Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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.

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.

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.

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)

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.

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.

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.

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.

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.
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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.

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.

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.

Theranostic platform technologies for therapy and imaging

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

10.5281/zenodo.7188057

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.

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.

Es hat kein Abstrakt vorgelegen

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).

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.

\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.

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.

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

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.

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.

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.

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).

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.

no abstract available

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.

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.

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.

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)”

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.

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.

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.

Simulated negative muon and pion yields from Mu2e-II target designs.
The work is related to Fermilab LDRD "Pion-production target conceptual studies for Mu2e-II" (FNAL-LDRD-2020-020)

High peak current electron beams from laser wakefield accelerators (LWFA) are capable to drive a particle driven wakefield (PWFA) in a subsequent stage. The intrinsic short duration of these driver beams opens the possibility for PWFA studies in a higher density regime of the order of 1018·cm-3. Since optical probing provides a reasonable contrast at this density range, direct insight into the particle-driven wakefields is possible. Here we present the results of femtosecond optical probing of such beam driven wakefields, showing pronounced differences in the morphology of beam driven plasma waves when surrounded by either neutral gas or a broad pre-generated plasma channel. Moreover, the shape and size of the first cavity of the wakefields correlates with the driver beam charge. The experimental results are supported by 3D particle-in-cell simulations performed with PIConGPU. This method can be extended to a detailed study of driver charge depletion by probing the evolution of the wakefield as it propagates through the plasma. This is an important step for further understanding and optimization of high energy efficiency PWFAs.

High peak current electron beams from laser wakefield accelerators (LWFA) are capable to drive a particle driven wakefield (PWFA) in a subsequent stage. The intrinsic short duration of these driver beams opens the possibility for PWFA studies in a higher density regime of the order of 1018·cm-3. Since optical probing provides a reasonable contrast at this density range, direct insight into the particle-driven wakefields is possible. Here we present the results of femtosecond optical probing of such beam driven wakefields, showing pronounced differences in the morphology of beam driven plasma waves when surrounded by either neutral gas or a broad pre-generated plasma channel. Moreover, the shape and size of the first cavity of the wakefields correlates with the driver beam charge. The experimental results are supported by 3D particle-in-cell simulations performed with PIConGPU. This method can be extended to a detailed study of driver charge depletion by probing the evolution of the wakefield as it propagates through the plasma. This is an important step for further understanding and optimization of high energy efficiency PWFAs.

Purpose

Currently, there is an intense debate on variations in intra-cerebral radiosensitivity and relative biological effectiveness (RBE) in proton therapy of primary brain tumours. Here, both effects were retrospectively investigated using late radiation-induced brain injuries (RIBI) observed in follow-up after proton therapy of patients with diagnosed glioma.
Methods

In total, 42 WHO grade 2–3 glioma patients out of a consecutive patient cohort having received (adjuvant) proton radio(chemo)therapy between 2014 and 2017 were eligible for analysis. RIBI lesions (symptomatic or clinically asymptomatic) were diagnosed and delineated on contrast-enhanced T1-weighted magnetic resonance imaging scans obtained in the first two years of follow-up. Correlation of RIBI location and occurrence with dose (D), proton dose-averaged linear energy transfer (LET) and variable RBE dose parameters were tested in voxel- and in patient-wise logistic regression analyses. Additionally, anatomical and clinical parameters were considered. Model performance was estimated through cross-validated area-under-the-curve (AUC) values.
Results

In total, 64 RIBI lesions were diagnosed in 21 patients. The median time between start of proton radio(chemo)therapy and RIBI appearance was 10.2 months. Median distances of the RIBI volume centres to the cerebral ventricles and to the clinical target volume border were 2.1 mm and 1.3 mm, respectively. In voxel-wise regression, the multivariable model with D, D × LET and periventricular region (PVR) revealed the highest AUC of 0.90 (95 % confidence interval: 0.89–0.91) while the corresponding model without D × LET revealed a value of 0.84 (0.83–0.86). In patient-level analysis, the equivalent uniform dose (EUD11, a = 11) in the PVR using a variable RBE was the most prominent predictor for RIBI with an AUC of 0.63 (0.32–0.90).
Conclusions

In this glioma cohort, an increased radiosensitivity within the PVR was observed as well as a spatial correlation of RIBI with an increased RBE. Both need to be considered when delivering radio(chemo)therapy using proton beams.

Crystal structures with degenerate electronic orbitals are unstable towards lattice distortions that lift the degeneracy. Although these Jahn–Teller distortions have profound effects on magnetism, they are typically unaffected by the onset of magnetic ordering because of a separation in energy scales. Here we show the contrary case in Pr₂Zr₂O₇, where orbital degeneracy remains down to the millikelvin range due to an interplay between spins and orbitals. Pr₂Zr₂O₇ is a multipolar spin ice with strongly localized 4f electrons in an even-number configuration, giving rise to a non-Kramers doublet that carries transverse quadrupolar and longitudinal dipolar moments. Our study of ultrapure single crystals of Pr₂Zr₂O₇ finds comprehensive evidence for enhanced spin–orbital quantum dynamics of the non-Kramers doublet. This dynamical Jahn–Teller effect is encapsulated by the liquid–gas metamagnetic transition that is characteristic of spin ice being accompanied by strong lattice softening. This behaviour suggests that a spin–orbital liquid state forms on the pyrochlore lattice at low
temperatures and low magnetic fields.

The understanding of transport and mixing in fluids in the presence and in the absence of external fields represents a challenging topic of strategic relevance for space exploration. Indeed, mixing and transport of components in a fluid are especially important during long term space missions where fuels, food, and other materials, needed for the sustainability of long space travels, must be processed under microgravity conditions. So far, the processes of transport and mixing have been investigated mainly at the macroscopic and microscopic scale. Their investigation at the mesoscopic scale is becoming increasingly important for the understanding of mass transfer in confined systems, such as porous media, biological systems, and microfluidic systems. Microgravity conditions will provide the opportunity to analyse the effect of external fields on optimizing mixing and transport in the absence of the convective flows induced by buoyancy on Earth. This would be of great practical applicative relevance to handle complex fluids under microgravity conditions for the processing of materials in space.

Real-time and online adaptive particle therapy in 10 years: a Delphi consensus analysis

P. Trnkova1, Y. Zhang2, T. Toshito3, B. Heijmen4, C. Richter5, M. Aznar6, F. Albertini2, A. Bolsi2, J. Daartz7, A. Knopf2,8, J. Bertholet9

1Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
2Center for Proton Therapy, Paul Scherrer Institute; Villigen, Switzerland
3Nagoya Proton Therapy Center, Nagoya City University West Medical Center, Nagoya, Japan
4Department of Radiotherapy, Erasmus University Medical Center (Erasmus MC), Rotterdam, the Netherlands
5 OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden – Rossendorf, Dresden, Germany
6 Division of Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
7Department of Radiation Oncology, Massachusetts General Hospital & Harvard Medical School, Boston MA 02114, United States of America
8 Institute for Medical Engineering and Medical Informatics, School of Life Sciences, University for Applied Sciences and Arts Northwestern Switzerland.
9 Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, Bern, Switzerland

Purpose/objectives: To collect experts’ opinion on the future of Online Adaptive Particle Therapy (OAPT) and Real Time Motion Management (RRMM) for a vision with a ten-year horizon.
Material/Methods: Following the POP-ART PT survey on current status [1], the present 3-round Delphi consensus study addresses the future of OAPT and RRMM with a panel of 11 experts using questionnaires. Second and third rounds were adapted based on the answers from the previous round to generate controlled opinion feedback (Figure 1). Full consensus (FC) or partial consensus (PC) were reached when all experts agreed or only one expert had a different opinion, respectively.
Results: OAPT will be the method of choice in ten years (PC), mainly in case of variable organ filling and performed with a single in-room imaging modality (FC). There was no consensus on whether offline adaptation will still be performed once OAPT is used clinically. All steps of OAPT require automation to maintain patient throughput (FC). Artificial Intelligence is needed for safe automation, with its central role seen in auto-segmentation (FC). Standardising reporting of endpoints in clinical trials (PC) and cumulative dose reporting (PC) is necessary. It is not currently clear what the best and fastest patient QA method for OAPT will be, and further investigations are required to answer this question (FC). As efficient workflows and tools are medical products, the clinical implementation requires cooperation between industry, research and clinic (FC) with automated and fast systems, reliable deformable registration for dose accumulation, and higher quality in-room imaging identified as the top three priorities (PC). The future importance of MRI-guided PT did not reach consensus.
RRMM is needed for near-real-time OAPT and to treat moving targets (FC) as it mitigates dose deteriorations for both, target and OARs (FC). It should combine multiple approaches, including breath-hold, rescanning, gating, or tracking (FC) based on individual patient selection criteria (FC) and pre-treatment motion characteristics (FC). Optimisation of rescanning parameters, motion model uncertainties and pre-treatment 4D evaluation were considered clinically important (FC). The need to report fractional 4D dose distribution in clinical trials did not reach consensus. 4D dose calculation and its uncertainty evaluation were identified as top requirements (FC). 4D log-file dose reconstruction, (surface) image-based gating/tracking, efficient image guidance and on-board MR guidance were considered of interest but without reaching consensus.
Conclusion: A DELPHI consensus analysis was performed to explore needed developments for OAPT and RRMM. Join efforts between industry research and clinics are needed to translate innovations into efficient and clinically feasible workflows for broad-scale implementation. Consistent reporting of well-defined endpoints should be included in clinical trials to evaluate the clinical impact of both methods.
[1] Zhang Y, Trnkova P et al, ESTRO 2021
Key words: Real time motion management, online adaptive particle therapy, consensus opinion

Ultrashort pulsed laser irradiation enables the generation of ferromagnetism in initially non-ferromagnetic materials, such as B2-ordered Fe60Al40. The paramagnetic B2 phase, defined by atomic planes of pure Fe, separated by Al-rich planes is randomized due to irradiation leading to the formation of the disordered A2 Fe60Al40 being ferromagnetic. This phase transition has been reported to rely on melting and subsequent resolidification, estimated to occur within 5 ns. However, the physical dynamics during the B2-A2 transition have yet to be investigated. Here, we demonstrate the temporal evolution of the
transient reflectance of Fe60Al40 during the B2-A2 transition measured by pump-probe reflectometry. The reflectance increases abruptly 5 ps after excitation with pulsed laser radiation (800 nm, 40 fs, 0.2 J/cm2) which can be attributed to the disordering process. Ex situ observations (Kerr microscopy, HR-TEM, electron holography) confirm that the laser-irradiated areas possess a high magnetization and the A2 structure. Furthermore, materials whose phase transition does not necessarily rely on resolidification may lead to a further reduction in the time needed for generating ferromagnetism by laser irradiation.

The Dresden Super-SIMS is a combination of the DREAMS facility and a CAMECA IMS7f-auto as the ion source, and combines the advantages of both worlds: on one hand the suppression of molecular isobaric background with a 6MV tandem accelerator and on the other the special and depth resolved information about the origin of the measured signals in the sample. This is possible without the samples undergoing any chemical treatment, and a polished surface (< a few nm) is sufficient for the measurement. While former attempts were intended to analyse semiconductor samples, the primary aim of Super-SIMS is the measurement of geological samples.
Nevertheless, first experiments were done with silicon to characterise the system and compare it with former attempts. Several samples
with known content of phosphorus, including the blank, from the former URI-Project (Ultra clean injector) at the Technical University of
Munich were measured. The sample with highest P content was used as internal reference material and the measurements showed a good agreement between measured concentrations by Super-SIMS and URI.

Following the recent developments in materials science and sample fabrication magnetic nanowires and nanotubes became an intensively studied research field in magnetism. However, it should be mentioned that the driving force behind can be attributed to the theoretical, both analytical and numerical predictions of novel magnetic textures and interesting features, such as chiral domain wall motion, the Spin-Cherenkov effect or the curvature-induced magnetochiral effects in general. In this chapter, the static properties of tubular nanomagnets will be reviewed, including magnetic configurations, domain walls, their types, and energetics as well as possible reversal mechanisms. The dynamical properties section is divided into two parts. The first part will guide you through the domain wall motion related to magnetochiral effects. The second part will discuss the general aspects of spin-wave propagation. Aspects, being static or dynamic, related to magnetochiral effects or curvature and topology will be addressed mostly. For those interested in a summary of experimental methods to fabricate tubular samples, an overview of all possible techniques one can use to characterize or measure magnetic tubes, or in a guide through all the analytical and numerical formalism developed to investigate the static and dynamic properties of magnetic nanotubes, we kindly ask to read these recently published excellent books by M. Vázquez [1, 2].

Purpose: The development of online-adaptive proton therapy (PT) is an essential requirement to overcome limitations encountered by day-to-day variations of the patient anatomy. Range verification could play an essential role in an online feedback loop for the detection of treatment deviations such as anatomical changes. Here, we present results of the first systematic patient study regarding the detectability of anatomical changes by a prompt-gamma imaging (PGI) slit-camera system.

Materials & Methods:  For 15 prostate-cancer patients, PGI measurements were performed during 105 fractions (201 fields) with in-room control CTs. Field-wise doses on control CTs were manually classified whether showing relevant or non-relevant
changes. Spot-wise ground-truth range shift information was retrieved by integrated depth-dose (IDD) analyses serving for a field-wise ground-truth classification. Spot-wise PGI-based range shifts were initially compared to corresponding IDD shifts and then combined in a PGI-model to match the field-wise IDD-based classification. This model was optimized and tested for a sub-cohort of 10 and 5 patients, respectively.

Results:  The correlation between PGI and IDD range shifts was high, ρ_pearson = 0.67 (p<0.01). Field-wise binary PGI-classification resulted in an area under the curve (AUC) of 0.72 and 0.80 for training and test cohort, respectively. The model detected relevant anatomical changes in the independent test cohort with a sensitivity and specificity of 74% and 79%, respectively.

Conclusion:  For the first time, evidence of the detection capability of anatomical changes in prostate-cancer PT from clinically acquired PGI data is shown. This emphasizes the benefit of PGI-based range verification and demonstrates its potential for online-adaptive PT.

Curvilinear magnetism is a research field studying curved nanowires and thin films with anisotropic and chiral magnetic responses are tailored by the geometry. The contemporary theories reach the level of maturity for ferromagnets [1,2]. At the same time, very little is done for antiferromagnets (AFMs), which are promising for low-power consuming and high-speed spintronic devices [2].

The simplest systems uncovering the specific features of AFM exchange in curvilinear geometries are spin chains, which can be arranged along plane and space curves. If the dipolar interaction is the dominating source of anisotropy, it renders the chain as the hard-axis AFM with the anisotropy axis along the tangential direction. There are two families of effects of geometry stemming from exchange. The first ones come from the spatial gradients of the Néel vector. A direction of local twists and bends of the chain manifests itself as the geometry-driven DMI and contributes to the tensor of total anisotropy [3]. As a consequence, the curvilinear AFM spin chain along space curve with exchange and dipolar interaction behaves as the chiral helimagnet, with the helimagnetic transition determined by the curvature and torsion of the curve. Such a chain arranged along the plane curve has the one ground state with the equilibrium Néel ordering perpendicular to the curve plane. In both cases, the easy axis of anisotropy arises from the exchange [3]. Localized bends of the curve also lead to the pinning of domain walls [4]. In addition to the chiral and anisotropic effects, the locally broken spatial symmetry of the AFM chain leads to the geometry-driven weak ferromagnetism. The strength of the emergent magnetization scales linearly with the curvature and torsion [5].

A unit cell of AFM contains a few spins. For the case of the single-ion anisotropy, its direction is varyring within the unit cell. This leads to the specific contributions to the magnetic responses stemming from anisotropy, such as an anisotropic term which mixes the tangential and normal components of the Néel and ferromagnetic order parameters as the DMI of longitudinal symmetry [5]. This can be of importance for non-collinear textures in one-dimensional AFMs, where the finite magnetization appears at inhomogeneity of the Néel vector.

[1] P. Fischer et al, APL Mater., 8, 010701 (2020); R. Streubel et al. Journal of Applied
Physics, 129, 210902 (2021)
[2] D. Makarov et al, Adv. Mater., 34, 2101758 (2022)
[3] O. Pylypovskyi, D. Kononenko et al, Nano Lett., 20, 8157–8162 (2020)
[4] K. Yershov, Phys. Rev. B, 105, 064407 (2022)
[5] O. Pylypovskyi et al, App. Phys. Lett., 118, 182405 (2021)

Drone-based aeromagnetic surveys are a cost- and time-effective tool for high resolution mapping of unexposed geological structures. This technology is particularly advantageous for areas where it is difficult or impossible to conduct ground-based surveys such as beneath water bodies. Uncrewed aerial vehicles (UAVs) are robust and versatile platforms adapted to ensure precise and more controlled surveying at different scales in operational conditions. During the last years we have been developing and testing a series of workflows to efficiently acquire and process aeromagnetic data. Using an inhouse developed python toolbox we automate the data quality assessment on-site and implement a data-driven decision making algorithm to optimise the survey operation. With low altitude flights (<12m) and tight line spacings we ensure the acquisition of high-quality, detailed maps facilitating the geophysical interpretation of small-scale geological features.

To demonstrate the potential of our approach we present a demanding study area on a lake in Rogaland, Norway with low GPS coverage (valley), high magnetic gradients affecting the navigation system of the drone and non-ideal weather conditions to showcase the advantages of UAV magnetic surveys.

The year 2022 marked 40 years since Aitchison published the article "The statistical analysis of compositional data". It is considered to be the foundation of contemporary compositional data analysis. It is time to review what has been accomplished in the field and what needs to be addressed. Astonishingly enough, many aspects seen as challenging in 1982 continue to lead to fruitful scholarly work. We commence with a bibliometric study, and continue with some hot topics such as multi-way compositions, compositional regression models, dealing with zero values, non-logratio transformations, new application fields, and a number of current loose ends. Finally, a tentative future research agenda is outlined.

Presentation of PIConGPU at DOE Booth at Supercomputing 2022

An extension to the wave packet description of quantum plasmas is presented, where the wave packet can be elongated in arbitrary directions. A generalised Ewald summation is constructed for the wave packet models accounting for long-range Coulomb interactions and fermionic effects are approximated by purpose-built Pauli potentials, self-consistent with the wave packets used. We demonstrate its numerical implementation with good parallel support and close to linear scaling in particle number, used for comparisons with the more common wave packet employing isotropic states. Ground state and thermal properties are compared between the models with differences occurring primarily in the electronic subsystem. Especially, the electrical conductivity of dense hydrogen is investigated where a 15% increase in DC conductivity can be seen in our wave packet model compared to other models.

Exploiting the strong electromagnetic fields that can be supported by a laser driven compact plasma accelerator enables generation of short, high-intensity pulses of high energy ions with special beam properties. The maturation of such laser driven ion accelerators from physics experiments to turn-key sources for applications will rely on breakthroughs in both, generated beam parameters (kinetic energy, flux), as well as increased scrutiny on reproducibility, robustness, and scalability to high repetition rate.
Recent developments at the high-power laser facility DRACO-PW enabled the production of polychromatic proton beams with unprecedented stability [1]. This facilitated the first in vivo radiobiological study using a laser-driven proton source [2]. For many related advanced applications, the ability to generate proton beams with energies beyond the 100 MeV frontier at a repetition rate and in a controllable way is essential and the subject of ongoing research.
Latest experimental studies concentrated on pre-expanded plastic foil target undergoing relativistically induced transparency using linearly polarized laser pulses with peak intensities beyond 1021 W/cm2. A complex suite of particle and optical diagnostics allowed characterization of spatial and spectral proton beam parameters and the stability of this regime for best acceleration performance exceeding 100 MeV cut-off energies. Combined hydrodynamic and 3D particle-in-cell simulations helped to identify the most promising target parameter range matched to the carefully measured prevailing laser contrast conditions.

Modeling properties of strongly correlated many-particle systems are of both fundamental and practical importance. At the same time, generating and probing these properties is challenging. To this end, laboratory model systems play a central role in studying correlated many-particle phenomena. In this presentation, we focus on a specific laboratory model system – dusty plasmas – to model collective particle behavior under controlled conditions. Thereby, we push the frontier of dusty plasma physics by predicting the generation of high harmonics in dusty plasmas with alternating screening length [1]. We found a simple phenomenological expression for the dispersion relation of higher harmonics. Moreover, it is shown that the periodically alternating screening causes a self-conjugate state with negative refraction. As the application, we speculate that our findings can serve as a test bed for studying the fundamental physics of a self-conjugate state with negative refraction in strongly correlated systems on the kinetic level.

[1] Z. A. Moldabekov et al., Phys. Rev. Research 3, 043187 (2021)

In ultra-short laser pulses, small changes in dispersion properties before the final focusing mirror can
lead to severe pulse distortions around the focus and therefore to very different pulse properties at the
point of laser-matter interaction yielding unexpected interaction results. The mapping between far and
near-field laser properties intricately depends on the spatial and angular dispersion properties as well as the
focal geometry. For a focusing Gaussian laser pulse subject to angular, spatial, and group delay dispersion,
we derive analytical expressions for its pulse-front tilt, duration, and width from a fully analytic expression
for its electric field in time-space domain. This expression is not only valid in and near the focus but along
the entire propagation distance from the focusing mirror to the focus. Together with expressions relating
angular, spatial, and group delay dispersion before focusing at an off-axis parabola to the respective values
in the pulse’s focus, these formulas are used to show in example setups that pulse-front tilts of lasers
with small initial dispersion can become several ten degrees large in the vicinity of the focus while being
small directly in the focus. The formulas derived here provide the analytical foundation for observations
previously made in numerical experiments. By numerically simulating Gaussian pulse propagation and
measuring properties of the pulse at distances several Rayleigh lengths off the focus we verified the analytic
expressions.

Warm dense matter is the state of matter naturally appearing in interiors of planets and stars. In laboratory warm dense matter is generated by laser heating and shock compression. Warm dense matter is also important as a transient state on the way to ignition in inertial confinement fusion experiments. Density response properties are important for the understanding process in warm dense matter for computation of optical and transport characteristics. In this presentation, I will discuss the theoretical foundations of the linear and non-linear density response theory for warm dense matter. Going beyond theoretical formulations, the calculations based on the KS-DFT method will be presented.

We developed a new method that allows one to compute material specific static exchange-correlation kernel across temperature regimes using standard DFT codes and for any XC functional available in Libxc [1]. In this presentation we show the results of the static exchange-correlation kernel analysis from computations using various XC functionals for dense electron gas and warm dense hydrogen. By comparing the data to the exact QMC results, we are able to understand the effect of thermal excitations and density inhomogeneity on the exchange-correlation kernel. Moreover, we discuss the results of the analysis of the accuracy of the commonly used exchange-correlation (XC) functionals for warm dense matter simulations [2-4]. The analysis is performed by comparing highly accurate path-integral quantum Monte-Carlo (QMC) data with KS-DFT results. Finally, a new methodology for the investigation of the non-linear static density response of WDM based on the KS-DFT method is presented [5].

[1] Zhandos A. Moldabekov, Maximilian Böhme, Jan Vorberger, David Blaschke, Tobias Dornheim, arXiv:2209.00928 (2022).
[2] Z. Moldabekov, T.Dornheim, M. Böhme, J. Vorberger, A. Cangi, The Journal of Chemical Physics 155, 124116 (2021).
[3] Z. Moldabekov, T.Dornheim, J. Vorberger, A. Cangi, Phys. Rev. B 105, 035134 (2022).
[4] Z. A. Moldabekov, T. Dornheim, G. Gregori, F. Graziani, M. Bonitz, A. Cangi, SciPost Phys. 12, 062 (2022).
[5] Z.Moldabekov, J. Vorberger, T. Dornheim, Journal of Chemical Theory and Computation 18, 2900–2912 (2022).

The KS-DFT is the standard method to model the electronic structure due to its accuracy and computational efficiency. The reduction in computation cost compared to other ab initio methods is due to a formally exact mapping onto an effective single-electron problem. DFT calculations of a various material properties require as input the so-called exchange—correlation (XC) kernel. Yet, little is known about the actual kernel of real materials, and hitherto no reliable universal way to compute it has been known. In this work, we present a new methodology to compute the static XC-kernel of any material; which needs no external input apart from the usual XC-functional. The application of the method is demostrated for the uniform electron gas and hydrogen. Moreover, we consider both ambient conditions and the warm-dense matter (WDM) parameters. In addition, our analysis of the static XC-kernel gives us valuable new insights into the construction of the XC-functionals for the application at WDM regime.

In this presentation we discuss the results of the analysis of the accuracy of the commonly used exchange-correlation (XC) functionals for warm dense matter simulation [1,2]. The analysis is performed by comparing the path-integral quantum Monte-Carlo (QMC) data with KS-DFT results. The relative deviation of the total density from the reference data is reported for different XC functionals in the case of the inhomogeneous electron gas. Furthermore, a new methodology for the investigation of the non-linear static density response WDM based on KS-DFT method is presented [3]. The results are verified by comparing to the QMC data when thermal temperature is equal to the Fermi temperature. New results for partially and strongly degenerate electrons are presented. Finally, we present the results of the analysis of the electronic local field correction as computed using various XC functionals. By comparing the data to the exact QMC results, we are able to understand the effect of the thermal excitations on XC functional.

[1] Z. Moldabekov, T.Dornheim, M. Böhme, J. Vorberger, A. Cangi, The Journal of Chemical Physics 155, 124116 (2021).
[2] Z. Moldabekov, T.Dornheim, J. Vorberger, A. Cangi, Phys. Rev. B 105, 035134 (2022).
[3] Z.Moldabekov, T. Dornheim, J. Vorberger, Journal of Chemical Theory and Computation (2022).

The collision of relativistic electron beams with highly intense, highly energetic and
short-pulsed light will give deep insights into the interactions of electromagnetic fields
and matter at extreme scales. Experimentally, those collisions might be addressed
at upcoming projects like HIBEF 2.0 at the EuropeanXFEL, SYLOS at ELI-ALPS or
LCLS-II at SLAC, to name a few. The precise theoretical description of such collision
experiments is very challenging and not fully covered by the currently available tools,
known from particle physics. We develop the open-source software library QED.jl,
which targets those gaps by
Modelling of (non-linear) Quantum Processes
providing new developments of
higher-order
pair production
state-of-the-art modelling tools w.r.t.
inelastic scattering
Processes
and annihilation
strong-field physics. This includes

• Modelling of particle physics

• Monte-Carlo event generation:

• Multivariate integration:

• Task scheduling using directed acyclic graphs:

• Code injection:

• Hardware-agnostic parallelisation:

Warm dense matter (WDM) is the state of matter at high pressures and temperatures. WDM is
relevant both for practical applications and for fundamental science. The practical significance is
due to the generation of the WDM state in experiments on nuclear fusion and the creation of new
materials under extreme conditions. From the point of view of fundamental science, the relevance
of WDM is due to the extreme conditions in the interiors of planets and stars.
Many questions regarding the interplay of quantum degeneracy, thermal excitations, and strong
correlations effects in WDM remain open. To solve this problem, we use an externally perturbed
WDM to investigate how electronic structure and excitations are affected by thermal excitations
and density inhomogeneities. The results are reported in our recent articles [1-4], where we
presented: a study of the quality of various exchange-correlation functionals in the KS-DFT method
[1,2]; the change in electronic excitations due to strong inhomogeneity and thermal effects [3]; and
a new KS-DFT based methodology for the investigation of the non-linear response of electrons
across temperature regimes relevant for WDM [4].

[1] Z. Moldabekov, T. Dornheim, M. Boehme, J. Vorberger, A. Cangi, J. Chem.Phys. 155 (2021)
124116.
[2] Z. Moldabekov, T. Dornheim, J. Vorberger, A. Cangi, Phys. Rev. B 105 (2022) 035134.
[3] Z. Moldabekov, T. Dornheim, A. Cangi, Sci. Rep. 12 (2022) 1093.
[4] Z. Moldabekov, J. Vorberger, T. Dornheim, J. Chem. Theory Comput. 18 (2022) 2900

Warm dense matter (WDM) is a state of matter with parameters between solids and
dense plasmas. WDM is characterized by the relevance of quantum degeneracy, thermal
excitations, and strong correlations. Many questions regarding the interplay of these
effects in WDM remain open. In this paper, we use an externally perturbed electron gas
to investigate how electronic structure and excitations are affected by thermal excitations
and density inhomogeneities. The results are reported in our recent articles [1-4]. We
present a study of the quality of various exchange-correlation functionals in the KS-DFT
method [1,2]. In addition, we show how electronic excitations change due to strong
inhomogeneity and thermal effects [3]. Based, on these results, we present a new KS-DFT
based methodology for the investigation of the non-linear response of electrons across
temperature regimes relevant for WDM [4].

References
[1] Z. Moldabekov, T.Dornheim, M. Boehme, J. Vorberger, A. Cangi, The Journal of Chem-
ical Physics 155, 124116 (2021).
[2] Z. Moldabekov, T.Dornheim, J. Vorberger, A. Cangi, Phys. Rev. B 105, 035134 (2022).
[3] Z. Moldabekov, T.Dornheim, A. Cangi, Scientific Reports 12, 1093 (2022)
[4] Z.Moldabekov, J. Vorberger, T. Dornheim, Journal of Chemical Theory and Computation,
accepted for publication (2022); arXiv:2201.01623.

The Hybrid Collaboration, a joint undertaking by HZDR, DESY, University of Strathclyde, LMU, and LOA, performed hybrid LPWFA experiments which utilize electron bunches from a laser wakefield accelerator (LWFA) as drivers of a plasma wakefield stage (PWFA) to demonstrate the feasibility of compact PWFAs serving as a test bed for the efficient investigation and optimization of PWFAs and their development into brightness boosters. To better understand the microscopic, nonlinear dynamic of these accelerators, the experiments were accompanied by 3D3V particle-in-cell simulations using PIConGPU.

Here, we present insights into the dynamics of the hybrid LPWFA that we gained from start-to-end simulations of the experimental setup at HZDR.
These regard electron injections due to hydrodynamic shocks, beam self-modulation and breakup, and cavity elongation - all backed-up by synthetic diagnostics that allow direct comparison with experimental measurements.
We discuss our approach to model these synthetic diagnostics directly within the PIConGPU simulation as well as modelling certain aspects of the experimental setup, such as the drive laser. Continuing this, the talk highlights a few recent technical advances in PIConGPU that enable better modelling of the micro-physics, experiment conditions, or signals of experiment diagnostics.

Introduction: The A2A adenosine receptor (A2AAR) is expressed in brain, vasculature and immune cells. According to the alterations of the A2AAR expression in multiple diseases, it is a highly attractive diagnostic and therapeutic target. We developed the A2AAR-specific PET radiotracer [18F]FLUDA and investigated it in healthy mice and piglets, in a rotenone-based mouse model of Parkinson’s disease (RMMPD) and in transgenic mice overexpressing the human A2AAR in heart (TG) [1 3].

Methods: On the basis of a one-pot two-step radiofluorination procedure, a remotely controlled automated radiosynthesis of [18F]FLUDA using the TRACERlab FX2N synthesis module was developed. In vitro autoradiography was performed with cryosections of tissue from animal models. In vivo stability was investigated in mouse by radio-HPLC analyses of blood plasma and brain homogenates. The biodistribution was investigated by dynamic PET/MR studies in healthy mice and piglets under control and blocking conditions (vehicle vs. blocking with 2.5 mg/kg tozadenant and/or 1.0 mg/kg istradefylline) and in both mouse models. The binding potential (BPND) in vivo was calculated using the simplified reference tissue modelling with the cerebellum as reference region. A single dose acute toxicity study was performed in Wistar rats according to the ICH guideline M3(R2). PET-derived radiation dosimetry was estimated in piglets.

Results: A reliable and reproducible procedure for the automated production of [18F]FLUDA was successfully established (Fig. 1A) [4]. In vitro autoradiography revealed highly selective binding and high affinity of [18F]FLUDA towards the A2AAR of the three species (KD values 0.7-5.9 nM, Fig. 1B). At 15 min after i.v. injection of [18F]FLUDA in mice, the parent fraction accounted for about 100% in brain and 71% in plasma. PET studies confirmed the specific binding of [18F]FLUDA in vivo to the striatal A2AAR in mice and piglets (BPND=3.9 and 1.3, Fig. 1C). The availability of A2AAR in the Parkinson’s disease model was not significantly different from the control. The cardiac overexpression of human A2AAR resulted in a significantly higher accumulation of activity compared to control (1.4-fold higher ratio of the area-under-the curves obtained for myocard and blood, 1-10 min p.i., p=0.001). Toxicity studies revealed no adverse effects up to a dose of 30 µg/kg of FLUDA (approx. 4,000-fold of expected human dose). The estimated effective dose of [18F]FLUDA in humans is 16.4 µSv/MBq, which is in the range of other 18F-labeled radiotracers [5].

Conclusion: We have demonstrated that [18F]FLUDA is suitable for the determination of the availability of A2AAR in the brain in vitro and in vivo. No safety concerns are expected upon administration of [18F]FLUDA according to toxicity and dosimetry data. These results encourage the clinical translation of [18F]FLUDA.

Acknowledgement: This work (project no. 100226753) was funded by the European-Regional-Development-Fund (ERDF) and Sächsische-Aufbaubank (SAB).

References: [1] T.H. Lai and M. Toussaint et al., EJNNMI 2021, 48:2727–2736; [2] D. Gündel and M. Toussaint, Pharmaceuticals 2022, 15; [3] D. Gündel et al., Int. J. Mol. Sci. 2022, 23, 1025; [4] T.H. Lai et al., J. Label. Compd. Radiopharm. 2022, 65:162–166; [5] B. Sattler et al., J. Nucl. Med. 2020, 61:1014.

We assess the accuracy of common hybrid exchange-correlation (XC) functionals (PBE0, PBE0-1/3, HSE06, HSE03, and B3LYP) within Kohn-Sham density functional theory (KS-DFT) for the harmonically perturbed electron gas at parameters relevant for the challenging conditions of warm dense matter. Generated by laser-induced compression and heating in the laboratory, warm dense matter is a state of matter that also occurs in white dwarfs and planetary interiors. We consider both weak and strong degrees of density inhomogeneity induced by the external field at various wavenumbers. We perform an error analysis by comparing to exact quantum Monte-Carlo results. In the case of a weak perturbation, we report the static linear density response function and the static XC kernel at a metallic density for both the degenerate ground-state limit and for partial degeneracy at the electronic Fermi temperature. Overall, we observe an improvement in the density response for partial degeneracy when the PBE0, PBE0-1/3, HSE06, and HSE03 functionals are used compared to the previously reported results for the PBE, PBEsol, LDA, AM05, and SCAN functionals; B3LYP, on the other hand, does not perform well for the considered system. Together with the reduction of self-interaction errors, this seems to be the rationale behind the relative success of the HSE03 functional for the description of the experimental data on aluminum and liquid ammonia at WDM conditions.

We present an analysis of the static exchange-correlation (XC) kernel computed from hybrid functionals with a single mixing coefficient such as PBE0 and PBE0-1/3. We break down the hybrid XC kernels into the exchange and correlation parts using the Hartree-Fock functional, the exchange-only PBE, and the correlation-only PBE. This decomposition is combined with exact data for the static XC kernel of the uniform electron gas and an Airy gas model within a subsystem functional approach. This gives us a tool for the nonempirical choice of the mixing coefficient at ambient and extreme conditions. Our analysis provides physical insights into the effect of the variation of the mixing coefficient in hybrid functionals, which is of immense practical value. The presented approach is general and can be used for other type of functionals like screened hybrids.

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The Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden, HLD) is a user facility for experiments at extreme sample conditions and an institute of the HZDR as well. The HLD provides access to magnets and measurement equipment that allows for experiments up to the feasibility limits of the magnetic-field scale. In particular, research on quantum condensed matter with novel electronic or magnetic properties is the central research area at HLD. As a central task, the HLD develops and operates world-class pulsed high-field magnets to make them available for excellent research by external and in-house users. It is the only installation in Germany and one of the four large user facilities in Europe which operate high-field magnets in combination with advanced measurement techniques; the other partner facilities are located in Grenoble, Nijmegen and Toulouse. The close cooperation between these high-field laboratories has been formalized by the foundation of the European Magnetic Field Laboratory (EMFL). Via a peer-reviewed proposal system, centrally managed by EMFL, the HLD provides leading-edge and in part unique experimental capabilities allowing for high-resolution measurement techniques for materials research in state-of-the-art pulsed magnets reaching top-level field strengths. All these experimental techniques are available over a broad temperature range too, most even down to millikelvin temperatures. The combination of infrared radiation produced by free-electron lasers of the neighboring superconducting electron accelerator ELBE with pulsed-field magnets is world unique. At HLD, a technology-development program for nondestructive pulsed magnets and pulsed power supplies is being carried out allowing to provide the highest possible fields for internal and external users. Various types of pulsed magnets have been designed and are in operation with recently realized dual-coil systems reaching magnetic fields of 85 and 95 T, available for users. Furthermore, a development program for pulsed-power supplies providing electrical currents of several 100 kA as well as electrical power of several GW is in work. These technological activities which make also use of modern simulation methods are under way for realizing a dedicated power supply at the European XFEL (HIBEF project) and for industrial applications, e.g. for electromagnetic pulse forming, joining, and welding as well as for medical engineering and hydrogen liquefaction. In cooperation with industrial and EMFL partners, the HLD will develop a new generation of all-superconducting high-field coils.

Gemeinsamer Beitrag in der Umweltzeitung zu biologischen Wegen der nachhaltigen Rückgewinnung von Selten Erd Elementen.

Presentation of the biomolecular toolbox of the biotechnology department and the BioKollekt research.

Presentation of research approaches at HIF towards a circular economy