21 – 25 organic synthesis steps (12-13 longest linear sequence).[4] The copper-64 labelled radiotracers exhibited log(D) values between –3.17 and –4.15. Binding affinities (Kd) were between 80.5 and 532.8 nmol/L. Depending on the number and pattern of sulfonate and phosphonate groups, the in vivo experiments showed drastically different pharmacokinetic profiles: The radiotracer containing three sulfonates showed long circulation times of 24 h due to albumin binding, renal clearance but low tumour uptake (SUVmax = 1.4). Substitution of one sulfonate with a phosphonate improved tumour uptake (SUVmax = 3.1), reduced the circulation time to two hours but showed a more hepatobiliary clearance. The less hydrophilic radiotracer in this series with a Kd of 82.4 ± 7.42 nM, bearing one sulfonate and one phosphonate showed the most favourable pharmacokinetic profile with a short circulation time, renal clearance and an increased tumour uptake (SUVmax = 3.5).

Conclusions
The radiotracer bearing one sulfonate and one phosphonate group exhibited the best pharmacokinetic profile. This radioligand will undergo further structural modifications to increase the binding affinity and improve the tumour uptake.

References
[1] M. A. Postow, M. K. Callahan, J. D. Wolchok, J. Clin. Oncol. 2015, 33, 1974-1982.
[2] S. L. Topalian, C. G. Drake, D. M. Pardoll, Cancer Cell 2015, 27, 450-461.
[3] S. Chatterjee, W. G. Lesniak, S. Nimmagadda., Mol. Imaging 2017, 16, 1-5.
[4] S. Stadlbauer, F. Krutzek, K. Kopka, EP21212444.0, 2021.

  • Lecture (Conference)
    35th Annual Congress of the European Association of Nuclear Medicine, 15.-19.10.2022, Barcelona, Espana

Permalink: https://www.hzdr.de/publications/Publ-36022
Publ.-Id: 36022


Small Molecule-Radioliganden für PET-Bildgebung von PD-L1 mit Kupfer-64

Krutzek, F.; Donat, C.; Ullrich, M.; Kopka, K.; Stadlbauer, S.

Ziel: Der Programmed Cell Death Ligand 1 (PD-L1) ist auf verschiedenen Tumorentitäten überexprimiert und hemmt die Immunantwort durch Bindung an PD-1 auf T-Zellen. Immuncheckpoint-Inhibitoren können diese Blockade aufbrechen und die Immunantwort reaktivieren. Da nur ca. 30% der Patienten auf eine solche Therapie ansprechen, besteht klinisch ein dringender Bedarf an einem nicht-invasiven PET/SPECT-Radioliganden, um die Ansprechrate der Patienten auf diese Therapie abzuschätzen.[1]

Methoden: Basierend auf den Strukturen von nicht-peptidischen PD-L1-Inhibitoren, wurden sechs verschiedene Radioliganden synthetisiert und mit [64Cu]Cu2+ markiert (HZDR, 30 MeV TR-FLEX-Zyklotron). Bindungsaffinitäten wurden auf stabil hPD-L1 überexprimierenden PC3 Zellen bestimmt. In vivo wurden qualitative PET/CT-Bilder (nanoSCAN PET/CT, Mediso) an NMRI-FoxN1-Nacktmäusen mit PC3-hPD-L1- und mock-Tumoren aufgenommen.

Ergebnisse:

Zwei PD-L1-Inhibitoren wurden synthetisch mit stark wasserlöslichen Säuregruppen, hydrophilen Linkern und NODAGA modifiziert (Abb. 1a).[2] Die LogD7.4-Werte der [64Cu]Cu-Radioliganden lagen zwischen –3,17 und –4,15 und die Bindungsaffinitäten (KD) zwischen 80,5 und 532,8 nM. Abhängig von der Zahl und dem Substitutionsmuster der Sulfon- und Phosphonsäuregruppen, zeigte sich in vivo eine stark unterschiedliche Pharmakokinetik. Der Radioligand mit R1 = SO2Me, R2 = PO3H2 und n = 0 zeigte in vivo eine kurze Zirkulationszeit, renale Ausscheidung, gute Tumoraufnahme (SUVmax = 3.5) und einen deutlichen Kontrast zwischen hPD-L1- und mock-Tumor (Abb. 1b).
Schlussfolgerungen: Der PD-L1-Radioligand mit je einer Sulfon- und Phosphonsäuregruppe wies das beste pharmakokinetische Profil auf. Um die Bindungsaffinität und die Tumoraufnahme zu verbessern, wird das Leitmotiv derzeit weiter modifiziert.

Referenzen:

[1] Postow M. A., Callahan M. K., Wolchok J. D. J. Clin. Oncol. 2015, 33, 1974-1982.
[2] Stadlbauer S., Krutzek F., Kopka K. EP21212444.0, 2021.

  • Lecture (Conference)
    28. Jahrestagung der Arbeitsgemeinschaft Radiochemie / Radiopharmazie, 22.-24.09.2022, Wart, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36021
Publ.-Id: 36021


Detection schemes for quantum vacuum diffraction and birefringence

Ahmadiniaz, N.; Cowan, T.; Grenzer, J.; Franchino-Vinas, S.; Laso García, A.; Smid, M.; Toncian, T.; Trejo Espinosa, M. A.; Schützhold, R.

Motivated by recent experimental initiatives, such as at the
Helmholtz International Beamline for Extreme Fields (HIBEF)
at the European X-ray Free Electron Laser (XFEL), we calculate
the birefringent scattering of x-rays at the combined field of
two optical (or near-optical) lasers and compare various scenarios.
%
In order to facilitate an experimental detection of quantum vacuum diffraction and
birefringence, special emphasis is placed on scenarios where the initial
and final x-ray photons differ not just in polarization, but also in
propagation direction (corresponding to scattering angles in the mrad regime)
and possibly energy.

Keywords: Strong Field QED; Vacuum qirefringence; Quantum vacuum diffraction; Euler-Heisenberg Lagrangian; XFEL; Laser; Light-by-light scattering

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Permalink: https://www.hzdr.de/publications/Publ-36020
Publ.-Id: 36020


Resummed heat-kernel and form factors for surface contributions: Dirichlet semitransparent boundary conditions

Franchino-Vinas, S.

In this article we consider resummed expressions for the heat-kernel's
trace of a Laplace operator, the latter including a potential and imposing Dirichlet semitransparent boundary conditions on a surface of codimension one in flat space.
We obtain resummed expressions that correspond to the first and second order expansion of the heat-kernel in powers of the potential.
We show how to apply these results to obtain the bulk and surface form factors of a scalar quantum field theory in $d=4$ with a Yukawa coupling to a background.
A characterization of the form factors in terms of pseudo-differential operators is given.

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Permalink: https://www.hzdr.de/publications/Publ-36019
Publ.-Id: 36019


Geometrizing the Klein–Gordon and Dirac equations in Doubly Special Relativity

Franchino-Vinas, S.; Relancio, J. J.

In this work we discuss the deformed relativistic wave equations, namely the Klein--Gordon and Dirac equations in a Doubly Special Relativity scenario.
We employ what we call a geometric approach, based on the geometry of a curved momentum space, which should be seen as complementary to the more spread algebraic one.
In this frame we are able to rederive well-known algebraic expressions, as well as to treat yet unresolved issues, to wit, the explicit relation between both equations, the discrete symmetries for Dirac particles, the fate of covariance, and the formal definition of a Hilbert space for the Klein--Gordon case.

Keywords: Doubly Special Relativity; Klein-Gordon equation; Dirac equation; Curved momentum space

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Permalink: https://www.hzdr.de/publications/Publ-36017
Publ.-Id: 36017


A hybrid multi-particle approach to range assessment-based treatment verification in particle therapy

Meric, I.; Alagoz, E.; Hysing, L.; Kögler, T.; Lathouwers, D.; Lionheart, W.; Mattingly, J.; Obhodas, J.; Pausch, G.; Pettersen, H.; Ratliff, H.; Rovituso, M.; Schellhammer, S.; Setterdahl, L.; Skjerdal, K.; Sterpin, E.; Sudac, D.; Turko, J. A. B.; Ytre-Hauge, K.

Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models. The results indicate that range shifts of 1 mm can be detected at relatively low proton intensities (6 million/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context range verification in PT.

Keywords: particle therapy; treatment verification; fast neutrons; prompt gamma rays; three dimensional imaging

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36016
Publ.-Id: 36016


Worldline instantons for the momentum spectrum of Schwinger pair production in space-time dependent fields

Degli Esposti, G.; Torgrimsson, G.

We show how to use the worldline-instanton formalism to calculate the momentum spectrum of the electron-positron pairs produced by an electric field that depends on both space and time. Using the LSZ reduction formula with a worldline representation for the propagator in a spacetime field, we make use of the saddle-point method to obtain a semiclassical approximation of the pair-production spectrum. In order to check the final result, we integrate the spectrum and compare with the results obtained using a previous instanton method for the imaginary part of the effective action.

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Permalink: https://www.hzdr.de/publications/Publ-36015
Publ.-Id: 36015


Recovery of Release Cloud from Laser Shock-Loaded Graphite and Hydrocarbon Targets: In Search of Diamonds

Schuster, A. K.; Voigt, K.; Klemmed, B.; Hartley, N. J.; Lütgert, B. J.; Bähtz, C.; Benad, A.; Brabetz, C.; Cowan, T.; Doeppner, T.; Erb, D.; Eychmueller, A.; Facsko, S.; Falcone, R. W.; Fletcher, L. B.; Frydrych, S.; Ganzenmüller, G. C.; Gericke, D. O.; Glenzer, S. H.; Grenzer, J.; Helbig, U.; Hiermaier, S.; Hübner, R.; Laso García, A.; Lee, H. J.; Macdonald, M. J.; McBride, E. E.; Neumayer, P.; Pak, A.; Pelka, A.; Prencipe, I.; Prosvetov, A.; Rack, A.; Ravasio, A.; Redmer, R.; Reemts, D.; Rödel, M.; Schoelmerich, M.; Schumacher, D.; Tomut, M.; Turner, S. J.; Saunders, A. M.; Sun, P.; Vorberger, J.; Zettl, A.; Kraus, D.

This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-36014
Publ.-Id: 36014


Integrated phycoremediation and ultrasonic-irradiation treatment (iPUT) for the enhanced removal of pharmaceutical contaminants in wastewater

Kurade, M. B.; Mustafa, G.; Zahid, M. T.; Awasthi, M. K.; Chakankar, M. V.; Pollmann, K.; Khan, M. A.; Park, Y. K.; Chang, S. W.; Chung, W.; Jeon, B.-H.

Ultrasonication using low frequencies of sound can increase cell organogenesis, which is beneficial for various industrial applications. This study demonstrates a novel approach of integrated phycoremediation and ultrasonication-irradiation treatment (iPUT) used for improving the degradation of sulfonamide antibiotics via a cumulative effect of combined treatments. Variable ultrasonication treatment (UT) (20 %-2 min to 40 %-10 min) was given to a model microalga, Chlamydomonas mexicana in two ways, 1) single ultrasonic treatment (SUT) and 2) multiple-intermittent ultrasonic treatments (IUT). The microalgal growth was slightly affected by SUT, while it significantly inhibited by IUT. The removal of sulfacetamide and sulfapyridine was significantly improved by >1.7-fold and >1.95-fold at 20 % of SUT and IUT treatment, respectively, compared to control. In the case of sulfamethazine, the SUT showed maximum removal (33.5 %) at 20 %, whereas IUT could achieve 27.5 % removal at the same ultrasonication conditions compared to 9.5 % removal in control. The IUT accelerated the degradation of sulfamethoxazole and sulfadimethoxine more than SUT showing a 9- fold and 12- fold increase in the removal of sulfamethoxazole and sulfadimethoxine with 20 % and 40 % treatments, respectively. The changes in microalgal cell morphology due to ultrasonication treatment were the main cause of enforced uptake and subsequent degradation of these ECs.

Keywords: phycoremediation

Permalink: https://www.hzdr.de/publications/Publ-36013
Publ.-Id: 36013


Carborane Analogues of Fenoprofen Exhibit Improved Antitumor Activity

Useini, L.; Mojić, M.; Laube, M.; Lönnecke, P.; Mijatović, S. S.; Maksimović-Ivanić, D.; Pietzsch, J.; Hey-Hawkins, E.

Fenoprofen is a widely used nonsteroidal anti-inflammatory drug (NSAID) against rheumatoid arthritis, degenerative joint disease, ankylosing spondylitis and gout. Like other NSAIDs, fenoprofen inhibits the synthesis of prostaglandins by blocking both cyclooxygenase (COX) isoforms, COX-1 the “house-keeping” enzyme and COX-2 the induced isoform from pathological stimuli. Unselective inhibition of both COX isoforms results in many side effects, but off-target effects have also been reported. The steric modifications of the drugs could afford the desired COX-2 selectivity. Furthermore, NSAIDs have shown promising cytotoxic properties. The structural modification of fenoprofen using bulky dicarba-closo-dodecaborane(12) (carborane) clusters and the biological evaluation of the carborane analogues for COX inhibition and antitumor potential showed that the carborane analogues exhibit stronger antitumor potential compared to their respective aryl-based compounds.

Permalink: https://www.hzdr.de/publications/Publ-36012
Publ.-Id: 36012


Investigating Brain Connectivity with Graph Neural Networks and GNNExplainer

Zhdanov, M.; Steinmann, S.; Hoffmann, N.

Functional connectivity plays an essential role in modern neuroscience. The modality sheds light on the brain's functional and structural aspects, including mechanisms behind multiple pathologies. One such pathology is schizophrenia which is often followed by auditory verbal hallucinations. The latter is commonly studied by observing functional connectivity during speech processing. In this work, we have made a step toward an in-depth examination of functional connectivity during a dichotic listening task via deep learning for three groups of people: schizophrenia patients with and without auditory verbal hallucinations and healthy controls. We propose a graph neural network-based framework within which we represent EEG data as signals in the graph domain. The framework allows one to 1) predict a brain mental disorder based on EEG recording, 2) differentiate the listening state from the resting state for each group and 3) recognize characteristic task-depending connectivity. Experimental results show that the proposed model can differentiate between the above groups with state-of-the-art performance. Besides, it provides a researcher with meaningful information regarding each group's functional connectivity, which we validated on the current domain knowledge.

Keywords: Graph neural networks; EEG; Functional connectivity

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Permalink: https://www.hzdr.de/publications/Publ-36011
Publ.-Id: 36011


Experimental dosimetric validation of an open-source treatment planning system for IMPT dose delivery at a horizontal PBS research beamline

Sepúlveda, C.; Gebauer, B.; Hoffmann, A. L.; Lühr, A.; Wahl, N.; Burigo, L.

Objectives: This study investigates the ability of the open-source treatment planning system (TPS) matRad to generate accurate intensity-modulated proton therapy (IMPT) plans for a real-world horizontal proton pencil beam scanning (PBS) research beamline. Initial validation for IMPT dose delivery is addressed by comparing simulation data with measurements.

Materials and Methods: The PBS delivery was modelled with Monte Carlo (MC) simulations using TOPAS version 3.7. First, base data measurements were performed to develop a proton beam model (BM) for the OncoRay horizontal PBS research beamline. Data include spot sizes in air, depth-dose profiles and a monitor unit (MU) calibration. BM data was then integrated into matRad to build base-data for IMPT treatment planning.
For initial validation of dose delivery, simple 3D box plans were generated at three depths (target beam entrance at 10, 15 and 20cm) covering energies from 115 to 195MeV. Absolute and relative doses were measured using a Semiflex 31013 ionization chamber (PTW Dosimetry) and a scintillation detector (Lynx®, IBA Dosimetry), respectively.

Results: Simulations and dose measurements showed good agreement of relative dose profiles at depths of 14.75, 18.05 and 24.05cm for field sizes of 5 x 5, 10 x 10 and 15 x 15cm2. The overall absolute difference of measured and planned target doses was ~1% (see Table 1).

Conclusions: Accurate MC-based BM was calculated and integrated into the TPS toolkit matRad. Absolute and relative measurements were in agreement with planned IMPT data. Full validation will be completed next months, including absolute and relative dosimetry of patient plans.

Permalink: https://www.hzdr.de/publications/Publ-36009
Publ.-Id: 36009


OPC UA Based User Data Interface at ELBE

Zenker, K.; Justus, M.; Steinbrück, R.

The Electron Linac for beams with high Brilliance and low Emittance (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is operated using the SCADA system WinCC by Siemens. The majority of ELBE systems is connected to WinCC via industrial Ethernet and proprietary S7 communication. However, in recent years there was a demand to provide a more open and platform independent access to ELBE machine data. The Industry 4.0 standard OPC UA has been chosen to implement such an interface. We will show how we use OPC UA as a common communication layer between industrial and scientific instruments as well as proprietary and open source control system software. Our solution makes use of commercially available hard- and software, namely Simatic STEP7, Simatic WinCC v7.x by Siemens and IBH Link UA by IBHsoftec. Combining these products we designed an OPC UA based user data interface, which features encrypted communication and access control from the control room via WinCC. It is available for internal use, e.g. for feedbacks, and external use, e.g to log ELBE data along with experiment data or to provide data to ELBE operators for machine optimizations.

Keywords: OPC UA

Related publications

  • Poster
    13th International Workshop on Emerging Technologies and Scientific Facilities Controls, 04.-07.10.2022, Dolní Břežany/Prague, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-36006
Publ.-Id: 36006


X-ray radiation transport in GPU accelerated Particle In Cell simulations

Ordyna, P.; Kluge, T.; Cowan, T.; Schramm, U.

Ultra-high-intensity laser pulse interactions with solid density targets are of central importance for
modern accelerator physics, Inertial Confinement Fusion(ICF) and astrophysics. In order to meet
the requirements of real-world applications, a deeper understanding of the underlying plasma
dynamics, including plasma instabilities and acceleration mechanisms, is needed. X-ray radiation
plays a substantial role in plasma physics, either as an integral part of a physical system itself or
as a useful diagnostic, hence it should be included in computational models.
Therefore, we bring a Monte Carlo based X-ray radiation transport module into our Particle In
Cell simulation framework PIConGPU. It allows, among others, for Thompson scattering, e.g. for
small-angle X-ray scattering (SAXS), and Faraday effect calculation for X-ray polarimetry - as
online, in-situ diagnostics.

  • Poster
    8. Annual MT Meeting, 26.-27.09.2022, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-36005
Publ.-Id: 36005


NuScale SMR 3-D modelling and analysis of boron dilution with the system code ATHLET in the framework of McSAFER

Diaz Pescador, E.; Jobst, M.; Kliem, S.

The small modular reactor (SMR) NuScale is modelled by Helmholtz-Zentrum Dresden Rossendorf (HZDR) in the framework of the EU H2020 McSAFER. NuScale is a SMR of integral pressurized type operated with light water driven by natural circulation. This work summarizes the reactor modelling approach with the system code ATHLET and presents the results from a boron dilution sequence, based on the Design Certification Application (DCA). Steady-state and transient results show agreement, thereby demonstrating ATHLET strong simulation capabilities on complex transients applied to SMR designs. The results show a decrease in core nominal boron concentration and subsequent reactivity insertion by the boron feedback. The reactor is tripped upon “high pressurizer pressure” setpoint and the actuation of the DHRS leads to a long term safe shutdown condition.

  • Contribution to proceedings
    KERNTECHNIK 2022, 21.06.2022, Leipzig, Germany
  • Lecture (Conference)
    KERNTECHNIK 2022, 21.06.2022, Leipzig, Germany

Permalink: https://www.hzdr.de/publications/Publ-36003
Publ.-Id: 36003


NuScale SMR 3-D Modelling and Applied Safety Analyses with the System Code ATHLET in the Framework of the EU H2020 McSAFER

Diaz Pescador, E.; Jobst, M.; Kliem, S.

Research and development of small modular reactors (SMRs) is receiving increasing attention by several countries and organizations due to flexibility, cost reduction and advanced safety features. The SMR NuScale is modelled by Helmholtz-Zentrum Dresden Rossendorf (HZDR) in the framework of the EU H2020 McSAFER project. NuScale is a SMR of integral pressurized water reactor (PWR) type, operated with light water driven by natural circulation in all operation modes. This work summarizes the modelling approach of a thermohydraulic model of NuScale SMR with the system code ATHLET, that includes a state-of-the-art 3-D reactor pressure vessel (RPV). The paper presents results and discussion from a boron dilution sequence at hot full power based on the Design Certification Application (DCA) report. Simulation results show agreement at steady-state and transient calculation, thereby demonstrating ATHLET strong simulation capabilities on complex sequences in SMR designs. The results show a decrease in core nominal boron concentration and subsequent reactivity insertion by boron feedback. The reactor is tripped upon “high pressurizer pressure” function by the insertion of the control rod banks. The actuation of the decay heat removal system (DHRS) provides long term core cooling to bring the reactor to a safe shutdown condition and preservation of shutdown margin is met during the simulation thereby complying with acceptance criterion.

Keywords: NuScale; SMR; ATHLET; Boron Dilution; McSAFER

  • Contribution to proceedings
    13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety, 06.09.2022, Hsinchu, Taiwan
  • Lecture (Conference) (Online presentation)
    13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety, 06.09.2022, Hsinchu, Taiwan

Permalink: https://www.hzdr.de/publications/Publ-36001
Publ.-Id: 36001


Nanoparticle depressants in fine particle seperation - The Efeect of Colloidal Silica in Calcium Mineral Flotation

Ben Said, B.; Pereira, L.; Rudolph, M.

The micro particle separation of calcium minerals by means of selective froth flotation is a challenging task. The difficulty arises because of the similar surface properties of the minerals, and thereby similar responses to various known families of flotation collectors (selectively adsorbing surfactants). Within the scope of this study colloidal silica is investigated as a potential selectively interacting nanoparticle depressant in the flotation process of calcium minerals. The effect of the colloidal silica and its interactions with the reagent system were investigated by varying its modification and specific surface area/particle size. Single-mineral microflotation of scheelite (calcium tungstate), fluorite (calcium fluoride), calcite (calcium carbonate) and apatite (calcium fluoro phosphate) were used to determine if colloidal silica would have any effect on the minerals. First results show that colloidal silica prevents calcite from floating while scheelite, fluorite and apatite are unaffected by the presence of the reagent, regardless of the dosage.
First batch flotation tests have shown significant differences between the three modifications in terms of the significant effect on the selectivity. The same finding was made when varying the specific surface area/particle size. Further surface chemistry studies will provide more insight on the depression mechanisms of colloidal silica in calcium mineral flotation.

Keywords: Froth Flotation; Nanoparticles; Adsorption; Bubble attachment; Particle interactions

  • Open Access Logo Lecture (Conference)
    9th World Congress on Particle Technology, 18.-22.09.2022, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-35997
Publ.-Id: 35997


Einsatz der FTC-Mini-Pilotanlage zur Optimierung von Flotationsprozessen Vorteile und Grenzen

Ben Said, B.; Pereira, L.; Rudolph, M.

Die Aufbereitung komplexer Erze durch neue Verfahren oder durch den Einsatz neuer oder ungewöhnlicher Reagenzien in der Flotation kann Probleme mit sich bringen. Insbesondere wenn neue Flotationsreagenzien verwendet werden oder ein kompliziertes Fließschema erforderlich ist, lassen sich die Auswirkungen auf den Betrieb anhand von Laborversuchen nicht ausreichend bestimmen. Es ist daher ratsam, Erze im kontinuierlichen Betrieb einer Pilotanlage zu untersuchen, bevor eine Aufbereitungsanlage im industriellen Maßstab installiert wird. Üblicherweise sind konventionelle Pilotanlagen, in denen 100 bis 1.000 kg/h Erzproben verarbeitet werden, eingesetzt, um die Machbarkeit des Verfahrens vor dem industriellen Maßstab zu belegen. Daraus ergeben sich detaillierte technische Daten, die für die Entwicklung eines endgültigen Prozessablaufs und die Dimensionierung der Ausrüstung erforderlich sind. Allerdings sind diese Pilotanlagen teuer in der Errichtung und im Betrieb. Als Alternative entwickelte das Falconbridge Technology Centre (FTC) 1999 in Zusammenarbeit mit Canadian Process Technologies Inc. eine Mini-Pilotanlage. Die FTC-Mini-Pilotanlage hat zunehmend an Bedeutung gewonnen, vor allem wegen der geringeren Probenmenge im Vergleich zur konventionellen Pilotanlage. In diesem Beitrag wird anhand der Ergebnisse der Batch-Flotation einer Fallstudie der Einsatz der FTC-Mini-Pilotanlage Optimierung des Flotationsprozesses von Scheelit unter Verwendung ein neuer Drücker aufgezeigt. Die Vorteile und Grenzen des Betriebs der Mini-Pilotanlage werden erörtert und die Ergebnisse im industriellen Maßstab validiert.

Keywords: Anlagenoptimierung; Flotationsprozess; Mineralienaufbereitung; Mini-Pilotanlage; Prozessoptimierung

  • Open Access Logo Lecture (Conference)
    Aufbereitung und Recycling 2022, 10.-11.11.2022, Freiberg, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-35996
Publ.-Id: 35996


Surrogate Modeling of Laser-Ion Acceleration in the Near-Critical Density Regime with Invertible Neural Networks

Miethlinger, T.; Garten, M.; Göthel, I.; Hoffmann, N.; Schramm, U.; Kluge, T.

The interaction of near-critical plasmas with ultra-intense laser pulses presents a promising approach to enable the development of very compact sources for high-energetic ions. However, current records for maximum proton energies are still below the required values for many applications, and challenges such as stability and spectral control remain unsolved to this day. In particular, significant effort per experiment and a high-dimensional design space renders naive sampling approaches ineffective. Furthermore, due to the strong nonlinearities of the underlying laser-plasma physics, synthetic observations by means of particle-in-cell (PIC) simulations are computationally very costly, and the maximum distance between two sampling points is strongly limited as well. Consequently, in order to build useful surrogate models for future data generation and experimental understanding and control, a combination of highly optimized simulation codes (we employ PIConGPU), powerful data-based methods, such as artificial neural networks, and modern sampling approaches are essential. Specifically, we employ invertible neural networks for bidirectional learning of parameter and observables, and autoencoder to reduce intermediate field data to a lower-dimensional latent representation.

Keywords: Invertible Neural Networks; Inverse Problems; Laser-Plasma; Laser-Ion Acceleration

  • Lecture (Conference) (Online presentation)
    DPG Spring Meeting Mainz 2022, 28.03.-01.04.2022, Mainz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35995
Publ.-Id: 35995


Surrogate Modeling of Laser-Plasma-Based Ion Acceleration with Invertible Neural Networks

Miethlinger, T.; Hoffmann, N.; Kluge, T.

The interaction of overdense and/or near-critical plasmas with ultra-intense laser pulses presents a promising approach to enable the development of very compact sources for high-energetic ions. However, current records for maximum proton energies are still below the required values for many applications, and challenges such as stability and spectral control remain unsolved to this day. In particular, significant effort per experiment and a high-dimensional design space renders naive sampling approaches ineffective. Furthermore, due to the strong nonlinearities of the underlying laser-plasma physics, synthetic observations by means of particle-in-cell (PIC) simulations are computationally very costly, and the maximum distance between two sampling points is strongly limited as well. Consequently, in order to build useful surrogate models for future data generation and experimental understanding and control, a combination of highly optimized simulation codes (we employ PIConGPU), powerful data-based methods, such as artificial neural networks, and modern sampling approaches are essential. Specifically, we employ invertible neural networks for bidirectional learning of parameter and observables, and autoencoder to reduce intermediate field data to a lower-dimensional latent representation.

Keywords: Invertible Neural Networks; Inverse Problems; Laser-Plasma; Laser-Ion Acceleration

  • Poster
    Platform for Advanced Scientific Computing 2022, 27.-29.06.2022, Basel, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-35994
Publ.-Id: 35994


Acceptance Rates of Invertible Neural Networks on Electron Spectra from Near-Critical Laser-Plasmas: A Comparison

Miethlinger, T.; Hoffmann, N.; Kluge, T.

While the interaction of ultra-intense ultra-short laser pulseswith near- and overcritical plasmas cannot be directly observed, experimentally accessible quantities (observables) often only indirectly giveinformation about the underlying plasma dynamics. Furthermore, theinformation provided by observables is incomplete, making the inverseproblem highly ambiguous. Therefore, in order to infer plasma dynamicsas well as experimental parameter, the full distribution over parameters given an observation needs to considered, requiring that models areflexible and account for the information lost in the forward process. Invertible Neural Networks (INNs) have been designed to efficiently modelboth the forward and inverse process, providing the full conditional posterior given a specific measurement. In this work, we benchmark INNsand standard statistical methods on synthetic electron spectra. First, weprovide experimental results with respect to the acceptance rate, whereour results show increases in acceptance rates up to a factor of 10. Additionally, we show that this increased acceptance rate also results in anincreased speed-up for INNs to the same extent. Lastly, we propose acomposite algorithm that utilizes INNs and promises low runtimes whilepreserving high accuracy.

Keywords: Invertible Neural Networks; Inverse Problems; Machine Learning; Particle-in-Cell; Laser-Plasma Physics

  • Open Access Logo Contribution to WWW
    https://arxiv.org/abs/2212.05836
    DOI: 10.48550/arXiv.2212.05836
    arXiv: 2212.05836
  • Open Access Logo Lecture (Conference)
    14th International Conference on Parallel Processing and Applied Mathematics, 11.-14.09.2022, Gdańsk, Polska
  • Open Access Logo Contribution to proceedings
    14th International Conference on Parallel Processing and Applied Mathematics, PPAM 2022, 11.-14.09.2022, Gdansk, Poland
    Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 273-284
    DOI: 10.1007/978-3-031-30445-3_23

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Permalink: https://www.hzdr.de/publications/Publ-35993
Publ.-Id: 35993


Effects of geometry on antiferromagnetic textures: boundaries and geometric curvature

Pylypovskyi, O.; Borysenko, Y.; Tomilo, A.; Kononeko, D.; Yershov, K.; Roessler, U.; Faßbender, J.; van den Brink, J.; Sheka, D.; Makarov, D.

Geometric curvature in nanowires and shells is established as a powerful method to tailor chiral and anisotropic responses in ferromagnets. Here, we apply the framework of curvilinear magnetism to antiferromagnetic (AFM) systems. First, we consider curvilinear AFM spin chains with the nearest-neighbor exchange and hard axis of anisotropy along the chain. Their shape is characterized by curvature K and torsion T. These functions determine the direction of the geometry-driven Dzyaloshinskii vector D and easy axis of anisotropy stemming from exchange. Furthermore, the broken translation symmetry in AFM chains arranged along space curves leads to the weakly ferromagnetic response proportional to K and T even if the magnetic texture is locally homogeneous. While the plane AFM chains possess the uniform ground state, the geometry-induced anisotropy axes and chiral response become pronounceable approaching spin-flop phase. Namely, in AFM rings the non-zero D leads to the appearance of canted state for the large enough K, while spin-flop phase splits in two phases by the value of K with different topology of the order parameter. For 3D chiral AFMs, the sample boundaries alter the width and produce an additional twist of domain walls and skyrmions near the surface.

O. V. Pylypovskyi, D. Y. Kononenko, K. V. Yershov et al, Nano Lett. 20, 8157 (2020)
O. V. Pylypovskyi, Y. A. Borysenko, J. Fassbender et al, Appl. Phys. Lett. 118, 182405 (2021)
O. V. Pylypovskyi, A. V. Tomilo, D. D. Sheka et al, Phys. Rev. B 103, 134413 (2021)
Y. A. Borysenko, D. D. Sheka, J. Fassbender et al, ArXiv:2208.02510 (2022)

Keywords: antiferromagnetism; curvilinear spin chains; spin-flop

  • Lecture (Conference) (Online presentation)
    APS March Meeting, 20.-22.03.2023, Online participation, USA

Permalink: https://www.hzdr.de/publications/Publ-35992
Publ.-Id: 35992


Flexomagnetism of thin Cr2O3 films

Makushko, P.; Kosub, T.; Pylypovskyi, O.; Hedrich, N.; Li, J.; Pashkin, O.; Avdoshenko, S.; Hübner, R.; Ganss, F.; Wolf, D.; Lubk, A.; Liedke, M. O.; Butterling, M.; Wagner, A.; Wagner, K.; Shields, B. J.; Lehmann, P.; Veremchuk, I.; Faßbender, J.; Maletinsky, P.; Makarov, D.

Cr2O3 is the only known uniaxial antiferromagnetic material that is also magnetoelectric at room temperature. This renders Cr2O3 a technologically relevant playground for the realisation of different device ideas for prospective antiferromagnetic spintronics. We discovered the presence of flexomagnetic effects in Cr2O3, which come about due to the impact of a strain gradient on the thermodynamic properties, namely on the Neel temperature. By combining magnetotransport and Nitrogen Vacancy magnetometry characterizations, we experimentally determine the presence of the gradient of the Neel temperature in a 50-nm-thick Cr2O3 thin film and quantify that the magnetic moment, generated by this new effect, can be as high as 15 μB/nm2. Furthermore, due to good oxide-oxide heteroepitaxy and respective compressive strain, the Neel temperature in Cr2O3 thin films can be enhanced persistently up to 100degC, which is 60degC higher than the bulk transition temperature. The emergent flexomagnetism-driven ferromagnetic order parameter in antiferromagnetic thin films offers more flexibility in the design of spintronic and magnonic devices and can be of relevance for other antiferromagnetic materials.

P. Makushko, T. Kosub, O. V. Pylypovskyi et al., Nature Communications (2022), in press.

Keywords: antiferromagnetism; flexomagnetism; Neel temperature

  • Lecture (Conference) (Online presentation)
    APS March Meeting, 20.-22.03.2023, Online participation, USA

Permalink: https://www.hzdr.de/publications/Publ-35991
Publ.-Id: 35991


(Data set) Distinction of charge transfer and Frenkel excitons in pentacene traced via infrared spectroscopy

Pinteric, M.; Roh, S.; Hammer, S.; Pflaum, J.; Dressel, M.; Uykur, E.

  1. Data from the publication are given in Origin format with Figure codes.
  2. More data are available upon request.

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Permalink: https://www.hzdr.de/publications/Publ-35990
Publ.-Id: 35990


Distinction of charge transfer and Frenkel excitons in pentacene traced via infrared spectroscopy

Pinteric, M.; Roh, S.; Hammer, S.; Pflaum, J.; Dressel, M.; Uykur, E.

Infrared spectroscopy studies on pentacene single crystals have been performed in the frequency range of 12 meV to 3 eV in reflection and transmission configurations as a function of temperature, down to 10 K. Our results reveal the dominant contributions of the excitonic bands at the absorption edge. The singlet transitions of the Frenkel excitons at 1.78 eV with 130 meV Davydov splitting have been identified. An additional excitonic feature observed at 1.83 eV can be assigned to a charge-transfer type exciton evidenced by the strong vibrational anomalies. On the other hand, the strong feature seen at 1.67 eV does not couple to the vibrational modes suggests that electronic origin in nature.

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Permalink: https://www.hzdr.de/publications/Publ-35989
Publ.-Id: 35989


(Data set)High-pressure investigations in CH3NH3PbX3 ( X = I, Br, and Cl): Suppression of ion migration and stabilization of low-temperature structure

Chan, Y. T.; Elliger, N.; Klis, B.; Kollar, M.; Horvath, E.; Forro, L.; Dressel, M.; Uykur, E.

The raw data can be obtained from the corresponding author
Martin Dressel: dressel@pi1.physik.uni-stuttgart.de

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Permalink: https://www.hzdr.de/publications/Publ-35988
Publ.-Id: 35988


Untersuchung zur Flotation von ultrafeinen Partikeln im neu entworfenen Trennapparat MultiDimFlot

Stefenelli, N.

Die Flotation ist ein Trennprozess, der in der Aufbereitung und Veredelung eines breiten Spektrums primärer Rohstoffe (Erze, Kohle, Karbonate etc.) sowie in diversen Recyclingprozessen eingesetzt wird [1]. Aufgrund des steigenden Bedarfs an Rohstoffen steht die Aufbereitungstechnik vor der Herausforderung fein- und feinstverwachsene Erze zu flotieren [2]. Daher ist es von großer Bedeutung die Grenzen der Flotierbarkeit in den ultrafeinen Bereich zu erweitern. Bei der Flotation handelt es sich um einen Nassprozess, dessen Trennprinzip auf der unterschiedlichen Benetzbarkeit der zu trennenden Feststoffpartikeln basiert. Hydrophobe Teilchen haften hierbei an eingebrachten Gasblasen und bilden Partikel-Blasen-Aggregate, die in der Suspension aufsteigen und einen Schaum bilden. Diese mit Wertstoff beladene Schaumschicht wird als Konzentrat von der Trübeoberfläche abgezogen. Die hydrophilen Partikel verbleiben hingegen in der Trübe [3]. In der Feinkornaufbereitung mit einem Partikelgrößenbereich von 10 μm bis 200 μm ist dieser Trennprozess weit verbreitet [4]. Die Flotation ultrafeiner Partikel mit einer Größe x < 10 μm stellt jedoch eine Vielzahl an verfahrenstechnischen Herausforderungen dar, sodass die herkömmlichen Flotationsapparate (mechanische Flotationsapparate, Flotationssäulen) entweder nicht oder nur ineffizient das hydrophile Gangmineral vom hydrophoben Wertstoff trennen. Im Rahmen des Projekts MultiDimFlot, welches Teil des DFG Schwerpunktprogramms 2045 MehrDimPart ist, wurde ein spezieller Trennapparat entwickelt, mit dem die Flotation ultrafeiner Partikel untersucht werden soll. Diese Apparatur kombiniert die Vorzüge des turbulenten Strömungsregimes in einer mechanischen Flotationszelle mit dem für die Flotationssäulen typischen tiefen Schaum. Die Flotierbarkeit eines binären Gemisches aus ultrafeinem Magnetit und Glaspartikel mit der MultiDimFlot-Apparatur wird im Zuge dieser Bachelor-Arbeit experimentell untersucht. Der Einfluss variierender Partikeleigenschaften auf den Flotationsprozess wird erforscht, weshalb Glaspartikel mit unterschiedlichen Partikelformen (Sphären, Fragmente und Fasern) und Hydrophobierungszuständen (nicht-, mäßig- und stark hydrophobiert) in Flotationsversuchen verwendet werden. Die experimentelle Arbeit umfasst drei Teile: Das Ziel des ersten Teils ist es, durch Variation der Parameter Rotordrehzahl und Luftzufuhr, geeignete Maschinen-parameter zur Flotation mäßig hydrophobierter, ultrafeiner Fragmente mit der MultiDimFlot-Apparatur zu finden. Im zweiten Teil wird mit den gewählten Betriebsparametern das Flotationsverhalten der übrigen Partikelsysteme untersucht. Der dritte Teil umfasst erste Testversuche zur Herstellung eines stationären Zustands und die Beprobung der Schaumsäule in unterschiedlichen Höhen.

  • Bachelor thesis
    TUBAF, 2022

Permalink: https://www.hzdr.de/publications/Publ-35987
Publ.-Id: 35987


Enhancing magnetic field support for the electrodeposition of nano-structured metal layers by reducing global cell flow

Huang, M.; Skibinska, K.; Zabinski, P.; Eckert, K.; Mutschke, G.

Magnetic fields could be a helpful tool for improving the growth of nanostructures on metal layers during electrodeposition processes. It is well known that an electrode-normal magnetic field promotes the growth of mm-sized conical structures by generating a supportive local electrolyte flow. However, we found recently that for smaller cones of μm/nm-size, this local flow may often be superseded by a stronger global cell flow, thus preventing the structuring effect. We therefore discuss improved cell setups to minimize the global flow and to enable the magnetic support of conical growth.

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Permalink: https://www.hzdr.de/publications/Publ-35986
Publ.-Id: 35986


Development of a system for the design and synthesis of tailor-made peptides for the treatment of polymers prior to plastic metallization

Kießlich, T.; Braun, R.; Lederer, F.; Pollmann, K.

Increasing demands in environmental protection and environmentally friendly solutions are important market drivers for the development of sustainable chemicals. Chromium (VI) is used in electroplating technology to pretreat polymers in order to achieve good metallization. However, it´s application requires special permits now. This is an EU strategy to prevent the use of dangerous and unhealthy Reduce substances. Finding replacements with conventional chemicals is increasingly difficult. In order to change the chemistry and microstructure of polymer surfaces at suitable temperatures and process times, very reactive chemicals are required, which pose a high risk. Currently available alternative Chromium (VI) -free technologies for polymer preconditioning have not yet been reach the industrial requirements.
One strategy to solve this problem is to focus on very specific and selective reactions. The main aim of this work is to develop a biological system that enables the development and synthesis of tailor-made, selective polymer-binding peptides. The system is based on what is known as phage surface display technology (PSD).
PSD generally uses a library of about 109 phages with various peptides fused to the phage coat proteins. All the phages in the library are unique. Phage particles are incubated with the target material (polymer) in three biopanning cycles. Only a few phages bind to surfaces and the unbound phage particles are removed when the target materials are washed. Finally, the attached phage particles were eluted and amplified in Escherichia coli cells. After the last cycle of biopanning, there are only a few individual phages left that have exceptionally high surface affinity. The phage particles are used for subsequent sequencing, modification and application. The peptides that are expressed by the selected phages are then characterized with regard to their sequence, their binding motif and their interaction with the target material.
.

  • Poster
    European Peptide Symposium, 29.08.-02.09.2022, Sitges, Spanien

Permalink: https://www.hzdr.de/publications/Publ-35984
Publ.-Id: 35984


Covid-19 Infections in Czechia

Abdussalam, W.

We provide post-processing data of daily infected COVID-19 cases for a municipality (Obec) level. The current data for municipality level is prepared on Czech_Obec_COVID19_Infections.csv. The file consists of five columns such as region, name, date, infected and population. The region denotes the ID of a county/state followed by its name in the next column. The inserted date of data is prepared in the third column followed by the number of dead and infected cases. Last but not least, the population of the county is provided in the last column.

This data hub was partially funded by the Where2Test project, which is financed by SMWK with tax funds on the basis of the budget approved by the Saxon State Parliament. This data hub was also partially funded by the Center of Advanced Systems Understanding (CASUS) which is financed by Germany’s Federal Ministry of Education and Research (BMBF) and by the Saxon Ministry for Science, Culture and Tourism (SMWK) with tax funds on the basis of the budget approved by the Saxon State Parliament.

Keywords: Covid-19; Czechia

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Permalink: https://www.hzdr.de/publications/Publ-35983
Publ.-Id: 35983


Seeded FEL lasing of the COXINEL beamline driven by the HZDR plasma accelerator

Labat, M.; Couperus Cabadağ, J. P.; Ghaith, A.; Irman, A.; Berlioux, A.; Berteaud, P.; Blache, F.; Bock, S.; Bouvet, F.; Briquez, F.; Chang, Y.-Y.; Corde, S.; Debus, A.; de Oliveira, C.; Duval, J.-P.; Dietrich, Y.; El Ajjouri, M.; Eisenmann, C.; Gautier, J.; Gebhardt, R.; Grams, S.; Helbig, U.; Herbeaux, C.; Hubert, N.; Kitegi, C.; Kononenko, O.; Kuntzsch, M.; La Berge, M.; Le, S.; Leluan, B.; Loulergue, A.; Malka, V.; Marteau, F.; Huy N. Guyen, M.; Oumbarek-Espinos, D.; Pausch, R.; Pereira, D.; Püschel, T.; Ricaud, J.-P.; Rommeluere, P.; Roussel, E.; Rousseau, P.; Schöbel, S.; Sebdaoui, M.; Steiniger, K.; Tavakoli, K.; Thaury, C.; Ufer, P.; Valleau, M.; Vandenberghe, M.; Veteran, J.; Schramm, U.; Couprie, M.-E.

Laser Plasma Accelerators (LPAs), harnessing gigavolt-per-centimeter accelerating fields, can generate high peak current, low emittance and GeV class electron beams paving the way for the realization of future compact free-electron lasers (FELs). Here, we report on the commissioning of the COXINEL beamline driven by the HZDR plasma accelerator and experimental demonstration of FEL lasing at 270 nm in a seeded configuration. Control over the radiation wavelength is achieved with an improved bandwidth stability. Furthermore, the appearance of interference fringes, resulting from the interaction between the phase-locked emitted radiation and the seed, confirms longitudinal coherence, representing a key feature of such a seeded FEL. These results are cross-checked with simulations, ELEGANT for beam optics and GENESIS for FEL radiation. We anticipate a navigable pathway toward smaller-scale free-electron lasers at extreme ultra-violet wavelengths.

Keywords: free electron laser; laser plasma accelerator; seeded FEL driven by LPA beams

  • Lecture (Conference)
    Advanced Accelerator Concepts (AAC), 06.-11.11.2022, Long Island, New York, USA
  • Invited lecture (Conferences)
    BLIN, 12.10.2022, Garching, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35982
Publ.-Id: 35982


Seeded free-electron laser driven by a compact laser plasma accelerator

Labat, M.; Couperus Cabadağ, J. P.; Ghaith, A.; Irman, A.; Berlioux, A.; Berteaud, P.; Blache, F.; Bock, S.; Bouvet, F.; Briquez, F.; Chang, Y.-Y.; Corde, S.; Debus, A.; de Oliveira, C.; Duval, J.-P.; Dietrich, Y.; El Ajjouri, M.; Eisenmann, C.; Gautier, J.; Gebhardt, R.; Grams, S.; Helbig, U.; Herbeaux, C.; Hubert, N.; Kitegi, C.; Kononenko, O.; Kuntzsch, M.; La Berge, M.; Le, S.; Leluan, B.; Loulergue, A.; Malka, V.; Marteau, F.; Huy N. Guyen, M.; Oumbarek-Espinos, D.; Pausch, R.; Pereira, D.; Püschel, T.; Ricaud, J.-P.; Rommeluere, P.; Roussel, E.; Rousseau, P.; Schöbel, S.; Sebdaoui, M.; Steiniger, K.; Tavakoli, K.; Thaury, C.; Ufer, P.; Valleau, M.; Vandenberghe, M.; Veteran, J.; Schramm, U.; Couprie, M.-E.

Seeded free-electron laser driven by a compact laser plasma accelerator
Free-electron lasers generate high-brilliance coherent radiation at
wavelengths spanning from the infrared to the X-ray domains. The recent
development of short-wavelength seeded free-electron lasers now allows
for unprecedented levels of control on longitudinal coherence, opening
new scientific avenues such as ultra-fast dynamics on complex systems
and X-ray nonlinear optics. Although those devices rely on state-of-the-art
large-scale accelerators, advancements on laser-plasma accelerators, which
harness gigavolt-per-centimetre accelerating fields, showcase a promising
technology as compact drivers for free-electron lasers. Using such
footprint-reduced accelerators, exponential amplification of a shot-noise
type of radiation in a self-amplified spontaneous emission configuration
was recently achieved. However, employing this compact approach for the
delivery of temporally coherent pulses in a controlled manner has remained
a major challenge. Here we present the experimental demonstration
of a laser-plasma accelerator-driven free-electron laser in a seeded
configuration, where control over the radiation wavelength is accomplished.
Furthermore, the appearance of interference fringes, resulting from the
interaction between the phase-locked emitted radiation and the seed,
confirms longitudinal coherence. Building on our scientific achievements,
we anticipate a navigable pathway to extreme-ultraviolet wavelengths,
paving the way towards smaller-scale free-electron lasers, unique tools for a
multitude of applications in industry, laboratories and universities.

Keywords: free electron laser; laser plasma accelerator; seeded FEL driven by LPA beams

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Permalink: https://www.hzdr.de/publications/Publ-35981
Publ.-Id: 35981


Stable and High-Quality Electron Beams from Staged Laser and Plasma Wakefield Accelerators

Foerster, F. M.; Döpp, A.; Haberstroh, F.; Grafenstein, K. V.; Campbell, D.; Chang, Y.-Y.; Corde, S.; Couperus Cabadağ, J. P.; Debus, A.; Gilljohann, M. F.; Habib, A. F.; Heinemann, T.; Hidding, B.; Irman, A.; Irshad, F.; Knetsch, A.; Kononenko, O.; Martinez De La Ossa, A.; Nutter, A.; Pausch, R.; Schilling, G.; Schletter, A.; Schöbel, S.; Schramm, U.; Travac, E.; Ufer, P.; Karsch, S.

We present experimental results on a plasma wakefield accelerator (PWFA) driven by high-current
electron beams from a laser wakefield accelerator (LWFA). In this staged setup stable and high-quality
(low-divergence and low energy spread) electron beams are generated at an optically generated hydro-
dynamic shock in the PWFA. The energy stability of the beams produced by that arrangement in the PWFA
stage is comparable to both single-stage laser accelerators and plasma wakefield accelerators driven by
conventional accelerators. Simulations support that the intrinsic insensitivity of PWFAs to driver energy
fluctuations can be exploited to overcome stability limitations of state-of-the-art laser wakefield
accelerators when adding a PWFA stage. Furthermore, we demonstrate the generation of electron bunches
with energy spread and divergence superior to single-stage LWFAs, resulting in bunches with dense phase
space and an angular-spectral charge density beyond the initial drive beam parameters. These results
unambiguously show that staged LWFA-PWFA can help to tailor the electron-beam quality for certain
applications and to reduce the influence of fluctuating laser drivers on the electron-beam stability. This
encourages further development of this new class of staged wakefield acceleration as a viable scheme
toward compact, high-quality electron beam sources.

Keywords: hybrid lwfa-pwfa

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Permalink: https://www.hzdr.de/publications/Publ-35980
Publ.-Id: 35980


Theranostic platform technologies for therapy and imaging

Feldmann, A.

Theranostic platform technologies for therapy and imaging

Keywords: theranostic; CAR T cell therapy; antibody

  • Invited lecture (Conferences)
    I&I retreat 2022, 09.-10.06.2022, Bonn, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35978
Publ.-Id: 35978


Theranostic Antibody- and CAR-based Platform Technology for Therapy and Imaging

Feldmann, A.

Theranostic Antibody- and CAR-based Platform Technology for Therapy and Imaging

Keywords: bispecific antibody; CAR T cell therapy; theranostics; UniCAR; RevCAR

  • Invited lecture (Conferences)
    Antibody Technologies and Therapeutics Conference, 11.-14.09.2022, Prato, Italien

Permalink: https://www.hzdr.de/publications/Publ-35977
Publ.-Id: 35977


Adaptor UniCAR and RevCAR platforms for flexible, switchable and combinatorial tumor targeting

Feldmann, A.; Loureiro, L. R.; Kegler, A.; Arndt, C.; Mitwasi, N.; Bergmann, R.; Koristka, S.; Hoffmann, A.; González Soto, K. E.; Kittel-Boselli, E.; Bartsch, T.; Drewitz, L.; Berndt, N.; Fasslrinner, F.; Bornhäuser, M.; Bachmann, M.

Chimeric antigen receptor (CAR) T-cells show remarkable therapeutic effects especially in B-cell derived leukemias and lymphomas. However, clinical translation of such an innovative immunotherapeutic approach in highly heterogeneous hematological malignancies like acute myeloid leukemia (AML) or solid tumors is still challenging due to life-threatening side effects, immune escape and disease relapse. To overcome such major hurdles and to address the unmet need for further improvements in CAR therapy, we have established flexible, switchable and programmable adaptor CAR platform technologies named UniCAR and RevCAR. These modular strategies consist of T-cells engineered with adaptor CARs which are primarily inactive as they are incapable to recognize surface antigens. Universal adaptor CAR T-cells can be flexibly redirected to any tumor antigen and controlled by targeting modules (TMs) cross-linking adaptor CAR T- and tumor cells resulting in tumor cell lysis. As an advancement of UniCARs, RevCARs lack the extracellular antigen-binding moiety reducing the receptor size and facilitating the genetical modification of T-cells with several RevCARs possessing different specificity and functionality. Thus, the RevCAR platform enables combinatorial tumor targeting following Boolean logic gates. So far, we have successfully shown preclinical applicability of the UniCAR and RevCAR approaches to target hematological malignancies as well as solid tumors in a flexible and specific manner using tumor cell lines and patient-derived materials. Remarkably, efficiency and switchability of UniCAR T-cells were even proven for the first time in patients in a clinical phase I study. Furthermore, by targeting of two different tumor antigens, combinatorial OR and AND gate logic targeting according to the rules of Boolean algebra was accomplished using the RevCAR platform. These achievements have a high potential for an improved and personalized tumor immunotherapy.

Keywords: UniCAR; RevCAR; CAR T cell therapy; combinatorial tumor targeting

  • Invited lecture (Conferences)
    3rd International Conference on Lymphocyte Engineering, 31.03.-02.04.2022, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35976
Publ.-Id: 35976


Mu2e Run I Sensitivity Projections for the Neutrinoless Muon to Electron Conversion Search in Aluminum

Abdi, F.; Abrams, R.; Adentunji, J.; Ahmed, W.; Alber, R.; Alexander, D.; Allen, D.; Allspach, D.; Alvarez-Garcia, C.; Ambrose, D.; Ambrosio, G.; Amirkhanov, A.; Andreev, N.; Ankenbrandt, C. M.; Appleby, R.; Arnold, D.; Artikov, A.; Atanov, N.; Badgley, K.; Ball, M.; Baranov, V.; Barker, J.; Barnes, E.; Barton, B.; Bartoszek, L.; Bellettini, G.; Bernstein, R. H.; Bersani, A.; Bianchi, I.; Biery, K.; Bini, S.; Blazey, G.; Bloise, C.; Boedigheimer, K.; Boi, S.; Bolton, T.; Bono, J.; Bonventre, R.; Borghi, S.; Borrel, L.; Bossert, R.; Bowcock, T.; Bowden, M.; Brandt, J.; Breach, M.; Brown, D.; Brown, D. N.; Brown, G.; Brown, H.; Budagov, I.; Buelher, M.; Bulugean, G.-M.; Byrum, K.; Campbell, M.; Cao, H.; Carey, R. M.; Caron, J. F.; Casey, B.; Casler, H.; Cervelli, F.; Cheban, S.; Chen, J.; Chen, M.; Cheng, C.-H.; Chislett, R.; Chitirasreemadam, N.; Chokheli, D.; Ciampa, K.; Ciolini, R.; Coghill, J.; Colao, F.; Coleman, R. N.; Corrodi, S.; Crescimbeni, L.; Crowley, C.; Culbertson, R.; Cummings, M. A. C.; Daniel, A.; Davydov, Y.; Demers, S.; Deshpande, A.; Devilbiss, M.; Dey, J.; Defelice, G.; de Gouvea, A.; Dhanraj, J.; Ding, D.; Ding, D.; Dinnon, M.; Diociaiuti, E.; Dixon, S.; Di Falco, S.; Djilkibaev, R.; Donati, S.; Drake, G.; Drendel, B.; Duerling, G.; Dukes, E. C.; Dychkant, A.; Echenard, B.; Eddy, N.; Edmonds, A.; Ehrlich, R.; Ekka, U.; Evans, R.; Evbota, D.; Fabbricatore, P.; Fagan, J.; Farinon, S.; Farrell, W.; Farris, P.; Feher, S.; Fellenz, B.; Fernandez, E.; Ferrari, A.; Ferrari, C.; Finley, J.; Flood, K.; Flumerfelt, E.; Fontana, F.; Francis, K.; Frand, M.; Frank, M.; Friedsam, H.; Gallo, G.; Gandrajula, R. P.; Gaponenko, A.; Gardner, M.; Gargiulo, R.; Gaugel, S.; Genser, K. L.; Gersabeck, M.; Ginther, G.; Gioiosa, A.; Giovannella, S.; Giusti, V.; Glagolev, V.; Glass, H.; Glenzinski, D. A.; Goadhouse, S.; Goodenough, L.; Grancagnolo, F.; Gray, P.; Group, C.; Hahn, A.; Hampai, D.; Hansen, S.; Happacher, F.; Harkness-Brennan, L.; Harrig, K.; Hartsell, B.; Hays, S.; Hedges, M.; Hedin, D.; Heller, K.; Herman, A.; Hirsh, S.; Hitlin, D. G.; Hocker, A.; Hooper, R.; Horton-Smith, G.; Huang, S.; Huedem, E.; Huffman, D.; Hung, P. Q.; Hungerford, E.; Ibrahim, A.; Israel, S.; Jenkins, M.; Johnstone, C.; Jones, M.; Jorjadze, V.; Judson, D.; Kampa, C.; Kargiantoulakis, M.; Kashikhin, V.; Kasper, P.; Keshavarzi, A.; Khalatian, V.; Kim, J.-H.; Kiper, T.; Knapp, D.; Knodel, O.; Knoepfel, K.; Kokosa, L.; Kolomensky, Y. G.; Koltick, D.; Kozlovsky, M.; Kozminski, J.; Kracczyk, G.; Kramp, M.; Krave, S.; Krempetz, K.; Kutschke, R. K.; Kwarciany, R.; Lackowski, T.; Lamm, M. J.; Lancaster, M.; Larwill, M.; Leavell, F.; Lee, M. J.; Leeb, D.; Lema-Sinchi, J.; Leveling, T.; Lewis, R.; Ley, A.; Li, B.; Li, Y.; Lin, D.; Lincoln, D.; Logashenko, I.; Lombardo, V.; Lopes, M. L.; Luca, A.; Lynch, K. R.; Mackenzie, M.; Makulski, A.; Manolis, J.; Maravin, Y.; Marciano, W. J.; Marini, A.; Martin, E.; Martinez, A.; Martini, M.; McArthur, D.; McConologue, F.; Mesmer, N.; Messerly, B.; Michelotti, L.; Middleton, S.; Miles, C.; Miller, J. P.; Miscetti, S.; Mitchell, D.; Miyashita, T.; Mokhov, N.; Molenaar, D.; Molzon, W.; Moore, J.; Morescalchi, L.; Morgan, J.; Mott, J.; Motuk, E.; Müller, S.; Mukherjee, A.; Murat, P.; Musenich, R.; Nagaslaev, V.; Narayanan, A.; Neely, R.; Neuffer, D. V.; Nguyen, M. T.; Nicol, T.; Niehoff, J.; Nogiec, J.; Norman, A.; Northrup, K.; O'Dell, V.; Oh, S.; Oksuzian, Y.; Olderr, P.; Olson, M.; Orris, D.; Oshinowo, B.; Ostojic, R.; Oyang, J.; Paesani, D.; Pagan, S.; Page, T.; Palladino, A.; Park, C.; Pasciuto, D.; Pedreschi, E.; Peterson, T.; Pezzullo, G.; Pilipenko, R.; Pla-Dalmau, A.; Plesniak, P.; Pohlman, N.; Pollack, B.; Poloubotko, V.; Popovic, M.; Popp, J. L.; Porter, F.; Prebys, E. J.; Price, J.; Prieto, P.; Pronskikh, V.; Pushka, D.; Quirk, J.; Rabehl, R.; Rachamin, R.; Raffaelli, F.; Ragheb, A.; Rakness, G.; Ray, R. E.; Rechenmacher, R.; Rivera, R.; Rizzo, G.; Roberts, B. L.; Roberts, S.; Roberts, T. J.; Robotham, W.; Roehrken, M.; Rubinov, P.; Rucinski, R.; Rusu, V. L.; Samavat, M. F.; Sanzani, E.; Saputi, A.; Sarra, I.; Sarychev, M.; Scarpine, V.; Schappert, W.; Schmitt, M.; Schmitter, P.; Schoo, D.; Schumacher, K.; Shi, X.; Singh, V.; Sobering, T.; Soleti, R.; Solt, M.; Song, H.; Song, E.; Spinella, F.; Srivastav, M.; Stefanik, A.; Stetzler, S.; Still, D.; Stortini, M.; Stratakis, D.; Strauss, T.; Sun, Y.; Suslov, I.; Syphers, M. J.; Szemraj, L.; Ta, J.; Taffara, A.; Tang, Z.; Tanovic, N.; Tartaglia, M.; Tassielli, G.; Taylor, R.; Tecchio, M.; Tickle, S.; Tinsley, D.; Tope, T.; Torkelson, A.; Tran, N.; Trevor, J.; Tschirhart, R. S.; Turnberg, S.; Uzunyan, S.; Varier, D.; Varier, D.; Velasco, M.; Vinas, L.; Vitali, B.; Vogel, G.; Wagner, R.; Wagner, R.; Wands, R.; Wang, Y.; Wang, C.; Wang, M.; Wardlaw, I.; Warren, M.; Werkema, S.; White Jr, H. B.; Whitmore, J.; Wielgos, R.; Wildberger, R.; Wills, L.; Winter, P.; Woods, R.; Worel, C.; Wu, Y.; Xia, L.; You, Z.; Yucel, M.; Zadeh, P.; Zanetti, A. M.; Zhadan, D.; Zhu, R.-Y.; Zifko, R.; Zutshi, V.

The Mu2e experiment at Fermilab will search for the neutrinoless μ − → e − conversion in
the field of an aluminum nucleus. The Mu2e data-taking plan assumes two running periods, Run I
and Run II, separated by an approximately two-year-long shutdown. This paper presents an estimate
of the expected Mu2e Run I search sensitivity and includes a detailed discussion of the background
sources, uncertainties of their prediction, analysis procedures, and the optimization of the experimental
sensitivity. The expected Run I 5σ discovery sensitivity is R μe = 1.2 × 10 − 15 , with a total expected
background of 0.11 ± 0.03 events. In the absence of a signal, the expected upper limit is R μe < 6.2 × 10 − 16
at 90% CL. This represents a three order of magnitude improvement over the current experimental limit
of R μe < 7 × 10 − 13 at 90% CL set by the SINDRUM II experiment.

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Permalink: https://www.hzdr.de/publications/Publ-35975
Publ.-Id: 35975


Investigation of the ¹⁴N(p,γ)¹⁵O reaction and its impact on the CNO cycle

Frentz, B.; Aprahamian, A.; Boeltzig, A.; Borgwardt, T.; Clark, A. M.; Deboer, R. J.; Gilardy, G.; Görres, J.; Hanhardt, M.; Henderson, S. L.; Howard, K. B.; Kadlecek, T.; Liu, Q.; Macon, K. T.; Moylan, S.; Reingold, C. S.; Robertson, D.; Seymour, C.; Strauss, S. Y.; Strieder, F.; Vande Kolk, B.; Wiescher, M.

The CNO cycle is the main energy source in massive stars during their hydrogen burning phase, and, for our
sun, it contributes at the ≈1% level. As the ¹⁴N(p,γ)¹⁵O reaction is the slowest in the cycle, it determines the
CNO energy production rate and thus the CNO contribution to the solar neutrino flux. These CNO neutrinos are
produced primarily from the β decay of ¹⁵O and, to a lesser extent, from the decay of ¹³N. Solar CNO neutrinos
are challenging to detect, but they can provide independent new information on the metallicity of the solar core.
Recently, CNO neutrinos from ¹⁵O have been identified for the first time with the Borexino neutrino detector
at the INFN Gran Sasso underground laboratory. There are, however, still some considerable uncertainties in
the ¹⁴N(p,γ)¹⁵O reaction rate under solar temperature conditions. The low energy reaction data presented
here, measured at the CASPAR underground accelerator, aim at connecting existing measurements at higher
energies and attempts to shed light on the discrepancies between the various data sets, while moving towards a
better understanding of the ¹⁴N(p,γ)¹⁵O reaction cross section. The present measurements span proton energies
between 0.27 and 1.07 MeV, closing a critical gap in the existing data. A multichannel R-matrix analysis was
performed with the entire new and existing data sets and is used to extrapolate the astrophysical S factors of the
ground state and the 6.79 MeV transition to low energies. The extrapolations are found to be in agreement with
previous work, but find that the discrepancies between measured data and R-matrix fits, both past and present,
still exist. We examine the possible reasons for these discrepancies and thereby provide recommendations for
future studies.

Permalink: https://www.hzdr.de/publications/Publ-35974
Publ.-Id: 35974


Low-energy Cross Section Measurements of ¹²C(p,γ) Deep Underground at LUNA

Skowronski, J.; Boeltzig, A.

The ¹²C(p,γ)¹³N reaction cross section is currently under investigation in the low-background environment of the Laboratory for Underground Nuclear Astrophysics (LUNA). It is being studied using different types of solid targets, and employing two complementary detection techniques: HPGe spectroscopy and activation counting. To reduce systematic uncertainties, targets have been accurately characterized and their degradation under the intense beam of the LUNA-400 accelerator monitored. We present the experimental techniques and the corresponding analyses used to extract the reaction cross section.

  • Open Access Logo Contribution to proceedings
    Nuclear Physics in Astrophysics - X, 04.-09.09.2022, CERN, Switzerland
    EPJ Web of Conferences: EDP Sciences, 2100-014X, 03002
    DOI: 10.1051/epjconf/202327903002

Permalink: https://www.hzdr.de/publications/Publ-35973
Publ.-Id: 35973


Thermal neutron background at Laboratorio Subterráneo de Canfranc (LSC)

Plaza, J.; Martínez, T.; Bécares, V.; Cano-Ott, D.; Villamarín, D.; Pérez De Rada, A.; Mendoza, E.; Pesudo, V.; Santorelli, R.; Peña, C.; Balibrea-Correa, J.; Boeltzig, A.

The thermal neutron background at Laboratorio Subterráneo de Canfranc (LSC) has been determined using several ³He proportional counter detectors. Bare and Cd shielded counters were used in a series of long measurements. Pulse shape discrimination techniques were applied to discriminate between neutron and gamma signals as well as other intrinsic contributions. Montecarlo simulations allowed us to estimate the sensitivity of the detectors and calculate values for the background flux of thermal neutrons inside Hall-A of LSC. The obtained value is (3.5±0.8)×10⁻⁶ n/cm²s, and is within an order of magnitude compared to similar facilities.

Keywords: Underground neutron background; Thermal neutron flux; ³He proportional counter; Pulse shape discrimination

Permalink: https://www.hzdr.de/publications/Publ-35972
Publ.-Id: 35972


Exploring Stars in Underground Laboratories: Challenges and Solutions

Aliotta, M.; Boeltzig, A.; Depalo, R.; Gyürky, G.

For millennia, mankind has been fascinated by the marvel of the starry night sky. Yet, a proper scientific understanding of how stars form, shine, and die is a relatively recent achievement, made possible by the interplay of different disciplines as well as by significant technological, theoretical, and observational progress. We now know that stars are sustained by nuclear fusion reactions and are the furnaces where all chemical elements continue to be forged out of primordial hydrogen and helium. Studying these reactions in terrestrial laboratories presents serious challenges and often requires developing ingenious instrumentation and detection techniques. Here, we reveal how some of the major breakthroughs in our quest to unveil the inner workings of stars have come from the most unexpected of places: deep underground. As we celebrate 30 years of activity at the first underground laboratory for nuclear astrophysics, LUNA, we review some of the key milestones and anticipate future opportunities for further advances both at LUNA and at other underground laboratories worldwide.

Keywords: stellar evolution; nucleosynthesis; nuclear astrophysics experiments; background suppression underground

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Permalink: https://www.hzdr.de/publications/Publ-35971
Publ.-Id: 35971


Data publication: Towards High-Repetition Rate Petawatt Laser Experiments with Cryogenic Jets Using a Mechanical Chopper System

Rehwald, M.; Assenbaum, S.; Bernert, C.; Curry, C. B.; Gauthier, M.; Glenzer, S. H.; Göde, S.; Schoenwaelder, C.; Treffert, F.; Schramm, U.; Zeil, K.

Rohdaten und Ausgewertete Messungen, die in der Publikation dargestellt sind.

Related publications

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Permalink: https://www.hzdr.de/publications/Publ-35970
Publ.-Id: 35970


PIConGPU: Scaling high-fidelity plasma simulations up to exascale compute systems and a view on recent applications

Debus, A.; Steiniger, K.; Bastrakov, S.; Bastrakova, K.; Bussmann, M.; Carstens, F.-O.; Chandrasekaran, S.; Garten, M.; Gruber, B. M.; Hernandez Arreguin, B.; Hübl, A.; Juckeland, G.; Kelling, J.; Lebedev, A.; Leinhauser, M.; Marre, B. E.; Meyer, F.; Ordyna, P.; Pausch, R.; Pöschel, F.; Rogers, D.; Schramm, U.; Sprenger, L.; Starke, S.; Thévenet, M.; Trojok, J.; Wang, M.; Widera, R.; Young, J.

PIConGPU’s latest release 0.6.0 in December 2021 brought a number of new features. Among these are an arbitrary-order Maxwell solver, the Higuera-Cary pusher, collisions, and incident field generation via the total field/scattered field technique enhancing its numerical stability and predictive capabilities.
Furthermore, there are various technical advances, most notably support of the HIP computational backend allowing to run on AMD GPUs. These advances are mainly driven by our participation in OLCF’s Frontier Center for Accelerated Application Readiness providing access to the hardware platform of the Frontier exascale supercomputer scheduled for deployment later this year. We show performance data and present recent applications of PIConGPU profiting from these developments. To these applications belongs the advanced laser-plasma accelerator scheme Traveling-wave electron acceleration (TWEAC), providing scalability to energies beyond 10 GeV while avoiding staging. We further present simulation campaigns modeling and delivering valuable insight into the micrometer and femtosecond plasma dynamics of existing experimental campaigns.

Keywords: PIConGPU; particle-in-cell code; TWEAC; Laser-plasma accelerator

  • Poster
    8. Annual MT meeting, 26.-27.9.2022, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35969
Publ.-Id: 35969


Towards High-Repetition Rate Petawatt Laser Experiments with Cryogenic Jets Using a Mechanical Chopper System

Rehwald, M.; Assenbaum, S.; Bernert, C.; Curry, C. B.; Gauthier, M.; Glenzer, S. H.; Göde, S.; Schoenwaelder, C.; Treffert, F.; Schramm, U.; Zeil, K.

Laser-plasma based ion accelerators require suitable high-repetition rate target systems that enable systematic studies at controlled plasma conditions and application-relevant particle flux. Self-refreshing, micrometer-sized cryogenic jets have proven to be an ideal target platform. Yet, operation of such systems in the harsh environmental conditions of high power laser induced plasma experiments have turned out to be challenging. Here we report on recent experiments deploying a cryogenic hydrogen jet as a source of pure proton beams generated with the PW-class ultrashort pulse laser DRACO. Damage to the jet target system during application of full energy laser shots was prevented by implementation of a mechanical chopper system interrupting the direct line of sight between the laser plasma interaction zone and the jet source.

Related publications

  • Open Access Logo Contribution to proceedings
    13th Int. Particle Acc. Conf. IPAC2022, 12.-17.06.2022, Bangkok, Thailand
    Proceedings of the 13th International Particle Accelerator Conference, Geneva, Switzerland: JACoW Publishing, 978-3-95450-227-1
    DOI: 10.18429/JACoW-IPAC2022-WEIXSP1

Permalink: https://www.hzdr.de/publications/Publ-35968
Publ.-Id: 35968


Supporting Data for PhD Dissertation of Klara Lünser, TU Dresden, 2022

Lünser, K.

This collection belongs to the PhD Dissertation of Klara Lünser with the title "Martensitische Phasenumwandlungen und Zwillingsbildung in epitaktisch gewachsenen Nickel-Titan-Schichten" (Martensitic phase transitions and twinning in epitaxial nickel-titanium thin films). The folder contains raw data of atomic force microscopy, resistivity, in situ scanning electron and pole figure measurements. It also contains the MATLAB code used for calculations of pole figures and inverse pole figures with martensite theories. The file "Probenzuordnung" explains which sample and data was used for which figure in the dissertation. 

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Permalink: https://www.hzdr.de/publications/Publ-35967
Publ.-Id: 35967


Self-evaluation Photon and Neutron RIs for FAIR data certification

Lambert, S.; McBirnie, A.; Matthews, B.; Fiedler, M.; Gagey, B.; Görzig, H.; Knodel, O.; Kourousias, G.; Markvardsen, A.; Minotti, C.; Ounsy, M.; Schön, S.; Soler, N.; Spruce, D.; Vukolov, A.; Collins, S.; Pozsa, K.

This ExPaNDS project deliverable describes a FAIR self-assessment undertaken by the ten
ExPaNDS partner Photon and Neutron Research Infrastructures (PaN RIs) over the
three-month period July – September 2022. After reviewing selected examples of existing
FAIR evaluation frameworks designed to enable assessment at different levels (dataset,
repository, and organisation), the report describes the evaluation approach adopted for the
ExPaNDS FAIR self-assessment. As no existing framework met our specific need to focus
on FAIR workflows and processes in PaN RIs, it was necessary to select, combine, and
adapt existing frameworks. Supported by four underlying guiding principles, our approach
drew heavily on the FAIR Principles, the RDA FAIR Data Maturity Model, and FAIRsFAIR’s
CoreTrustSeal+FAIRenabling framework. Post-evaluation feedback from ExPaNDS partners
indicated that they found the FAIR self-assessment a useful and valuable exercise for
understanding current levels of FAIRness at their facilities and for articulating what
implementations they have in progress or planned to support FAIR in future. A key output of
the ExPaNDS FAIR evaluation is the collected self-assessment reports from the ten partner
facilities. These reports are published openly and in full as part of the deliverable. In addition,
the self-assessments are supplemented with some high-level observations on the state of
the FAIR journey across the ExPaNDS facilities.

Keywords: FAIR; Metadata; ExPaNDS; European Photon and Neutron facilities

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Permalink: https://www.hzdr.de/publications/Publ-35966
Publ.-Id: 35966


Traveling-wave electron accelerators – leveraging exascale computing towards scalable laser-plasma accelerators

Debus, A.; Steiniger, K.; Widera, R.; Bastrakov, S.; Carstens, F.-O.; Meyer, F.; Pausch, R.; Lebedev, A.; Garten, M.; Kluge, T.; Kelling, J.; Hernandez Arreguin, B.; Young, J.; Pöschel, F.; Hübl, A.; Rogers, D.; Juckeland, G.; Chandrasekaran, S.; Bussmann, M.; Schramm, U.

Traveling-wave electron acceleration (TWEAC) is an advanced laser-plasma accelerator scheme, which is neither limited by dephasing, nor by pump depletion or diffraction. Such accelerators are scalable to energies beyond 10 GeV without the need for staging and are candidates for future compact electron-positron colliders based on existing CPA lasers.
Requiring to model a large plasma volume in 3D at high-resolution over an extended acceleration distance for high-fidelity results, TWEAC simulations need exascale compute resources -- even "small" test simulations need hundreds of GPUs.
We present recent progress in TWEAC simulations and various technical advances in the 3D3V particle-in-cell code PIConGPU that enable running on the upcoming Frontier cluster (#1 in TOP500), most notably support of the HIP computational backend allowing to run on AMD GPUs, as well as openPMD, PICMI and algorithmic developments. These advances are mainly driven by our participation in OLCF’s Frontier Center for Accelerated Application Readiness providing access to the hardware platform of the Frontier exascale supercomputer. We show performance data and present recent applications of PIConGPU profiting from these developments.

Keywords: TWEAC; Traveling-wave electron accelerators; laser pulse-front tilt; Laser-plasma accelerator; PIConGPU; particle-in-cell code

  • Poster
    EuroNNAc Special Topic Workshop 2022, 18.-24.09.2022, Isola d'Elba, Italien

Permalink: https://www.hzdr.de/publications/Publ-35965
Publ.-Id: 35965


Ultrafast melting of Warm Dense Cu studied by x-ray spectroscopy

Smid, M.; Köhler, A.; Bowers, B.; Chang, Y.-Y.; Couperus Cabadağ, J. P.; Huang, L.; Kozlová, M.; Kurz, T.; La Berge, M.; Pan, X.; Perez-Martin, P.; Ruiz De Los Panos, I. L.; Schöbel, S.; Vorberger, J.; Zarini, O.; Cowan, T.; Schramm, U.; Irman, A.; Falk, K.

We present novel experimental results of ultra fast heating of Warm Dense Cu diagnosed by means of x-ray absorption and emission spectroscopy carried out at the Draco laser facility at HZDR in 2021. A thin Cu foil was directly heated to few eV temperature by an ultra short laser pulse (40 fs, 2e15 W/cm2) and probed with variable delay in the range 0.2-20 ps by a laser-driven betatron radiation. This betatron radiation, created by a laser wakefield accelerator, is an unique x-ray source with its ultra short duration and broadband spectrum, therefore ideally suited for studies of non-equilibrium dense plasmas while its high brightness allows for single-shot measurement. The sample is studied via the X-ray absorption spectroscopy in the region above the Cu K-edge. This method provides temporally-resolved information about both the ionic structure of the matter and its temperature during the process of ultrafast heating and melting of the material. The measured spectra are understood and analyzed by using Ab initio simulations and the temporal evoution of heatig and melting is compared to PIC simulations to infer the electron to ion energy transer.

  • Lecture (Conference)
    64th Annual Meeting of the APS Division of Plasma Physics, 17.-21.10.2022, Spokane, United States of America

Permalink: https://www.hzdr.de/publications/Publ-35964
Publ.-Id: 35964


High-fidelity particle-in-cell simulations at multiple scales

Debus, A.

The particle-in-cell method is central to providing a kinetic description of the relativstic, nonlinear plasma dynamics -- particularly when interacting with ultrashort laser pulses and particle beams. Its broad applicability ranges from advanced plasma accelerators of electrons or ions, warm dense matter to astrophysics. A major challenge to a better understanding is to integrate disparate spatial and temporal scales, as well as physics into consistent, predictive models that can be compared to experimental results. While the large-scale dynamics is often determined by hydrodynamic evolution, the microscale physics includes ionization, radiation processes from infrared to xrays, atomic physics, as well as QED effects. Interfacing and integrating domain-specific numerical codes, such as particle trackers, FEL codes, requires data standards for seamless data exchange. Based on recent examples from plasma accelerator research using the 3D3V particle-in-cell code PIConGPU, I will outline the state-of-the art and challenges of particle-in-cell simulations to and show current strategies of solving them in large-scale simulations on heterogenous high-performance computing environments.

Keywords: Particle-in-cell; PIConGPU; multi-scale

  • Invited lecture (Conferences)
    Multiscale Modeling of Matter under Extreme Conditions, 11.-16.09.2022, Görlitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35963
Publ.-Id: 35963


Chelator-based non-peptidic radiotracers for PET imaging of PD-L1 with copper-64

Krutzek, F.; Donat, C.; Ullrich, M.; Loureiro, L. R.; Kopka, K.; Stadlbauer, S.

Objective: The programmed cell death-ligand 1 (PD-L1) is upregulated on many different cancers and allows the tumor cells to evade immune response through binding to the PD-1 receptor.[1] Monoclonal antibodies, i.e. checkpoint inhibitors, are able to break this blockade and thus reactivate the immune system.[2] However, only 30% of the patients respond to antibody-based immunotherapy. Because PD-L1 is heterogeneously expressed within and across tumor sites, there is an urgent clinical need for a non-invasive, diagnostic imaging approach helping for therapy decision. Radiotracers for PET and SPECT imaging are able to meet these requirements. Especially small molecules are favourable, because of their short clearance times and for providing high imaging contrast.[3]

Methods: Modification of two literature known small molecule PD-L1 inhibitors with water-solubilizing groups, different linkers and a DOTA chelator resulted in six different radioligands. Labeling was performed with Cu-64 (HZDR, 30 MeV TR-FLEX cyclotron) and binding affinities to PD-L1 were determined in vitro on transduced PC3 cells stably overexpressing human PD-L1. Qualitative PET scans (nanoSCAN PET/CT scanner, Mediso) were performed in NMRI-FoxN1-nude mice bearing PC3-hPD-L1 xenografted tumors.

Results: Organic synthesis started from biaryl building blocks (R1 = H, R2 = Br and R1 = R2 = Me), which underwent a Mitsunobu reaction with the central chloroaryl moiety. The bis(sulfonic acid) group was attached via a sarcosine spacer. Three different linker structures were synthesized and attached by Cu(I)-catalyzed click reaction. Synthesis was finished with DOTA conjugation and subsequent quantitative labeling with Cu-64 under standard labeling conditions was achieved. Using the shake flask method, log(D) values ranging from –1.5 to –2.5 were obtained. Saturation binding assays revealed that biphenyl compounds with R1 = R2 = Me showed promising binding affinities to PD-L1 (KD between 60 and 123 nM). In micro-PET experiments, the radioligands exhibited unusual high circulation times. PET images obtained after 15 h p.i. showed the highest tumor uptake and moderate uptake in the liver.
Conclusion: A library of new PD-L1 targeting non-peptide radiotracers based on small molecule lead structures bearing water-soluble groups and a chelator was successfully synthesized. All compounds showed moderate binding affinities toward PD-L1. Qualitative PET/CT scans showed a moderate uptake in PD-L1 positive tumors. For improved pharmacokinetics the lipophilicity should be further reduced and DOTA replaced by more optimal chelators such as NODAGA to avoid possible copper transchelation in the liver.

References:

[1] M. A. Postow, M. K. Callahan, J. D. Wolchok, J Clin Oncol 2015, 33, 1974-1982.
[2] S. L. Topalian, C. G. Drake, D. M. Pardoll, Cancer cell 2015, 27, 450-461.
[3] S. Chatterjee, W. G. Lesniak, S. Nimmagadda, Mol. Imaging 2017, 16, 1-5.

  • Lecture (Conference)
    International Symposium on Radiopharmaceutical Sciences, 29.05.-02.06.2022, Nantes, France

Permalink: https://www.hzdr.de/publications/Publ-35962
Publ.-Id: 35962


Traveling-wave electron accelerators – towards scalable laser-plasma accelerators beyond 10GeV

Debus, A.; Steiniger, K.; Widera, R.; Bastrakov, S.; Carstens, F.-O.; Meyer, F.; Pausch, R.; Garten, M.; Kluge, T.; Kelling, J.; Hernandez Arreguin, B.; Young, J.; Pöschel, F.; Hübl, A.; Rogers, D.; Juckeland, G.; Chandrasekaran, S.; Bussmann, M.; Schramm, U.

Traveling-wave electron acceleration (TWEAC) is an advanced laser-plasma accelerator scheme, which is neither limited by dephasing, nor by pump depletion or diffraction. Such accelerators are scalable to energies beyond 10 GeV without the need for staging and are candidates for future compact electron-positron colliders based on existing CPA lasers. TWEAC utilizes two pulse-front tilted laser pulses whose propagation directions enclose a configurable angle. The accelerating cavity is created along their overlap region in the plasma and can move at the vacuum speed of light. The oblique laser geometry enables to constantly cycle different laser beam sections through the interaction region, hence providing quasi-stationary conditions of the wakefield driver.

The TWEAC geometry enables to access to a wide range of regimes, which are customizable in cavity geometry, laser-to-electron energy efficiency and the required laser properties at different plasma densities, making the scheme suitable for high-rep rate lasers at low energies per pulse to multi-PW laser facilities. Exploring these regimes in high-fidelity simulations is computationally highly demanding, as these need to include large plasma volumes in 3D at high-resolution over an extended acceleration distance. Since even "small" test simulations need hundreds of GPUs, TWEAC simulations require exascale compute resources.

We present recent progress in TWEAC simulations and various technical advances in the 3D3V particle-in-cell code PIConGPU that enable running on the upcoming Frontier cluster, most notably support of the HIP computational backend allowing to run on AMD GPUs, as well as openPMD, PICMI and algorithmic developments. These advances are mainly driven by our participation in OLCF’s Frontier Center for Accelerated Application Readiness providing access to the hardware platform of the Frontier exascale supercomputer. We show performance data and recent applications of PIConGPU profiting from these developments.

Keywords: Traveling-wave electron acceleration; TWEAC; PIConGPU; Laser-plasma accelerator; Particle-in-cell simulations

  • Lecture (Conference)
    Advanced Accelerator Concepts Workshop 2022, 06.-11.11.2022, Long Island, New York, USA

Permalink: https://www.hzdr.de/publications/Publ-35961
Publ.-Id: 35961


PIConGPU + X – Building blocks for successful Exascale accelerator simulations

Debus, A.; Steiniger, K.; Widera, R.; Bastrakov, S.; Carstens, F.-O.; Meyer, F.; Pausch, R.; Garten, M.; Bernert, C.; Kluge, T.; Willmann, A.; Kelling, J.; Hernandez Arreguin, B.; Young, J.; Pöschel, F.; Hübl, A.; Rogers, D.; Juckeland, G.; Hoffmann, N.; Chandrasekaran, S.; Schramm, U.; Bussmann, M.

Exascale computing is close to becoming a reality. As technology progresses, it has become clear that heterogeneous computing is going to stay and adapting to new hardware is an ongoing challenge. Since 2015 PIConGPU has paved the way to accelerating plasma simulations across compute platforms using the Alpaka framework. This has enabled early adaption to new compute hardware and readiness for Exascale compute capabilities.
However, experience has shown that the real challenges are of a different nature. The first is in detailed analysis of the data produced in simulations. Here, we present our current work on I/O, code coupling, visual analytics and large-scale data analytics.
The second, and more pressing challenge, is comparison to experiment. Here, not only has the increasing quality of experiments put more demand on simulation quality, but more and more the demand for fast, close to real time analysis has grown. This puts high quality simulations to the test, as runs on supercomputers tend to be costly. We present workflows to match experiment and simulations and a future look on how feedback loops between experiment and simulation can be optimized.

Keywords: Particle-in-cell; PIConGPU; exascale; performance portable; synthetic diagnostics

  • Invited lecture (Conferences)
    Advanced Accelerator Concepts Workshop 2022, 06.-11.11.2022, Hyatt Regency, Hauppauge, Long Island, NY, USA

Permalink: https://www.hzdr.de/publications/Publ-35960
Publ.-Id: 35960


Sub-band gap infrared absorption in Si implanted with Mg

Wang, M.; Shaikh, M. S.; Kentsch, U.; Heller, R.; Zhou, S.

Single-crystalline Mg-implanted Si layers are synthesized by ion implantation followed by pulsed laser melting. The Mg doping concentration is reaching 10²¹ cm⁻³. The Raman, Rutherford backscattering spectrometry/channeling and particle induced x-ray emission measurements confirm the recrystallization of the Mg-implanted Si layer. A strong below band gap infrared absorption over the wavelength range of 1.4–6.2 µm (0.2–0.87 eV, in the mid-infrared range) has been observed in the Mg-implanted Si layers. It is associated with deep levels induced by Mg atoms at high implantation level. This work points out the potential of Mg-implanted Si for room-temperature light detection in a broad infrared range for the new generation of Si-based photonics.

Keywords: sub-band gap absorption; ion implantation; infrared photoresponse; deep-level impurity; Mg-implanted

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Permalink: https://www.hzdr.de/publications/Publ-35959
Publ.-Id: 35959


Learning Electron Bunch Distribution along a FEL Beamline by Normalising Flows

Willmann, A.; Couperus Cabadağ, J. P.; Chang, Y.-Y.; Pausch, R.; Ghaith, A.; Debus, A.; Irman, A.; Bussmann, M.; Schramm, U.; Hoffmann, N.

Understanding and control of Laser-driven Free Electron Lasers remain to be difficult problems that require highly intensive experimental and theoretical research. The gap between simulated and experimentally collected data might complicate studies and interpretation of obtained results. In this work we developed a deep learning based surrogate that could help to fill in this gap. We introduce a surrogate model based on normalising flows for conditional phase-space representation of electron clouds in a FEL beamline. Achieved results let us discuss further benefits and limitations in exploitability of the models to gain deeper understanding of fundamental processes within a beamline.

  • Poster
    Machine Learning and the Physical Sciences, 03.12.2022, the New Orleans Convention Center in New Orleans, USA
  • Open Access Logo Contribution to proceedings
    Machine Learning and the Physical Sciences workshop, 03.12.2022, New Orleans, USA

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Permalink: https://www.hzdr.de/publications/Publ-35958
Publ.-Id: 35958


Spectroscopy of XFEL heated Cu and x-ray absorption in laser-produced Warm Dense Cu

Smid, M.

We report on a recent (Feb 2022) experiment on the spectroscopic characterization of XFEL-heated Cu foil targets. The 1-5μm thick Cu foils were irradiated by the tightly focused XFEL beam (~1μm focus, up till 1mJ in energy, European XFEL), heating the target to more then 100 eV, and clearly observing emission from ions up till Cu 25+. Three crystal spectrometers were measuring the emission and scattering in the range ~ 8000 - 9800 eV, i.e. covering the lines of Cu Kα and Kβ, including their ionized satellites. The XFEL photon energy was varied in the range 8.8-9.8 keV. The primary aim is to resolve the continuum lowering by checking the shifts of K edge for various ionizations, in a similar manner as was done earlier on lighter elements. Apart from this, many interesting phenomena can be studied from this extensive dataset, like the double-core hole (hollow ion) emission and its shift, resnonances, XRTS, and even Xanes absorption, by comparing the emission from the front and rear sides of the target. Having those data available in a well characterized system provides a high demand as well as benchmark for precise atomic simulations, and in general leads to a better understanding of Warm Dense Copper on the atomic physics level.

  • Lecture (Conference)
    Radiative Properties of Hot Dense Matter, 14.-18.11.2022, Santa Fe, United States of America

Permalink: https://www.hzdr.de/publications/Publ-35957
Publ.-Id: 35957


Combined Au/Ag nanoparticle creation in ZnO nanopillars by ion implantation for optical response modulation and photocatalysis

Macková, A.; Jagerová, A.; Lalik, O.; Mikšová, R.; Poustka, D.; Mistrík, J.; Holý, V.; Schutter, J. D.; Kentsch, U.; Marvan, P.; Azarov, A.; Galeckas, A.

ZnO nanopillars were implanted with Au-400 keV and Ag-252 keV ions with ion fluences from 1 × 10¹⁵ cm⁻² to 1 × 10¹⁶ cm⁻². We compared ZnO nanopillars solely implanted with Au-ions and dually-implanted with Au and Ag-ions. Rutherford Back-Scattering spectrometry (RBS) confirmed Ag and Au embedded in ZnO nanopillar layers in a reasonable agreement with theoretical calculations. A decreasing thickness of the ZnO nanopillar layer was evidenced with the increasing ion implantation fluences. Spectroscopic Ellipsometry (SE) showed a decrease of refractive index in the nanopillar parts with embedded Au, Ag-ions. XRD discovered vertical domain size decreasing with the proceeding radiation damage accumulated in ZnO nanopillars which effect was preferably ascribed to Au-ions. SE and diffuse reflectance spectroscopy (DRS) showed optical activity of the created nanoparticles at wavelength range 500 – 600 nm and 430 – 700 nm for the Au-implanted and Au, Ag-implanted ZnO nanopillars, respectively. Photoluminescence (PL) features linked to ZnO deep level emission appear substantially enhanced due to plasmonic interaction with metal nanoparticles created by Ag, Au-implantation. Photocatalytic activity seems to be more influenced by the nanoparticles presented in the layer rather than the surface morphology. Dual implantation with Ag, Au-ions enhanced optical activity to a larger extent without significant morphology deterioration as compared to the solely Au-ion implanted nanopillars.

Keywords: ZnO nanopillars; Au/Ag nanoparticles; ion implantation; SPR; doped ZnO nanostructures

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Permalink: https://www.hzdr.de/publications/Publ-35956
Publ.-Id: 35956


Data publication: Energy relaxation and electron-phonon coupling in laser-excited metals

Zhang, J.; Qin, R.; Zhu, W.; Vorberger, J.

DFT data and results for Al and Cu for the DOS, phonon DOS, and Eliashberg function depending on the electron temperature.

Keywords: electron-phonon; DFT; laser; laser-matter interaction; two-temperature model; relaxation; energy transfer

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Permalink: https://www.hzdr.de/publications/Publ-35955
Publ.-Id: 35955


Nonlinear dynamics of Dirac fermions in topological HgTe structures

Uaman Svetikova, T. A.; Pashkin, O.; de Oliveira, T.; Bayer, F.; Berger, C.; Fuerst, L.; Buhmann, H.; Molenkamp, L. W.; Helm, M.; Kiessling, T.; Winnerl, S.; Kovalev, S.; Astakhov, G.

High harmonic generation (HHG) has applications in various fields, including ultrashort pulse measurements, material characterization and imaging microscopy. Strong THz nonlinearity and efficient third harmonic generation (THG) were demonstrated in graphene [1], therefore it is natural to assume the presence of the same effect in other Dirac materials, such as topological insulators (TI). Topological states can be found in HgTe quantum wells with a thickness of more than 6.3 nm [2], and strained 3D Hg1-xCdxTe thin films with cadmium fraction x < 0.16 [3].
We used a series of HgTe samples corresponding to three qualitatively different cases: 2D trivial and topological structures and 3D topological insulators. By using moderate THz fields, the presence of highly efficient THG was measured in these samples at different temperatures and THz powers. This provides insight into physical mechanisms leading to THG in TIs. For in-depth understanding of Dirac fermions dynamics and dominating scattering mechanisms in HgTe TI, we conducted THz pump-probe experiments that reveal several relaxation time scales.

[1] Hafez, H. A. et al., Nature 561, 507 (2018).
[2] Bernevig, B. et al. Science 314, 5806 (2006): 1757-1761.
[3] Brüne, C., et al. Phys. Rev. Lett. 106, 12 (2011): 126803.

Keywords: topological insulators; HgTe; nonlinear dynamics

  • Lecture (Conference)
    3rd QMA retreat, 12.-14.10.2022, Friedrichroda, Deutschland
  • Poster
    DPG Meeting of the Condensed Matter Section (SKM): Regensburg 2022, 04.-09.09.2022, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35954
Publ.-Id: 35954


Nonlinear parameters of Dirac fermions in HgTe structures: trivial and topological

Uaman Svetikova, T. A.; Pashkin, O.; de Oliveira, T.; Bayer, F.; Berger, C.; Fuerst, L.; Buhmann, H.; Molenkamp, L. W.; Helm, M.; Kiessling, T.; Winnerl, S.; Kovalev, S.; Astakhov, G.

High harmonic generation (HHG) has applications in various fields, including ultrashort pulse measurements, material characterization and imaging microscopy. Strong THz nonlinearity and efficient third harmonic generation (THG) were demonstrated in graphene [1], therefore it is natural to assume the presence of the same effect in other Dirac materials, such as topological insulators (TI) [2,3]. Topological states can be found in HgTe quantum wells with a thickness of more than 6.3 nm [4], and strained 3D Hg1-xCdxTe thin films with cadmium fraction x < 0.16 [5]. We used a series of HgTe samples corresponding to three qualitatively different cases: 2D trivial and topological structures and 3D topological insulators. By using moderate THz fields, the presence of highly efficient THG was measured in these samples at different temperatures and THz powers. This provides insight into physical mechanisms leading to THG in TIs. For in-depth understanding of Dirac fermions dynamics and dominating scattering mechanisms in HgTe TI, we
conducted THz pump-probe experiments that reveal several relaxation time scales.

[1] Hafez, H. A. et al., Nature 561, 507 (2018).
[2] Kovalev, S. et al. Quantum Materials 6.1 (2021): 1-6.
[3] Giorgianni, F. et al. Nature Сommunications 7.1 (2016): 1-6.
[4] Bernevig, B. et al. Science 314, 5806 (2006): 1757-1761.
[5] Brüne, C. et al. Phys. Rev. Lett. 106, 12 (2011): 126803.

  • Poster
    International conference on Complexity and Topology in Quantum Matter, 25.-29.07.2022, Würzburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35953
Publ.-Id: 35953


Data publication: Characterization of laser wakefield acceleration efficiency with octave spanning near-IR spectrum measurements

Streeter, M. J. V.; Ma, Y.; Kettle, B.; Dann, S. J. D.; Gerstmayr, E.; Albert, F.; Bourgeois, N.; Cipiccia, S.; Cole, J. M.; Gallardo González, I.; Hussein, A. E.; Jaroszynski, D. A.; Falk, K.; Krushelnick, K.; Lemos, N.; Lopes, N. C.; Lumsdon, C.; Lundh, O.; Mangles, S. P. D.; Najmudin, Z.; Rajeev, P. P.; Sandberg, R.; Shahzad, M.; Smid, M.; Spesyvtsev, R.; Symes, D. R.; Vieux, G.; Thomas, A. G. R.

10.5281/zenodo.7188057

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  • Reseach data in external data repository
    Publication year 2022
    License: Creative Commons Attribution 4.0 International
    Hosted on https://zenodo.org/record/7188057: Link to location
    DOI: 10.5281/zenodo.7188057

Permalink: https://www.hzdr.de/publications/Publ-35952
Publ.-Id: 35952


Characterization of laser wakefield acceleration efficiency with octave spanning near-IR spectrum measurements

Streeter, M. J. V.; Ma, Y.; Kettle, B.; Dann, S. J. D.; Gerstmayr, E.; Albert, F.; Bourgeois, N.; Cipiccia, S.; Cole, J. M.; Gallardo González, I.; Hussein, A. E.; Jaroszynski, D. A.; Falk, K.; Krushelnick, K.; Lemos, N.; Lopes, N. C.; Lumsdon, C.; Lundh, O.; Mangles, S. P. D.; Najmudin, Z.; Rajeev, P. P.; Sandberg, R.; Shahzad, M.; Smid, M.; Spesyvtsev, R.; Symes, D. R.; Vieux, G.; Thomas, A. G. R.

We report on experimental measurements of energy transfer efficiencies in a GeV-class laser wakefield accelerator. Both the transfer of energy from the laser to the plasma wakefield and from the plasma to the accelerated electron beam was diagnosed by simultaneous measurement of the deceleration of laser photons and the acceleration of electrons as a function of plasma length. The extraction efficiency, which we define as the ratio of the energy gained by the electron beam to the energy lost by the self-guided laser mode, was maximized at 19±3% by tuning the plasma density and length. The additional information provided by the octave-spanning laser spectrum measurement allows for independent optimization of the plasma efficiency terms, which is required for the key goal of improving the overall efficiency of laser wakefield accelerators.

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Permalink: https://www.hzdr.de/publications/Publ-35951
Publ.-Id: 35951


Deterministic multi-level spin orbit torque switching using focused He+ ion beam irradiation

Kurian, J.; Joseph, A.; Cherifi-Hertel, S.; Fowley, C.; Hlawacek, G.; Dunne, P.; Romeo, M.; Atcheson, G.; Coey, J. M. D.; Doudin, B.

He+ ion irradiation is used to pattern multiple areas of Pt/Co/W films with different irradiation doses in Hall bars. The resulting perpendicular magnetic anisotropy landscape enables selective multilevel currentinduced switching, with full deterministic control of the position and order of the individual switching elements. Key pattern design parameters are specified, opening a way to scalable multilevel switching devices.

Keywords: spintronics; spin orbit torque switching; nanomagnetism; ion beam irradiation; Hall bars

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Permalink: https://www.hzdr.de/publications/Publ-35950
Publ.-Id: 35950


Material requirements and choices for non destructive pulsed magnets

Zherlitsyn, S.

Es hat kein Abstrakt vorgelegen

  • Invited lecture (Conferences)
    2022 MRS fall meeting & exhibit, 27.11.-02.12.2022, Boston, USA

Permalink: https://www.hzdr.de/publications/Publ-35949
Publ.-Id: 35949


Data publication: Intrinsic energy flow in laser-excited 3d ferromagnets

Zahn, D.; Jakobs, F.; Seiler, H.; Butcher, T. A.; Engel, D.; Vorberger, J.; Atxitia, U.; William Windsor, Y.; Ernstorfer, R.

DFT data concerning the electronic structure and electron-phonon coupling of Co and Fe. NOT the atomistic spin simulations. NO experimental data.

Keywords: ferromagnet; iron; cobalt; lattice; spin; relaxation

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Permalink: https://www.hzdr.de/publications/Publ-35948
Publ.-Id: 35948


Data publication: Electron-ion temperature relaxation in warm dense hydrogen observed with picosecond resolved X-ray scattering

Fletcher, L. B.; Vorberger, J.; Schumaker, W.; Ruyer, C.; Goede, S.; Galtier, E.; Zastrau, U.; Alves, E. P.; Baalrud, S. D.; Baggott, R. A.; Barbrel, B.; Chen, Z.; Döppner, T.; Gauthier, M.; Granados, E.; Kim, J. B.; Kraus, D.; Lee, H. J.; Macdonald, M. J.; Mishra, R.; Pelka, A.; Ravasio, A.; Roedel, C.; Fry, A. R.; Redmer, R.; Fiuza, F.; Gericke, D. O.; Glenzer, S. H.

DFT-MD and HNC data for cryogenic hydrogen and for two-temperature hydrogen

Keywords: warm dense matter; x-ray scattering; relaxation; femtosecond; hydrogen jet

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Permalink: https://www.hzdr.de/publications/Publ-35947
Publ.-Id: 35947


Analyzing the filamentation of MeV-range proton bunches in a laser-driven ion beamline and optimizing their peak intensity

Metternich, M.; Nazary, H.; Schumacher, D.; Brabetz, C.; Kroll, F.; Brack, F.-E.; Ehret, M.; Blažević, A.; Schramm, U.; Bagnoud, V.; Roth, M.

In this article, we report on the latest investigations and achievements in proton beam shaping with our laser-driven ion beamline at GSI Helmholtzzentrum für Schwerionenforschung GmbH. This beamline was realized within the framework of the Laser Ion Generation, Handling, and Transport (LIGHT) collaboration to study the combination of laser-driven ion beams with conventional accelerator components. At its current state, the ions are accelerated by the high-power laser PHELIX via target normal sheath acceleration, and two pulsed high-magnetic solenoids are used for energy selection, transport, and transverse focusing. In between the two solenoids, there is a rf cavity that gives the LIGHT beamline the capability to longitudinally manipulate and temporally compress ion bunches to sub-nanosecond durations. To get optimal results, the rf cavity has to be synchronized with the PHELIX laser and therefore a reliable measurement of the temporal ion beam profile is necessary. In the past, these measurements showed unexpected correlations between the temporal beam profile and the phase as well as the electric field strength of the cavity. In this article, we present a numerical simulation of the beam transport through the LIGHT beamline which explains this behavior by a beam filamentation. We also report on our latest experimental campaigns, in which we combined transverse and longitudinal focusing for the first time. This led to proton bunches with a peak intensity of (3.28±0.24)×108 protons/(ns mm2) at a central energy of (7.72±0.14) MeV. The intensity refers to a circle with a diameter of (1.38±0.02) mm that encloses 50% of the protons in the focal spot at the end of the beamline. The temporal bunch width at this position was (742±40) ps (FWHM).

Keywords: Laser acceleration; TNSA; Proton beam; beamline

Permalink: https://www.hzdr.de/publications/Publ-35946
Publ.-Id: 35946


Investigation of the ¹⁰B(p,α)⁷Be reaction from 0.8 to 2.0 MeV

Vande Kolk, B.; Macon, K. T.; Deboer, R. J.; Anderson, T.; Boeltzig, A.; Brandenburg, K.; Brune, C. R.; Chen, Y.; Clark, A. M.; Danley, T.; Frentz, B.; Giri, R.; Görres, J.; Hall, M.; Henderson, S. L.; Holmbeck, E.; Howard, K. B.; Jacobs, D.; Lai, J.; Liu, Q.; Long, J.; Manukyan, K.; Massey, T.; Moran, M.; Morales, L.; Odell, D.; O'Malley, P.; Paneru, S. N.; Richard, A.; Schneider, D.; Skulski, M.; Sensharma, N.; Seymour, C.; Seymour, G.; Soltesz, D.; Strauss, S.; Voinov, A.; Wüstrich, L.; Wiescher, M.

Background: A multitude of broad interfering resonances characterize the ¹⁰B(p,α)⁷Be cross section at low energies. The complexity of the reaction mechanism, as well as conflicting experimental measurements, have so far prevented a reliable prediction of the cross section over the energy ranges pertinent for a boron-proton fusion reactor environment.

Purpose: To improve the evaluated cross section of the ¹⁰B(p,α)⁷Be reaction, this study targets the proton energy region from 0.8 to 2.0 MeV, where kinematic overlap of the scattered protons and reaction α particles have made past measurements very challenging.

Method: New detailed studies of the reaction have been performed at the Edwards Accelerator Laboratory at Ohio University and the Nuclear Science Laboratory at the University of Notre Dame using time-of-flight and degrader foil techniques, respectively.

Results: Proton and α-particle signals were clearly resolved using both techniques, and 16 point differential cross sections were measured over an angular range of θlab=45° and 157.5°. A comprehensive R-matrix analysis of the experimental data, including data from previous low-energy studies of the ¹⁰B(p,α)⁷Be, ¹⁰B(p,p)¹⁰B, and ¹⁰B(p,γ)¹¹C reactions, was achieved over the region of measurement. Using a representative set of previous data, the fit was extended to very low energies.

Conclusions: On the basis of this data and R-matrix analysis, a more reliable and consistent description of the ¹⁰B(p,α)⁷Be cross section has been established. The uncertainty over the energy range of this study has been reduced from ≈20% to ≈10%, and the level structure over this region has been clarified considerably.

Permalink: https://www.hzdr.de/publications/Publ-35943
Publ.-Id: 35943


Mineralogy and microfabric as foundation for a new particle-based modelling approach for industrial mineral separation

Pereira, L.

\chapter*{Abstract}
The raw materials sector is one of the most important building blocks in the transition to a renewables-based energy system. This is because, as opposed to the current energy system, which relies mainly on fossil fuels, the new system will require a considerable amount of mineral raw materials to construct the devices required for energy production (e.g., solar panels, wild mills, etc.). Despite efforts to boost secondary metal production via recycling in a circular economy framework, substantial volumes of minerals and metals will still need to be added from the geo- to the anthroposphere within the context of the energy transition. This primary investment is inevitable before recycling-based raw material production can satisfy demand. Therefore, mining will remain indispensable for the foreseeable future.

For millennia, our society has been exploring and exploiting mineral deposits. Consequently, most of the easily exploitable high-grade deposits, which were of primary interest given their obvious technical and economic advantages, have already been depleted. For the future, the mining sector will have to efficiently produce metals and minerals from low-grade orebodies with complex mineralogical and microstructural properties -- these are generally referred to as complex orebodies. The exploitation of such complex orebodies carries significant technical risks. However, these risks may be reduced by applying modelling tools that are reliable and robust.

In a broad sense, modelling techniques are already applied to estimate the resources and reserves contained in a deposit, and to evaluate the potential recovery (i.e., behaviour in comminution and separation processes) of these materials. This thesis focusses on the modelling of recovery processes, more specifically mineral separation processes, suited to complex ores.

Despite recent developments in the fields of process mineralogy and geometallurgy, current mineral separation modelling methods do not fully incorporate the available information on ore complexity. While it is well known that the mineralogical and microstructural properties of individual particles control their process behaviour, currently widely applied modelling methods consider only distributions of bulk particle properties, which oftentimes require much simplification of the particle data available. Moreover, many of the methods used in industrial plant design and process modelling are based on the chemical composition of the samples, which is only a proxy for the mineralogical composition of the ores.

A modelling method for mineral separation processes suited to complex ores should be particle-based, taking into consideration all quantifiable particle properties, and capable of estimating uncertainties. Moreover, to achieve a method generalizable to diverse mineral separation units (e.g., magnetic separation or flotation) with minimal human bias, strategies to independently weight the importance of different particle properties for the process(es) under investigation should be incorporated.

This dissertation introduces a novel particle-based separation modelling method which fulfills these requirements. The core of the method consists of a least absolute shrinkage and selection operator-regularized (multinomial) logistic regression model trained with a balanced particle dataset. The required particle data are collected with scanning electron microscopy-based automated mineralogy systems. Ultimately, the method can quantify the recovery probability of individual particles, with minimal human input, considering the joint influence of particle shape, size, and modal and surface compositions, for any separation process.

Three different case studies were modelled successfully using this new method, without the need for case-specific modifications: 1) the industrial recovery of pyrochlore from a carbonatite deposit with three froth flotation and one magnetic separation units, 2) the laboratory-scale magnetic separation of a complex skarn ore, and 3) the laboratory-scale separation of apatite from a sedimentary ore rich in carbonate minerals by flotation. Moreover, the generalization potential of the method was tested by predicting the process outcome of samples which had not been used in the model training phase, but came from the same geometallurgical domain of a specific ore deposit. In each of these cases, the method obtained high predictive accuracy.

In addition to its predictive power, the new particle-based separation modelling method provides detailed insights into the influence of specific particle properties on processing behaviour. To name a couple, the influence of size on the recovery of different carbonate minerals by flotation in an industrial operation; and a comparison to traditional methodologies demonstrated the limitation of only considering particle liberation in process mineralogy studies -- the associated minerals should be evaluated, too. Finally, the potential application of the method to minimize the volume of test work required in metallurgical tests was showcased with a complex ore.

The approach developed here provides a foundation for future developments, which can be used to optimize mineral separation processes based on particle properties. The opportunity exists to develop a similar approach to model the comminution of single particles and ultimately allow for the full prediction of the recovery potential of complex ores.

Keywords: Geometallurgy; particle-based separation model; minerals processing

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Permalink: https://www.hzdr.de/publications/Publ-35942
Publ.-Id: 35942


On the impact of grinding conditions in the flotation of semi-soluble salt-type mineral-containing ores – driven by surface or particle geometry effects?

Pereira, L.; Kupka, N.; Hoang, D. H.; Michaux, B.; Saquran, S. S. S.; Ebert, D.; Rudolph, M.

Grinding and flotation operations are often studied independently, despite the well-established grinding influence on flotation performance. At most, this influence is studied with microflotation of pure minerals, which hinders a thorough evaluation of the problem. Here, we study the relation between grinding condition and flotation without material simplification. Clearlier, we assess if variations in flotation performance after distinct grinding environments are driven by particle size and shape or by variations in pulp properties. Three ores were studied: scheelite, apatite, and fluorite. These were dry-, wet-, and wet conditioned-ground before flotation in a laboratory mechanical cell. Results were evaluated with bulk- and particle-specific methodologies. For each grinding environment, variations in flotation performance (e.g., apatite and scheelite particles float faster after dry and wet conditioned-grinding, respectively) and selectivity (e.g., higher after dry grinding for the fluorite and apatite ores and irrelevant for the scheelite ore) were quantified. Yet, the impact of particle shape is system specific, i.e. entrainment increases for rounder particles in the apatite and scheelite ores while true flotation is higher for these particles in the fluorite ore. We conclude that the selectivity of these semi-soluble salt-type mineral systems is driven by pulp chemistry variations caused by distinct grinding environments.

Keywords: grinding-flotation interactions; semi-soluble salt-type minerals; geometallurgy; particle-based modelling; surface interactions

Permalink: https://www.hzdr.de/publications/Publ-35941
Publ.-Id: 35941


ELBE: An Accelerator Driven Radiation Source at its Best

Klopf, J. M.; Arnold, A.; Evtushenko, P.; Freitag, M.; Justus, M.; Kösterke, I.; Kuntzsch, M.; Lehnert, U.; Ryzhov, A.; Schamlott, A.; Schneider, C.; Schurig, R.; Schwarz, A.; Steinbrück, R.; Xiang, R.; Zenker, K.; Michel, P.

The heart of the ELBE Center for High Power Radiation Sources is a superconducting RF (SRF) linac, which accelerates electrons up to 35 MeV for driving a diverse set of secondary radiation sources. The ELBE linac is particularly unique in the capability of accelerating a continuous beam of ultrashort bunches of electrons at very high repetition rates (up to 26 MHz). This extremely high-power electron beam is selectively directed into specially designed beamlines to drive secondary radiation sources for THz/IR photons (FELBE and TELBE), positrons (pELBE), neutrons (nELBE), and gamma radiation (ELBE), each with dedicated laboratories and instrumentation. Users from all over the world utilize the advanced radiation sources at ELBE for a wide array of both fundamental and applied studies of matter, health, energy, and technology.
The ELBE accelerator was first commissioned in 2001 in the form of a grid-pulsed 250 kV thermionic gun followed by two stages of RF bunching to inject beam into a linac comprised of two SRF cryomodules, each containing two 9-cell DESY TTF-type niobium accelerating cavities. Through continuous development and research, the ELBE facility has achieved many major advancements in accelerator technology, the most important being the ELBE SRF Gun program, which has designed, built, and commissioned several prototype SRF electron guns for high bunch charge, high average current, and low emittance. The ELBE SRF Gun-II is the first and only electron source of its type to deliver electron beam to a user experiment, and is now in routine operation for the TELBE and pELBE beamlines.
An overview of the performance parameters of the ELBE accelerator and secondary sources will be presented in this talk along with a summary of the experimental capabilities available to users. Highlights of recent user results will also be presented to help illustrate the great potential ELBE provides for a diverse scientific community. Beamtime proposals are accepted and reviewed by an external scientific advisory committee twice per year.
https://www.hzdr.de/db/Cms?pNid=1732

Keywords: linac; SRF; electron accelerator; FEL; THz; positrons; neutrons; gamma radiation

Related publications

  • Invited lecture (Conferences)
    UWr – CASUS – HZDR International Conference on Advanced Systems Research, 11.-15.07.2022, Hotel Wyndham Wrocław Old Town, Poland

Permalink: https://www.hzdr.de/publications/Publ-35940
Publ.-Id: 35940


Underground Measurements of Nuclear Reaction Cross-Sections Relevant to AGB Stars

Ananna, C.; Barile, F.; Boeltzig, A.; Giulio Bruno, C.; Cavanna, F.; Francesco Ciani, G.; Compagnucci, A.; Csedreki, L.; Depalo, R.; Ferraro, F.; Masha, E.; Piatti, D.; Rapagnani, D.; Skowronski, J.

Nuclear reaction cross sections are essential ingredients to predict the evolution of AGB stars and understand their impact on the chemical evolution of our Galaxy. Unfortunately, the cross sections of the reactions involved are often very small and challenging to measure in laboratories on Earth. In this context, major steps forward were made with the advent of underground nuclear astrophysics, pioneered by the Laboratory for Underground Nuclear Astrophysics (LUNA). The present paper reviews the contribution of LUNA to our understanding of the evolution of AGB stars and related nucleosynthesis.

Keywords: Underground Nuclear Astrophysics; Stellar Evolution; Stellar Nucleosynthesis

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Permalink: https://www.hzdr.de/publications/Publ-35939
Publ.-Id: 35939


Applying particle-based separation modelling on 3D particle data to better quantify the influence of particle size and shape in flotation

Guimaraes Da Silva Tochtrop, C.; Pereira, L.; Da Assuncao Godinho, J. R.; Gupta, S.; Liipo, J.; Boone, M.; Rudolph, M.

X-Ray computed tomography (XRCT) enables the 3D characterization of particulate materials with a better description of their micro-structural and geometric properties. Recent developments permit quantifying accurately the composition of the particulate material in 3D. Particle-based separation modelling methods have driven significant studies relating microstructural properties with particle process behaviour. Yet, these methods have never been fed with the more complete 3D XRCT particle data. We address this gap in this work.
We use as a case study the flotation of a sulphide-rich ore, where we quantify the relation between the flotation kinetics of individual particles, their microstructural properties and two flotation cell hydrodynamic parameters: rotational speed and air flow rate. Given the meticulous description of particle geometric properties provided by XRCT, we obtained a more precise evaluation of the influence of particle shape in its recovery. This methodology is also applicable to other ores and mineral separation units.

Keywords: Geometallurgy; particle-based separation model; 3D particle characterization

  • Contribution to proceedings
    Process Mineralogy, 01.-04.11.2022, Sitges, Spain
    Process Mineralogy '22

Permalink: https://www.hzdr.de/publications/Publ-35938
Publ.-Id: 35938


The Future of 3D Characterization

Pereira, L.; Da Assuncao Godinho, J. R.; Boone, M.; Heron, M.

The partners of the EIT Raw Materials funded project 2D3Dscopy kindly invite you to "The Future of 3D Characterization" prior to the 2022 MEI conference in Process Mineralogy in November. The workshop will provide you with insides into the latest developments in 3D particle characterization and particle-based process optimization.

Keywords: Geometallurgy; particle-based separation model; 3D particle characterization

  • Lecture (Conference)
    Process Mineralogy, 01.-04.11.2022, Sitges, Spain

Permalink: https://www.hzdr.de/publications/Publ-35937
Publ.-Id: 35937


The FELBE THz/IR FEL: Overview of the Facility and User Activities

Klopf, J. M.; Evtushenko, P.; Helm, M.; Kehr, S. C.; Lehnert, U.; Michel, P.; Pashkin, O.; Winnerl, S.; Zvyagin, S.

The FELBE User Facility at the ELBE Center for High-Power Radiation Sources offers a pair of FELs that deliver beam to eight different user labs. The FELs are driven by a two-stage Superconducting RF (SRF) linac, which produces a quasi-CW beam (13 MHz/1 mA) at an energy of up to 36 MeV. The tuning range spanned by the two FELs extends from the mid IR to THz (5 – 250 m). The spectral range and ultrashort pulse width (p ≈ 0.7 – 25 ps) are ideal for time-resolved measurements of many types of transient processes in low-dimensional materials [1], quantum structures [2], and correlated systems [3]. The high pulse energy can also drive nonlinear phenomena [4] and strong coupling [5] in light-matter interactions. The FELBE User Labs are equipped with instrumentation and synchronized ultrashort table-top lasers (i.e. Ti:Sa oscillators, regens, OPAs, SFG/DFG) which facilitate various classes of degenerate (single-color), and non-degenerate (two-color) pump-probe experiments. Optical cryostats and an 8 T split coil magnet are also available for low temperature and magnetic field dependent studies. Furthermore, the FELBE beamline extends into the adjacent High Field Magnet Lab (HLD) for performing magneto-optical spectroscopy measurements at fields up to 70 T [6]. The high repetition rate and tunability of the FELBE beam has uniquely enabled revolutionary methods in scattering-Scanning Nearfield Optical Microscopy (s­SNOM) to image novel light-matter interactions with resolution far below the diffraction limit [7]. Proposals for beamtime on FELBE and the other secondary sources at ELBE are invited from users twice a year.
(https://www.hzdr.de/FELBE).

[1] T. Venanzi, et al., ACS Photonics 8, 2931-2939 (2021).
[2] J. Schmidt, et al., Optics Express 28, 25358-25370 (2020).
[3] M. M. Jadidi, et al., Phys. Rev. B 102, 245123 (2020).
[4] F. Meng, et al., Phys. Rev. B 102, 075205 (2020).
[5] B. Piętka, et al., Phys. Rev. Lett. 119, 077403 (2017).
[6] M. Ozerov, et al., Phys. Rev. Lett. 113, 157205 (2014).
[7] T. V. A. G. de Oliveira, et al., Adv. Mater. 33, 2005777 (2021).

Keywords: THz; FEL; ultrafast dynamics; correlated systems; low-dimmensional materials; quantum structures; nanoscale

Related publications

  • Invited lecture (Conferences)
    TERFEL : International Conference on Free Electrons Laser Applications in Infrared and THz Studies of New States of Matter, 05.-08.07.2022, Novotel Warszawa Centrum, Poland

Permalink: https://www.hzdr.de/publications/Publ-35936
Publ.-Id: 35936


Predictive Geometallurgy - SGA Shortcourse

Tolosana Delgado, R.; Pereira, L.; Frenzel, M.; Da Assuncao Godinho, J. R.; Birtel, S.; de Boever, W.; Dosbaba, M.; Taylor, R.; Gutzmer, J.

Geometallurgy aims to optimise the mineral value chain based on a spatially resolved, precise and quantitative understanding of the geology and mineralogy of the ores. Predictive geometallurgy goes beyond this by introducing forecasting models for ore behaviour, and taking into account operational economics and global mineral markets. The course is divided into two main blocks: First, introductory presentations on advanced material characterization as well as current principles and applications of geometallurgy are pre-recorded, and can be watched independently by the audience.
The second part of the course will consist of a live interactive session with time to discuss questions on the talks with the presenters. Its major goal is to enforce the concepts developed in the first part of the course through hands-on exercises using web-based apps. This will allow participants to get a good feel for the data types common in geometallurgical programmes, and how they can be integrated into a geometallurgical model to be used in mine planning, scheduling and mine optimisation.

Keywords: Geometallurgy; 3D particle characterization; geostatistics; particle-based separation modelling

  • Lecture (Conference) (Online presentation)
    SGA Biennial meeting, 26.-31.03.2022, Rotorua, New Zealand

Permalink: https://www.hzdr.de/publications/Publ-35935
Publ.-Id: 35935


LUNA (Laboratory for Underground Nuclear Astrophysics): A Long Success Story with New Goals in Sight

Imbriani, G.; Junker, M.; Boeltzig, A.; Ciani, G. F.; Piatti, D.

no abstract available

Keywords: LUNA; Nuclear Astrophysics; Underground; Ion Beam Accelerator; Nuclear Cross Section Measurements; Low-Background; Gran Sasso National Laboratory (LNGS)

Related publications

Permalink: https://www.hzdr.de/publications/Publ-35934
Publ.-Id: 35934


Particle-based modelling applied to understand the influence of comminution environment on the flotation of semi-soluble salt type minerals

Pereira, L.; Kupka, N.; Hoang, D. H.; Michaux, B.; Saquran, S. S. S.; Ebert, D.; Rudolph, M.

Semi-soluble salt type minerals (SSSM) are important industrial minerals as well as common gangue minerals in diverse metal deposits. Being able to understand and improve the process behaviour of these minerals is thus of high relevance for many parts of the raw materials value chain. The surface properties as well as the interactions of these minerals with the fluid media grant them a distinguishable behaviour in flotation. In this study, we investigate the influence of particle geometric properties (size and shape) caused by distinct comminution environments (dry, wet, and wet with reagents) on the process behaviour of three ore types containing SSSM: an apatite, a fluorite, and a scheelite ore. A particle-based separation modelling method was applied to quantify the flotation kinetics of individual particles according to all tangible properties quantifiable with automated mineralogy (modal and surface composition, size, and shape). Our approach, which requires minimal human-input, captured well-documented flotation behaviours related to particle size (e.g., the Rmax of minerals recovered via entrainment is generally higher for the fine size fraction). In regards to particle shape, it clearly influences the flotation behaviour of particles. Yet, even in a controlled study such as we have performed here, the relation between mineral type, grinding environment, and flotation performance is very convoluted and no general conclusion can be drawn. This challenge in evaluating the influence of particle shape in flotation can explain the high number of controversial studies regarding the topic.

Keywords: Geometallurgy; Comminution; Semi-soluble salt-type minerals; flotation; particle-based separation modelling

  • Contribution to proceedings
    Procemin Geomet 2022, 05.-07.10.2022, Santiago, Chile
    18th International Conference on Mineral Processing and Geometallurgy

Permalink: https://www.hzdr.de/publications/Publ-35933
Publ.-Id: 35933


Using particle-based separation models to evaluate the selectivity of different collectors in chalcopyrite flotation

Pereira, L.; Schach, E.; Frenzel, M.; Tolosana Delgado, R.; Rudolph, M.; Gutzmer, J.

Particle-based separation models are a powerful tool for modelling and understanding mineral separation processes at the level of single particles. Latest developments in this field have enabled the incorporation of complete particle datasets from image-analysis based techniques, thus allowing for the full integration of material complexity into process models. So far, these models have mostly been applied to static processes, without variations in operating conditions. In this contribution, we used particle-based separation models to understand variations in the flotation behavior of a fine-grained and low-grade chalcopyrite-dominated copper ore using different collectors: PAX and kerosene. This approach highlights the influence of particle size and shape on the flotation of chalcopyrite-bearing particles. Moreover, it demonstrates that detailed information on mineral associations is critical to achieve a full description of the process behavior of single particles. Full association data should therefore be used instead of simplified ore mineral liberation data whenever possible. Finally, results indicate that higher selectivity against pyrite can be achieved when kerosene is used as a collector instead of PAX. In addition, ideas for improving separation (e.g., higher grade and recovery) are discussed based on detailed particle information.

Keywords: Geometallurgy; particle-based separation model; chalcopyrite; pyrite; kerosene; pax; flotation

  • Contribution to proceedings
    Copper International Conference 2022, 13.-17.11.2022, Santiago, Chile
    Volume 10: Geometallurgy

Permalink: https://www.hzdr.de/publications/Publ-35932
Publ.-Id: 35932


Effects of surfactant on lift coefficient of ellipsoidal bubbles in the viscous-force dominant regime

Chen, J.; Hayashi, K.; Legendre, D.; Lucas, D.; Tomiyama, A.

Effects of surfactants on lift coefficients, CL, of single ellipsoidal bubbles rising through linear shear flows were investigated. Two types of surface-active agents, i.e. Triton X-100 and 1-octanol, were used. The liquid properties except for the surface tension were identical to those in a clean system of logM = -5.5, where M is the Morton number. The range of the bubble Reynolds number was 0.1 < Re < 70. Bubble shapes were either spherical or ellipsoidal. Comparing with clean bubbles, less deformation of contaminated bubbles was confirmed due to the fact that surfactant tends to accumulate on the bubble interface, making it behave like solid particles. A shape correlation without taking the dimensionless shear rate into account gave good evaluations of the bubble aspect ratio, which means that the shear rate is not a dominant factor causing the change of shape deformation. However, drag coefficients were affected by the shear rate. Making use of a correlation for bubbles in stagnant liquid, a new correlation of drag coefficients was deduced, which agreed well with the experimental data. Both clean and contaminated CL data showed similar tendency, i.e. after a drastic decrease to a local minimum, CL value slightly increases with increasing the bubble Reynolds number, Re, and then gradually decreases to negative values. A difference in concentration of Trion X-100 resulted in only a slight change in CL at high Re regime. Different types of surfactant resulted in noticeably different values of CL especially at low Re. The CL of small spherical bubbles in contaminated systems could be reproduced by a correlation for solid particles, supporting that fully-contaminated spherical bubbles behave like solid spheres. For deformed bubbles, the lift coefficients can be expressed by relating the negative lift force due to shape deformation with the drag force.

Keywords: Bubble; Aspect ratio; Surfactant; Lift coeffcient

Permalink: https://www.hzdr.de/publications/Publ-35931
Publ.-Id: 35931


Bioleaching of mine tailings using acidophilic bacteria and organic acids

Kaufer, T.; Kutschke, S.; Pollmann, K.

Fine-grained tailings from ore processing represent a considerable raw material potential and could be used in the cement industry, as base and surface sealing material for landfills or for dam construction. Those mine tailings are mostly deposited wet in so-called tailings ponds. Storage involves a certain environmental risk, for example mobilization of heavy metals and dam failures with catastrophic consequences. To prevent such environmental disasters in the future and to make these raw materials reusable again, a remediation concept for tailings ponds is therefore necessary. Bioleaching is to be used to modify the composition of the material to meet certain guidelines for its use in the construction industry. For this purpose, various acidophilic bacteria such as Sulfobacillus acidophilus DSM 10332, Leptospirillum ferrooxidans DSM 2705 and other acidophilic consortia were tested. In addition, the yeast Yarrowia lipolytica DSM 3286 was cultivated for the production of citric acid and the bacterium Bacillus licheniformis DSM 13 was cultivated for the production of γ-polyglutamic acid. The bioleaching with these organic acid supernatants and 10 % tailing concentration showed the most promising results to date. The culture supernatant containing 30 g/L citric acid was able to leach 43 % of Pb, 37 % of Zn, 8 % of Ca, 4 % of Mn and 3 % of Fe. Further research and a combination of different processes such as flotation and chemical leaching will also be necessary to optimize the extraction capacities. The authors acknowledge the financial support by the Federal Ministry of Education and Research of Germany in the framework of “Resource Efficient Circular Economy – Construction and Mineral Material Cycles (ReMin)”

Keywords: Bioleaching; Remediation; acidophilic bacteria; Yeast; Mineral Tailings

  • Poster
    Emerging Applications of Microbes (2nd edition), 07.-08.12.2022, Leuven, Belgien

Permalink: https://www.hzdr.de/publications/Publ-35930
Publ.-Id: 35930


Demonstration of Trojan horse injection in a hybrid LWFA-driven PWFA

Ufer, P.; Nutter, A.; Chang, Y.-Y.; Corde, S.; Couperus Cabadağ, J. P.; Debus, A.; Döpp, A.; Moritz Foerster, F.; Gilljohann, M.; Heinemann, T.; Hidding, B.; Karsch, S.; Köhler, A.; Kononenko, O.; Pausch, R.; Schöbel, S.; Martinez De La Ossa, A.; Schramm, U.; Irman, A.

In a hybrid LWFA-driven PWFA (LPWFA) electron beams from a laser wakefield acceleration (LWFA) stage are utilized to drive a plasma wave in a subsequent plasma wakefield acceleration (PWFA) stage for acceleration of witness electron bunches to high energies. This concept allows for the exploration of PWFA-physics in a compact setup and harnessing the advantages of both plasma acceleration schemes in order to generate high-quality electron beams. Here we present results of Trojan horse injection in this hybrid plasma acceleration configuration. The DRACO laser is focused onto a gas target (LWFA stage), creating a plasma wakefield to accelerate a high peak current electron bunch. While such a beam is propagating in the second gas jet (PWFA stage), consisting of a mixture of high and low ionization threshold gas, an auxiliary low energy laser pulse intercepts the generated wakefield perpendicularly to release electrons from the highest ionization level in the first cavity. The generated witness beams show improved beam quality, such as lower energy spread compared to the drive electron beam. The realization of Trojan horse injection in LPWFA is a further step towards applications based on high brightness electron beams such as free electron lasers.

  • Poster
    EuroNNAc Special Topics Workshop, 18.-24.09.2022, La Biodola, Italia

Permalink: https://www.hzdr.de/publications/Publ-35929
Publ.-Id: 35929


High-order nonlinear terahertz probing of the two-band superconductor MgB2: Third- and fifth-order harmonic generation

Reinhoffer, C.; Pilch, P.; Reinold, A.; Derendorf, P.; Kovalev, S.; Deinert, J.-C.; Ilyakov, I.; Ponomaryov, O.; Chen, M.; Xu, T.-Q.; Wang, Y.; Gan, Z.-Z.; Wu, D.-S.; Luo, J.-L.; Germanskiy, S.; Mashkovich, E. A.; van Loosdrecht, P. H. M.; Eremin, I. M.; Wang, Z.

We report on high-order harmonic generation in the two-band superconductor MgB 2 driven by intense
terahertz electromagnetic pulses. Third- and fifth-order harmonics are resolved in time domain and investigated
as a function of temperature and in applied magnetic fields crossing the superconducting phase boundary. The
high-order harmonics in the superconducting phase reflects nonequilibrium dynamics of the superconducting
order parameter in MgB2, which is probed via nonlinear coupling to the terahertz field. The observed temperature
and field dependence of the nonlinear response allows to establish the superconducting phase diagram.

Keywords: Terahertz; Superconductivity; Harmonic Generation; Magnetic Fields; Nonlinear Processes

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Permalink: https://www.hzdr.de/publications/Publ-35928
Publ.-Id: 35928


Experimental results of Trojan horse injection in a hybrid LPWFA

Ufer, P.; Nutter, A.; Chang, Y.-Y.; Corde, S.; Couperus Cabadağ, J. P.; Debus, A.; Döpp, A.; Heinemann, T.; Hidding, B.; Gilljohann, M.; Karsch, S.; Köhler, A.; Kononenko, O.; Pausch, R.; Schöbel, S.; Martinez De La Ossa, A.; Schramm, U.; Irman, A.

A hybrid (LPWFA) plasma accelerator combines the two schemes of plasma acceleration, using a laser (LWFA) and an electron beam (PWFA) to drive the plasma wave, with the goal to combine the advantages of both methods. This concept allows studies of PWFA-physics in compact setups as well as generating high-quality electron beams to fulfill the demands of secondary light sources like FELs. We present experimental results from hybrid plasma accelerators using plasma cathode injection also known as Trojan horse injection. A short-pulsed laser is used as the injector in the second stage of the accelerator propagating perpendicular to the electron beam. When timed such, that injector laser and the first cavity of the wakefield overlap, the creation of low-energy-spread witness beams have been observed.

  • Lecture (Conference) (Online presentation)
    DPG-Frühjahrstagung Mainz, 28.03.-01.04.2022, Mainz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-35927
Publ.-Id: 35927


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