Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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34118 Publications

Off-harmonic optical probe diagnostic for high intensity laser interaction with hydrogen targets

Zeil, K.; Bernert, C.; Kraft, S.; Loeser, M.; Metzkes-Ng, J.; Obst-Huebl, L.; Rehwald, M.; Schlenvoigt, H.-P.; Siebold, M.; Ziegler, T.; Schramm, U.

The development of high-intensity short-pulse lasers in the Petawatt regime offers the possibility to design new compact accelerator schemes by utilizing high-density targets for the generation of high energy ion beams. The optimization of the acceleration process demands comprehensive diagnostic of the plasma dynamics involved, for example via spatially and temporally resolved optical probing. Experimental results can then be compared to numerical particle-in-cell simulations, which is particularly sensible in the case of cryogenic hydrogen jet targets [1]. However, strong plasma self-emission and conversion of the plasma’s drive laser wavelength into its harmonics often masks the interaction region and interferes with the data analysis. Recently, the development of a stand-alone and synchronized probe laser system for off-harmonic probing at the DRACO laser operated at the Helmholtz-Zentrum Dresden–Rossendorf showed promising performance [2].
Here, we present an updated stand-alone probe laser system applying a compact CPA system based on a synchronized fs mode-locked oscillator operating at 1030 nm, far off the plasma’s drive laser wavelength of 800 nm. A chirped volume Bragg grating is used as a hybrid stretcher and compressor unit [3]. The system delivers 160 fs pulses with a maximum energy of 0.9 mJ. By deploying the probe laser pulses in laser-proton acceleration experiments with renewable cryogenic hydrogen jet targets, the plasma self-emission could be significantly suppressed while studying the temporal evolution of the expanding plasma jet. Hence, for varied drive laser contrast parameters, by the use of a plasma mirror, the on target contrast was measured and correlated to the temporal drive laser profile.

References

[1] L. Obst, et al. Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets. Sci. Rep., 7:10248, 2017.
[2] T. Ziegler, et al. Optical probing of high intensity laser interaction with micron-sized
cryogenic hydrogen jets. Plasma Phys. Control. Fusion, 2018. doi:10.1088/1361-6587/
aabf4f.
[3] L. Loeser, et al. A compact and robust millijoule CPA laser system based on Yb:CaF₂ delivering 160fs pulses. under review.

  • Lecture (Conference)
    Laser Plasma Accelerator Workshop, 09.05.2019, Split, Kroatien

Permalink: https://www.hzdr.de/publications/Publ-30633
Publ.-Id: 30633


Ion acceleration from ultra-thin foil targets using a PW-class laser with optimized temporal pulse profile

Zeil, K.; Bernert, C.; Bock, S.; Brack, F.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Obst-Huebl, L.; Pueschel, T.; Rehwald, M.; Schlenvoigt, H.-P.; Ziegler, T.; Schramm, U.

Laser-driven ion acceleration promises to provide a compact solution for demanding applications like radio-biology experiments. For that, controlling particle beam parameters particularly in experiments with high energy Petawatt class ultra-short pulse systems with high repetition rate is a mandatory, yet challenging task. The performance of the plasma acceleration is strongly dependent on the complex laser target interaction which in turn is determined by the temporal laser intensity profile and spatio-temporal couplings on a large dynamic range. Plasma mirror setups have proven to significantly improve the temporal contrast by reducing pre-pulse intensity and steepening the rising edge of the main laser pulse, enabling the investigation of laser proton acceleration using ultra-thin and near critical density targets. Here we present benchmark experiments using the DRACO Petawatt laser at HZDR irradiating ultra-thin foil targets. A combination of particle and plasma diagnostics for ions and electrons as well as reflected and transmitted light revealed clear indications of acceleration in the relativistic transparency regime. The experiments were complemented by a suite of different laser pulse diagnostics, including self-referenced spectral interferometry with extended time excursion for single shot contrast analysis to characterize the laser pulse properties at the high power focus as realistic as possible.

  • Lecture (Conference)
    European Advanced Accelerator Conference, 17.09.2019, Elba, Italien

Permalink: https://www.hzdr.de/publications/Publ-30632
Publ.-Id: 30632


SPCI-Reconstruction

Kornek, D.; Berthold, J.; Kögler, T.

Single plane Compton imaging (SPCI) is a novel approach to medical imaging of gamma radiation [1]. The possible range of applications includes nuclear imaging and range verification in proton therapy. For the purpose of image reconstruction, a software tool written in ROOT [2] and named SPCI-Reconstruction [3] has been developed. The implementation features the well-established MLEM algorithm for binned data [4] as well as a Monte-Carlo based algorithm called Origin Ensemble [5]. Given a precalculated system matrix and a file containing the measurements, the emission densities of the gamma radiation source can be backprojected into a voxel-based image space.

[1] Pausch G et al. A novel scheme of compton imaging for nuclear medicine. 2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD).

[2] CERN. ROOT – Data Analysis Framework. Release 6.12/04 - 2017-12-13. https://root.cern.ch/content/release-61204.

[3] Kornek D. Anwendung von Maximum-Likelihood Expectation-Maximization und Origin Ensemble zur Rekonstruktion von Aktivitätsverteilungen beim Single Plane Compton Imaging (SPCI). Master's thesis. TU Dresden. 2019.

[4] Shepp LA, Vardi Y. Maximum likelihood reconstruction for emission tomography. IEEE Trans Med Imaging. 1982; 1(2):113-22.

[5] Sitek A. Representation of photon limited data in emission tomography using origin ensembles. Phys Med Biol. 2008 June; 53(12):3201-3216.

Keywords: single plane compton imaging; compton camera; image reconstruction; maximum-likelihood expectation-maximization; origin ensemble; nuclear medicine; range verification in particle therapy

  • Software in the HZDR data repository RODARE
    Publication date: 2020-01-17
    DOI: 10.14278/rodare.191
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30631
Publ.-Id: 30631


Process Metallurgy in Circular Economy System Design: Challenges & Solutions

Reuter, M. A.; Bartie, N.

Realising the circular economy (CE) is faced with some significant challenges. Process metallurgy and its infrastructure play key roles at the heart of making the CE work. Therefore, the enabling role of process metallurgy within the CE will be central to the discussion in this paper, touching among others on product and system design as well as the key metallurgical and other process fundamentals that need to be investigated and understood to make the CE a reality. The central role of materials and its processing will be discussed in an integrated circular cities perspective. A key focus will be a discussion on designing a resilient “Smart Materials Grid” using and innovating metallurgical process engineering tools, which will manage the flows through Sustainable Circular Cities. The discussion will be using copper as leitmotiv of the discussion i.e. from copper ore, to metal, to complex products, recycling, product design and simulation and its impact.

Keywords: circular economy; Process metallurgy; “Smart Materials Grid”; Sustainable Circular Cities

  • Invited lecture (Conferences)
    COM 2019 Hosting Copper 2019, 18.-21.08.2019, Vancouver, Canada

Permalink: https://www.hzdr.de/publications/Publ-30630
Publ.-Id: 30630


Effects of He ion irradiation on gold nanoclusters: a Molecular Dynamics study

Ghaderzadeh, S.; Ghorbani Asl, M.; Kretschmer, S.; Hlawacek, G.; Krasheninnikov, A.

The interpretation of helium ion microscopy (HIM) images of crystalline metal clusters requires microscopic understanding of the effects of He ion irradiation on the system, including energy deposition and associated heating, as well as channeling patterns. While channeling in bulk metals has been studied at length, there is no quantitative data for small clusters. We carry out molecular dynamics simulations to investigate the behavior of gold nano-particles with diameters of 5–15 nm under 30 keV He ion irradiation. We show that impacts of the ions can give rise to substantial heating of the clusters through deposition of energy into electronic degrees of freedom, but it does not affect channeling, as clusters cool down between consecutive impact of the ions under typical imaging conditions. At the same time, high temperatures and small cluster sizes should give rise to fast annealing of defects so that the system remains crystalline. Our results show that ion-channeling occurs not only in the principal low-index, but also in the intermediate directions. The strengths of different channels are specified, and their correlations with sputtering-yield and damage production is discussed, along with size-dependence of these properties. The effects of planar defects, such as stacking faults on channeling were also investigated. Finally, we discuss the implications of our results for the analysis of HIM images of metal clusters.

Keywords: Helium Ion Microscope; Channeling effect; Nano particles; Ion irradiation

  • Lecture (Conference)
    AVS 66th International Symposium & Exhibition, 20.-25.10.2019, Columbus, United States of America

Permalink: https://www.hzdr.de/publications/Publ-30629
Publ.-Id: 30629


Effects of gold nanoclusters under He ion irradiation: a molecular dynamics study

Ghaderzadeh, S.; Ghorbani Asl, M.; Hlawacek, G.; Krasheninnikov, A.

Ion channeling is a well-known effect in ion irradiation processes, which is a result of ion moving between the rows of atoms. It drastically affects the ion distribution, ion energy-loss and consequently the damage production in the target. Therefore one could derive the ion-channeling pattern out of the energy-loss behavior of ion-target interaction.
Ion channeling effect is studied for a few pure element crystals and also for some compounds in a systematic way [1]. In this work, we focus on nano-structures which are of major importance, due to their high surface-to-volume ratio. Our results, for different gold cluster sizes, show that ion-channeling occurs not only in the principal low-index, but also in other directions in between. The strengths of different channels are specified, and their correlations with sputtering-yield and damage production is discussed.

Keywords: Helium Ion Microscope; Nano particles; Channeling effect; Ion irradiation

  • Poster
    Towards Reality in Nanoscale Materials X, 12.-14.02.2019, Levi, Finland

Permalink: https://www.hzdr.de/publications/Publ-30627
Publ.-Id: 30627


Process Metallurgy is Fundamental to the Circular Economy

Reuter, M. A.

Metals are eminently recyclable, and by recycling and refining complex materials, the interconnected metals sector is responding to the increasing scarcity of certain metals. In this way, the metals sector is delivering and recovering the technology and base metals for the Circular Economy (CE). Moreover, metals are at the heart of the energy infrastructures that now run Circular Cities, and they will play an even greater part in the future. Metals are key enablers in the CE, as it is capable of dissolving and carrying a multitude of technology elements. The recovery and recycling of several critical technology elements is based on refining them from molten metal through well-developed metallurgical processes in which these act as carrier metals. To put it simply, process metallurgy is fundamental if countries want to innovate leading positions in the global CE. This presentation is gleaning from a recent policy brief developed by industry and academia within the EU ETN SOCRATES.

Keywords: Circular Economy; Circular Cities; process metallurgy; SOCRATES

  • Invited lecture (Conferences)
    Waste innovation for a circular economy / Cutting Edge Science and Engineering Symposium, 27.-29.05.2019, Clayton, Australien

Permalink: https://www.hzdr.de/publications/Publ-30626
Publ.-Id: 30626


Traveling-Wave Electron Acceleration - Energy-efficient Laser-plasma acceleration beyond the dephasing and depletion limits

Debus, A.; Pausch, R.; Hübl, A.; Steiniger, K.; Widera, R.; Cowan, T.; Schramm, U.; Bussmann, M.

We present Traveling-Wave Electron Acceleration (TWEAC), a novel compact electron accelerator scheme based on laser-plasma acceleration. While laser-plasma accelerators provide multi-GeV electron beams today, the acceleration to higher energies is limited. The sub-luminal group-velocity of plasma waves let electrons outrun the accelerating field.

In order to control the speed of the accelerating plasma cavity, 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. Supported by 3D particle-in-cell simulations using PIConGPU, we show that TWEAC offers constant acceleration without a dephasing electron beam while avoiding usual laser pump depletion within the interaction region. This opens the way for electron energies beyond 10 GeV, possibly towards TeV class electron beams, without the need for multiple laser-accelerator stages. For lower GeV-scale electron energies, TWEAC at high plasma densities and 10TW-class laser systems could enable compact accelerators at kHz-repetition rates.

After analyzing stability of acceleration and possible limits of the scheme, we present energy scaling laws for both laser as well as electrons and detail experimental design considerations. By comparing the energy efficiency of various TWEAC designs to LWFA, we find using simulations that for low-angle TWEAC setups, it is possible to accelerate high-charge bunches with laser to electron beam energy efficiencies close to 50%, which exceeds energy efficiencies typically attained with LWFA.

Keywords: Laser-produced plasmas; Plasma-based accelerators; Laser-wakefield acceleration; Traveling-wave electron acceleration; TWEAC

  • Lecture (Conference)
    Laser-Plasma Accelerator Workshop 2019, 05.-10.5.2019, Split, Kroatien

Permalink: https://www.hzdr.de/publications/Publ-30624
Publ.-Id: 30624


Tomographic imaging of two-phase flow

Hampel, U.

The presentation gives an overview on the application of x-ray tomographic imaging for flow analysis in nuclear safety research. Its application is exemplified for two-phase flow imaging around a flow obstacle and gas holdup measurement in a heated rod bundle.

Keywords: tomographic imaging; X-ray tomography; two-phase flow; rod bundle

  • Lecture (Conference)
    3rd Sino-German Symposium on Fundamentals of Advanced Nuclear Safety Technology SG-FANS-3, 25.-27.09.2019, Xi'an, China

Permalink: https://www.hzdr.de/publications/Publ-30623
Publ.-Id: 30623


Determining impact of LWFA injection schemes on electron bunch profiles and peak currents based on broadband, spectral CTR diagnostics at single shot

Debus, A.; Zarini, O.; Laberge, M.; Couperus Cabadağ, J. P.; Köhler, A.; Kurz, T.; Schöbel, S.; Kraemer, J.; Hannasch, A. J.; Zgadzaj, R.; Mewes, H.; Meißner, H.; Bussmann, M.; Downer, M.; Schramm, U.; Irman, A.

Laser-wakefield accelerators (LWFA) feature electron bunch durations on a fs-scale. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future compact X-ray light sources. Resolution limits, as well as the limited reproducibility of electron bunches, pose big challenges for LWFA beam diagnostics.

Spectral measurements of broadband transition radiation from LWFA electron bunches passing through a metal foil are especially promising for analyzing ultrashort longitudinal bunch characteristics ranging from of tens of fs down to sub-fs.

Our broadband, single-shot spectrometer combines the TR spectrum in UV/VIS (200-1000nm), NIR (0.9-1.7μm) and mid-IR (1.6-12μm). A complete characterization and calibration of the spectrometer has been done with regard to wavelengths, relative spectral sensitivities and absolute photometric sensitivity. Our spectrometer is able to characterize electron bunches with charges as low as 1 pC and resolve time-scales from 0.7 to 40 fs. In addition, complementary data on the transverse bunch profile is provided by simultaneously imaging the CTR in the far- and near-field.

We present recent experimental results of different LWFA injection mechanisms, such as self-truncated ionization-injection and self-injection. By analyzing the transition radiation spectra and reconstructing electron bunch profiles including error analysis, we determine electron bunch profiles and peak currents of the respective injection regimes. In addition to bunch durations and peak currents, we discuss sub-fs beam micro-structures and systematic experimental scans of the nitrogen doping concentration for ionization-induced injection.

Keywords: LWFA; Laser-wakefield acceleration; peak current; injection scheme; broadband spectrometer; single-shot bunch length measurement; coherent transition radiation; absolute calibration; electron bunch duration; longitudinal profile; absolute calibration; UV; VIS; NIR; MIR

  • Lecture (Conference)
    Laser-Plasma Accelerator Workshop 2019, 05.-10.5.2019, Split, Kroatien

Permalink: https://www.hzdr.de/publications/Publ-30622
Publ.-Id: 30622


Imaging techniques for multiphase flows - Needs and recent developments

Hampel, U.

The presentation gives an overview over the state of the art in imaging techniques for multiphase flows in chemical engineering.

Keywords: imaging techniques; multiphase flow

  • Invited lecture (Conferences)
    Bernal Fluids Day, 26.06.2019, Limerick, Irland

Permalink: https://www.hzdr.de/publications/Publ-30621
Publ.-Id: 30621


Experimental analysis of reactive bubbly flows

Kipping, R.; Kryk, H.; Hampel, U.

Bubble column reactors are widespread in the chemical industry [1]. Hydrodynamics and mass transfer processes in bubble column reactors are difficult to predict, as they occur at different length and time scales. Thus, numerous parameters affect the performance of bubble column reactors in terms of yield and selectivity. These are the gas holdup, bubble size, bubble interfacial area, liquid-phase velocity, and mass transfer coefficients. In addition, the kinetics of the chemical reactions in a bubble column and the mixing of the reactants play a significant role and may even feedback on mass transfer and hydrodynamics. Within a German DFG Priority Programme we investigate the coupling between hydrodynamics, mass transfer and reaction in bubbly flows across the scales and with real chemical reaction systems [2]. Within this framework, our group studies the macroscale processes in laboratory bubble columns with selected experimental techniques. In our presentation, we will introduce two different ways for time-resolved local chemical species concentration measurement, i.e. the analysis of OH- consumption during chemisorption of CO2 in alkaline solution by electrochemical analysis using a wire-mesh sensor as well as chemical conversion of NO in Fe(II) (EDTA) solution with a fiber optical photospectrometry technique.

Keywords: bubble columns; mass transfer; chemical species concentration measurement

  • Lecture (Conference)
    Gas-Liquid and Gas-Liquid-Solid Reactor Engineering (GLS-14), 30.05.-03.06.2019, Guilin, China

Permalink: https://www.hzdr.de/publications/Publ-30620
Publ.-Id: 30620


Vacancy-Hydrogen Dynamics in Samples during Low Temperature Baking

Wenskat, M.; Bate, C.; Cizek, J.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Wagner, A.; Reschke, D.; Weise, H.

The recent discovery of a modified low temperature baking process established an increased accelerating gradient of TESLA shaped cavities through reduction of surface losses.
A possible explanation for the performance gain is the suppression of lossy nanohydrides via defect trapping, with vacancy-hydrogen (v+nH) complexes forming at the lower temperatures. Utilizing Doppler broadening Positron Annihilation Spectroscopy, Positron Annihilation Lifetime Spectroscopy and Nuclear Reaction Analysis, samples made from European XFEL niobium sheets and cavity cut-outs were investigated. The evolution of vacancies, hydrogen and their interaction at different temperature levels have been studied during in-situ and ex-situ annealing and in-situ cooldowns.
Measurements of niobium samples and a correlation between RF, material properties, and v+nH distribution in cavity cut-outs have been carried out.

Keywords: PAS; Nb; superconductivity; defects; hydrogen

Permalink: https://www.hzdr.de/publications/Publ-30619
Publ.-Id: 30619


Evaluation of separation and segregation in dynamic air classifiers

Buchmann, M.; Mütze, T.

Dynamic air classifiers separate particles in a gas flow due to their different trajectories. The characteristic property of separation is the settling velocity of the particles which is influenced by their size, shape, and density. The present contribution takes a close look at the separation behaviour of heterogeneous feeds, in which valuables and gangue minerals show significant differences in density. A new concept of multi-dimensional characterization of a separation process is presented and compared to the classical approach of the evaluation by partition curves (split factor, cut size, separation efficiency etc.) The new concept utilises the complex information from an automated mineral liberation analysis (MLA) and provides information of the enrichment and segregation of individual mineral phases in the products.

  • Open Access Logo Contribution to proceedings
    16th European Symposium on Comminution & Classification (ESCC 2019), 02.-04.09.2019, Leeds, United Kingdom
    DOI: 10.5518/100/17

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30617
Publ.-Id: 30617


Accelerated magnetic re-ordering in Ne+ irradiated FeAl thin films

Liedke, M. O.; Ehrler, J.; Bali, R.; Butterling, M.; Hirschmann, E.; Wagner, A.; Cizek, J.

Thermally activated (re)ordering processes in ferromagnetic Fe60Al40 thin films during in-situ annealing have been investigated by magnetometry and positron annihilation spectroscopy supported with atomic superposition calculations. A ferromagnetic A2-disordered phase coexists with a paramagnetic B2-ordered phase in the as-grown sputter deposited films. Due to thermal treatment at elevated temperature of 773K the B2-phase can be fully established. However, employing Ne+ irradiation as a tool to generate a pure A2-phase and subsequent mild temperature annealing the activation temperature for (re)ordering can be decreased to only 400K. It will be shown that due to immobile large vacancy clusters, which are dominant in the as-grown films and possess a high thermal activation barrier the ordering is strongly hindered.
Ion irradiation breaks down these pinning defects strongly accelerating thermal diffusion and reordering. These results provide insights into thermal reordering processes in binary alloys, and the consequent effect on magnetic behavior.

Keywords: positron annihilation spectroscopy; FeAl; AIDA; MePS; PALS; PAS

  • Lecture (Conference)
    DPG-Frühjahrstagung — Regensburg, 31.03.2019, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30616
Publ.-Id: 30616


Electrical field-controlled ON-OFF ferromagnetism in single metal oxide films

Liedke, M. O.; Butterling, M.; Quintana, A.; Menéndez, E.; Hirschmann, E.; Sireus, V.; Nogués, J.; Sort, J.; Wagner, A.; Elsherif, A. G. A.

With respect to applications, substituting electric currents, which are nowadays used to operate spintronic devices, with electric fields, would result in a reduction of both the energy consumption and cost [1]. Co3O4 is a candidate for a tunable, non-volatile energy-efficient functional material whose magnetic properties can be controlled by electric voltage. In our current investigations the as-grown Co3O4 films consist of a paramagnetic (PM) phase only, which is transformed to a ferromagnetic (FM) state by electrolyte-gated and defect-mediated O and Co transport. A negative voltage reduces Co3O4 to Co (FM: ON), resulting in a phase separated material with Co- and O-rich regions. Applying a positive bias, the process is reversed oxidizing Co back to Co3O4 (PM: OFF). We will show that atoms migration is driven by rather complex vacancy states and a clear increase of the grain boundaries volume after negative biasing assists to O transport. Moreover, concomitantly with the PM phase transition due to the positive biasing the structural defects picture reverses to a large extent as well, which manifests as reduction in volume of both vacancy clusters and grain boundaries. Doppler broadening and positron annihilation lifetime spectroscopy have been used as an in-situ probe of electric field driven ionic transport of Co and O via different type of defects in Co3O4 systems [2].
[1] Y. Shiota, et al. Nature Mater. 11, 39 (2012)
[2] A. Quintana, E. Menéndez, M. O. Liedke, M. Butterling, A. Wagner, et al. ACS Nano 12, 10291 (2018)

Keywords: positron; positron annihilation spectroscopy; AIDA; magnetism; voltage

  • Poster
    “From Matter to Materials and Life” (MML), 12.02.2019, Dresden, Deutschland
  • Invited lecture (Conferences)
    15th International Workshop on Slow Positron Beam Techniques & Applications (SLOPOS-15), 02.09.2019, Prague, Czech Republic
  • Lecture (Conference)
    The European Materials Research Society (E-MRS) Fall Meeting, 16.09.2019, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-30615
Publ.-Id: 30615


Measurement systems for liquid metals

Wondrak, T.

This talk represents an introduction into measurement techniques for liquid metals including invasive probes, ultrasonic and inductive methods as well as x-ray radiography.

Keywords: liquid metal; measurement techniques

  • Invited lecture (Conferences)
    PAMIR summer school 2019, 02.-5.7.2019, Reims, France

Permalink: https://www.hzdr.de/publications/Publ-30614
Publ.-Id: 30614


Inductive measurement techniques for liquid metals

Wondrak, T.

This talk represents an introduction into inductive measurement techniques for liquid metals.

Keywords: liquid metals; inductive measurement techniques; flow measurement

  • Invited lecture (Conferences)
    MHD Modelling School 2019, 14.-18.10.2019, Riga, Latvia

Permalink: https://www.hzdr.de/publications/Publ-30613
Publ.-Id: 30613


Misunterstandings – how dies the mining industry present itself in Europe and how is it perceived by society?

Reuter, M. A.

Europe’s mining sector aligns itself with the sustainability agenda through concepts such as the circular economy, the coming energy and resource transition, a zero-waste economy, etc. Ironically, these concepts also cause misunderstandings within society, most notably that no more mining or smeltering will be needed. This can be seen in the current debate on the ban of lead, i.e. lead is a necessary carrier element for many CRMs and lead-metallurgy is fundamental for a true circular economy. Is education enough to overcome these misunderstandings or is something else needed?

Keywords: Mireu; research; Social License to Operate; SLO; sustainability; circular economy; lead

  • Invited lecture (Conferences)
    3rd SLO workshop: ensuring SLO is adaptive and resilient, 05.-06.06.2019, Brüssel, Belgien

Permalink: https://www.hzdr.de/publications/Publ-30612
Publ.-Id: 30612


Contribution to the structure of the periodic classification of metals - Metals enable Future® Metalle vernetzen Zukunft®

Reuter, M.

The importance of metals in society //
The fundamental role of metals (incl. lead) in a circular society//
Metallurgical infrastructure criticality in a circular society

Keywords: metals; circular society; circular economy

  • Invited lecture (Conferences)
    EMC 2019 – 10th European Metallurgical Conference, 23.-26.06.2019, Düsseldorf, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30610
Publ.-Id: 30610


Inductive and resistive methods for gas detection

Wondrak, T.; Gundrum, T.; Willers, B.

This talk gives an overview about resistive and inductive methods for bubble detection in liquid metals.

Keywords: liquid metal; bubble detection

  • Lecture (Conference)
    ESFR-SMART European Workshop on Instrumentation for the Safety of Liquid Metal Facilities, 10.-12.04.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30609
Publ.-Id: 30609


Contactless inductive flow tomography

Wondrak, T.; Ratajczak, M.; Stefani, F.

This talk gives an overview of the contactless inductive flow tomography and recent developments at HZDR.

Keywords: contactless inductive flow tomography; inductive flow measurement; liquid metal

  • Lecture (Conference)
    ESFR-SMART European Workshop on Instrumentation for the Safety of Liquid Metal Facilities, 10.-12.04.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30608
Publ.-Id: 30608


“UniCAR”-modified off-the-shelf NK-92 cells for targeting of GD2-expressing tumour cells

Mitwasi, N.; Feldmann, A.; Arndt, C.; Koristka, S.; Berndt, N.; Jureczek, J.; Loureiro, L.; Bergmann, R.; Máthé, D.; Hegedüs, N.; Kovács, T.; Zhang, C.; Oberoi, P.; Jäger, E.; Seliger, B.; Rössig, C.; Temme, A.; Eitler, J.; Tonn, T.; Schmitz, M.; Hassel, J.; Jäger, D.; Wels, W.; Bachmann, M.

Antigen-specific redirection of immune effector cells with chimeric antigen receptors (CARs) demonstrated high therapeutic potential for targeting cancers of different origins. Beside CAR-T cells, natural killer (NK) cells represent promising alternative effectors that can be combined with CAR technology. Unlike T cells, primary NK cells and the NK cell line NK-92 can be applied as allogeneic off-the-shelf products with a reduced risk of toxicities. We previously established a modular universal CAR (UniCAR) platform which consists of UniCAR-expressing immune cells that cannot recognize target antigens directly but are redirected by a tumour-specific target module (TM). The TM contains an antigen-binding moiety fused to a peptide epitope which is recognized by the UniCAR molecule, thereby allowing an on/off switch of CAR activity, and facilitating flexible targeting of various tumour antigens depending on the presence and specificity of the TM. Here, we provide proof of concept that it is feasible to generate a universal off-the-shelf cellular therapeutic based on UniCAR NK-92 cells targeted to tumours expressing the disialoganglioside GD2 by GD2-specific TMs that are either based on an antibody-derived single-chain fragment variable (scFv) or an IgG4 backbone. Redirected UniCAR NK-92 cells induced specific killing of GD2-expressing cells in vitro and in vivo, associated with enhanced production of interferon-γ. Analysis of radiolabelled proteins demonstrated that the IgG4-based format increased the in vivo half-life of the TM markedly in comparison to the scFv-based molecule. In summary, UniCAR NK-92 cells represent a universal off-the-shelf platform that is highly effective and flexible, allowing the use of different TM formats for specific tumour targeting.

Permalink: https://www.hzdr.de/publications/Publ-30607
Publ.-Id: 30607


Pulsed-Magnet Developments at the Dresden High Magnetic Field Laboratory

Zherlitsyn, S.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    MT 26 - International Conference on Magnet Technology, 22.-27.09.2019, Vancouver, Canada

Permalink: https://www.hzdr.de/publications/Publ-30606
Publ.-Id: 30606


Pressure-Tuning the Quantum Spin Hamiltonian of the Triangular Lattice Antiferromagnet Cs2CuCl4: High-Field ESR Studies

Zvyagin, S.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Conference EPR-75 (Electron Paramagnetic Resonance (EPR)), 23.-27.09.2019, Kazan, Russia

Permalink: https://www.hzdr.de/publications/Publ-30604
Publ.-Id: 30604


Spin-Lattice Coupling in a Yafet-Kittel Ferrimagnetic Spinel

Miyata, A.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    14th Asia-Pacific Physics Conference (APPC), 17.-22.11.2019, Kuching, Malaysia

Permalink: https://www.hzdr.de/publications/Publ-30603
Publ.-Id: 30603


Materialien die sich Kälte merken

Gottschall, T.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Verständliche Wissenschaft 2019, 14.02.2019, Geesthacht, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30602
Publ.-Id: 30602


Magnetocaloric materials for solid-state refrigeration

Gottschall, T.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Institutsseminar Fraunhofer IWS, 02.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30601
Publ.-Id: 30601


A short history about (nearly) everything concerning bio-research in Dresden

Schäfer, S.

  • Lecture (others)
    Vorlesung an der Universidad de Granada, 17.12.2019, Granada, Spain

Permalink: https://www.hzdr.de/publications/Publ-30600
Publ.-Id: 30600


Development of turbulent cellular structures in Rayleigh-Benard convection in a finite liquid metal layer

Tasaka, Y.; Akashi, M.; Yanagisawa, T.; Vogt, T.; Eckert, S.

Large-scale, coherent flow structures of Rayleigh-Bénard convection in a finite liquid metal layer were examined experimentally by means of ultrasonic Doppler velocimetry. The fluid layer with aspect ratio of five and L = 40 mm in height was filled with eutectic alloy of GaInSn (Prandtl number, Pr = 0.03), and multiple ultrasonic transducers for the velocimetry were mounted in the side wall of the vessel to capture three-dimensional structures of the convection.
Spatio-tempral velocity maps obtained at different Rayleigh numbers in the range, 7900 < Ra < 180000, elucidated emergences of wavy-roll-like coherent structures, where the roll axis is determined quasi-randomly. The roll structure takes transition with reducing the number of rolls from four to three as Ra increases via intermediate regime between the two conditions, four or three rolls. With further increase of Ra a cellular structure with characteristics of fully developed thermal turbulence occupies the entire fluid layer. We will discuss details on derivation of the power law and relation with turbulent superstructures that have recently been discussed.

Keywords: Rayleigh-Benard convection; liquid metal; velocity measurements; coherent structures

  • Lecture (Conference)
    17th European Turbulence Conference, 03.-06.09.2019, Torino, Italy

Permalink: https://www.hzdr.de/publications/Publ-30597
Publ.-Id: 30597


Liquid Metal Model Experiments for Continuous Casting of Steel

Schurmann, D.; Eckert, S.

Experimental investigations of the fluid flow in the continuous casting mold are performed at the Mini-LIMMCAST facility of HZDR, which is a liquid metal mockup operated with GaInSn at room temperature. Velocity measurements in the non-transparent liquid metal are performed by means of the ultrasound Doppler velocimetry (UDV), which enables the reconstruction of the complex flow pattern in the mold. The focus of our study is on the influence of different electromagnetic actuators like electromagnetic brakes (EMBr) or electromagnetic stirring (EMS) on the mold flow in slab and bloom geometries.

Keywords: experimental investigation; liquid metal model; continuous casting; electromagnetic brake; electromagnetic stirring

  • Lecture (others)
    CFD and Thermomechanics Days, 04.-06.02.2020, Online, Internet

Permalink: https://www.hzdr.de/publications/Publ-30596
Publ.-Id: 30596


Novel low resistivity glass: MRPC detectors for ultra high rate applications

Liu, Z.; Beyer, R.; Dreyer, J.; Fan, X.; Greifenhagen, R.; Kim, D.-W.; Kotte, R.; Laso García, A.; Naumann, L.; Römer, K.; Stach, D.; Uribe Estrada, C.; Williams, M. C. S.; Zichichi, A.

Multigap Resistive Plate Chambers (MRPCs) are often used as time-of-flight (TOF) detectors for high-energy physics and nuclear experiments thanks to their excellent time accuracy. For the Compressed Baryonic Matter (CBM) TOF system, MRPCs are required to work at particle fluxes on the order of 1-10 kHz/cm² for the outer region and 10-25 kHz/cm² for the central region. Better time resolution will allow particle identification with TOF techniques to be performed at higher momenta. From our previous studies, a time resolution of 25 ps has been obtained with a 20-gap MRPC of 140 µm gap size with enhanced rate capbability. By using a new type of commercially available thin low-resistivity glass, further improvement MRPC rate capability is possible. In order to study the rate capability of the 10-gap MRPC built with this new low-resistivity glass, we have performed tests using the continuous electron beam at ELBE. This 10-gap MRPC, with 160 µm gaps, reaches 97% efficiency at 19.2 kV and a time resolution of 36 ps at particle fluxes near 2 kHz/cm². At a flux of 100 kHz/cm², the efficiency is still above 95% and a time resolution of 50 ps is obtained, which would fulfil the requirement of CBM TOF system.

Keywords: Multigap resistive plate chamber; Low resistivity glass; Rate capability; Efficiency; Time resolution

Permalink: https://www.hzdr.de/publications/Publ-30595
Publ.-Id: 30595


Interprofessionelle Kooperation in klinischen Studien. Zunehmender Bedarf, Komplexität und Anregungen am Beispiel einer prospektiv-onkologischen Multicenter-Studie.

Zippel, C.; Giesel, F.; Kopka, K.

Um neue Erkenntnisse in für Patienten nützliche Behandlungsansätze überführen zu können, werden in der medizinischen (onkologischen) Translationsforschung zunehmend prospektive klinische Studien initiiert. Damit diese Studien möglichst effizient und effektiv durchgeführt werden können, bedarf es der engen Kooperation und Kommunikation von Experten aus verschiedenen Berufsgruppen. In diesem Aufsatz beleuchten wir am Beispiel der prospektiven onkologisch-klinischen DKTK-PSMA-Studie der Phasen-I/-II „68Ga-PSMA-11 in Hochrisiko-Prostatakrebs“, welche wesentlichen Professionen bei der Planung, Vorbereitung und Durchführung von (nuklearmedizinisch) klinischen Studien involviert sein können und welche essenziellen Aufgaben diese zur Verwirklichung der Studie leisten. Darauf aufbauend führen wir allgemeine organisatorische Maßnahmen an, durch welche die interprofessionelle Zusammenarbeit bei künftig weiteren (nicht nur onkologischen)
Studien gefördert werden kann.

Downloads:

  • Secondary publication expected from 10.02.2021

Permalink: https://www.hzdr.de/publications/Publ-30594
Publ.-Id: 30594


Challenges of the Circular Economy

Reuter, M. A.

A Circular Economy (CE) paradigm aims to maximize sustainability and resource efficiency by extending product life cycles and using wastes as resources. So, what is the brave step that will deliver the CE for modern services, complex products, and society in general? Questions we should, among others, ask and attempt to answer are (i) What are the challenges to achieve this move forward? (ii) What does the metallurgical infrastructure have to be that maximally recovers materials from increasingly complex products and services, while returning high quality materials back into the CE? (iii) What smart energy and water grid will maximize resource efficiency and minimize exergy destruction of an increasingly complex society and system? In order to answer these questions, the role of metallurgical processing systems, smart materials production, digital technology platforms, product design etc. will be discussed in the context of Sustainable Circular Cities. It will furthermore be shown how digitalized real-time simulation and control of material and metal flow and metallurgical processing systems i.e. the “Smart Materials Grid - SMG” will form the heart of the CE system. The SMG will integrate into the water, energy, transport, heavy industry, and other grid systems and will help drive the resource efficiency of the future “Sustainable Circular Cities.” This will help to enable “Smart Sustainable Living” by also helping to quantify and realize the United Nation’s Sustainability Development Goals.

Keywords: Circular Economy; sustainability; resource efficiency; CE

  • Invited lecture (Conferences)
    REWAS 2019 Plenary Session, 10.-14.03.2019, San Antonio, Texas, USA

Permalink: https://www.hzdr.de/publications/Publ-30593
Publ.-Id: 30593


Sub-10 nm Radiolabeled Barium Sulfate Nanoparticles as Carriers for Theranostic Applications and Targeted Alpha Therapy

Reissig, F.; Zarschler, K.; Hübner, R.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.

The treatment of patients suffering from cancer with α-particle-emitting therapeutics continues to receive increasing interest. The range of radiopharmaceutically relevant α-emitters is limited to only a few radionuclides (e.g. actinium-225 and bismuth-213) as stable chelators or carrier systems for safe transport of the radioactive cargo are often lacking. Encapsulation of α-emitters into solid inorganic systems can help to diversify the portfolio of candidate radionuclides, providing that these nanomaterials effectively retain both the parent and the recoil daughters. We therefore focus on the design of stable and defined nanocarrier-based systems for various radionuclides including the promising α-emitting radionuclide radium-224. Hence, we report on the synthesis of sub-10 nm alendronate-functionalized barium sulfate nanoparticles, into whose matrix different radiometals including zirconium-89, indium-111, barium-131, barium-133, lutetium-177 and radium-224 were stably incorporated with appropriate yields. Our delivery systems show stabilities of g.t. 90% up to seven days regarding the radiometal release from the BaSO4 matrix. Furthermore, radium-224-labeled particles possess stabilities of 80% regarding the decay chain product lead-212. In fact, the majority of nanoparticles withstand the α-recoil and keeps the daughter radionuclides trapped. Noteworthy, due to the accessibility of reactive alendronate amine groups on their surface, it is possible to further modify this functionalized inorganic system by common amine-coupling strategies as exemplified herein by conjugation of fluorescein isothiocyanate. The synthesized nanoparticles exhibit some degree of nonspecific protein binding upon exposure to human serum, offering the possibility to add beneficial properties of a protein corona to the intrinsic features of the nanosystem.

Keywords: radium; alpha therapy; nanoparticle; delivery system

Permalink: https://www.hzdr.de/publications/Publ-30591
Publ.-Id: 30591


New Strategies for Imaging of Brain Cancer with Radiopharmaceuticals

Brust, P.

Background:
Brain cancer is a challenge for the health care system because of major problems for treatment. Radical surgery is not possible. Radiation treatment is restricted by missing borderlines, and drug treatment is limited by the blood-brain barrier. Therefore, glioblastoma multiforme, the most aggressive type of primary brain tumors, has a median overall survival of only ~12 months. Although new molecular pathways are being constantly discovered, translation of basic science into clinical practice is rather slow. Major obstacles in the resistance to therapy are heterogeneity of brain tumors, multiple genetic alterations, and their diffuse, infiltrative behavior. Hence monitoring of pathways related to tumor etiology and growth is highly important.
Methodology:
Positron emission tomography (PET) offers the potential to identify key signaling and metabolic pathways in tumors and to discover drugs for targeted therapy. An important prerequisite for PET is the development of radiolabeled molecules (radiotracer) to investigate impaired brain functions in living human subjects. Fluorine-18 is currently the most favorable radionuclide that is routinely used for radiolabeling because of its half-life of 109.8 min. The presentation will focus on the development of fluorine-18 labelled radiotracers bridging from basic science to biomedical application and focusing on four targets of major importance for brain cancer.
Results and Discussion:
Cannabinoids are known to induce apoptosis of glioma cells and the extent of cannabinoid CB2 receptor expression is related to tumor malignancy. The challenge in radiotracer development is the high expression of CB1 receptors. Therefore our strategies will be presented to achieve highly selective PET radiotracers for CB2 receptors.
The immunosuppressive effects of adenosine and the adenosine-triggered activation of catabolic energy production account for pro-cancer roles of extracellular adenosine. Accordingly, plasma-membrane-bound adenosine receptors were identified as new targets in the immunotherapy of brain tumors. Currently, we have PET radiotracers for A2A and A2B receptors under development, which are regarded as potential tools for therapy monitoring.
Sigma receptors, previously regarded as opioid receptors, are comprised of the σ1 and σ2 subtypes and represent orphan receptors of different families. While the σ1 receptor is a molecular chaperone, which interacts with various ion channels and G-protein coupled receptors, the σ2 receptor (TMEM97) is an intracellular protein located at the endoplasmatic reticulum that binds numerous drugs. There is evidence that both subtypes are important for glioblastoma growth thus facilitating the ongoing development of selective PET radiotracers for both subtypes in our department.
Furthermore, as other cancers glioblastoma is characterized by metabolic reprogramming to preferentially undergo aerobic glycolysis. The elevated production of lactate is accompanied by the increased expression of monocarboxylate transporters (MCTs). Accordingly a therapeutic approach targeting MCTs is a promising strategy in brain cancer treatment. A PET radiotracer for peripheral MCT1/MCT4 imaging has already been developed by us and will be discussed concerning its suitability for glioblastoma imaging.
Conclusion:
Numerous attempts are ongoing for molecular characterization of brain cancer with PET radiopharmaceuticals. It is expected that they will support in the future patient stratification and hence individualized therapy.

  • Lecture (Conference)
    International Symposium on Trends in Radiopharmaceuticals - ISTR 2019, 28.10.-01.11.2019, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-30590
Publ.-Id: 30590


Metallurgy is fundamental to the Circular Economy

Reuter, M. A.

The importance of metals in society,
The fundamental role of metals (incl. lead) in a circular society,
Metallurgical infrastructure criticality in a circular society

Keywords: metals; circular society

Related publications

  • Invited lecture (Conferences)
    International Lead Association conference, 19.-21.06.2019, Madrid, Spanien

Permalink: https://www.hzdr.de/publications/Publ-30589
Publ.-Id: 30589


Disturbing-free determination of yeast concentration in DI water and in glucose using impedance biochips

Kiani, M.; Du, N.; Vogel, M.; Raff, J.; Hübner, U.; Skorupa, I.; Bürger, D.; Schulz, S. E.; Schmidt, O. G.; Blaschke, D.; Schmidt, H.

Deionized water and glucose with yeast (Saccharomyces cerevisiae) of optical density OD600 ranging from 4 to 16 has been put in the ring electrode region of impedance biochips and impedance has been measured in dependence on the added volume (20, 21, 22, 23, 24, 25 L). Modeled impedance of the biochip reveals a linear relationship between the impedance model parameters and yeast concentration. Presented biochips allow for continuous impedance measurements without interrupting the cultivation of the yeast. A multiparameter fit of the impedance model parameters allows to determine the concentration of yeast cy in the range from cy = 3.3x107 to cy = 17x107 cells/mL. This work shows that independent on the liquid, DI water or glucose, the change of the impedance model parameters with increasing added volume of the liquid is clearly distinguishable from the change of impedance model parameters with increasing concentration of added yeast in the ring electrode region of the impedance biochips.

Keywords: Biochips; impedance spectroscopy; yeast Saccharomyces cerevisiae; electrical equivalent circuit; biomaterial; biosensing

Permalink: https://www.hzdr.de/publications/Publ-30588
Publ.-Id: 30588


Lead Metallurgy is Fundamental to the Circular Economy Policy Brief SOCRATES EU MSCA-ETN

Reuter, M.; Malfliet, A.; Blanpain, B.

Metals are eminently recyclable, and by recycling and refining complex materials, the EU's interconnected metals sector is responding to the increasing scarcity of certain metals. In this way, we are delivering and recovering the technology and base metals for the EU's Circular Economy (CE). Moreover, metals are at the heart of the energy infrastructures that now run Circular Cities, and they will play an even greater part in the future. One of these metals is lead. With respect to this familiar metal, industry is fully aware that in order to keep on using it, the associated risks need to be well managed at all times. Importantly, lead is a key enabler in the CE, as it is capable of dissolving and carrying a multitude of technology elements. The recovery and recycling of several critical technology elements is based on refining them from lead through well-developed metallurgical processes in which the lead acts as a carrier metal. Limiting lead metallurgy would have a detrimental impact, not only on the lead industry itself, but on all the industries linked to it. It is therefore critical that we maintain and further develop the lead infrastructure and know-how in Europe. To put it simply, lead metallurgy is fundamental if the EU wants to retain its leading position in the global CE. Executive Summary the 5 lessons learned: • Lesson 1: Lead is frequently seen as a problematic metal that can be detrimental to human health; what is much less well known is its fundamental role in extrac-tive metallurgy and how this is closely associated with the Circular Economy. • Lesson 2: Molten lead has unique properties that means it can act as an efficient liquid carrier for critical raw materials such as In, Bi, Cd and Te. • Lesson 3: Restricting lead metallurgy in the EU would not only have a detrimental impact on the lead industry, but also on all the industries linked to it that work with elements like Ag, Cu, Sb, Sn, Te, and Zn. • Lesson 4: The focus must be on correctly and comprehensively minimising the risks of lead-containing materials for society and carefully managing them, rather than attempting to ban the use of lead. • Lesson 5: An environmentally friendly and energy-efficient lead infrastructure together with the associated research and know-how in Europe is absolutely vital if the continent is to maintain its global leadership in the Circular Economy.

Keywords: recyclable; recycling; EU's Circular Economy; CE; Circular Cities; lead; research

Related publications

  • Other report
    ---: ETN Socrates, 2019
  • Lecture (Conference)
    Fifth SOCRATES network-wide event, 19.-21.02.2019, Leicester, England

Permalink: https://www.hzdr.de/publications/Publ-30586
Publ.-Id: 30586


Process metallurgy and systems in circular city design – the challenges

Reuter, M. A.

Realising the circular economy is faced with some significant challenges. Process metallurgy and its infrastructure play key roles at the heart of making the circular economy work. The enabling role of process metallurgy within the circular economy and circular cities will be discussed, touching also on product and system design.

Keywords: circular economy; process metallurgy; product and system design

  • Invited lecture (Conferences)
    Connecting Innovation in the Raw Materials Sector / EIT Raw Materials summit 2019, 20.-22.05.2019, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30585
Publ.-Id: 30585


PET-Radiopharmaka - höchste Ansprüche an die Herstellung von radioaktiven Arzneimitteln für Patienten

Knieß, T.

"Radiopharmaka sind Arzneimittel die Radionuklide enthalten, deren Strahlungsaktivität unter anderem auch häufig auch für die Diagnose von Krebserkrankungen genutzt wird. Dabei werden bildgebende Verfahren angewandt, wo die emittierte Strahlung von einer Gamma-Kamera oder einem Tomographen aufgezeichnet wird. Für die Herstellung der Radiopharmaka werden spezielle Kenntnisse, Verfahren und Ausrüstungen benötigt. Der Vortrag beschreibt die Herstellung solcher kurzlebigen radioaktiven Arzneimittel im Helmholtz-Zentrum Dresden-Rossendorf und skizziert deren Anwendung in der Nuklearmedizin."

  • Lecture (others)
    Akademische Woche 2020, 05.02.2020, Meißen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30584
Publ.-Id: 30584


Stability criterion for the magnetic separation of rare-earth ions

Lei, Z.; Fritzsche, B.; Eckert, K.

The stability criterion for the magnetic separation of rare-earth ions is studied, taking dysprosium Dy(iii) ions as an example. Emphasis is placed on quantifying the factors that limit the desired high enrichment. During magnetic separation, a layer enriched in Dy(iii) ions is generated via the surface evaporation of an aqueous solution which is levitated by the Kelvin force. Later, mass transport triggers instability in the enriched layer. The onset time and position of the instability is studied using an interferometer. The onset time signals that an advective process which significantly accelerates the stratification of enrichment is taking place, although the initial phase is quasi-diffusion-like. The onset position of the flow agrees well with that predicted with a generalized Rayleigh number (Ra∗=0) criterion which includes the Kelvin force term acting antiparallel to gravity. Further three-dimensional analysis of the potential energy, combining magnetic and gravitational terms, shows an energy barrier that has to be overcome to initiate instability. The position of the energy barrier coincides well with the onset position of the instability.

Keywords: Evaporation; Flow instability; Instability control; Optical interferometry; Transport phenomena

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30582
Publ.-Id: 30582


Spectral tomography for 3D mineral and chemical analysis

Da Assuncao Godinho, J. R.; Renno, A.; de Schryver, T.; Masschaele, B.

A new analytical tool for mineral analysis will be introduced: Laboratory-based Spectral 3D X-ray Computed Tomography (Sp-CT). Results from a spectral imaging detector, prototype installed inside a TESCAN CoreTOM micro-CT system, will be presented and discussed in the context of mineralogical and chemical analysis of geological materials. The technique will be demonstrated to allow:
a) 3D mineral classification from the transmitted energy spectrum characteristic of a mineral phase.
b) Quick bulk chemical quantification of heavy elements with K-edge > 20 keV at high concentrations that are difficult to analyse by other methods.
c) Reducing common CT artefacts such as scattering and beam hardening, as well as improved contrast by selectively choose the most convenient energy range.
The advantages of Sp-CT will open new possibilities in geometallurgy and minerals processing research to move from the predominant 2D based image characterization towards more representative 3D characterization. These are fundamental steps to enable automated and routine 3D characterization that ultimately has the potential to provide faster and lower cost analysis to, for example, the mining industry, as well as more comprehensive rock characterization technique for Earth sciences research.

Keywords: XRCT; spectral XRCT

  • Poster
    PRORA - 10. Fachtagung Prozessnahe Röntgenanalytik, 28.-29.11.2019, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30581
Publ.-Id: 30581


Applications in the Resource Industry - Between Handheld Instruments and 4D Methods

Renno, A.; Da Assuncao Godinho, J. R.; Gutzmer, J.; Kelly, N.; Reuter, M.; Seidel, P.; Sittner, J.; Winardhi, C. W.

An exemplary overview of the use of X-ray-based analytical methods in the resource industry, underpinned by examples, gives a very heterogeneous picture. The use of these methods is considered in the exploration, mining, mechanical processing and metallurgical/chemical processing of primary and secondary mineral and metallic raw materials.
Although X-ray diffraction, fluorescence, absorption and luminescence as well as various tomographic methods cover a very broad spectrum of methods, in many cases their use is apparently rather arbitrary, regardless of the respective matrix, technology and location.
For example for offline characterisation of raw materials and intermediates, established and reliable methods as well as pure estimation methods are used. In inline analytics, ad-hoc analytical instruments are used in addition to metrologically well-proven measuring systems that are well integrated into the respective technological processes. The enforcement of state standards with regard to environmental protection and resource use leads to a significant increase in the use of analytical technology and increased requirements for the certification of procedures.
A conspicuous feature is the constantly growing use of mobile "handheld devices", which are often used at decisive points to control the flow of materials. Very often, it can be observed that these devices, which in principle are very powerful, work under their respective capabilities or lead to significantly wrong results due to insufficiently thought-out and implemented measuring methods.
Almost all inline analytical methods used for sorting or process monitoring have the characteristic that they only lead to binary decisions. A comprehensive characterization of the material flow, which would lead both to flexible adaptation of the technologies used subsequently and to a significantly more differentiated splitting of the material flow, is a consequence of the ever more complex properties of the primary and secondary raw materials. This is the result of the change to economic forms with significantly stronger elements of a circular economy.
On the basis of current research at the HIF, it is presented how such a multi-effective measuring system could be designed. Furthermore, the advantages of the use of 3D methods in the characterization of primary and secondary raw materials as well as in the description of technological processes will be demonstrated. Both spectral XRCT (X-Ray Computed Tomography) and dynamic time-resolved XRCT methods are used.

Keywords: Resource Industry; Process Analysis; X-Ray Methods

  • Invited lecture (Conferences)
    PRORA - 10. Fachtagung Prozessnahe Röntgenanalytik, 28.-29.11.2019, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30580
Publ.-Id: 30580


Halogen analysis of sulphide minerals at the ultratrace level – first applications of the Dresden Super-SIMS

Renno, A.; Rugel, G.; Wiedenbeck, M.; Ziegenrücker, R.

The integration of an ion source having very high spatial resolution with a tandem accelerator is a long-standing concept for improving analytical selectivity and sensitivity by orders of magnitude [1]. Translating this design concept into reality has its challenges [e.g. 2,3], meaning this approach has seldom been employed for mineralogical and geochemical research [e.g. 4].
Supporting a strong focus on natural, metallic and mineral resources, the Helmholtz Institute Freiberg for Resource Technology installed a so-called Super-SIMS at the Ion Beam Center at HZDR in Dresden-Rossendorf; this highly novel tool is devoted to the characterization of minerals and ores. The secondary ion beam from a CAMECA IMS 7f-auto is injected into the 6MV Dresden Accelerator Mass Spectrometry [5] facility, which effectively eliminates all molecular species from the ion beam.
We will present the current status of this initiative and will report our first results from halogen determinations (F, Cl, Br, I) in both sphalerite and galena. These data demonstrate a systematic and significant change in the counting rates of all halogens in mineralogically distinct areas of both minerals. Furthermore, we will describe our concepts for the quantification of these data at ultratrace levels.


[1] Matteson (2008) Mass Spec Rev 27, 470-484. [2] Ender et al. (1997) NIMB 123, 575-578. [3] Fahey et al. (2016) Anal Chem 88, 7145-7153. [4] Sie et al. (2000) NIMB 172, 228-234. [5] Rugel et al. (2016) NIMB 370, 94-100.

Keywords: SIMS; Super-SIMS; Halogen; Sphalerite; Galena

  • Lecture (Conference)
    GEOMÜNSTER 2019, 22.-25.09.2019, Münster, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30579
Publ.-Id: 30579


Halogen analysis at the ultratrace level – first applications of the Dresden Super-SIMS

Renno, A.; Akhmadaliev, S.; Belokonov, G.; Böttger, R.; Borany, J.; Kaever, P.; Meyer, M.; Noga, P.; Rugel, G.; Tiessen, C. J.; Wagner, N.; Wiedenbeck, M.; Wu, H.; Ziegenrücker, R.

The integration of an ion source having very high spatial resolution with a tandem accelerator is a long-standing concept for improving analytical selectivity and sensitivity by orders of magnitude [1]. Translating this design concept into reality has its challenges [e.g. 2,3], meaning this approach has seldom be used in the framework of geochemical research [e.g. 4].
Supporting a strong focus on natural, metallic and mineral resources, the Helmholtz Institute Freiberg for Resource Technology installed a so-called Super-SIMS at the Ion Beam Center at HZDR; this highly novel tool is devoted to the characterization of minerals and ores. The secondary ion beam from a CAMECA IMS 7f-auto is injected into the 6MV Dresden Accelerator Mass Spectrometry [5] facility, which quantitatively eliminates effectively all molecular species from the ion beam.
We will present the current status of this initiative and will report on the performance parameters of the Dresden Super-SIMS as well as first results from halogen determinations in sphalerite and galena. Furthermore, we will describe our concepts for the quantification of these data at the ultratrace level.
[1] Matteson (2008) Mass Spec Rev 27, 470-484. [2] Ender et al. (1997) NIMB 123 575-578. [3] Fahey et al. (2016) Anal Chem 88, 7145-7153. [4] Sie et al. (2000) NIMB 172, 228-234. [5] Rugel et al. (2016) NIMB 370 94-100.

Keywords: SIMS. Super-SIMS; Sphalerite; Halogen

  • Lecture (Conference)
    GOLDSCHMIDT 2019, 18.-23.08.2019, Barcelona, Spanien

Permalink: https://www.hzdr.de/publications/Publ-30578
Publ.-Id: 30578


Single-Shot Multi-keV X-Ray Absorption Spectroscopy Using an Ultrashort Laser-Wakefield Accelerator Source

Kettle, B.; Gerstmayr, E.; Streeter, M. J. V.; Albert, F.; Baggott, R. A.; Bourgeois, N.; Cole, J. M.; Dann, S.; Falk, K.; Gallardo González, I.; Hussein, A. E.; Lemos, N.; Lopes, N. C.; Lundh, O.; Ma, Y.; Rose, S. J.; Spindloe, C.; Symes, D. R.; Smid, M.; Thomas, A. G. R.; Watt, R.; Mangles, S. P. D.

Single-shot absorption measurements have been performed using the multi-keV x rays generated by alaser-wakefield accelerator. A 200 TW laser was used to drive a laser-wakefield accelerator in a modewhich produced broadband electron beams with a maximum energy above 1 GeVand a broad divergence of ≈15mrad FWHM. Betatron oscillations of these electrons generated1.2 0.2×106photons=eV in the5 keV region, with a signal-to-noise ratio of approximately 300∶1. This was sufficient to allow high-resolution x-ray absorption near-edge structure measurements at theKedge of a titanium sample in a singleshot. We demonstrate that this source is capable of single-shot, simultaneous measurements of both theelectron and ion distributions in matter heated to eV temperatures by comparison with density functionaltheory simulations. The unique combination of a high-flux, large bandwidth, few femtosecond durationx-ray pulse synchronized to a high-power laser will enable key advances in the study of ultrafast energeticprocesses such as electron-ion equilibration.

Permalink: https://www.hzdr.de/publications/Publ-30577
Publ.-Id: 30577


Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures

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

Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used for imaging applications. Non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials can provide insight into their processing, structure, and performance. To demonstrate the imaging capability of X-rays from an LWFA we have examined an irregular eutectic in the aluminum-silicon (Al-Si) system. The lamellar spacing of the Al-Si eutectic microstructure is on the order of a few micrometers, thus requiring high spatial resolution. We present comparisons between the sharpness and spatial resolution in phase contrast images of this eutectic alloy obtained via X-ray phase contrast imaging at the Swiss Light Source (SLS) synchrotron and X-ray projection microscopy via an LWFA source. An upper bound on the resolving power of 2.7 ± 0.3 μm of the LWFA source in this experiment was measured. These results indicate that betatron X-rays from laser wakefield acceleration can provide an alternative to conventional synchrotron sources for high resolution imaging of eutectics and, more broadly, complex microstructures.

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Permalink: https://www.hzdr.de/publications/Publ-30576
Publ.-Id: 30576


Renewable Methanol Synthesis

Roode-Gutzmer, Q. I.; Kaiser, D.; Bertau, M.

Renewable methanol production is an emerging technology that bridges the gap in the shift from fossil fuel to renewable energy. Two thirds of the global emission of CO₂ stems from humanity’s increasing energy need from fossil fuels. Renewable energy, mainly from solar and wind energy, suffers from supply intermittency, which current grid infrastructures cannot accommodate. Excess renewable energy can be harnessed to power the electrolysis of water to produce hydrogen, which can be used in the catalytic hydrogenation of waste CO₂ to produce renewable methanol. This review considers methanol production in the current context, regionally for Europe, which is dominated by Germany, and globally by China. Appropriate carbon-based feedstock for renewable methanol production is considered, as well as state-of-the-art renewable hydrogen production technologies. The economics of renewable methanol production necessitates the consideration of regionally relevant methanol derivatives. The thermodynamics, kinetics, catalytic reaction mechanism, operating conditions and reactor design are reviewed in the context of renewable methanol production to reveal the most up to date understanding.

Keywords: Catalysis; Energy storage; Hydrogenation of CO₂; Renewable methanol; Waste CO₂

Permalink: https://www.hzdr.de/publications/Publ-30575
Publ.-Id: 30575


The role of gas impurities on the optical properties of sputtered Ti(Al)N coatings

Bohovičová, J.; Meško, M.; Méndez, Á.; Julin, J. A.; Munnik, F.; Hübner, R.; Grenzer, J.; Čaplovič, Ľ.; Krause, M.

In this study, we investigated the role of impurities, such as H, C, and O on the optical properties of the Ti(Al)N coatings. For comparison, coatings were prepared by direct-current magnetron sputtering (DC-MS) and high-power impulse magnetron sputtering (HiPIMS) at the same average power. The elemental composition of the thin films was measured by elastic recoil detection analysis. Regardless of the deposition technique used, no significant difference in H and C concentrations were found. The analysis showed, that HiPIMS coatings contain less O impurities than the corresponding DC-MS films, despite the lower deposition rate. The reduced residual O content in HiPIMS coatings can be explained by the cleaning effect of the bombarding ions. Moreover, densification effects presumably suppress post-deposition oxidation. Given the reduced O content, HiPIMS films showed higher optical reflectance for the entire measured spectral range.

  • Lecture (Conference)
    The 15th International Symposium on Sputtering and Plasma Processes, ISSP 2019, 11.-14.06.2019, Kanazawa, Japan
  • Poster
    The 15th International Symposium on Sputtering and Plasma Processes, ISSP 2019, 11.-14.06.2019, Kanazawa, Japan
  • Contribution to proceedings
    The 15th International Symposium on Sputtering and Plasma Processes, ISSP 2019, 11.-14.06.2019, Kanazawa, Japan

Permalink: https://www.hzdr.de/publications/Publ-30572
Publ.-Id: 30572


THEREDA – Thermodynamic Reference Database

Moog, H. C.; Scharge, T.; Bok, F.; Brendler, V.; Richter, A.; Morin, D.; Thoenen, T.; Altmaier, M.; Cevirim-Papaioannou, N.; Gaona, X.; Marquardt, C.; Freyer, D.; Pannach, M.; Sohr, J.

Part of the process to assess the safety of disposal sites for radioactive or chemical-toxic waste is the predictive modeling of the solubility of hazardous components in a complex aqueous solution. To ensure the reliability of thermodynamic equilibrium modeling as well as to facilitate the comparison of such calculations done by different institutions it is necessary to create a mutually accepted thermodynamic reference database.
To meet this demand in Germany several institutions joined efforts and created THEREDA. It contains a relational databank whose structure was designed in a way that promotes internal consistency of thermodynamic data. It serves as back end to a variety of supplementary programs which allow for adding, editing, and extracting subsets of data. Data considered cover the needs of Gibbs Energy Minimizers and Law-of-Mass-Action programs alike. Interaction parameters for an arbitrary number of mixed phases and p,T-functions of thermodynamic data may also be entered. At present, Pitzer- and SIT-parameters for the aqueous phase are considered.
To enhance public use THEREDA is accessible via internet.

Keywords: THEREDA; Thermodynamic Reference Database; Pitzer

  • Poster
    International Workshop on “How to integrate geochemistry at affordable costs into reactive transport for large-scale systems”, 05.-07.02.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30570
Publ.-Id: 30570


Ultrafast Mid-Infrared and Terahertz Phenomena in Graphene

Winnerl, S.

Graphene, the first atomically thin 2D material that was intensely investigated since its discovery in 2014, is a gapless semiconductor or semimetal with linear dispersion. Consequently, graphene absorbs light at all energies, in particular also at low photon energies in the THz frequency range. Here we show that pump-probe experiments at low photon energies can provide deep insights into the carrier dynamics. In particular, electron-phonon scattering can be disentangled from Coulomb scattering processes [1, 2]. Coulomb scattering in graphene is responsible for a number of unusual effects like strong Auger scattering under Landau quantization [3].
With respect to applications we present a graphene based detector with ultrafast response time of 40 ps. It operates in the very broad frequency range from visible to THz radiation [4].
[1] S. Winnerl, M. Orlita, P. Plochocka, P. Kossacki, M. Potemski, T. Winzer, E. Malic, A. Knorr, M. Sprinkle, C. Berger, W. A. de Heer, H. Schneider und M. Helm, Phys. Rev. Lett. 107, 237401 (2011).
[2] J. C. König-Otto, M. Mittendorff, T. Winzer, F. Kadi, E. Malic, A. Knorr, C. Berger, W. A. de Heer, A. Pashkin, H. Schneider, M. Helm und S. Winnerl, Phys. Rev. Lett. 117, 087401 (2016).
[3] M. Mittendorff, F. Wendler, E. Malic, A. Knorr, M. Orlita, M. Potemski, C. Berger, W. A. de Heer, H. Schneider, M. Helm und S. Winnerl, Nature Phys. 11, 75 (2015).
[4] M. Mittendorff, J. Kamann, J. Eroms, D. Weiss, C. Drexler, S. D. Ganichev, J. Kerbusch, A. Erbe, R. J. Suess, T. E. Murphy, S. Chatterjee, K. Kolata, J. Ohser, J. C. König-Otto, H. Schneider, M. Helm, S. Winnerl, Optics Express 23, 28728 (2015).

Keywords: graphene; terahertz; ultrafast

  • Invited lecture (Conferences)
    Sino-German Bilateral Symposium on Low Dimensional Semiconductors and Opto-electronics Integration, 14.-17.11.2019, Changsha, China

Permalink: https://www.hzdr.de/publications/Publ-30568
Publ.-Id: 30568


Ge-based photoconductive emitters producing gapless broadband THz spectra

Singh, A.; Pashkin, O.; Winnerl, S.; Helm, M.; Schneider, H.

We present photoconductive emitters based on Ge featuring gapless broadband spectra up to 13 THz. Thus they can fill the gap in the 5 – 10 THz range and can be excited with fiber lasers.

Keywords: terahertz; broadband; photoconductive emitters

  • Lecture (Conference)
    CLEO/Europe-EQEC 2019, 23.-27.06.2019, Munich, Germany

Permalink: https://www.hzdr.de/publications/Publ-30567
Publ.-Id: 30567


Nonlinear THz resoponse of graphene plasmonic structures

Winnerl, S.; Jadidi, M. M.; Chin, M.; Seidl, A.; Schneider, H.; Helm, M.; Drew, H. D.; Murphey, T. E.; Mittendorff, M.

Ribbons and discs based on doped graphene feature strong tunable plasmonic resonances. We show that excitation with THz radiation results in strong changes of transmission, even at moderate pump fluences. The response is due to a broadening and redshift for the plasmonic absorption line as charge carriers are heated. The response time is determined by the cooling of carriers, which is of the order of 10 ps.

Keywords: graphene; plasmonics; nonlinear terahertz spectroscopy

  • Invited lecture (Conferences)
    META 2019, the 10th International Conference on Metamaterials, Photonic Crystals and Plasmonics, 23.-26.07.2019, Lisbon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-30566
Publ.-Id: 30566


Nonlinear THz spectroscopy in low-dimensional semiconductors using a free-electron laser

Winnerl, S.; Schmidt, J.; König-Otto, J.; Mittendorff, M.; Schneider, H.; Helm, M.

Sources for intense THz pulses allow one to investigate interesting nonlinear effects in various solid-state systems in a time-resolved manner. Here we discuss perturbative and non-perturbative nonlinear effects in graphene-based systems and GaAs/AlGaAs quantum wells, respectively, which are excited by intense, tunable, narrowband THz pulses from a free-electron laser (FEL).
For the graphene-based samples we have pursued two strategies to resonantly enhance the linear and nonlinear response. One way is to apply a magnetic field perpendicular to the graphene layer.
This splits the linear band structure into a set of non-equidistant Landau levels. Four-wave mixing experiments on the lowest Landau levels reveal a strong nonlinearity and a rapid dephasing of the microscopic polarization on sub-ps timescales [1]. The second path for resonant enhancement is the fabrication of ribbons and discs of doped graphene that feature a strong plasmonic response [2]. The nonlinearity corresponding to the plasmonic response is based on a red-shift and broadening of the absorption line caused by carrier heating.
While the previously discussed phenomena are perturbative nonlinear effects, FEL pulses are also well suited to generate non-perturbative effects such as the intraexcitonic Autler-Townes effect and double dressing of polaritons in microcavities [3, 4]. Here we present novel results on the dressing of subbands in a single GaAs/AlGaAs quantum well by THz photons. To this end, the transition between the second and third subband was resonantly pumped with the FEL. Broadband probing by THz time-domain spectroscopy using GaP crystals for optical rectification enabled us to observe the THz-dressing of the electronic states. Namely Autler-Townes splitting occurs at the transition between the first and second subband while the transition from the second to the third subband is split into a Mollow triplet.
We are grateful to our collaborators M. M. Jadidi, T. E. Murphy, A. Belyanin, and E. Malic.
REFERENCES
1. König-Otto, J. C., Wang, Y., Belyanin, A., Berger, C. de Heer, W. A., Orlita, M., Pashkin, A., Schneider, H., Helm, M., Winnerl, S. "Four-wave mixing in Landau-quantized graphene," Nano Lett., Vol. 17, 2184-2188, 2017.
2. Jadidi, M. M., Daniels, K. M., Myers-Ward, R. L., Gaskill, D. K., Konig-Otto, J. C., Winnerl, S., Sushkov, A. B., Drew, H. D., Murphy, T. E., Mittendorff, M. "Optical control of plasmonic hot carriers in graphene," ACS Photonics, Vol. 6, 302307, 2019.
3. Wagner, M., Schneider, H., Stehr, D., Winnerl, S., Andrews, A. M., Schartner, S., Strasser, G., Helm, M. "Observation of the intraexciton Autler-Townes effect in GaAs=AlGaAs semiconductor quantum wells," Phys. Rev. Lett., Vol. 105, 167401, 2010.
4. Pietka, B., Bobrovska, N., Stephan, D., Teich, M., Krol, M., Winnerl, S., Pashkin, A., Mirek, R., Lekenta, K., Morier-Genoud, F., Schneider, H., Deveaud, B., Helm, M., Matuszewski, M., Szczytko, J. "Doubly dressed bosons: exciton polaritons in a strong terahertz field," Phys. Rev. Lett., Vol. 119, 077403, 2017.

Keywords: Free-electron laser; terahertz; nonlinear spectroscopy; low-dimensional semiconductors

  • Invited lecture (Conferences)
    Photonics & Electromagnetics Research Symposium (PIERS), 17.-20.06.2019, Rome, Italy

Permalink: https://www.hzdr.de/publications/Publ-30565
Publ.-Id: 30565


THz nonlinear optics in graphene ribbons

Jadidi, M. M.; Daniels, K. M.; Myers-Ward, R.; Gaskill, D. K.; König-Otto, J.; Winnerl, S.; Sushkov, A.; Drew, H. D.; Murphy, T. E.; Mittendorff, M.

Graphene plasmonics is an emerging field due the unique combination of spectral tunability, strong plasmonic resonance and low losses. Here we study the nonlinear optical properties of graphene bilayer ribbons, featuring a plasmonic resonance at 3.9 THz, in time resolved experiments. A redshift of the plasmonic resonance is observed upon excitation with picosecond THz pulses. The unconventional nonlinear effect is explained by the optical response of hot carriers. Already at fairly low fluences in the µJ/cm2 range strong changes in transmission in the 10 % range can be induced. This strong response, together with the fast recovery determined by the electron cooling time (∼10 ps), makes the system promising for optical switching applications.

Keywords: graphene; plasmonics; nonlinear optics

  • Lecture (Conference)
    DPG-Frühjahrstagung, 31.03.-05.04.2019, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30564
Publ.-Id: 30564


High Power Lasers for Advanced Accelerator Development at the ELBE Center Dresden

Schramm, U.

Presentation of High Power Lasers Activities for
Advanced Accelerator Development
at the ELBE Center Dresden

Keywords: high power lasers

  • Invited lecture (Conferences)
    Helmholtz Laser and Photonics Meeting 2019, 03.-04.12.2019, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30563
Publ.-Id: 30563


Emergence of nanoscale patterns under ion induced non-equilibrium conditions

Facsko, S.

Various self-organized nanoscale patterns emerge on surfaces which are irradiated by low- or medium-energy ion beams [1]. Depending on the irradiation conditions, hexagonally ordered dot or pit patterns, checkerboard patterns, as well as periodic ripple patterns are formed spontaneously due to the non-equilibrium conditions induced by continuous ion irradiation. In the collision cascade induced by an ion impact several defects, including interstitials, vacancies, ad-atoms and more complex defects are created. Below the recrystallization temperature, the surface is thus quickly amorphized by continuous ion irradiation and massive mass-transport takes place due to momentum-transfer from the ions to the near-surface atoms. Furthermore, ion sputtering is eroding the material non-homogeneously inducing a roughening instability.
On amorphous or amorphized surfaces, the formation of periodic patterns at high ion fluences results from an interplay of different roughening mechanisms, e.g. curvature dependent sputtering, ballistic mass redistribution, or altered surface stoichiometry on binary materials, and smoothing mechanisms, e.g. surface diffusion or viscous flow. Therefore, the patterns obey the symmetry given by the ion beam direction, i.e. hexagonal near order at normal incidence and two-fold symmetry with the ripple direction oriented perpendicular or parallel to the ion beam direction at off-normal incidence.
If the temperature during ion irradiation is above the recrystallization temperature of the material, ion induced defects are dynamically annealed and amorphization is prevented. The diffusion of ion-induced vacancies and ad-atoms on the crystalline surface is now additionally affected by the Ehrlich-Schwoebel barrier, like in molecular beam epitaxy. Vacancies and ad-atoms are trapped on terraces and can nucleate to form pits or terraces, respectively. Patterns formed in this regime exhibit the symmetry of the crystal structure of the irradiated surface and often have inverse pyramidal shapes with well-defined facets [2,3]. Therefore, this mechanism is called “reverse epitaxy”.
1.1. Ion induced patterns on Ge and GaAs
In Fig. 1 examples of ion irradiation induced pattern are shown for amorphized Ge surface (a, b) and for Ge (001) (c) and GaAs (001) (d) irradiated above their respective recrystallization temperatures of 250° and 200°C.
1.2. Modelling pattern formation by continuum equations
Pattern formation on ion irradiated surfaces can be modelled my atomistic simulation methods, such as molecular dynamics (MD) and Monte-Carlo (kMC), or by continuum equations. Due to the large area and high fluences, MD and MC cannot cover the large dynamic range, however, they can provide valuable insight into defect generation and ion induced mass transport. Continuum equations on the other hand are coarse grain approximations, which can cover much larger spatial and temporal regimes. Information from MD or MC can furthermore be used as input for predictive modelling of new materials and irradiation conditions.

Keywords: ion beams; ion-surface interaction; nanopattering

  • Invited lecture (Conferences)
    23rd International Workshop on Inelastic Ion-Surface Collisions, 17.-22.11.2019, Matsue, Japan

Permalink: https://www.hzdr.de/publications/Publ-30562
Publ.-Id: 30562


Ion beam modification and ion beam analysis in current materials research

Facsko, S.; Heller, R.; Munnik, F.; Klingner, N.; Hlawacek, G.

Introduction to the IOne Beam Cneter and Current Research.

Keywords: Ion beam analysis; ion beam modification

  • Lecture (Conference)
    NATO Advanced Training Course: “Spintronics Radar Detectors”, 14.-18.10.2019, Athens, Greece

Permalink: https://www.hzdr.de/publications/Publ-30561
Publ.-Id: 30561


Comparison of Si and Ge surface patterns produced by ion irradiation in the reverse epitaxy regime

Facsko, S.; Xin, O.; de Schultz, R.; Erb, D.

In addition to sputtering, ion irradiation is often also leading to restructuring of the surface and a plethora of surface patterns can appear. At irradiation temperatures high enough to dynamically anneal defects induced by the collision cascades the surface remains crystalline. Still, a high density of ion-induced surface vacancies and adatoms remains and their diffusion is affected by the Ehrlich-Schwoebel (ES) barrier, i.e. an additional diffusion barrier to cross terrace steps. These defects are therefore trapped on terraces, nucleate and form pits or mounds [1]. In this way three dimensional, faceted nanostructures are formed, reflecting the underlying crystal lattice. Due to the similarity to growth of three-dimensional structures in molecular beam epitaxy this mechanism is called reverse epitaxy.
We will present patterns on Si and Ge surface induced by low energy, normal incidence, high fluence ion irradiation at temperatures above the recrystallization temperature. Patterns with very different symmetry can result, depending on the surface orientation: pyramidal structures with four-fold symmetry on the (001) surface, with three-fold and six-fold symmetry on the (111) surface and elongated structures with two-fold symmetry on the (011) surface [2].
Although Si and Ge have the same diamond crystal lattice, the resulting patterns and facets are different: on Ge(001) predominantly (105) facets are formed, whereas (115) facets are found on Si(001). Similarly, on Si(111) the pattern exhibits a six-fold symmetry with (123) facets, whereas on Ge(111) the patterns are formed by (356) facets and exhibit a three-fold symmetry. The formation mechanism and possible effects leading to these differences on Ge and Si surfaces will be presented and discussed.

Keywords: ion beams; nanopatterning; ion-surface interaction

  • Lecture (Conference)
    10th International Workshop on Nanoscale Pattern Formation at Surfaces (NanoPatterning 2019), 07.-10.07.2019, Surrey, England

Permalink: https://www.hzdr.de/publications/Publ-30560
Publ.-Id: 30560


Interaction of low-energy ions with surfaces and 2D materials

Facsko, S.

The ion beam centre (IBC) of the Helmholtz-Zentrum Dresden-Rossendorf is a user facility primarily dedicated to research and application of ion beam techniques in materials research. The IBC comprises various ion beam facilities (accelerators, ion beam implanters, plasma-based ion beam equipment, focused / highly-charged ion facilities) which provide a wide energy range between 10 eV and 60 MeV. Besides these facilities, structural analysis (electron microscopy and spectroscopy, X-ray scattering techniques) and sample or device processing (under clean-room conditions) are part of the IBC to deliver a “complete” user service.
Special focus of the IBC is material research with low energy ions. Irradiations of surfaces with low energy ions can induce the formation of patterns with periodicities in the range of tens to hundreds of nanometers. At off-normal angle of incidence between 50° and 70° to the surface normal ripple patterns oriented perpendicular to the ion beam direction are observed. At normal incidence or for incidence angles smaller than 50° smoothing dominates on elemental materials, like Si and Ge. However, in contrast to irradiations at room temperature pattern formation is observed at normal ion incidence irradiations performed at temperatures above the recrystallization temperature of the material. Depending on the surface orientation checkerboard patterns with two-fold, three-fold, or six-fold symmetry reflecting the crystal structure of the irradiated surface are formed (Fig. 1).
Moreover, single impacts of low energy ions are used to create nanostructures and in thin membranes and for doping of 2D materials, like graphene and MoS2. In this case of highly charged ions the release of the potential leads to a local phase transformation of the material and subsequently to the formation of dots, pits or holes. Currently, a new facility for low energy ion nanoengineering is commissioned comprising a 100 keV accelerator for ion irradiations and MEIS, thin film deposition system, and different analytic tools for nanoscale analysis and characterization.

Keywords: ion beams; ion surface interaction; 2D materials

  • Lecture (others)
    Physics Seminar, 26.05.2019, Uppsala, Schweden

Permalink: https://www.hzdr.de/publications/Publ-30558
Publ.-Id: 30558


Advancing laser plasma accelerators by means of femto-scale diagnostics

Schramm, U.

Invited talk on the role of femtoscale probing on laser plasma particle acceleration

Keywords: laser plasma accelerator

  • Invited lecture (Conferences)
    Conference on High Intensity and Attosecond Laser Science CHILI, 09.-11.12.2019, Tel Aviv, Israel

Permalink: https://www.hzdr.de/publications/Publ-30557
Publ.-Id: 30557


Joining of two different ceramic nanomaterials for bottom-up fabrication of heterojunction devices

Rajbhar, M.; Das, P.; Satpati, B.; Möller, W.; Facsko, S.; Böttger, R.; Ramgir, N.; Chatterjee, S.

Fabrication of device though bottom-up approach and using nanowires as building blocks has received significant attention as one can build flexible electronics which can handle stress better than thin film based device. However successful joining of the nanowires for fabrication of such device remains a challenge till date. While several well researched joining techniques are available for metal based nanowires, the same for ceramic nanowires is scarce at present. In this work we explore ion beam induced formation of heterojunction between two metal oxide nanowires, namely hydrogen titanate (H2Ti3O7) and cuprous oxide (Cu2O). The electron microscopy studies reveal detailed structural modifications at the joining sections. The ion beam modifications are explained using state-of-the-art TRI3DYN simulations, which details about migration of atoms, defects, sputtering, redeposition and atomic mixing between the two nanowires and emphasize that such junction formation is caused mainly due to atomic collisional effects.

Keywords: Ceramic nanomaterials; Metal oxides; Welding; Heterojunction; Ion-surface interaction; Nanowires

Permalink: https://www.hzdr.de/publications/Publ-30556
Publ.-Id: 30556


Characterizing laser-plasma ion accelerators driving an intense neutron beam via nuclear signatures

Favalli, A.; Guler, N.; Henzlova, D.; Croft, S.; Falk, K.; Gautier, D. C.; Ianakiev, K. D.; Iliev, M.; Palaniyappan, S.; Roth, M.; Fernandez, J. C.; Swinhoe, M. T.

Compact, bright neutron sources are opening up several emerging applications including detection of nuclear materials for national security applications. At Los Alamos National Laboratory, we have used a short-pulse laser to accelerate deuterons in the relativistic transparency regime. these deuterons impinge on a beryllium converter to generate neutrons. During the initial experiments where these neutrons were used for active interrogation of uranium and plutonium, we observed β-delayed neutron production from decay of 9Li, formed by the high-energy deuteron bombardment of the beryllium converter. Analysis of the delayed neutrons provides novel evidence of the divergence of the highest energy portion of the deuterons (i.e., above 10 MeV/nucleon) from the laser axis, a documented feature of the breakout afterburner laser-plasma ion acceleration mechanism. these delayed neutrons form the basis of non-intrusive diagnostics for determining the features of deuteron acceleration as well as monitoring neutron production for the next generation of laser-driven neutron sources.

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Permalink: https://www.hzdr.de/publications/Publ-30554
Publ.-Id: 30554


DDR1 (discoidin domain receptor tyrosine kinase 1) drives glioblastoma therapy resistance by modulating autophagy

Vehlow, A.; Cordes, N.

Therapy resistance of tumor cells is a major obstacle for efficient anticancer treatment approaches and has been attributed to tumor heterogeneity as well as genetic and epigenetic changes. Accumulating evidence demonstrates that tumor cell adhesion to the extracellular matrix acts as an additional essential factor conferring tumor cell resistance to both radio- and chemotherapeutic intervention.
Our recent study demonstrates that DDR1 (discoidin domain receptor tyrosine kinase 1) elicits therapy resistance of glioblastoma multiforme (GBM) stem-like and bulk cells through its adhesion to extra-cellular matrix and the subsequent modulation of macroautophagy/autophagy. Mechanistically, DDR1 associates with a YWHA/14–3-3-BECN1-AKT1 multiprotein complex favoring pro-survival/anti-autophagic and resistance-mediating AKT-MTOR signaling. In turn, inhibition of DDR1 sensitizes glioblastoma cells to radio- and chemotherapy by inducing autophagy. Collectively, our study suggests that DDR1 may be a potential target for sensitizing glioblastoma cells to combination therapies through its efficient induction of autophagic cell death.

Keywords: Autophagy; discoidin domain receptor tyrosine kinase 1; glioblastoma; radiochemotherapy; therapy resistance

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30552
Publ.-Id: 30552


Interaction of Discoidin Domain Receptor 1 with a 14-3-3-Beclin-1-Akt1 Complex Modulates Glioblastoma Therapy Sensitivity

Vehlow, A.; Klapproth, E.; Jin, S.; Hannen, R.; Hauswald, M.; Bartsch, J. W.; Nimsky, C.; Temme, A.; Leitinger, B.; Cordes, N.

Glioblastoma (GBM) is highly refractory to therapy and associated with poor clinical outcome. Here, we reveal a critical function of the promitotic and
adhesion-mediating discoidin domain receptor 1 (DDR1) in modulating GBM therapy resistance. In GBM cultures and clinical samples, we show a
DDR1 and GBM stem cell marker co-expression that correlates with patient outcome. We demonstrate that inhibition of DDR1 in combination with
radiochemotherapy with temozolomide in GBM models enhances sensitivity and prolongs survival superior to conventional therapy. We identify a 14-
3-3-Beclin-1-Akt1 protein complex assembling with DDR1 to be required for prosurvival Akt and mTOR signaling and regulation of autophagy-associated therapy sensitivity. Our results uncover a mechanism driven by DDR1 that controls GBM therapy resistance and provide a rationale target for the development of therapy-sensitizing agents.

Permalink: https://www.hzdr.de/publications/Publ-30551
Publ.-Id: 30551


Photons or protons for reirradiation in (non-)small cell lung cancer: Results of the multicentric ROCOCO

Troost, E. G. C.; Wink, K. C. J.; Roelofs, E.; Simone, C. B.; Makocki, S.; Löck, S.; van Kollenburg, P.; Dechambre, D.; Minken, A. W. H.; van der Stoep, J.; Avery, S.; Jansen, N.; Solberg, T.; Bussink, J.; de Ruysscher, D.

objective: Locally recurrent disease is of increasing concern in (non-)small cell lung cancer [(N)SCLC] patients. Local reirradiation with photons or particles may be of benefit to these patients. In this multicentre in silico trial performed within the Radiation Oncology Collaborative Comparison (ROCOCO) consortium, the doses to the target volumes and organs at risk (OARs) were compared when using several photon and proton
techniques in patients with recurrent localised lung cancer scheduled to undergo reirradiation.
Methods: 24 consecutive patients with a second primary (N)SCLC or recurrent disease after curative- intent, standard fractionated radio(chemo)therapy were included in this study. The target volumes and OARs were centrally contoured and distributed to the participating ROCOCO sites. Remaining doses to the OARs were calculated on an individual patient’s basis. Treatment planning was performed by the
participating site using the clinical treatment planning system and associated beam characteristics.
results: Treatment plans for all modalities (five photon and two proton plans per patient) were available for 22 patients (N = 154 plans). 3D-conformal photon therapy and double-scattered proton therapy delivered significantly lower doses to the target volumes. The highly conformal techniques, i.e., intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), CyberKnife, TomoTherapy and intensity-modulated proton therapy (IMPT), reached the highest doses in the target volumes. Of these, IMPT was able to statistically significantly decrease the radiation doses to the OARs.
conclusion: Highly conformal photon and proton beam techniques enable high-dose reirradiation of the target volume. They, however, significantly differ in the dose deposited in the OARs. The therapeutic options, i.e., reirradiation or systemic therapy, need to be carefully weighed and discussed with the patients.
advances in knowledge: Highly conformal photon and proton beam techniques enable high-dose reirradiation of the target volume. In light of the abilities of the various highly conformal techniques to spare specific OARs, the therapeutic options need to be carefully weighed and patients included in the decision-making process.

Downloads:

  • Secondary publication expected from 20.12.2020

Permalink: https://www.hzdr.de/publications/Publ-30550
Publ.-Id: 30550


Impact of Cancer-Associated Fibroblast on the Radiation-Response of Solid Xenograft Tumors

Steer, A.; Cordes, N.; Jendrossek, V.; Klein, D.

Increasing evidence indicates that the heterogeneous tumor stroma supports therapy resistance at multiple levels. Fibroblasts, particularly cancer-associated fibroblasts (CAFs) are critical components of the tumor stroma. However, the impact of CAFs on the outcome of radiotherapy (RT) is poorly understood. Here, we investigated if and how fibroblasts/CAFs modulate the radiation response of malignant tumors by altering cancer cell radiosensitivity or radioresistance in vitro and in vivo. The influence of fibroblasts on cancer cell proliferation, cell death induction and long-term survival after RT was studied using different sets of fibroblasts and cancer cells in an indirect co-culture (2D) system to analyse potential paracrine interactions or a 3D model to study direct interactions. Paracrine signals from embryonic NIH-3T3 fibroblasts promoted MPR31.4 prostate and Py8119 breast cancer cell proliferation. Indirect co-culture with L929 skin fibroblasts induced higher levels of apoptosis in irradiated MPR31.4 cells, while they promoted proliferation of irradiated Py8119 cells. In addition, NIH-3T3 fibroblasts promoted long-term clonogenic survival of both tumor cell types upon irradiation in the 3D co-culture system when compared to non-irradiated controls. Also in vivo, co-implantation of cancer cells and fibroblasts resulted in different effects depending on the respective cell combinations used: co-implantation of MPR31.4 cells with NIH-3T3 fibroblasts or of Py8119 cells with L929 fibroblasts led to increased tumor growth and reduced radiation-induced tumor growth delay when compared to the respective tumors without co-implanted fibroblasts. Taken together, the impact of fibroblasts on cancer cell behavior and radiation sensitivity largely depended on the respective cell types used as they either exerted a pro-tumorigenic and radioresistance-promoting effect, an anti-tumorigenic effect, or no effect. We conclude that the plasticity of fibroblasts allows for such a broad spectrum of activities by the same fibroblast and that this plasticity is at least in part mediated by cancer cell-induced fibroblast activation toward CAFs.

Keywords: cancer-associated fibroblast; fibroblast; cancer therapy; radiation therapy; radiation resistance; tumor stoma; tumor microenvironment

Permalink: https://www.hzdr.de/publications/Publ-30549
Publ.-Id: 30549


Network-based analysis of prostate cancer cell lines reveals novel marker gene candidates associated with radioresistance and patient relapse

Seifert, M.; Peitzsch, C.; Gorodetska, I.; Börner, C.; Klink, B.; Dubrovska, A.

Radiation therapy is an important and effective treatment option for prostate cancer, but high-risk patients are prone to relapse due to radioresistance of cancer cells. Molecular mechanisms that contribute to radioresistance are not fully understood. Novel computational strategies are needed to identify radioresistance driver genes from hundreds of gene copy number alterations. We developed a network-based approach based on lasso regression in combination with network propagation for the analysis of prostate cancer cell lines with acquired radioresistance to identify clinically relevant marker genes associated with radioresistance in prostate cancer patients. We analyzed established radioresistant cell lines of the prostate cancer cell lines DU145 and LNCaP and compared their gene copy number and expression profiles to their radiosensitive parental cells. We found that radioresistant DU145 showed much more gene copy number alterations than LNCaP and their gene expression profiles were highly cell line specific. We learned a genome-wide prostate cancer-specific gene regulatory network and quantified impacts of differentially expressed genes with directly underlying copy number alterations on known radioresistance marker genes. This revealed several potential driver candidates involved in the regulation of cancer-relevant processes. Importantly, we found that ten driver candidates from DU145 (ADAMTS9, AKR1B10, CXXC5, FST, FOXL1, GRPR, ITGA2, SOX17, STARD4, VGF) and four from LNCaP (FHL5, LYPLAL1, PAK7, TDRD6) were able to distinguish irradiated prostate cancer patients into early and late relapse groups. Moreover, in-depth in vitro validations for VGF (Neurosecretory protein VGF) showed that siRNA-ediated gene silencing increased the radiosensitivity of DU145 and LNCaP cells. Our computational approach enabled to predict novel radioresistance driver gene candidates. Additional preclinical and clinical studies are required to further validate the role of VGF and other candidate genes as potential biomarkers for the prediction of radiotherapy responses and as potential targets for radiosensitization of prostate cancer.

Permalink: https://www.hzdr.de/publications/Publ-30548
Publ.-Id: 30548


Impact of prophylactic cranial irradiation on overall survival of patients with advanced non-small-cell lung cancer

Schmidt, J.; Appold, S.; Troost, E. G. C.

Hintergrund: In einer randomisierten Phase-III-Studie sollte untersucht werden, ob eine prophylaktische Ganzhirnbestrahlung bei kurativ-intendiert behandelten Patienten mit einem nicht-kleinzelligen Bronchialkarzinom (NSCLC) im Stadium III Einfluss auf das Auftreten von symptomatischen Hirnmetastasen hat.

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30547
Publ.-Id: 30547


Can Local Ablative Radiotherapy Revert Castration-resistant Prostate Cancer to an Earlier Stage of Disease

Lohaus, F.; Zöphel, K.; Löck, S.; Wirth, M.; Kotzerke, J.; Krause, M.; Baumann, M.; Troost, E. G. C.; Hölscher, T.

In prostate cancer, disease progression after primary treatment and subsequent andro-
gen deprivation therapy is common. Intensification of systemic treatment is the stan-
dard of care. Recently, 68[16_TD$DIFF]Ga prostate-specific membrane antigen positron emission
tomography (PSMA-PET) imaging was introduced to identify oligometastatic prostate
cancer patients. In this retrospective, exploratory study, we report on the efficacy of
PSMA-PET-guided local ablative radiotherapy (aRT) in 15 oligometastatic castration-
resistant prostate cancer (CRPC) patients, selected from our prospective institutional
database and treated between 2013 and 2016. After multidisciplinary discussion, aRT
was delivered with two different schedules. Androgen deprivation therapy remained
unchanged. Prostate-specific antigen (PSA) response and time to PSA progression were
analysed. For comparison, individual time to PSA progression without aRT was estimated
by individual PSA doubling time (PSADT). PSA response was observed in 11 patients
(73%). Mean time to PSA progression or last follow-up was 17.9 mo, as opposed to 2.9 mo
estimated from the PSADT without aRT (p <0.001). A relevant subset of CRPC patients
had a PSA response with aRT to PET-positive lead metastases. A prospective trial is in
preparation.
Patient summary: In selected patients with prostate-specific antigen (PSA) increase
during androgen deprivation, metastases were detected with prostate-specific mem-
brane antigen positron emission tomography imaging. Fifteen patients with three or
fewer metastases were treated with high-dose radiotherapy. Subsequently, PSA values
dropped in 11 patients and in six patients no PSA progression was detected for >12 mo.

Keywords: Castration-resistant prostate; cancer; Ablative radiotherapy; Stereotactic ablative body; radiotherapy; Oligometastatic prostate cancer; Prostate-specific membrane; antigen positron emission; tomography

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30545
Publ.-Id: 30545


Some unusual effects in magnetic fields

Zherlitsyn, S.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Humboldt-Kolleg, International Conference „To grasp the whole world”, 04.-06.12.2019, Lissabon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-30544
Publ.-Id: 30544


Independent validation of tumour volume, cancer stem cell markers and hypoxia-associated gene expressions for HNSCC after primary radiochemotherapy

Linge, A.; Schmidt, S.; Baumann, M.; Krenn, C.; Bandurska-Luque, A.; Platzek, I.; Neubeck, V. C.; Appold, S.; Nowak, A.; Gudziol, V.; Buchholz, F.; Baretton, B. B.; Lohaus, F.; Löck, S.; Krause, M.

Objective: To independently validate the impact of tumour volume, p16 status, cancer stem cell (CSC) marker expression and hypoxia-associated gene signatures as potential prognostic biomarkers for patients with locally advanced head and neck squamous cell carcinoma (HNSCC), who underwent primary radiotherapy or radiochemotherapy (RCTx). These markers have previously been reported in a study of the German Cancer Consortium Radiation Oncology Group (DKTK-ROG) (Linge et al., 2016).
Materials and methods: In this retrospective monocentric study, 92 patients with locally advanced HNSCC were included. Univariable and multivariable logistic regressions and Cox models presented in the study of the DKTK-ROG were validated using the area under the curve (AUC) and the concordance index (ci), respectively. The primary endpoint of this study was loco-regional tumour control (LRC) after primary RCTx.
Results: Although both cohorts significantly differed in the proportion of the tumour subsites, the parameters tumour volume, p16 status and N stage could be validated regarding LRC and overall survival (OS) using multivariable Cox regression (LRC ci: 0.59, OS ci: 0.63). These models were slightly improved by combination with the putative CSC marker CD44 (LRC ci: 0.61, OS ci: 0.69). The logistic regression model for 2-year LRC based on tumour volume, p16 status and CD44 protein was validated with an AUC of 0.64. The patient stratification based on hypoxia-associated gene signatures status was similar to the original study but without significant differences in LRC and OS.
Conclusions: In this validation study, the inclusion of the putative CSC marker CD44 slightly improved the prognostic performance of the baseline parameters tumour volume, p16 status and N stage. No improvement was observed when including expressions of the hypoxia-associated gene signatures. Prospective validation on a larger cohort is warranted to assess the clinical relevance of these markers.

Keywords: Biomarker; HNSCC; Cancer stem cells; HPV; Hypoxia; Primary radiochemotherapy

Permalink: https://www.hzdr.de/publications/Publ-30543
Publ.-Id: 30543


In-situ Investigations of Solid-Liquid Interfaces by means of RBS

Baghban Khojasteh Mohammadi, N.; Apelt, S.; Bergmann, U.; Facsko, S.; Heller, R.

Solid-liquid interfaces are of crucial significance since their presence in nature is ubiquitous. They play a fundamental role in diverse fields as biology, fluid physics, radiation physics, geological and environmental research, surface science and electro-chemistry. Binnig and Rohrer (Nobel Price 1986) considered the significance of the solid-liquid interface as:

"The solid-liquid interface is, in our opinion, the interface of the future." [1]

Investigating phenomena at the interface of a solid and an aqueous solution, where chemical reactions, oxidation, corrosion, adhesion, dissolution and ion exchange may take place, represents a challenging task. The techniques applied should not influence any of these processes, they should be able to access the interface (through the liquid or through the solid) and simultaneously deliver quantitative information on the interface properties.

A new versatile experimental setup for in-situ Rutherford backscattering spectrometry at solid-liquid interfaces enabling direct and quantitative measurements with highest sensitivity is presented [2]. An electro-chemical liquid cell with a three-electrode arrangement was mounted at the IBCs 2MV Van-de-Graaff accelerator. A thin Si3N4 window (thickness down to 150 nm) separates the vacuum of the detector chamber from the electrolyte in the cell.

In a first study, we investigated the attachment of Ba onto the Si3N4 surface as a function of contact time and pH value of the electrolyte solution (see Fig. 1). From these measurements, we can deduce the evolution of the double layer with sub-monolayer sensitivity in a direct and quantitative manner.

Despite focusing on a particular system as presented here, the setup allows to conduct a large variety of in-situ investigations at solid-liquid interfaces such as monitoring of electro-chemical reactions, segregation, adsorption, dissolution and corrosion processes.

Details of the setup, its capabilities and limitations are presented and the results of first measurements are discussed in detail.


[1] G. Binnig and H. Rohrer, Reviews of Modern Physics 71 (1999), 324.
[2] N. B. Khojasteh, S. Apelt, U. Bergmann, S. Facsko and R. Heller, Review of Scientific Instruments (2019), submitted.

Keywords: Ion beam analysis; Rutherford backscattering; RBS; elemental analysis; solid-liquid interface; electric double layer

  • Lecture (Conference)
    24th International Conference on Ion Beam Analysis, 13.-18.10.2019, Antibes, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-30542
Publ.-Id: 30542


Modern Ion Beam Techniques for Elemental Analysis of Surfaces and Interfaces at the nm Scale

Heller, R.

The general trend in technology and science to create, process and analyze small structures on the nm scale leads to new challenges in modern ion beam analysis (IBA). This is accompanied by higher demands on the lateral resolution as well as on high precision determination of elemental compositions on an atomic depth scale.

Thinner layer structures are closely related to an increased sensitivity on external impacts. Even the transport of a sample to the place of analysis under ambient conditions can lead to unwanted (chemical) modifications at the surface. Furthermore, in technological developments not only the state of a system after processing but the process itself may be of particular interest. “Online” IBA under process conditions is thus highly desired.

Classical IBA methods like RBS (Rutherford Backscattering Spectrometry), ERD (Elastic Recoil Detection Analysis), PIXE (Particle Induced X-Ray Emission) or PIGE (Particle Induced Gamma Emission), either applied as broad beam or as a micro probe, can therefore quickly reach their limits.

In the present contribution, we give an overview on recent and ongoing developments of new IBA techniques and approaches at the HZDR Ion Beam Center (IBC) addressing the above-mentioned difficulties. These developments include in particular

- the implementation of IBA in a helium ion microscope enabling elemental mapping on the nm scale,
- the unification of different IBA techniques in complex experimental chambers including in-situ capabilities,
- a new setup for in-operando, online and quantitative analysis of solid-liquid interfaces with sub mono-layer sensitivity,
- A new low-energy ion laboratory equipped with a Medium Energy Ion Scattering (MEIS) chamber for quantitative elemental depth profiling on the nm scale.

We will give an overview on these techniques and their capabilities. Since the IBC is an international user facility all presented techniques are available for external users experiments.

Keywords: Ion beam analysis; elemental composition; imaging; materials analysis; nano scale; backscattering

  • Poster
    18th European Conference on Applications of Surface and Interface Analysis, 15.-20.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30541
Publ.-Id: 30541


Efficacy and safety of carbon-ion radiotherapy for locally recurrent rectal cancer: results of the J-CROS Study 1404 Rectum

Jentsch, C.; Troost, E. G. C.

Hintergrund In dieser retrospektiven Arbeit untersuchten die Autoren die Wirksamkeit und Sicherheit einer Kohlenstoffionentherapie lokal rezidivierter Rektumkarzinome.

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30540
Publ.-Id: 30540


Photocatalytic biocidal effect of copper doped TiO2 nanotube coated surfaces under laminar flow, illuminated with UVA light on Legionella pneumophila

Oder, M.; Koklič, T.; Umek, P.; Podlipec, R.; Štrancar, J.; Dobeic, M.

Legionella pneumophila can cause a potentially fatal form of humane pneumonia (Legionnaires’ disease), which is most problematic in immunocompromised and in elderly people. Legionella species is present at low concentrations in soil, natural and artificial aquatic systems and is therefore constantly entering man-made water systems. The environment temperature for it’s ideal growth range is between 32 and 42°C, thus hot water pipes represent ideal environment for spread of Legionella. The bacteria are dormant below 20°C and do not survive above 60°C. The primary method used to control the risk from Legionella is therefore water temperature control. There are several other effective treatments to prevent growth of Legionella in water systems, however current disinfection methods can be applied only intermittently thus allowing Legionella to grow in between treatments. Here we present an alternative disinfection method based on antibacterial coatings with Cu-TiO2 nanotubes deposited on preformed surfaces. In the experiment the microbiocidal efficiency of submicron coatings on polystyrene to the bacterium of the genus Legionella pneumophila with a potential use in a water supply system was tested. The treatment thus constantly prevents growth of Legionella pneumophila in presence of water at room temperature. Here we show that 24-hour illumination with low power UVA light source (15 W/m2 UVA illumination) of copper doped TiO2 nanotube coated surfaces is effective in preventing growth of Legionella pneumophila. Microbiocidal effects of Cu-TiO2 nanotube coatings were dependent on the flow of the medium and the intensity of UV-A light. It was determined that tested submicron coatings have microbiocidal effects specially in a non-flow or low-flow conditions, as in higher flow rates, probably to a greater possibility of Legionella pneumophila sedimentation on the coated polystyrene surfaces, meanwhile no significant differences among bacteria reduction was noted regarding to non or low flow of medium.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-30539
Publ.-Id: 30539


A Monte Carlo based radiation response modelling framework to assess variability of clinical RBE in proton therapy

Eulitz, J.; Lutz, B.; Wohlfahrt, P.; Dutz, A.; Enghardt, W.; Karpowitz, C.; Krause, M.; Troost, E. G. C.; Lühr, A.

he clinical implementation of a variable relative biological effectiveness (RBE) in proton therapy is currently controversially discussed. Initial clinical evidence indicates a variable proton RBE, which needs to be verified. In this study, a radiation response modelling framework for assessing clinical RBE variability is established. It was applied to four selected glioma patients (grade III) treated with adjuvant radio(chemo)therapy and who developed late morphological image changes on T1-weighted contrast-enhanced (T1w-CE) magnetic resonance (MR) images within approximately two years of recurrence-free follow-up. The image changes were correlated voxelwise with dose and linear energy transfer (LET) values using univariable and multivariable logistic regression analysis.
The regression models were evaluated by the area-under-the-curve (AUC) method performing a leave-one-out cross validation. The tolerance dose TD50 at which 50% of patient voxels experienced toxicity was interpolated from the models. A Monte Carlo (MC) model was developed to simulate dose and LET distributions, which includes variance reduction (VR) techniques to decrease computation time. Its reliability and accuracy were evaluated based on dose calculations of the clinical treatment planning system (TPS) as well as absolute dose measurements performed in the patient specific quality assurance.
Morphological image changes were related to a combination of dose and LET. The multivariable models revealed cross-validated AUC values of up to 0.88. The interpolated TD50 curves decreased with increasing LET indicating an increase in biological effectiveness. The MC model reliably predicted average TPS dose within the clinical target volume as well as absolute water phantom dose measurements within 2% accuracy using dedicated VR settings.
The observed correlation of dose and LET with late brain tissue damage suggests considering RBE variability for predicting chronic radiation-induced brain toxicities. The MC model simulates radiation fields in patients precisely and time-efficiently. Hence, this study encourages and enables in-depth patient evaluation to assess the variability of clinical proton RBE.

Keywords: proton therapy; clinical RBE; Monte Carlo; passive scattering

Permalink: https://www.hzdr.de/publications/Publ-30538
Publ.-Id: 30538


Correlation between FMISO-PET based hypoxia in the primary tumour and in lymph node metastases in locally advanced HNSCC patients

Bandurska-Luque, A.; Löck, S.; Haase, R.; Richter, C.; Zöphel, K.; Perrin, R.; Appold, S.; Krause, M.; Steinbach, J.; Kotzerke, J.; Hofheinz, F.; Zips, D.; Baumann, M.; Troost, E. G. C.

Purpose: This secondary analysis of the prospective study on repeat [18F]fluoromisonidazole (FMISO)-PET in patients with locally advanced head and neck squamous cell carcinoma (HNSCC) assessed the correlation of hypoxia in the primary tumour and lymph node metastases (LN) prior to and during primary radiochemotherapy.
Methods: This analysis included forty-five LN-positive HNSCC patients having undergone FMISO-PET/CTs at baseline, and at week 1, 2 and 5 of radiochemotherapy. The quantitative FMISO-PET/CT parameters maximum standardised uptake value (SUVmax, corrected for partial volume effect) and peak tumour-to-background ratio (TBRpeak) were estimated in the primary tumour as well as in index and large LN, respectively. Statistical analysis was performed using the Spearman correlation coefficient q.
Results: In 15 patients with large LN (FDG-PET positive volume >5 ml), there was a significant correlation between the hypoxia measured in the primary tumour and the large LN at three out of four time-points using the TBRpeak (baseline: q= 0.57, p = 0.006; week 2: q= 0.64, p = 0.003 and week 5: q= 0.68, p = 0.001). For the entire cohort (N = 45) only assessed prior to the treatment, there was a statistically significant, though weak correlation between FMISO-SUVmax of the primary tumour and the index LN (q= 0.36, p = 0.015).
Conclusions: We observed a significant correlation between FMISO-based hypoxia in the primary tumour and large lymph node(s) in advanced stage HNSCC patients. However, since most patients only had relatively small hypoxic lymph node metastases, a comprehensive assessment of the primary tumour and lymph node hypoxia is essential.

Keywords: Hypoxia; FMISO; PET; Primary tumour; Lymph node metastases; Locally advanced HNSCC; Radiochemotherpy

Permalink: https://www.hzdr.de/publications/Publ-30537
Publ.-Id: 30537


Morphology Modification of Si Nanopillars under Ion Irradiation at Elevated Temperatures

Xu, X.; Heinig, K.-H.; Möller, W.; Engelmann, H.-J.; Klingner, N.; Gharbi, A.; Tiron, R.; Borany, J.; Hlawacek, G.

Ion beam irradiation of vertical nanopillar structures can be utilized to fabricate a vertical gate-all-around (GAA) single electron transistor (SET) device in a CMOS-compatible way. After irradiation of Si nanopillars (with a diameter of 35 nm and a height of 70 nm) by either 50 keV broad beam Si+ or 25 keV focused Ne+ beam from a helium ion microscope (HIM) at room temperature and a fluence of 2e16 ions/cm2, strong deformation of the nanopillars has been observed which hinders further device integration. This is attributed to ion beam induced amorphization of Si allowing plastic flow due to the ion hammering effect, which, in connection with surface capillary forces, dictates the final shape. However, plastic deformation can be suppressed under irradiation at elevated temperatures (investigated up to 672 K). Then, as confirmed by bright-field transmission electron microscopy, the substrate and the nanopillars remain crystalline and are continuously thinned radially with increasing fluence down to a diameter of 10 nm. This is attributed to enhanced forward sputtering through the sidewalls of the pillar, and found in reasonable quantitative agreement with the predictions from 3D ballistic computer simulation using the TRI3DYN program.
This work is supported by the European Union’s H-2020 research project ‘IONS4SET’ under Grant Agreement No. 688072.

  • Poster
    AVS 66th International Symposium & Exhibition, 24.10.2019, Columbus, USA

Permalink: https://www.hzdr.de/publications/Publ-30536
Publ.-Id: 30536


Realization of wafer-scale nanogratings with sub-50 nm period through vacancy epitaxy

Huang, Q.; Jia, Q.; Feng, J.; Huang, H.; Yang, X.; Grenzer, J.; Huang, K.; Zhang, S.; Lin, J.; Zhou, H.; You, T.; Yu, W.; Facsko, S.; Jonnard, P.; Wu, M.; Giglia, A.; Zhang, Z.; Liu, Z.; Wang, Z.; Wang, X.; Ou, X.

Gratings, one of the most important energy dispersive devices, are the fundamental building blocks for the majority of optical and optoelectronic systems. The grating period is the key parameter that limits the dispersion and resolution of the system. With the rapid development of large X-ray science facilities, gratings with periodicities below 50 nm are in urgent need for the development of ultrahigh-resolution X-ray spectroscopy. However, the wafer-scale fabrication of nanogratings through conventional patterning methods is difficult. Herein, we report a maskless and high-throughput method to generate wafer-scale, multilayer gratings with period in the sub-50 nm range. They are fabricated by a vacancy epitaxy process and coated with X-ray multilayers, which demonstrate extremely large angular dispersion at approximately 90 eV and 270 eV. The developed new method has great potential to produce ultrahigh line density multilayer gratings that can pave the way to cutting edge high-resolution spectroscopy and other X-ray applications.

Keywords: GRATINGS; SCATTERING; ARRAYS

Permalink: https://www.hzdr.de/publications/Publ-30535
Publ.-Id: 30535


High resolution materials modification with low fluence Helium Ion Microscopy

Hlawacek, G.

Helium Ion Microscopy (HIM) is best known for its high resolution imaging capabilities of both
conductive as well as insulating samples. However, since the introduction of Ne as a source gas for the
gas field ion source (GFIS) an increasing number of nano-fabrication applications are realized. While
the use of Neon as an imaging gas results in a somewhat lower lateral resolution (1.8 nm for 25 keV Ne +
compared to 0.5 nm for 30 keV He + ) the user usually benefits from the much higher cross section for
nuclear stopping. The latter results in a larger number of sputtered atoms, vacancies, interstitials and
chemical bonds broken directly by small impact parameter collisions.
After a brief introduction of the technique I will present results obtained using direct write milling, low
fluence ion beam irradiation and ion beam based mixing. In all cases the electronic, optical or magnetic
properties of the target material will be altered at the nano-scale in a controlled way to achieve new
functionality. The examples comprise
∙ Irradiation of 2D materials including a discussion on the achievable resolution
∙ The fabrication of a lateral spin valve and other magnetic structures using low fluence focused ion
beam irradiation
∙ Irradiation of Si nanostructures at elevated temperatures to avoid amorphization
∙ Irradiation of SiC with very low fluencies
For many of the presented examples the critical length scale of the nanostructure is smaller or in the
range of collision cascade. This size regime can not easily be accessed with traditional broad beam based
ion irradiation and holds many promises but also challenges that need to be overcome to enable new
device concepts and new functional materials on the nano-scale. The use of in-situ instrumentation to
characterize and influence the irradiated material during the irradiation is a key element for the above
examples.
This work is supported by the European Union’s H-2020 research project ‘IONS4SET’ under Grant
Agreement No. 688072.

Keywords: HIM; modification

  • Invited lecture (Conferences)
    1st Sino-German Symposium on "Defect Engineering in SiC Device Manufacturing - Atomistic Simulations, Characterization and Processing" DESiC 2019, 12.11.2019, Peking, China

Permalink: https://www.hzdr.de/publications/Publ-30534
Publ.-Id: 30534


Up to 70 THz bandwidth from an implanted Ge photoconductive antenna excited by a femtosecond Er:fibre laser

Singh, A.; Pashkin, O.; Winnerl, S.; Welsch, M.; Beckh, C.; Sulzer, P.; Leitenstorfer, A.; Helm, M.; Schneider, H.

Phase-stable electromagnetic pulses in the THz frequency range offer several unique capabilities in time-resolved spectroscopy. However, the diversity of their application is limited by the covered spectral bandwidth. In particular, the upper frequency limit of photoconductive emitters - the most widespread technique in THz spectroscopy – reaches only up to 7 THz in the regular transmission mode due to the absorption by infrared-active optical phonons. Here, we present ultra-broadband (extending up to 70 THz) THz emission from an Au implanted Ge emitter which is compatible with modelocked fibre lasers operating at 1.1 and 1.55 um wavelengths with pulse repetition rates of 10 and 20 MHz, respectively. This result opens a perspective for the development of compact THz photonic devices operating up to multi-THz frequencies which are compatible with Si CMOS technology.

Permalink: https://www.hzdr.de/publications/Publ-30533
Publ.-Id: 30533


Focused ion beam materials modification with noble gas ions

Hlawacek, G.

I will present results obtained using Helium Ion Microscopy (HIM) [1] in various nanostructuring projects. The common goal of the research is to change the electronic or magnetic properties of the target material at the nano-scale in a controlled way to achieve new functionality. Where applicable this new functionality will be measured in-situ during the nanostructure fabrication process.
For all presented examples the critical length scale of the nanostructure is smaller or in the range of collision cascade.
This size regime can not easily be accessed with traditional broad beam based ion irradiation and holds many promises but also challenges that need to be overcome to enable new device concepts and new functional materials on the nano-scale.

  • Invited lecture (Conferences)
    IISC23, 20.11.2019, Matsue, Japan

Permalink: https://www.hzdr.de/publications/Publ-30532
Publ.-Id: 30532


Nanostructure characterization with ions

Hlawacek, G.

Helium Ion Microscopy (HIM) is best known for its high resolution imaging capabilities of both conductive as well as insulating samples. Over the last decade several efforts have been made to also add high spatial resolution analytic capabilities to the instrument. In many cases the starting point for these efforts was given by existing high energy ion beam analysis techniques. In particular TOF-RBS, magnetic sector SIMS and TOF-SIMS have successfully been realized. In addition in-situ probing, and in-operando methods are used to evaluate directly the effect of ion beam irradiation on nanostructures.
New developments aim at the improving of magnetic sector SIMS and the implementation of scanning transmission ion microscopy.
This work is supported by European Union’s H-2020 research project ‘npSCOPE’ under Grant Agree-ment No. 720964 and the FNR STHIM project under grant number I7748, and by the German BMWi via Grant 03ET7016 and 03THW12F01.

Keywords: HIM; SIMS; STIM

  • Invited lecture (Conferences)
    8th EU Korea Nanoworkshop, 25.11.2019, Brüssel, Belgien

Permalink: https://www.hzdr.de/publications/Publ-30531
Publ.-Id: 30531


Analytic approaches for Helium Ion Microscopy

Klingner, N.; Hlawacek, G.; Laura, W.; Heller, R.

Helium Ion Microscopy (HIM) has become a wide spread imaging and nanofabrication technology.
However, existing HIM users can currently not perform elemental analysis in an easy and cost efficient
way. We present results obtained using a light weight retrofitable Time of Flight Secondary Ion Mass
Spectrometer (TOF-SIMS). I will briefly give an overview on new developments in our TOF-SIMS setup
which allows to obtain information on the elemental composition of the sample. The lateral resolution
for the presented TOF-SIMS add-on has been measured to be 8 nm. While not a dedicated high
mass resolution instrument it allows to answer many scientific questions by combining the high lateral
resolution of the HIM with elemental information. The examples include but are not limited to battery
materials and corrosion protection of steel.

Keywords: HIM; SIMS; batteries

  • Lecture (Conference)
    AVS, 24.10.2019, Columbus, USA

Permalink: https://www.hzdr.de/publications/Publ-30530
Publ.-Id: 30530


Tailoring magnetic nanostructures with a He-Ne ion microscope

Hlawacek, G.; Bali, R.; Lenz, K.; Samad, F.; Peter, D.

Tailoring magnetic nanostructures with a He-Ne ion microscope

Keywords: HIM; magnetism

  • Lecture (Conference)
    Spins, Waves and Interactions 2019, 5.9.2019, Greifswald, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30529
Publ.-Id: 30529


Avoiding amorphization during ion beam irradiation and critical dimension reduction of nanostructures

Xu, X.; Hlawacek, G.; Engelmann, H.-J.; Bischoff, L.; Heinig, K.-H.; Borany, J.

Ion beam induced collateral damage is becoming an issue in FIB processing, as it limits the
application of ion beams for nanostructure fabrication. This is of special importance for the
application of focused ion beams for nanostructure fabrication.
Here, we present an approach to mitigate the ion beam induced damage inflicted on semi -
conductor nanostructures during ion beam irradiation. Nanopillars (with a diameter of
35 nm and a height of 70 nm) have been irradiated with both, a 50 keV Si + broad beam and
a 25 keV focused Ne + beam from a helium ion microscope (HIM). Upon irradiation of the
nanopillars at room temperature with a medium fluence (2x10 16 ions/cm2), strong plastic
deformation has been observed which hinders further device integration. The shape and
crystallinity has been studied by HIM and TEM. This differs from predictions made by
Monte-Carlo based simulations using the TRI3DYN. However, irradiation at elevated tem-
peratures with the same fluence not only preserves the shape of the nanopillars but allows
for controlled diameter reduction by as much as 50 % without significant change in pillar
height.
It is well known that above a critical temperature amorphization of silicon is prevented in-
dependent of the applied fluence. At high enough temperatures and for not too high flux
this prevents the ion beam hammering and viscous flow of the nanostructures. These two
effects are responsible for the shape change observed at low temperature. We find that ir-
radiation above 650 K preserves the crystalline nature of the pillars and prevents viscous
flow. In addition, a steady thinning process of the nanopillars to a diameter of 10 nm with-
out a significant change in height is observed for higher fluencies at elevated temperatures.
As the original pillar diameter is smaller than the size of the collision cascade, enhanced
forward sputtering through the sidewalls of the pillar is responsible for this pillar-thinning
effect. Results for various ion beam energies, fluencies, fluxes and temperatures will be
presented and compared to TRI3DYN simulations. Such a reliable and CMOS-compatible
process could serve as a potential down scaling technique for large-scale fabrication of
nanostructure based electronics and many other FIB based milling applications.

Keywords: HIM

  • Lecture (Conference)
    EU-F-N 2019, 14.6.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30528
Publ.-Id: 30528


Analytic approaches for Helium Ion Microscopy

Hlawacek, G.; Klingner, N.; Veligura, V.; Xu, X.; Serralta Hurtado De Menezes, E.; Schmeink, A. H.; Borany, J.; Facsko, S.

Helium Ion Microscopy (HIM) utilizes a Gas Field Ion Source (GFIS) to create a Helium or Neon
ion beam with a diameter better than 0.5 nm and 1.8 nm, respectively. The method is well known
for its high resolution imaging and nano-fabrication capabilities which it is able to provide not only for
conducting but also insulating samples without the need for a conductive coating. However, the existing
GFIS based focused ion beam (FIB) tools suffer from the lack of a well integrated analytic method that
can enrich the highly detailed morphological images with material properties contrast. While HIM
technology is relatively young several efforts have been made to add such an analytic capability to
the technique. So far, ionoluminescence, secondary electron spectroscopy, backscattering spectrometry
(BS), and secondary ion mass spectrometry (SIMS) using a magnetic sector or time of flight (TOF)
setup have been demonstrated. In addition in-situ experiments can be performed that allow to directly
and in real time investigate the effect of the focused ion beam on the materials under various conditions.
I will present our efforts to perform in-situ experiments in the Helium Ion Microscope and enhance its
analytic capabilities. In the first part of my presentation I will give an overview of the in-situ characteri-
zation capabilities of the HZDR Orion NanoFab including in-situ heating and electrical characterization.
In the second part of the talk I will focus on different analytic approaches tested in the past. I will
briefly give an overview on ionoluminescence in the HIM and than present our newly developed TOF-BS
and TOF-SIMS setup which allow to obtain information on the composition of the sample. They both
utilize the same cost efficient and minimal invasive pulsing scheme for the primary ion beam. The lateral
resolution reached for TOF-BS is approximately 50 nm while for TOF-SIMS a value of 8 nm could be
reached. First images will be presented and the performance of the TOF-SIMS spectrometer will be
discussed.

Keywords: HIM; SIMS

  • Invited lecture (Conferences)
    Zakopane School of Physics, 24.5.2019, Zakopane, Polen

Permalink: https://www.hzdr.de/publications/Publ-30527
Publ.-Id: 30527


In-situ experiments and characterization in the Helium Ion Microscope

Hlawacek, G.

In-situ experiments in the HIM

Keywords: HIM

  • Open Access Logo Invited lecture (Conferences)
    Ion beams for future technologies 2019, 2.4.2019, Dubrovnik, Kroatien

Permalink: https://www.hzdr.de/publications/Publ-30526
Publ.-Id: 30526


Avoiding amorphization in silicon nano structures

Hlawacek, G.; Xu, X.; Engelmann, H.-J.; Heinig, K.-H.; Möller, W.; Ahmed, G.; Raluca, T.; Bischoff, L.; Prüfer, T.; Hübner, R.; Facsko, S.; Borany, J.

Helium Ion Microscopy (HIM) [1, 2] is best known for its high resolution imaging capabilities of both
conductive as well as insulating samples. However, since the introduction of Ne as an imaging gas for the
gas field ion source (GFIS) an increasing number of nano-fabrication applications are realized. While
the use of Neon as an imaging gas results in a somewhat lower lateral resolution (1.8 nm for 25 keV
Ne compared to 0.5 nm for 30 keV He) the user usually benefits from the much higher cross section for
nuclear stopping. The latter results in a larger number of sputtered atoms and bonds broken directly
by small impact parameter collisions.
After a brief introduction of the technique I will present results obtained using direct write milling low
fluence ion beam irradiation and ion beam based mixing. In all three cases the electronic or magnetic
properties of the target material will be altered at the nano-scale in a controlled way to achieve new
functionality. The examples comprise
∙ The fabrication of semiconducting graphene nano-ribbons by direct milling [3]
∙ The fabrication of a lateral spin valve structure using low fluence ion irradiation [4]
∙ The formation of individual 3 nm Si clusters for a room temperature single electron transistor [5]
For all presented examples the critical length scale of the nanostructure is smaller or in the range of
collision cascade. This size regime can not be accessed with traditional broad beam based ion irradiation
and holds many promises but also challenges that need to be overcome to enable new device concepts
and new functional materials on the nano-scale.
This work is supported by the European Union’s H-2020 research project ‘IONS4SET’ under Grant
Agreement No. 688072

Keywords: HIM; modification

  • Lecture (Conference)
    DPG Frühjahrstagung, 3.4.2019, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30525
Publ.-Id: 30525


Spatially resolved materials modification using Helium Ion Microscopy

Hlawacek, G.

Helium Ion Microscopy (HIM) [1, 2] is best known for its high resolution imaging capabilities of both
conductive as well as insulating samples. However, since the introduction of Ne as an imaging gas for the
gas field ion source (GFIS) an increasing number of nano-fabrication applications are realized. While
the use of Neon as an imaging gas results in a somewhat lower lateral resolution (1.8 nm for 25 keV
Ne compared to 0.5 nm for 30 keV He) the user usually benefits from the much higher cross section for
nuclear stopping. The latter results in a larger number of sputtered atoms and bonds broken directly
by small impact parameter collisions.
After a brief introduction of the technique I will present results obtained using direct write milling low
fluence ion beam irradiation and ion beam based mixing. In all three cases the electronic or magnetic
properties of the target material will be altered at the nano-scale in a controlled way to achieve new
functionality. The examples comprise
∙ The fabrication of semiconducting graphene nano-ribbons by direct milling [3]
∙ The fabrication of a lateral spin valve structure using low fluence ion irradiation [4]
∙ The formation of individual 3 nm Si clusters for a room temperature single electron transistor [5]
For all presented examples the critical length scale of the nanostructure is smaller or in the range of
collision cascade. This size regime can not be accessed with traditional broad beam based ion irradiation
and holds many promises but also challenges that need to be overcome to enable new device concepts
and new functional materials on the nano-scale.
This work is supported by the European Union’s H-2020 research project ‘IONS4SET’ under Grant
Agreement No. 688072

Keywords: Helium ion microscopy; materials modification

  • Lecture (others)
    Institutsseminar, 31.01.2019, Strassbourg, Frankreich
  • Invited lecture (Conferences)
    EIPBN, 30.5.2019, Minneapolis, USA

Permalink: https://www.hzdr.de/publications/Publ-30524
Publ.-Id: 30524


Mapping of Magnetic Metastable States in Synthetic Antiferro- and Ferrimagnets with Perpendicular Magnetic Anisotropy

Salikhov, R.; Samad, F.; Koch, L.; Böhm, B.; Hellwig, O.

Magnetic multilayers (MLs) with perpendicular magnetic anisotropy (PMA), such as Co/Pt or
Co/Pd, are the host materials for a variety of metastable magnetic configurations, e.g. aligned or labyrinth
stripe domains, bubble domains and their mixtures. The magnetic morphology at remanence mostly depends
on the specific demagnetization routine using an external magnetic field [1], whereas the characteristic size of
the magnetic objects (domain period or bubble radius) is mostly determined by the design parameters of the
magnetic MLs (e.g. the thickness of Co layer, periodicity and the number of repeats X) [1,2]. Interleaving the
Co/Pt blocks by Ru or Ir layers, which promote antiferromagnetic (AF) interlayer coupling between PMA ML
blocks, results in a class of artificial magnetic structures, known as synthetic antiferromagnets (SAFs) with
PMA. The AF interlayer exchange energy alters the typical energy balance, thus modifying the morphology
and characteristic size of magnetic domain states in PMA SAFs [1]. Stabilisation of magnetic bubble domain
states in SAFs is of particular practical interest [3], whereas other new magnetic configurations are of interest
for fundamental research. Here we present the mapping of magnetic states in SAFs for different
demagnetization protocols and ML parameters by means of monitoring the remanent magnetization Mr during
the AC or DC demagnetization process itself and performing magnetic force microscopy (MFM) imaging at the
intermediate states of interest (Fig. 1). The aligned stripe domain state is characterised by almost zero Mr,
whereas bubble domains [4] and mixed states (Fig. 1) manifest themselves by an enhanced Mr. The magnetic
states for SAFs with tunable parameters such as Co thickness and repetition number X will be presented. We
will also discuss the magnetic behaviour in synthetic ferrimagnets, where the two ML block sub-lattices have
different magnetic moments.
References: [1] O. Hellwig, A. Berger, J. B. Kortright, JMMM, Vol. 319, p.13-55 (2007)
[2] I. Lemesh, F. Büttner, G. S. D. Beach, Phys. Rev. B, Vol. 95, p.174423 (2017)
[3] K. Chesnel, A. S. Westover, C. Richards, Phys. Rev. B, Vol. 98, p.224404 (2018)
[4] A. Hubert, R. Schäfer, Magnetic Domains, Springer Berlin (2009)

  • Lecture (Conference)
    64th Annual Conference on Magnetism and Magnetic Materials (MMM 2019), 04.-08.11.2019, Las Vegas, Nevada, USA

Permalink: https://www.hzdr.de/publications/Publ-30523
Publ.-Id: 30523


ESUO - The European Synchrotron and FEL User Organisation: Aims and activities

Arčon, I.; Arikan, P.; Bittencourt, C.; Boscherini, F.; Braz Fernandes, F. M.; Brooks, N.; Casu, B.; D'Astuto, M.; Feiters, M.; Froideval, A.; Granroth, S.; Gross, S.; Gutt, C.; Hase, T.; Jablonska, K.; Jergel, M.; Khan, A.; Kirm, M.; Kokkinidis, M.; Kövér, L.; Lamba, D.; Larsen, H. B.; Lechner, R. T.; Le Hir, R.; Logan, D. T.; López, O.; Lorentz, K.; Mariani, C.; Marinkovic, B.; Mcguinness, C.; Meedom Nielsen, M.; Micetic, M.; Mickevicius, S.; Mikulík, P.; Petukhov, A.; Pietsch, U.; Pokroy, B.; Purans, J.; Renault, L.; Santoro, G.; Shivachev, B.; Stangl, J.; Tromp, M.; Vankó, G.; Blasetti, C.; Freire Anselmo, A. S.; Grobosch, M.; Helm, M.; Schramm, B.; Vollmer, A.

The European Synchrotron and free-electron laser User Organisation (ESUO) established in 2010 represents about 22.000 users. It is composed of 30 member countries. Our vision is to support a thriving (European) synchrotron and FEL user community with equal opportunities of access and participation for all scientists, based solely on the scientific merit of their ideas.

  • Poster
    EMFL User Meeting 2019, 25.06.2019, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-30521
Publ.-Id: 30521


Exploiting Hysteresis in a Multicaloric Cooling Cycle

Gottschall, T.

für den Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Annual Conference on Magnetism and Magnetic Materials 2019, 04.-08.11.2019, Las Vegas, USA

Permalink: https://www.hzdr.de/publications/Publ-30520
Publ.-Id: 30520


Multicaloric materials and their characterization

Gottschall, T.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Ruhr Symposium 2019, 09.10.2019, Duisburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30519
Publ.-Id: 30519


The activities of the European Synchrotron and FEL User Organisation for even brighter European Photon Science

Pietsch, U.; Arčon, I.; Arikan, P.; Bittencourt, C.; Boscherini, F.; Braz Fernandes, F. M.; Brooks, N.; Casu, B.; D'Astuto, M.; Feiters, M.; Froideval, A.; Granroth, S.; Gross, S.; Gutt, C.; Hase, T.; Jablonska, K.; Jergel, M.; Khan, A.; Kirm, M.; Kokkinidis, M.; Kövér, L.; Lamba, D.; Larsen, H. B.; Lechner, R. T.; Le Hir, R.; Logan, D. T.; López, O.; Lorentz, K.; Mariani, C.; Marinkovic, B.; Mcguinness, C.; Meedom Nielsen, M.; Micetic, M.; Mickevicius, S.; Mikulík, P.; Petukhov, A.; Pokroy, B.; Purans, J.; Renault, L.; Santoro, G.; Shivachev, B.; Stangl, J.; Tromp, M.; Vankó, G.; Blasetti, C.; Freire Anselmo, A. S.; Grobosch, M.; Helm, M.; Schramm, B.; Vollmer, A.

The European Synchrotron and FEL User Organisation (ESUO) represents about 22 000 users of the European synchrotron radiation (SR) and Free-Electron Laser (FEL) facilities, which offer various kinds of experiments ranging from physics over life sciences up to cultural heritage. Established in 2010, ESUO is composed of national delegates from 30 European member states and associated countries and is headed by an executive board of eight members. Our vision is to support a thriving (European) synchrotron and FEL user community with equal opportunities of access and participation for all scientists, based solely on the scientific merit of their ideas.

  • Invited lecture (Conferences)
    ESUO Regional Workshop at PHOTONICA 2019 Conference, 28.08.2019, Belgrade, Serbia

Permalink: https://www.hzdr.de/publications/Publ-30518
Publ.-Id: 30518


Preparation and Characterization of Solar Thermal Absorbers by Nanoimprint Lithography and Sputtering

Mitteramskogler, T.; Haslinger, M. J.; Wennberg, A.; Fernandez Martínez, I.; Muehlberger, M.; Krause, M.; Guillén, E.

Selective solar absorbers comprised of plasmonic materials offer great flexibility in design along with a highly promising optical performance. However, the nanopattern generation, typically done with electron beam writing, is a very time-intensive process. In this work, we present a fast, scalable, and flexible method for the fabrication of plasmonic materials by the combination of a deposition mask prepared by nanoimprint lithography and thin film deposition by magnetron sputtering. The fabrication process was first performed on silicon wafer substrates using AFM and SEM measurements to calibrate the deposition time, determine maximal deposition height, and characterize samples. Afterwards, the process was transferred to polished Inconel NiCr-alloy substrates used in high temperature solar absorbers. To investigate the adhesion properties of the nanostructure on the substrate, two different deposition methods were investigated: DC magnetron sputtering and High Power Impulse Magnetron Sputtering (HiPIMS).

Keywords: Solar absorbers; nanoimprint lithography; HiPIMS

  • Contribution to proceedings
    2019 MRS Spring Meeting & Exhibition, 22.-26.04.2019, Phoenix, USA
    MRS Advances 4(2019)35, 1905-1911: Cambridge
    DOI: 10.1557/adv.2019.285
  • Lecture (Conference)
    2019 MRS Spring Meeting & Exhibition, 22.-26.04.2019, Pheonix, USA

Permalink: https://www.hzdr.de/publications/Publ-30516
Publ.-Id: 30516


High temperature in-air stability of solar absorber coatings based on aluminium titanium oxynitride nanocomposites

Heras, I.; Krause, M.; Rincón, G.; Guillén, E.; Azkona, I.; Lungwitz, F.; Munnik, F.; Escobar Galindo, R.

One of the major challenges in Concentrating Solar Power (CSP) implies an increase of the working temperature of the solar receiver. In particular, current central tower systems operate at maximum temperatures of 550 ºC mainly due to the severe degradation that the state of the art absorber paints (i.e. Pyromark®) suffer at higher temperatures. In previous works [1,2] aluminum titanium oxynitrides AlyTi1-y(OxN1-x) were shown to be excellent candidate materials for solar selective coatings (SSC). These results confirmed that the designed SSCs based on materials withstand breakdown at 600 ºC in air after 900 hours of thermal cycling.
In this paper we discuss the high temperature (up to 700ºC) stability in air of a solar absorber coating based on AlyTi1-y(OxN1-x) deposited by cathodic vacuum arc (CVA) at higher working pressure (P = 2.1 Pa) than those discussed in [1] and [2]. The composition, morphology and microstructure of the films were characterized by ion beam analysis, scanning and transmission electron microscopy and X-ray diffraction. The optical properties were determined by ellipsometry and spectrophotometry (UV-Vis-NIR, FTIR). The microstructural and morphological characterization shows the formation of a solid solution of AlTiN crystalline nanoparticles embedded in an amorphous Al2(O, N)3 matrix. This particular microstructure results in a coating with a high absorption coefficient within the whole wavelength range of interest (0,3 to 25 um) as modeled by spectroscopic ellipsometry. Hence, this single layer absorber shows a solar absorptance, α, of 92% and an emissivity, εRT, of 70%. The addition of an antireflective Al2O3 layer and post deposition thermal treatments improved the optical properties of the absorber to better values (α=96% and εRT=60%) than those of Pyromark®. The thermal stability in air of the absorber was firstly analyzed by cyclic heating tests, showing no degradation after 300h of cycles in air at 700ºC. Subsequently, the samples were tested in a solar furnace at 650 °C and 800 ºC for 12 hours at environmental conditions. Therefore, this absorber coating can be a feasible alternative to absorber paints for next generation of concentrated solar power plants operating at high temperature.
[1] I. Heras et al., Sol. Energy Mat. Solar Cells, 176, 81-92 (2018)
[2] R. Escobar-Galindo et al., Sol. Energy Mat. Solar Cells, 185, 183-191 (2018)

Keywords: Solar selective coatings; thermal stability; optical properties; concentrated solar power; optical simulation; oxynitrides

  • Lecture (Conference)
    2019 MRS Spring Meeting & Exhibition, 22.-26.04.2019, Phoenix, USA

Permalink: https://www.hzdr.de/publications/Publ-30515
Publ.-Id: 30515


ESUO - The European Synchrotron and FEL User Organisation

Arčon, I.; Arikan, P.; Bittencourt, C.; Boscherini, F.; Braz Fernandes, F. M.; Brooks, N.; Casu, B.; D'Astuto, M.; Feiters, M.; Froideval, A.; Granroth, S.; Gross, S.; Gutt, C.; Hase, T.; Jablonska, K.; Jergel, M.; Khan, A.; Kirm, M.; Kokkinidis, M.; Kövér, L.; Lamba, D.; Larsen, H. B.; Lechner, R. T.; Le Hir, R.; Logan, D.; López, O.; Lorentz, K.; Mariani, C.; Marinkovic, B.; Mcguinness, C.; Meedom Nielsen, M.; Micetic, M.; Mickevicius, S.; Mikulík, P.; Petukhov, A.; Pietsch, U.; Pokroy, B.; Purans, J.; Renault, L.; Santoro, G.; Shivachev, B.; Stangl, J.; Tromp, M.; Vankó, G.; Freire Anselmo, A. S.; Blasetti, C.; Grobosch, M.; Helm, M.; Schramm, B.; Vollmer, A.

The European Synchrotron and free-electron laser User Organisation (ESUO) established in 2010 represents about 22.000 users. It is composed of 30 member countries. Our vision is to support a thriving (European) synchrotron and FEL user community with equal opportunities of access and participation for all scientists, based solely on the scientific merit of their ideas.

  • Poster
    11th Joint BER II and BESSY II User Meeting, 04.-06.12.2019, HZB, Germany

Permalink: https://www.hzdr.de/publications/Publ-30514
Publ.-Id: 30514


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