Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41356 Publications

Steel casting characterisation: contactless inductive flow tomography and mutual inductance tomography

Wondrak, T.; Peyton, A. J.

Monitoring the steel flow through the submerged entry nozzle (SEN) and in the mould during continuous casting presents a challenge for the instrumentation system because of the high temperature environment and the opaqueness of the liquid steel. In this article we describe the development of two complimentary electromagnetic instrumentation systems which are able to visualise the steel flow profile in the SEN by means of Mutual Inductance Tomography (MIT) and the mean 2D/3D flow structure in the mould by means of Contactless Inductive Flow Tomography (CIFT). The flow structure in both sites is crucial for the quality of steel in respect of cleanliness and surface quality. The article will cover the development of both techniques from first principles and initial tests on a scaled (approx. 1:10) laboratory model of the continuous casting process. The experiments were performed with argon gas and GaInSn as an analogue for liquid steel, which has similar conductive properties as molten steel and allows the measurements at room temperature. The article will close with describing hot tests and subsequent plant tests.

Keywords: contactless inductive flow tomography; mutual inductance tomography; flow measurement; continuous casting; steel flow; tomography

  • Book chapter
    Rafael Colás, George E. Totten: Encyclopedia of Iron, Steel, and Their Alloys, New York: Taylor & Francis Group,, 2016, 978-1-4665-1104-0, 3320-3332

Publ.-Id: 21278

Flow visualization by means of contactless inductive flow tomography in the presence of a magnetic brake

Ratajczak, M.; Wondrak, T.; Timmel, K.; Stefani, F.; Eckert, S.

In continuous casting DC magnetic fields perpendicular to the wide faces of the mold are used to control the flow in the mold. Especially in this case, even a rough knowledge of the flow structure in the mold would be highly desirable. The contactless inductive flow tomography (CIFT) allows to reconstruct the dominating two-dimensional flow structure in a slab casting mold by applying one external magnetic field and by measuring the flow induced magnetic fields outside the mold. For a physical model of a mold with a cross section of 140 mm × 35 mm we present preliminary measurements of the flow field in the mold in the presence of a magnetic brake. In addition, we show first reconstructions of the flow field in a mold with the cross section of 400 mm × 100 mm demonstrating the upward scalability of CIFT.

Keywords: continuous casting; contactless inductive flow tomography; flow measurement

  • Journal for Manufacturing Science and Production 15(2015)1, 41-48
    DOI: 10.1515/jmsp-2014-0037
    ISSN: 2191-4184
  • Invited lecture (Conferences)
    TMS 2015 144th annual meeting & exhibition, 15.-19.03.2015, Orlando, United States of America

Publ.-Id: 21277

Europium(III)-Calcite study with site-selective TRLFS

Peschel, S.; Schmidt, M.; Stumpf, T.

Calcite is an important mineral that plays a significant role in nuclear waste disposal concerning the safety and performance in geological formations. At these sites it can be found in the near field as a secondary phase (weathering of the geochemical barrier) and as a rock-forming mineral in the surrounding rocks. Geochemically, calcite has the potential to adsorb as well as incorporate guest ions with a similar ionic radius, such as europium and curium, for calcium in the host lattice. Because of the long half-lives of actinides like curium and americium, they and their lanthanide homologues (i.e., europium) are the subject of recent research.
Calcite samples were doped with Eu(III) in batch experiments. Calcium carbonate powder was contacted with a Eu(III) solution (5 x 10-7 M) in a calcium carbonate saturated solution with a NaCl (10 mM) background electrolyte solution. Batch samples were analyzed at varying contact times to understand the step-by-step kinetic and mechanistic behavior of incorporation of Eu(III) into the solid phase. After the contact period, the supernatant was investigated with ICP-MS. The Eu(III) concentration in solution varies from 0.1 to 3.2 % of the initial concentration, which indicates that almost all Eu(III) is adsorbed.
The calcite powder was examined with site-selective TRLFS at temperatures below 20 K. The direct excitation of the 7F0 →5D0 transition in the range of 576-581 nm and the integration of the respective emission spectra yields a characteristic excitation spectrum. These excitation spectra show only one broad peak with a maximum at ~579.2 nm, independent of the sorption time (up to 31 days). This behavior is dissimilar to that determined by Stumpf and Fanghänel [1] who investigated Cm(III) sorption on calcite with NaClO4 as background electrolyte and found 2 peaks, which change over time. Lifetime measurements of our samples exhibit biexponential decay indicative of two species. The first specie has a lifetime of 460 to 985 µs and the second 2155 to 4577 µs. Using Horrock´s equation[2] the number of coordinating water molecules in the first sphere surrounding the Eu(III) can be determined. This value corresponds to its location (surface sorbed vs incorporated) on or within the calcite lattice. Therefore, calculated values of 0.5 to 1.7 indicate the formation of an inner sphere sorption species whereas a value of 0 is indicative of incorporation of the Eu(III) within the calcite. The emission spectrum shows a threefold splitting of the 7F1 band.This indicates a ligand field with low symmetry. To better understand these surface species, future measurements with CTR and RAXR will be performed.

[1] Stumpf, T. and T. Fanghanel (2002). J. of Colloid and Interface Science 249(1), 119-122.
[2] Horrocks (1979) J. Am. Chem. Soc. 101, 334.

Keywords: site-selective TRLFS; Europium; Calcite

  • Poster
    Advanced Techniques in Actinide Spectroscopy 2014 (ATAS 2014), 03.-07.11.2014, Dresden, Deutschland

Publ.-Id: 21276

Sorption of (trivalent) actinides and lanthanides

Hellebrandt, S.; Schmidt, M.; Stumpf, T.

The study of trivalent actinides is of particular importance for the safety assessment of nuclear waste disposal sites due to the predominance of this valence in deep geological formations. In particular, studying the solution-solid interface chemistry of these trivalent radioelements in the aqueous phase with a mineral is fundamental for better understanding their interactions at or within the surface of a host phase in a repository. As a relevant near field material (geotechnical barrier) for nuclear waste disposal sites, clay minerals are very important due to their retardation properties. Muscovite, a phyllosilicate material of aluminum and potassium, is very similar to clay minerals but less complex, so we are able to assign results from muscovite to clay minerals. Additionally, investigations concerning trace concentration of actinides appearing in the far field of a nuclear waste disposal are also of interest. Site-Selective Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) is a characterizational technique that can probe the behavior of low concentrated actinides on a molecular level. As a complementary technique resonant anomalous x-ray reflectivity (RAXR) will be used to get a deeper insight and a verification of the TRLFS results.

TRLFS, the main tool
The aim of this study focuses on understanding the surface interactions of muscovite with aqueous trivalent actinides and lanthanides using Eu(III) and Cm(III), and characterization of the solid and aqueous phase species using TRLFS. Europium (III) is used as a non-radioactive homologue for trivalent actinides due to its similar chemical behavior and its spectroscopic properties as a probe for TRLFS. Direct excitation of the 7F05D0 electron transition and consecutive integration of the respective emission generates information pertaining to the chemical coordination and environment of the Eu(III). First investigations in the muscovite-europium system show that there appears one poorly defined species (broad excitation peak) present at one site. Lifetime measurements of the luminescence are used in accordance with the Horrocks equation (europium) [1] and the number of coordinated waters can be determined. The lifetimes between 208 and 230 µs indicates 4 to 5 coordinated water ligands in the inner sphere. As a consequence of this the europium species is interpreted as inner-sphere sorption on the surface of muscovite.

[1] Horrocks, W.D. and Sudnick, D.R. (1979) J. Am. Chem. Soc. 101, 334-340.

  • Poster
    2nd International Workshop on Advanced Techniques in Actinide Spectroscopy (ATAS 2014), 03.-07.11.2014, Dresden, Deutschland

Publ.-Id: 21275

AER Working Group D on VVER safety analysis – report of the 2014 meeting

Kliem, S.

The AER Working Group D on VVER reactor safety analysis held its 23th meeting in Garching, Germany, during the period 12-13 May, 2014. The meeting was hosted by the GRS Garching and was held in conjunction with the eighth workshop on the OECD Benchmark for Uncertainty Analysis in Best-Estimate Modelling (UAM) for Design, Operation and Safety Analysis of LWRs. Altogether 21 participants attended the meeting of the working group D, 19 from AER member organizations and 2 guests from non-member organization. The co-ordinator of the working group, Mr. S. Kliem, served as chairman of the meeting.
The meeting started with a general information exchange about the recent activities in the participating organizations.
The given presentations and the discussions can be attributed to the following topics:

  • Safety analyses methods and results
  • Code development and benchmarking including the calculation of the OECD/NEA Benchmark for the Kalinin-3 VVER-1000 NPP and 7th AER Dynamic Benchmark
  • Future activities
A list of the participants and a list of the handouts distributed at the meeting are attached to the report. The corresponding PDF-files of the handouts can be obtained from the chairman.
  • Lecture (Conference)
    24th Symposium of AER on VVER Reactor Physics and Reactor Safety, 14.-18.10.2014, Sochi, Russian Federation
  • Contribution to proceedings
    24th Symposium of AER on VVER Reactor Physics and Reactor Safety, 14.-18.10.2014, Sochi, Russian Federation
    Proceedings of the 24th Symposium of AER on VVER Reactor Physics and Reactor Safety, Budapest: MTA Energoatom, 415-420

Publ.-Id: 21274

Recent developments in (H)LM measurement techniques

Wondrak, T.; Eckert, S.; Franke, S.; Shevchenko, N.; Buchenau, D.; Stefani, F.; Gerbeth, G.

In the field of advanced heavy-liquid-metal (HLM) cooled systems the knowledge of flow properties of the liquid metal is important for the design, the operation and the safety of such systems. The measurement of the flow properties is usually hampered by the high temperature and the opaqueness of liquid melts. We will give an overview of the recent developments of measurement techniques which can be used for model experiments as wells as for instrumenting a HLM cooled system. This includes ultrasound Doppler velocimetry, x-ray radioscopy and several inductive techniques like inductive flow meters and the contacless inductive flow tomography.

Keywords: liquid metal; flow measurement

  • Invited lecture (Conferences)
    SEARCH/MAXSIMA 2014 International Workshop, 07.-10.10.2014, Karlsruhe, Germany

Publ.-Id: 21272

Measurement techniques for the flow in a model of a continuous caster

Wondrak, T.; Timmel, K.; Stefani, F.; Eckert, S.; Shevchenko, N.; Röder, M.

In order to examine the flow structure in a continuous casting mold which is important for the quality of the produced steel, at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) three different models of a continuous caster are available to study the flow in a continuous casting mold. Those cold liquid metal models which use metallic alloys with low melting point e.g. up to 200 °C offer the application of different measurement techniques like ultrasound doppler velocimetry, x-ray and potential probes for flow investigation. Second, these models can be used to study the influence of magnetic actuators to the flow due to their high conductivity, contrary to water models. Third, these models can be used to develop new measurement techniques which can be applied in a real caster.
We will give a short overview of the measurement techniques available for those models. Additionally we will present the newly developed Contactless Inductive Flow Tomography which can reconstruct the flow in the mold by measuring the flow induced perturbation of an applied magnetic field. This technique has the ability to be deployed in a real caster.

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

  • Contribution to proceedings
    8th European Continuous Casting Conference, 23.-26.06.2014, Graz, Österreich
    Proceedings of the 8th eccc
  • Lecture (Conference)
    8th European Continuous Casting Conference, 23.-26.06.2014, Graz, Österreich


Publ.-Id: 21270

Source Terms, Shielding Calculations and Soil Activation for a Medical Cyclotron

Konheiser, J.; Naumann, B.; Ferrari, A.; Brachem, C.; Müller, S.

Calculations of the shielding and estimates of soil activation for a medical cyclotron are presented in this work. Based on the neutron source term from the 18O(p,n)18F reaction produced by a 28 MeV proton beam, neutron and gamma dose rates outside the building were estimated with the Monte Carlo code MCNP6(1). The neutron source term was calculated with the MCNP6 code and FLUKA(2) code as well as with supplied data by the manufacturer. Soil activation was performed using the FLUKA code.
The estimated dose rate in the public area is about 0.035 μSv/h and thus significantly below the reference value of 0.5 μSv/h(3). After 5 years of continuous beam operation and a subsequent decay time of 30 days, the activity concentration of the soil is about 0.34 Bq/g. Significant discrepancies between the manufacturer supplied data for the neutron source term and the calculations done using the MCNP6 and FLUKA codes were found.

Keywords: radiation shielding; cyclotron; soil activation; Monte Carlo; 18F production; dose rate


Publ.-Id: 21269

Quantitative assessment of the asphericity of pretherapeutic FDG uptake as an independent predictor of outcome in NSCLC.

Apostolova, I.; Rogasch, J.; Buchert, R.; Wertzel, H.; Achenbach, H. J.; Schreiber, J.; Riedel, S.; Furth, C.; Lougovski, A.; Schramm, G.; Hofheinz, F.; Amthauer, H.; Steffen, I. G.


The aim of the present study was to evaluate the predictive value of a novel quantitative measure for the spatial heterogeneity of FDG uptake, the asphericity (ASP) in patients with non-small cell lung cancer (NSCLC).


FDG-PET/CT had been performed in 60 patients (15 women, 45 men; median age, 65.5 years) with newly diagnosed NSCLC prior to therapy. The FDG-PET image of the primary tumor was segmented using the ROVER 3D segmentation tool based on thresholding at the volume-reproducing intensity threshold after subtraction of local background. ASP was defined as the relative deviation of the tumor's shape from a sphere. Univariate and multivariate Cox regression as well as Kaplan-Meier (KM) analysis and log-rank test with respect to overall
(OAS) and progression-free survival (PFS) were performed for clinical variables, SUVmax/mean, metabolically active tumor volume (MTV), total lesion glycolysis (TLG), ASP and "solidity", another measure of shape irregularity.


ASP, solidity and "primary surgical treatment" were significant independent predictors of PFS in multivariate Cox regression with binarized parameters (HR, 3.66; p < 0.001, HR, 2.11; p = 0.05 and HR, 2.09; p = 0.05), ASP and "primary surgical treatment" of OAS (HR, 3.19; p = 0.02 and HR, 3.78; p = 0.01, respectively). None of the other semi-quantitative PET parameters showed significant predictive value with respect to OAS or PFS. Kaplan-Meier analysis revealed a probability of 2-year PFS of 52% in patients with low ASP compared to 12% in patients with high ASP (p < 0.001). Furthermore, it showed a higher OAS rate in the case of low versus high ASP (1-year-OAS, 91% vs. 67%: p = 0.02).


The novel parameter asphericity of pretherapeutic FDG uptake seems to provide better prognostic value for PFS and OAS in NCSLC compared to SUV, metabolic tumor volume, total lesion glycolysis and solidity.

Publ.-Id: 21268

Abschlussbericht zum BMBF-Verbundprojekt Partitioning II: Multifunktionelle Komplexbildner mit N, O, S-Donorliganden für d- und f-Elemente - Synthese, Komplexbildung, Struktur und Transportverhalten

Günther, A.; Mansel, A.; Schulz, K.; Paulik, S.; Poetsch, M.; Bernhard, G.

Hauptziel des Verbundprojektes war es, die Wechselwirkung von neu synthetisierten supramolekularen Komplexbildnern mit N,O,S-Donorfunktionen gegenüber d- und f-Elementen zu untersuchen. Dabei standen für das HZDR im Teilprojekt 1 die Komplexierung von N,O-Donorliganden insbesondere mit den Aktiniden U(VI) und Cm(III) und den Lanthaniden Eu(III), Ce(III) und Yb(III) in wässriger und erstmalig in organischer Lösung in Abhängigkeit vom pH-Wert bzw. Redoxspannung im Mittelpunkt. Es wurden die entsprechenden Komplexstöchiometrien und die spektroskopischen Eigenschaften der gebildeten Komplexe mittels UV-Vis-Spektroskopie, verschiedener laserinduzierter Methoden als auch IR-Spektroskopie bestimmt. Durch Anwendung der NMR-und EXAFS-Spektroskopie konnten strukturelle Aussagen zu den Metallkomplexen in Lösung gemacht werden. Mit Hilfe von UV-Vis Daten war es möglich, reproduzierbare Komplexbildungskonstanten von Aktinid- bzw.- Lanthanidkomplexen mit verschiedenen ß-Diketonen sowie Schiffschen Basen in Lösung zu bestimmen. Ergebnisse der Arbeiten des HZDR im Teilprojekt 2 zeigten, dass die Wechselwirkung von wasserlöslichen Calixarenen mit Radionuklidmetallionen sowie das Adsorptionsverhalten von Calixarenen an Geomatrizes unter naturnahen Bedingungen (pH 4 - 9) vernachlässigbar sind. Für die Flüssig-Flüssig-Extraktion von divalenten Metallionen mittels Radiotracertechnik wurden wasserunlösliche Calixarene ermittelt, die elementselektiv die Radionuklide 85Sr, 56Co, 64Cu und 65Zn aus der wässrigen Phase separieren können. Für Strontium eignet sich Bis-Salicyliden-diamino-calixaren, welches sich unter milden Bedingungen rückextrahieren lässt. Dicarboxy-calixaren extrahiert die d-Elemente quantitativ. Diese Extraktion ist nicht vollständig reversibel. Für die gebildeten Calixaren-Komplexe wurden spektroskopische Daten ermittelt. Die Extraktionsverfahren wurden für vier natürliche Wässer erfolgreich angewendet. Festphasenfixierte Calixarene sorbieren die Radionuklide quantitativ, jedoch ist eine vollständige Desorption nicht realisierbar.

Keywords: radionuclide; actinide; lanthanide; Schiff base; ß-diketone; calixarene; complexation; spectroscopy; extraction; radiotracer technique

Related publications

  • Other report
    Dresden-Rossendorf: HZDR, 2014
    128 Seiten

Publ.-Id: 21265

Feasibility and limitations of laser-driven proton therapy: A treatment planning study.

Hofmann, K.; Masood, U.; Pawelke, J.; Wilkens, J.

Laser-acceleration of particles may offer a cost- and spaceefficient alternative for future radiation therapy with particles. Laser-driven particle beams are pulsed with very short bunch times, and a high number of particles is delivered within one laser shot which cannot be portioned or modulated during irradiation. The goal of this study was to examine whether good treatment plans can be produced for laser-driven proton beams and to investigate the feasibility of a laser-driven treatment unit.

An exponentially decaying proton spectrum was tracked through a gantry and energy selection beam line design to produce multiple proton spectra with different energy widths centered on various nominal energies. These spectra were fed into a treatment planning system to calculate spot scanning proton plans using different lateral widths of the beam and different numbers of protons contained in the initial spectrum. The clinical feasibility of the resulting plans was analyzed in terms of dosimetric quality and the required number of laser shots as an estimation of the overall treatment time.

We were able to produce treatment plans with plan qualities of clinical relevance for a maximum initial proton number per laser shot of 6*108. However, the associated minimum number of laser shots was in the order of 104, indicating a long delivery time in the order of at least 15 minutes, when assuming an optimistic repetition rate of the laser system of 10 Hz.

With the simulated beam line and the assumed shape of the proton spectrum it was impossible to produce clinically acceptable treatment plans that can be delivered in a reasonable time. The situation can be improved by a method or a device in the beam line which can modulate the number of protons from shot to shot.

  • Abstract in refereed journal
    Medical Physics 41(2014), 112-112
    DOI: 10.1118/1.4887876
  • Lecture (Conference)
    American Association of Physicists in Medicine (AAPM) 56th Annual Meeting, 20.-24.07.2014, Austin, Texas, USA

Publ.-Id: 21264

Realizing a laser-driven electron source applicable for radiobiological tumor irradiation

Nicolai, M.; Sävert, A.; Reuter, M.; Schnell, M.; Polz, J.; Jäckel, O.; Karsch, L.; Schürer, M.; Oppelt, M.; Pawelke, J.; Kaluza, M.

  • Lecture (Conference)
    41st IOP Plasma Physics Conference, 14.-17.04.2014, London, UK
  • Contribution to proceedings
    41st IOP Plasma Physics Conference, 14.-17.04.2014, London, UK
    Book of Abstracts (2014) 18
  • Lecture (Conference)
    Frühjahrstagung des Fachverbandes Plasmaphysik der Deutschen Physikalischen Gesellschaft, 17.-21.03.2014, Berlin, Deutschland
  • Contribution to proceedings
    Frühjahrstagung des Fachverbandes Plasmaphysik der Deutschen Physikalischen Gesellschaft, 17.-21.03.2014, Berlin, Deutschland
    Verhandl. DPG 49,2 (VI) (2014) P26.3

Publ.-Id: 21262

Source and shielding calculations at a PET cyclotron and possible activation in the soil

Konheiser, J.; Ferrari, A.; Naumann, B.; Müller, S.; Brachem, C.

This presentation summarizes the results of the Monte Carlo simulation of the shielding calculations and estimates of the soil activation for the new cyclotron of the HZDR (Helmholtz-Zentrum Dresden-Rossendorf). The dose values were determined on base of the resulting neutron flux at the 18F production. The calculations were carried out with the Monte Carlo code MCNP5. The neutron source was used both calculated with ALICE-91 code (manufacturer) and calculated with MCNP6. The comparison of the sources shows that ALICE-91 produced significantly fewer neutrons. The calculation of the soil activations was performed with FLUKA. In addition the effects of the energy increasing of the protons from 24 to 28 MeV were evaluated.
It could be shown that the expected total dose rate in the public area is about 0.1 mSv/h and thus significantly below the permissible value of 0.5 microSv/h. The activities generated in the soil are mainly determined by radionuclides with short half-life. After 5 years of continuous beam operation and a subsequent decay time of 30 days, the allowable value is used up only to 0.2%.

Keywords: Monte Carlo simulation; cyclotron; 18F production; dose rate; neutron soure

  • Lecture (others)
    14. AAA Workshop, 01.12.2014, Garching, Germany

Publ.-Id: 21261

New systematically modified vesamicol analogs and their affinity and selectivity for the vesicular acetylcholine transporter – A critical examination of the lead structure.

Barthel, C.; Sorger, D.; Deuther-Conrad, W.; Scheunemann, M.; Schweiger, S.; Jäckel, P.; Roghani, A.; Steinbach, J.; Schüürmann, G.; Sabri, O.; Brust, P.; Wenzel, B.

To verify vesamicol as lead structure in the development of radioligands for imaging of VAChT in the brain by PET, we systematically modified this molecule and investigated five different groups of derivatives. Structural changes were conducted in all three ring systems A, B, and C resulting in a library of 67 different vesamicol analogs. Based on their in vitro binding affinity toward VAChT as well as σ1 and σ2 receptors, we performed an extensive structure-affinity relationship (SAR) study regarding both affinity and selectivity. The compounds possessed VAChT affinities in the range of 1.32 nM (benzovesamicol) to > 10 µM and selectivity factors from 0.1 to 73 regarding σ1 and σ2 receptors, respectively. We could confirm the exceptional position of benzovesamicols as most affine VAChT ligands. However, we also observed that most of the compounds with high VAChT affinity demonstrated considerable affinity in particular to the σ1 receptor. Finally, none of the various vesamicol analogs in all five groups showed an in vitro binding profile suitable for specific VAChT imaging in the brain.

Keywords: VAChT; Vesamicol; PET; Sigma receptors

Publ.-Id: 21260

Development of laser-driven proton radiotherapy

Pawelke, J.

  • Invited lecture (Conferences)
    4th University Cancer Center Discussion Platform on Radiation Research in Oncology, 30.04.2014, Dresden, Germany

Publ.-Id: 21259

Charge Exchange and energy loss of slow highly charged ions in 1nm thick carbon nanomembranes

Wilhelm, R. A.; Gruber, E.; Ritter, R.; Heller, R.; Facsko, S.; Aumayr, F.

It has been demonstrated in recent years that slow highly charged ions can be used as an efficient tool for nano-structure formation on in- sulating solid surfaces mainly by deposition of their potential energy. By reducing the solid thickness into the nano-meter range a limit is reached where on the one hand the ion may not be completely neutralized in the solid membrane and on the other hand dissipation of the deposited energy may be limited to two spacial dimensions. To investigate the energy deposition and neutralization processes in 2D- materials by slow highly charged ions we performed charge exchange and energy loss measurements of slow highly charged Xe ions transmitted through ultra thin polymeric carbon membranes. Surprisingly, two distinct exit charge state distributions accompanied by charge ex- change dependent kinetic energy losses are observed. The energy loss for ions exhibiting large charge loss shows a quadratic dependency on the incident charge state, indicating that equilibrium stopping force values do not apply in this case. The combination of charge transfer and kinetic energy loss measurements allows us to link the two differ- ent exit charge state distributions to ion trajectories through distinct local electron densities distributions in the membrane.

Related publications

  • Lecture (Conference)
    Frühjahrestagung der Deutschen Physikalischen Gesellschaft - Sektion Festkörperphysik, 31.03.-04.04.2014, Dresden, Deutschland
  • Poster
    73th IUVSTA Workshop on Nanostructures on two-dimensional solids, 22.-26.09.2014, Eisenerz, Österreich
  • Lecture (Conference)
    Ionenstrahlworkshop 2014, 20.-22.07.2014, Paderborn, Deutschland
  • Lecture (Conference)
    Physics on a Boat, 03.-05.06.2014, Helsinki, Finnland

Publ.-Id: 21258

Ion beam synthesis for hybrid nanoelectronics: beyond silicon limits

Prucnal, S.; Lugstein, A.; Glaser, M.; Helm, M.; Zhou, S.; Skorupa, W.

A key milestone for the next generation of high-performance nanoelectronic devices is the monolithic integration of III-V compound semiconductor materials with silicon technology. The incorporation of different functional III-V nano- and optoelectronic elements on a single chip enables performance progress, which can overcome the downsizing limit in silicon technology. Conventionally, the integration of III-V semiconductors with Si is based on the heteroepitaxial growth of multi-layered structures on Si or a variety of wafer bonding techniques. Devices based on such structures combine the high carrier mobility and high luminescence efficiency of III-V semiconductors with the advantages of well-developed silicon technology. We have shown that the ion beam implantation technique (fluences of 1x1016 ion/cm2 to 4x1016 ion/cm2) followed by millisecond-range flash lamp annealing can be successfully utilised for the fabrication of different Si/III-V heterojunctions on bulk Si and SOI substrates [1-3]. Recently, we have extended the application of ion beam implantation followed by ms liquid-phase processing into the fabrication of hybrid 1D materials. We have demonstrated axial heteronanowires consisting of III-V compound semiconductor and Si using advanced processing steps of silicon technology [4]. The clou of this approach is the phase formation within milliseconds via the liquid phase leading to excellent crystalline properties in the volume and at the interface of the nanocrystals. This paves the way for a hybrid 1D nano-/optoelectronics with high-mobility and optically active materials, compatible to standard Si technology. Moreover, this kind of processing on the nanoscale could lead to a renewed interest in the field of ion beam synthesis. 1. S. Prucnal, et al., Nano Lett. 11, 2814 (2011). 2. S. Prucnal, et al., Nanotechnology 23, 485204 (2012). 3. S. Prucnal, et al., J. Appl. Phys. 115, 074306 (2014). 4. S. Prucnal, et al., Nano Research, submitted (2014).

Keywords: III-V; ion implantation; liquid-phase processing; FLA

Related publications

  • Lecture (Conference)
    19th International Conference on Ion Beam Modification of Materials (IBMM 2014), 14.-19.09.2014, Leuven, Belgium

Publ.-Id: 21257

OFOCell concept for low cost silicon photovoltaics

Prucnal, S.; Skorupa, W.

The incredible growth rates of the PV solar industry have allowed manufacturing efficiencies that are unheard of in other industries. Nowadays in the solar cells industry the main effort is directed to the cost reduction of the solar panels fabrication which will decrease the average price per kWh from presence 0.20 €/kWh down to 0.07 €/kWh in 2020. Generally it is realized by using much cheaper polycrystalline wafers, reduction of the overall wafer thickness and/or simplification of the production complexity. We propose the simplification of the production process of silicon solar cells using only one step millisecond annealing for the whole solar cell processing and replacing standard phosphorous thermal diffusion by plasma immersion ion implantation. Our technology can be directly transferred to an in-line production process leading to significant cost reduction and decreasing the amount of chemicals used during solar cell manufacturing. Due to one step millisecond range flash lamp annealing (FLA) the overall thermal budget needed for the solar cell fabrication is significantly reduced. Moreover the emitter formed by ion implantation and FLA is clean and allows the precise control of the dopant concentration and width of the p-n junction.

Keywords: FLA; solar cells; silicon

Related publications

  • Poster
    E-MRS 2014 SPRING MEETING, 26.-30.05.2014, Lille, France

Publ.-Id: 21256

Purification of SoG silicon by millisecond range internal gettering of metal impurities

Prucnal, S.; Bregolin, F. L.; Krockert, K.; Wiesenhütter, U.; Skorupa, W.

Cost reduction is the overall goal in the further development of the photovoltaic technologies. The solar-grade (SoG) mc-Si produced by upgrading metallurgical-grade silicon is an attractive material for low-cost solar cells. The remaining impurities after the purification process, mainly transition metals, are the main obstacle towards highly efficient solar cells, effectively limiting the minority carrier lifetime. Here we propose a novel method for the purification of SoG silicon by a millisecond range low thermal budget internal gettering process. The solar cells were produced by Plasma Immersion Ion Implantation of phosphorous using PH3 gas source and millisecond range Flash Lamp Annealing (ms-FLA). To study the metal distribution during ms-FLA, Cz-Silicon wafer were intentionally doped with iron. An influence of different thermal treatments on the diffusion of iron and the optoelectronic properties of metal contaminated silicon wafers were investigated by RBS, cross-section TEM, Raman spectroscopy, photoluminescence and surface photovoltage spectroscopy. We have shown that diffusion of metal impurities into the space charge region can be avoided by an one step ms-FLA step, only. It will be presented that the implanted phosphorous is electrically activated and all defects introduced into silicon during the ion implantation process are removed while metal impurities are kept far away from the p-n junction region. The effect of hydrogen co-implanted with phosphorous on the redistribution of iron will be explored. ms-FLA is demonstrated here as a very promising technique for the emitter formation in SoG silicon using an low thermal budget, only.

Keywords: Si; solar cells; FLA; photovoltaics

Related publications

  • Lecture (Conference)
    E-MRS 2014 SPRING MEETING, 26.-30.05.2014, Lille, France

Publ.-Id: 21255

Improved SoG silicon substrates produced by internal gettering of metal impurities induced by millisecond-range flash lamp annealing

Bregolin, F. L.; Prucnal, S.; Krockert, K.; Mathey, A.; Wiesenhütter, U.; Skorupa, W.

The research highlights for the further development of silicon based solar cell technologies focus on the cost reduction by applying inexpensive materials such as Solar Grade Multicrystalline Silicon (SoG mc-Si) and/or the simplification of the production process. Replacement of standard diffusion based doping by ion implantation reduces two of the solar cell production steps: elimination of the phosphosilicate glass (PSG) cleaning and edge isolation steps. Although ion implantation doping got very recently distinct consideration for doping of monocrystalline solar material, efficient doping of multicrystalline solar material remains the main challenge to reduce the costs. The usefulness of the plasma immersion ion implantation system (PIII) combined with advanced flash lamp annealing (FLA) was already validated. We have shown that within the millisecond annealing time, implanted phosphorous is electrically activated and silicon is recrystallized. Simultaneously, the diffusion of metal impurities and their activation is suppressed.

Keywords: Multicrystalline Silicon; flash lamp annealing; plasma immersion ion implantation

Related publications

  • Lecture (Conference)
    X-th International Conference Ion Implantation and other Applications of Ions and Electrons, 23.-26.06.2014, Kazimierz Dolny, Poland

Publ.-Id: 21254

Hyperdoping of semiconductors by ion implantation and ultrafast annealing: solid vs. liquid phase epitaxy

Prucnal, S.; Gao, K.; Skorupa, I.; Liu, F.; Skorupa, W.; Zhou, S.

Hyperdoped semiconductors exhibit exotic physical properties opening new routes for the fabrication of highly-sensitive photodetectors, intermediate band solar cells and ultra-fast nanoelectronics. The engineering of the electronic band structure in semiconductors by hyperdoping allows the strong enhancement of the below-band-gap photocurrent generation, insulator-to-metal transition (IMT) or creation of new magneto-optoelectronic devices. Hyperdoping requires an incorporation of foreign elements into the lattice side of the semiconductor far above the solid solubility limits. To this day the hyperdoping was realised either by the low-temperature molecular beam epitaxy or by the femtosecond or nanosecond liquid phase epitaxy during laser annealing. Here, we propose the novel millisecond range solid phase epitaxy performed by the flash lamp annealing (FLA) technique with a time range in between rapid thermal annealing and laser melting. The FLA was successfully utilised to fabricate ferromagnetic GaMnAs alloys with excellent optical properties, an IMT in the chalcogen doped Si with a substitutional rate higher than 70% or highly-conductive TCO (aluminium doped ZnO). Experimental data show that ion implantation followed by the millisecond range FLA is a cost-effective and high-throughput alternative for the processing of the hyperdoped semiconductors with outstanding properties.

Keywords: Hyperdoping; Si; GaAs; insulator-to-metal transition

Related publications

  • Invited lecture (Conferences)
    ION 2014 - X-th International Conference on Ion Implantation and Other Applications of Ions and Electrons, 23.-26.06.2014, Kazimierz Dolny, Poland

Publ.-Id: 21253

Utilization of flash lamp annealing for processing of low-cost TCO layers

Mathey, A.; Prucnal, S.; Wiesenhütter, K.; Vines, L.; Lindberg, P.; Svensson, B.; Bregolin, F. L.; Skorupa, W.

Aluminum-doped zinc oxide (AZO) is one of the most promising transparent conductive oxides (TCO) characterized by low resistivity, high transparency and most of all, by low cost of fabrication. AZO thin-films were deposited on p-type Si wafers via r.f. magnetron sputtering either at room temperature or at 400 oC and subsequently annealed in the millisecond-range, utilizing flash lamp annealing (FLA). Here, we have investigated the influence of the deposition parameters and post-deposition FLA treatment on the optoelectronic properties of the AZO layer. It is shown that the millisecond range flash lamp annealing significantly enhances the electrical activation of Al and suppresses secondary phase formation during post-deposition annealing. Moreover, the optoelectronic and microstructural properties of the FLA treated samples are independent on the deposition temperature. This, in turn opens the possibility for a further, highly-desired cost reduction of the overall fabrication process. The FLA technique is cost-effective and a high-throughput alternative for processing of AZO films.

Keywords: AZO; flash lamp annealing; magnetron sputtering

Related publications

  • Poster
    ION 2014 X-th International Conference on Ion Implantation and Other Applications of Ions and Electrons, 23.-26.06.2014, Kazimierz Dolny, Poland

Publ.-Id: 21252

Influence of Flash Lamp Annealing on the Optical Properties of CIGS Layer

Prucnal, S.; Jiao, F.; Reichel, D.; Zhao, K.; Cornelius, S.; Turek, M.; Pyszniak, K.; Drozdziel, A.; Skorupa, W.; Helm, M.; Zhou, S.

Copper indium gallium diselenide (CIGS) becomes more significant for solar cell applications as an alternative to silicon. The quality of the layer has a critical impact on the final efficiency of the solar cell. An influence of the post-deposition millisecond range flash lamp annealing on the optical and microstructural properties of the GIGS films was investigated. Based on the Raman and photoluminescence spectroscopy, it is shown that flash lamp annealing reduces the defect concentration and leads to an increase of the photoluminescence intensity by a factor of six compared to the nonannealed sample. Moreover, after flash lamp annealing the degradation of the photoluminescence is significantly suppressed and the absolute absorption in the wavelength range of 200-1200 nm increases by 25%.

Keywords: CIGS; flash lamp annealing; solar cells; photoluminescence

Related publications

Publ.-Id: 21251

III–V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy

Prucnal, S.; Glaser, M.; Lugstein, A.; Bertagnolli, E.; Stöger-Pollach, M.; Zhou, S.; Helm, M.; Reichel, D.; Rebohle, L.; Turek, M.; Zuk, J.; Skorupa, W.

Direct integration of high-mobility III-V compound semiconductors with existing Si based CMOS processing platforms presents a main challenge to increase the CMOS performance and the scaling trend. Silicon hetero-nanowires with integrated III-V segments are one of the most promising candidates for advanced nano-optoelectronics as first demonstrated using molecular beam epitaxy techniques. Here we demonstrate a novel route for InAs/Si hybrid nanowire fabrication via millisecond range liquid-phase epitaxy regrowth using sequential ion beam implantation and flash-lamp annealing. We show that such highly mismatched systems can be monolithically integrated within a single nanowire. Optical and microstructural investigations confirm the high quality hetero-nanowire fabrication coupled with the formation of atomically sharp interface between Si and InAs segments. Such hybrid systems open new routes for future high-speed and multifunctional nanoelectronic devices on a single chip.

Keywords: liquid phase epitaxy; InAs; heteronanowires; silicon; ion implantation

Related publications

Publ.-Id: 21250

Optoelectronic properties of ZnO film on silicon after SF6 plasma treatment and milliseconds annealing

Prucnal, S.; Gao, K.; Zhou, S.; Wu, J.; Cai, H.; Gordan, O. D.; Zahn, D. R. T.; Larkin, G.; Helm, M.; Skorupa, W.

Zinc oxide thin film is one of the most promising candidates for the transparent conductive layer in microelectronic and photovoltaic applications, due to its low resistivity and high transmittance in the visible spectral range. In this letter we present optoelectronic and structural properties of fluorine doped ZnO films deposited at low temperature on a silicon substrate. The fluorine doping was made by post-deposition SF6 plasma treatment and activation by the millisecond range flash lamp annealing. Both the microstructural and optical investigations confirm the formation of a high-quality, highly-doped n-type ZnO layer. The current-voltage characteristics show a heterojunction between n++-ZnO and Si. Moreover, it is shown that the SF6 plasma treatment efficiently passivates the surface state and bulk defects in the ZnO film.

Keywords: ZnO; plasma immersion ion implantation; pulsed laser deposition; flash lamp annealing; SF6

Related publications

Publ.-Id: 21249

The influence of different signal-to-background ratios on spatial resolution and F18-FDG-PET quantification using point spread function and time-of-flight reconstruction

Rogasch, J. M. M.; Hofheinz, F.; Lougovski, A.; Furth, C.; Ruf, J.; Großer, O. S.; Mohnike, K.; Hass, P.; Walke, M.; Amthauer, H.; Steffen, I. G.


F18-fluorodeoxyglucose positron-emission tomography (FDG-PET) reconstruction algorithms can have substantial influence on quantitative image data used, e.g., for therapy planning or monitoring in oncology. We analyzed radial activity concentration profiles of differently reconstructed FDG-PET images to determine the influence of varying signal-to-background ratios (SBRs) on the respective spatial resolution, activity concentration distribution, and quantification (standardized uptake value [SUV], metabolic tumor volume [MTV]).


Measurements were performed on a Siemens Biograph mCT 64 using a cylindrical phantom containing four spheres (diameter, 30 to 70 mm) filled with F18-FDG applying three SBRs (SBR1, 16:1; SBR2, 6:1; SBR3, 2:1). Images were reconstructed employing six algorithms (filtered backprojection [FBP], FBP + time-of-flight analysis [FBP + TOF], 3D-ordered subset expectation maximization [3D-OSEM], 3D-OSEM + TOF, point spread function [PSF], PSF + TOF). Spatial resolution was determined by fitting the convolution of the object geometry with a Gaussian point spread function to radial activity concentration profiles. MTV delineation was performed using fixed thresholds and semiautomatic background-adapted thresholding (ROVER, ABX, Radeberg, Germany).


The pairwise Wilcoxon test revealed significantly higher spatial resolutions for PSF + TOF (up to 4.0 mm) compared to PSF, FBP, FBP + TOF, 3D-OSEM, and 3D-OSEM + TOF at all SBRs (each P < 0.05) with the highest differences for SBR1 decreasing to the lowest for SBR3. Edge elevations in radial activity profiles (Gibbs artifacts) were highest for PSF and PSF + TOF declining with decreasing SBR (PSF + TOF largest sphere; SBR1, 6.3%; SBR3, 2.7%). These artifacts induce substantial SUVmax overestimation compared to the reference SUV for PSF algorithms at SBR1 and SBR2 leading to substantial MTV underestimation in threshold-based segmentation. In contrast, both PSF algorithms provided the lowest deviation of SUVmean from reference SUV at SBR1 and SBR2.


At high contrast, the PSF algorithms provided the highest spatial resolution and lowest SUVmean deviation from the reference SUV. In contrast, both algorithms showed the highest deviations in SUVmax and threshold-based MTV definition. At low contrast, all investigated reconstruction algorithms performed approximately equally. The use of PSF algorithms for quantitative PET data, e.g., for target volume definition or in serial PET studies, should be performed with caution

  • especially if comparing SUV of lesions with high and low contrasts.

Keywords: FDG-PET/CT reconstruction; PSF; TOF; Spatial resolution; Metabolic tumor volume delineation; Signal-to-background ratio; Radial activity concentration profile; Gibbs artifact; Ringing artifact; Gibbs phenomenon

Publ.-Id: 21247

Spin coated targets for filamentation studies

Kraft, S.

In our presentation we report on the experimental observation of spatially modulated proton beams.

  • Lecture (Conference)
    Targert Fabrication Workshop 5, 06.-11.07.2014, St. Andrews, Great Britain

Publ.-Id: 21246

Status of laser ion acceleration at HZDR

Kraft, S.

Within the last years, numerous activities in laser particle acceleration have been taken place at the 100TW ultra-short pulse Laser system Draco at HZDR. Special emphasis was laid on developing an ion beam suitable for applications. In order to achieve high proton energies various approaches such as mass limited targets and active pre-plasma formation have been tested.

Recently, the laser is upgraded to a dual beam system delivering 30f pulses with 100TW as well as synchronized 1PW pulses. The talk will give an overview over the particle acceleration activities focussing on Laser ion acceleration as well as a current status of the laser upgrade in Dresden.

  • Invited lecture (Conferences)
    Seminar der Plasmaphysik, 12.11.2014, Darmstadt, Deutschland

Publ.-Id: 21245

Development of a compact particle therapy facility with laser driven ion beams via novel pulse powered gantry systems

Masood, U.; Baumann, M.; Bussmann, M.; Cowan, T.; Enghardt, W.; Hermannsdörfer, T.; Hofmann, K.; Kaluza, M.; Karsch, L.; Kroll, F.; Schramm, U.; Schürer, M.; Wilkens, J.; Pawelke, J.

  • Contribution to proceedings
    53th Particle Therapy Cooperative Group (PTCOG) Meeting, 08.-14.06.2014, Shanghai, China, 299

Publ.-Id: 21244

Fast measurement of 3-d dose distributions

Pawelke, J.

  • Invited lecture (Conferences)
    29th Conference on Clinical and Experimental Research in Radiation Oncology (CERRO 29), 18.-25.01.2014, Les Menuires, France

Publ.-Id: 21243

Entwicklung von Elektromagneten mit kurzen, hohen Strompulsen für die Laser basierte Protonentherapie

Schürer, M.; Hermannsdörfer, T.; Karsch, L.; Kroll, F.; Masood, U.; Pawelke, J.

Related publications

  • Lecture (Conference)
    7. Tagung Feinwerktechnische Konstruktion, 05.-06.11.2013, Dresden, Deutschland
  • Contribution to proceedings
    7. Tagung Feinwerktechnische Konstruktion, 05.-06.11.2013, Dresden, Deutschland
    In: T. Nagel (Ed.): Trends in der Feinwerktechnik. Mechatronik 5, München: IGT Verlag, 13-14

Publ.-Id: 21242

Uranium sorption on montmorillonite at high ionic strengths: Surface complexation modelling

Fritsch, K.; Schmeide, K.

The current results of surface complexation modelling of U(VI) complexes on montmorillonite in NaCl and a NaCl/CaCl2/MgCl2 mixed electrolyte of high ionic strength are presented.

Keywords: uranium sorption; argillaceous rock; clay; uranium; montmorillonite; high ionic strength; surface complexation modelling

  • Lecture (others)
    7. Workshop des Verbundprojekts „Rückhaltung endlagerrelevanter Radionuklide im natürlichen Tongestein und in salinaren Systemen“, 28.-29.10.2014, Saarbrücken, Deutschland

Publ.-Id: 21240

Simulations of precessing flows in cylindrical geometry

Giesecke, A.

no abstract available

Keywords: Precession; DRESDYN; DYNAMO

  • Lecture (Conference)
    MHD Days 2014, 02.-03.12.2014, Potsdam, Germany

Publ.-Id: 21239

Radiolabelling of colloids for highly sensitive detection in transport studies Vortrag im Rahmen des BELBaR WP2 und WP4 Projekttreffens, 30.-31. Oktober, Prag

Hildebrand, H.; Schymura, S.; Kulenkampff, J.; Lippmann-Pipke, J.; Franke, K.

In dem Vortrag wurde für einen Teil des BELBaR Konsortiums ein Überblick über am HZDR/FSL vorhandene Radiomarkierungsmöglichkeiten für Kolloide bzw. Nanopartikel gegeben.

  • Lecture (others)
    Joined meeting of WP2 and WP4 within the EC project BELBaR, 30.-31.10.2014, Prag, Tschechische Republik

Publ.-Id: 21238

Cyclopeptides containing the DEKS motif as conformationally restricted collagen telopeptide analogues: synthesis and conformational analysis

Wodtke, R.; Ruiz-Gómez, G.; Kuchar, M.; Pisabarro, M. T.; Novotná, P.; Urbanová, M.; Steinbach, J.; Pietzsch, J.; Löser, R.

The collagen telopeptides play an important role for lysyl oxidase-mediated crosslinking, a process which is deregulated during tumour progression. The DEKS motif which is located within the N-terminal telopeptide of the α1 chain of type I collagen has been suggested to adopt a βI-turn conformation upon docking to its triple-helical receptor domain, which seems to be critical for lysyl oxidase-catalysed deamination and subsequent crosslinking by Schiff-base formation. Herein, the design and synthesis of cyclic peptides which constrain the DEKS sequence in a β-turn conformation will be described. Lysine-side chain attachment to 2-chlorotrityl chloride-modified polystyrene resin followed by microwave-assisted solid-phase peptide synthesis and on-resin cyclisation allowed for an efficient access to head-to-tail cyclised DEKS-derived cyclic penta- and hexapeptides. An Nε-(4-fluorobenzoyl)lysine residue was included in the cyclopeptides to allow their potential radiolabelling with fluorine-18 for PET imaging of lysyl oxidase. Conformational analysis by 1H NMR and chiroptical (electronic and vibrational CD) spectroscopy together with MD simulations demonstrated that the concomitant incorporation of a D-proline and an additional lysine for potential radiolabel attachment accounts for a reliable induction of the desired βI-turn structure in the DEKS motif in both DMSO and water as solvents. The stabilised conformation of the cyclohexapetide is further reflected by its resistance to trypsin-mediated degradation. In addition, the deaminated analogue containing allysine in place of lysine has been synthesised via the corresponding ε-hydroxynorleucine containing cyclohexapeptide. Both ε-hydroxynorleucine and allysine containing cyclic hexapeptides have been subjected to conformational analysis in the same manner as the lysine-based parent structure. Thus, both a conformationally restricted lysyl oxidase substrate and product have been synthetically accessed, which will enable their potential use for molecular imaging of these important enzymes.

Publ.-Id: 21237

Colloidal Probe Atomic Force Microscopy to determine the Floatability of Minerals in Ores

Rudolph, M.

Flotation is without a doubt one of the major processes for the separation of fine minerals and it has been applied for more than a century. A key task of a successful flotation separation is to find the proper chemical treatment to selectively hydrophobize and thus float a certain mineral phase using molecules or ions referred to as collectors, depressants, regulators and frothers. Commonly floatability is determined by microflotation tests using the Hallimond tube with pure mineral phases. This method however requires the pure mineral phase which is very often not even taken from the same deposit which is going to be processed. In this paper we present a new approach to in-situ determine and even map the floatability of finely disseminated mineral phases within cross-sections of an ore. It is based on measuring hydrophobic effects using colloidal probe atomic force microscopy with a hydrophobic polystyrene probe based on force spectroscopy with a lateral resolution of only a few nanometers. Coupled confocal Raman spectroscopy on the same locality enables the identification of the mineral phase. We present the working principles of the method and show which signals in the force spectra characteristic for hydrophobic interactions can be used to define floatability and which can then be mapped as single quantities, e.g. jump-into-contact events due to nanobubble occurrence or parameters of the long range interaction curves most probably due to capillary effects.
A finely grained silicate ore containing the valuable rare earth mineral eudialyte from southern Sweden as well as pure samples of magnetite are presented as substrates to demonstrate the capability of this new approach.
This method will not only help to find the proper flotation chemistry but it can furthermore help in researching and unravelling problems of floatability within similar mineral phases.

  • Contribution to proceedings
    International Mineral Processing Congress 2014, 20.-24.10.2014, Santiago de Chile, Chile
    Proceedings of the XXVII International Mineral Processing Congress – IMPC 2014

Publ.-Id: 21236

Subcritical bifurcation to turbulence in precessing flow

Gundrum, T.; Herault, J.; Steglich, C.; Giesecke, A.; Stefani, F.; Gerbeth, G.

Subcritical bifurcation to turbulence in precessing flow in the water mockup for the DRESDYN Experiment

Keywords: Precession driven dynamo; Subcritical bifurcation; metastable transition

  • Lecture (Conference)
    MHD Days 2014, 02.-03.12.2014, Potsdam, Deutschland

Publ.-Id: 21235

Supernova-Produced 26Al and 60Fe in Deep-Sea Sediments

Feige, J.; Wallner, A.; Fifield, L. K.; Merchel, S.; Rugel, G.; Steier, P.; Tims, S.; Winkler, S. R.; Golser, R.

Massive stars, which end their lives in a supernova (SN) explosion, eject freshly produced nuclides into the surrounding interstellar medium. Among them long-lived radionuclides, that can be deposited into terrestrial archives, if such an event occurs close to the Solar System.
About 100 samples of four deep-sea sediment cores originating from the Indian Ocean were analyzed for their content in the isotopes 26Al and 60Fe for the time range of 2-3 Myr. These nuclides are produced in SNe and the time range corresponds to an 60Fe enhancement observed in a deep-ocean crust sample (Knie et al., 2004). The method used for analysis is accelerator mass spectrometry (AMS), a very sensitive technique for the detection of long-lived radionuclides.
A clear signal of 60Fe throughout the whole measured time period was observed. This observation is in contrast to a narrow peak if originating from a direct input from a single SN. Further, no 60Fe was detected in much older or younger sediment samples. A concurring SN-signal of 26Al is, however, hidden underneath a dominant terrestrial background from continuous atmospheric and in-situ production. The resulting limits on the ratios of 60Fe/26Al were compared to nucleosynthesis models.

Keywords: AMS; supernova; radionuclide

Related publications

  • Lecture (Conference)
    DPG Frühjahrstagung des Arbeitskreises Atome, Moleküle, Quantenoptik und Plasmen (AMOP), 23.-27.03.2015, Heidelberg, Deutschland

Publ.-Id: 21234

High-energy diode-pumped D2O-cooled multislab Yb:YAG and Yb:QX-glass lasers

Siebold, M.; Loeser, M.; Röser, F.; Albach, D.; Schramm, U.

We investigated the performance of multislab Yb:QX and Yb:YAG laser amplifiers using low absorption heavy-water (D2O) as coolant. We demonstrated a pulse energy of 1 J at a repetition rate of up to 10 Hz.

Keywords: Laser amplifiers; Laser cooling; Lasers, diode-pumped; Lasers, ytterbium

  • Lecture (Conference)
    Advanced Solid State Lasers (ASSL) Conference, 16.-21.11.2014, Shanghai, China
  • Contribution to proceedings
    Advanced Solid State Lasers (ASSL) Conference, 16.-21.11.2014, Shanghai, China
    Advanced Solid State Lasers 2014, OSA Technical Digest, 978-1-55752-822-3

Publ.-Id: 21233

Broadband, diode-pumped Yb-doped fused bulk silica laser

Röser, F.; Loeser, M.; Albach, D.; Siebold, M.; Schramm, U.; Grimm, S.; Brand, D.; Langner, A.; Schötz, G.; Schönfeld, D.

We successfully demonstrated cw lasing of ytterbium-doped fused bulk silica glass. We achieved a highly polarized output with a slope efficiency of 52% and a wavelength tuning range from 1005-1110 nm.

Keywords: Lasers, diode-pumped; Lasers, ytterbium; Lasers, solid-state; Laser materials

  • Lecture (Conference)
    Advanced Solid State Lasers (ASSL) Conference, 16.-21.11.2014, Shanghai, China
  • Contribution to proceedings
    Advanced Solid State Lasers (ASSL) Conference, 16.-21.11.2014, Shanghai, China
    Advanced Solid State Lasers 2014, OSA Technical Digest, 978-1-55752-822-3

Publ.-Id: 21232

Interaction of uranium with isolated microorganisms of the former uranium mine Königstein (Saxony, Germany)

Gerber, U.; Krawczyk-Bärsch, E.; Arnold, T.; Stumpf, T.

The uranium waste mine Königstein (Saxony, Germany) is heavily polluted with heavy metals, especially with uranium. Despite the high concentrations of heavy metals, the mine is a reservoir for many different microorganisms that have evolved special strategies to survive in these extreme environments. Their ubiquitous occurrence is of fundamental interest to understand the migration behavior of radionuclides within the biosphere. Furthermore, microorganisms are the beginning of the food chain, and therefore the transfer of bound uranium along this food chain could rise to a serious threat to human health. Biosorption of radionuclides especially uranium by microorganisms regulates the mobility of the metal in the environment. Thus, microorganisms could be used to clean-up contaminated soils, sediments, and waters by removing uranium and other radionuclides, due to bioremediation processes.

Keywords: Uranium; Königstein; Interaction; Microorganisms

  • Poster
    Projekttreffen TransAqua, 25.-27.11.2014, Karlsruhe, Deutschland

Publ.-Id: 21230

Kontaminationsfreie Injektion von Radiotracern für die Prozesstomographie von Transportprozessen in Geomaterialien

Kulenkampff, J.

Prozessverständnis und Modellierung von Transport in natürlichen geklüfteten oder porösen Geomaterialien (Böden, Gesteine) sind aufgrund der komplizierten geometrischen Randbedingungen auf der Mikroskala und der heterogenen Struktur und Zusammensetzung des Materials besonders schwierige Aufgaben. Gewöhnlich werden wie in weniger komplexen technischen Materialien, wie Filtern oder Reaktoren, einfache Modelle zur Beschreibung der Porzesse angewendet, die nur eine grobe Beschreibung der Prozesse erlauben und außerhalb ihres begrenzten Gültigkeitsbereichs versagen. Bei einer solchen Parametrisierung anhand von Durchbruchkurven wird das Material als Blackbox betrachtet und mit wenigen Parametern beschrieben (Abb. 1). Die Nutzung von Radioisotopen als Tracer für den mobilen Stoff ermöglicht Einblicke in den räumlich-zeitlichen Verlauf des Transports im Innern des opaken Versuchskörpers mit höchster Sensitivität und ohne chemische oder physikalische Rückwirkung auf den Prozess. Außerdem ist die einfache und selektive Detektierbarkeit geringster Konzentrationen von Radiotracern oft vorteilhaft. Präferentielle Transportwege, die Verzögerung des Transports durch Wechselwirkungen und gegebenenfalls auch die Immobilisierung der beobachteten Spezies im Versuchskörper können so erfasst werden (Abb. 2).
Es werden zylindrische Probekörper hergestellt (Durchmesser bis 30-100 mm, Länge 50-300 mm), mit Fluidanschlüssen an den Stirnflächen. Im Transportversuch wird kontinuierlich eine Trägerlösung mit Fließraten von 5 µL/min bis 5 mL/min injiziert. In Abhängigkeit vom Probenvolumen wird der Trägerlösung ein Tracerpuls (1-5 mL) hinzugefügt. Dieser Tracerpuls wird mit Positronen-Emissions-Tomographie quantitativ in seinem räumlich-zeitlichen Verlauf mit einer räumlichen Auflösung im Bereich von 1 mm erfasst. Für den Tracerpuls eingesetzte Aktivitäten betragen zwischen 1 MBq und 500 MBq. Sie werden mit einer Empfindlichkeit von 10 – 100 Bq/µL erfasst, was einer Sensitivität im picomolaren Bereich entspricht. Geeignete Radionuklide sind z. B. 18F, 124I, 64Cu, 58Co, 22Na mit Halbwertszeiten von Stunden bis Jahren. Mögliche Beobachtungszeiten sind etwa 10 Halbwertszeiten – also Tage bis Jahrzehnte.
Positronen-Emissions-Tomographie (PET) (Abb. 3) ist als höchst sensitive Methode der funktionellen medizinischen Diagnostik bekannt und wird vor allem in der Krebsdiagnostik und der biomedizinischen Forschung angewendet. Wegen des hohen Aufwandes gibt es wenige examplarische Anwendungen auf technischen Gebieten. Insbesondere wird PET in der Forschungsstelle Leipzig des HZDR seit über 10 Jahren erfolgreich für die Untersuchung von Prozessen in Geomaterialien eingesetzt (s. Literaturangaben).
Eine wichtige Rolle nimmt die zuverlässige Injektion des Tracers ein. Dabei sind Sicherheits- und Strahlenschutzaspekte zu berücksichtigen. Je nach Untersuchungsaufgabe werden unterschiedliche Pumpen eingesetzt (Schlauchpumpen, einfache Spritzenpumpen mit handelsüblichen Injektionsspritzen, HPLC-Pumpen, ISCO-Spritzenpumpen). Bei den zwei letzteren kann die Kontamination der Pumpe durch die Nutzung von Injektionsschleifen für den Radiotracer vermieden werden. Insbesondere bei langlebigen Tracern (58Co, 22Na) ist dabei aber besondere Vorsicht geboten.
Ergbebnis der Untersuchung sind zeitlich aufgelöste tomographische Darstellungen der Tracerkonzentration (Abb. 4). Hieraus lassen sich

  • lokale Tracerverteilungen
  • prozessabhängiges effektives Volumen
  • effektiv wirksamer Anteil innere Oberfläche (bei Wechselwirkungen)
  • Geschwindigkeitsverteilung
bestimmen. Gegenüber der Parametrisierung von Transportuntersuchungen durch Modellanpassung an Durchbruchkurven ergeben sich so verlässlichere real gemessenen Parametersätze und gleichzeitig eine bisher nicht erreichbare Verbesserung des Prozessverständnisses.
Richter, M., Gruendig, M., Zieger, K., Seese, A. and Sabri, O., 2005. Positron emission tomography for modelling of geochemical transport processes in clay. Radiochimica Acta, 93: 643-651.
Kulenkampff, J., Gründig, M., Richter, M. and Enzmann, F., 2008. Evaluation of positron-emission-tomography for visualisation of migration processes in geomaterials. Physics and Chemistry of the Earth, Parts A/B/C, 33(14–16): 937-942.
Wolf, M.; Kulenkampff, J.; Enzmann, F.; Gründig, M.; Richter, M.; Lippmann-Pipke, J.; Mittmann, H., 2010. 3D-Visualisierung und Quantifizierung von Fluidströmungen in Salinargestein mittels Positronen-Emissions-Tomographie. EDGG Exkursionsführer & Tagungspublikationen 244(2010), Hannover: Deutschen Gesellschaft für Geowissenschaften e.V.
Kulenkampff, J.; Gründig, M.; Korn, N.; Zakhnini, A.; Barth, T.; Lippmann-Pipke, J., 2013. Application of high-resolution positron-emission-tomography for quantitative spatiotemporal process monitoring in dense material. 7. World Congress on Industrial Process Tomography, 02.-05.09.2013, Krakow, Poland.
Bittner, L.; Kulenkampff, J.; Gründig, M.; Lippmann-Pipke, J.; Enzmann, F. , 2014. Direct Observation of Waterglass Impregnation of Fractured Salt Rock with Positron Emission Tomography. International Conference on the Performance of Engineered Barriers: Backfill, Plugs & Seals, 06.-07.02.2014, Hannover, Deutschland
  • Lecture (others)
    ISCO-Anwendertreffen, 09.12.2014, Potsdam, Deutschland

Publ.-Id: 21229

Refined reconstruction of liquid-gas interface structures for stratified two-phase flow using wire-mesh sensor

Schleicher, E.; Aydin, T. B.; Vieira, R. E.; Torres, C. F.; Pereyra, E.; Sarica, C.; Hampel, U.

Wire-mesh sensors (WMS), developed at HZDR [11], [2], are widely used to visualize two-phase flows and measure flow parameters, such as phase fraction distributions or gas phase velocities quantitatively and with a very high temporal resolution. They have been extensively applied to a wide range of two-phase gas-liquid flow problems with conducting and non-conducting liquids. However, for very low liquid loadings, the state of the art data analysis algorithms for WMS data suffer from the comparably low spatial resolution of measurements and from boundary effects, caused by e.g. flange rings - especially in the case of capacitance type WMS. In the recent past, diverse studies have been performed on two-phase liquid-gas stratified flow with low liquid loading conditions in horizontal pipes at the University of Tulsa. These tests cover oil-air flow in a 6-inch ID pipe and water-air flow in a 3-inch ID pipe employing dual WMS with 32x32 and 16x16 wires, respectively. For oil-air flow experiments, the superficial liquid and gas velocities vary between 9.2 m/s ≤ νSG ≤ 15 m/s and 0.01 m/s ≤ νSL ≤ 0.02 m/s, respectively [1]. In water-air experiments, the superficial liquid and gas velocities vary between 9.1 m/s ≤ νSG ≤ 33.5 m/s and 0.03 m/s ≤ νSL ≤ 0.2 m/s, respectively [14], [15]. In order to understand the stratified wavy structure of the flow, the reconstruction of the liquid-gas interface is essential. Due to the relatively low spatial resolution in the WMS measurements of approximately 5 mm, the liquid-gas interface recognition has always an unknown uncertainty level. In this work a novel algorithm for refined liquid-gas interface reconstruction is introduced for flow conditions where entrainment is negligible.

Keywords: Keywords Wire-mesh sensor; two-phase flow; stratified flow; liquid-gas interface recognition

Publ.-Id: 21228

Accumulation of plutonium in mammalian wildlife tissues following dispersal by accidental-release tests

Johansen, M. P.; Child, D. P.; Caffrey, E. A.; Davis, E.; Harrison, J. J.; Hotchkis, M. A. C.; Payne, T. E.; Ikeda-Ohno, A.; Thiruvoth, S.; Twining, J. R.; Beresford, N. A.

We examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife inhabiting the relatively undisturbed, semi-arid former Taranaki weapons test site, Maralinga, Australia. The accumulation of absorbed Pu was highest in the skeleton, followed by muscle, liver, kidneys, and blood. Pu activity concentrations in lung tissues were elevated relative to the body average. Foetal transfer was higher in the wildlife data than in previous laboratory studies. The amount of Pu in the gastrointestinal tract was highly elevated relative to that absorbed within the body, potentially increasing transfer of Pu to wildlife and human consumers that may ingest gastrointestinal tract organs. The Pu distribution in the Maralinga mammalian wildlife generally aligns with previous studies related to environmental exposure (e.g. Pu in humans from worldwide fallout), but contrasts with the partitioning models that have traditionally been used for human worker-protection purposes (approximately equal deposition in bone and liver) which appear to under-predict the skeletal accumulation in environmental exposure conditions.

Keywords: actinides; plutonium; nuclear debris; accumulation; wildlife; radio ecology

Publ.-Id: 21227

Undesired air entrainment by vortex formation - experimental investigations on the resulting phase fraction distributions in a centrifugal pump using gamma-ray computed tomography

Schäfer, T.; Bieberle, A.; Neumann, M.; Hampel, U.

Air entrainment may occur in situations, where water is conveyed from a reservoir. There hollow vortices may form as a consequence of low liquid level and pre-existing fluid swirling. Particularly, such a situation may be prevailing in nuclear power plants, e.g. when emergency cooling water is taken from a liquid reservoir, like the condensation chamber. Presence of gas in pumps may lead to abrasion at impeller blades, strong vibrations with damaging of bearings and loss of cooling for shaft and bearings and early fatigue as a consequence. At least it will lead to decreasing pump performance even to the point of abrupt collapse of flow rate. The presented work contributes quantitative measurements, visualizations and analyses of gas-liquid phase distributions to the fundamental understanding of the effects of air entrainment in centrifugal pumps. Advanced tomographic measuring methods with high spatial resolution were applied to investigate the two-phase distribution in the impeller region of an industrial centrifugal pump.

Keywords: gamma-ray computed tomography; centrifugal pump; gas entrainment; two-phase flow

  • Poster
    East German Centre of Competence in Nuclear Technology Workshop of Doctoral Candidates, 04.12.2014, Zittau, Deutschland

Publ.-Id: 21226

Application of gamma-ray computed tomography for the analysis of gas holdup distributions in centrifugal pumps

Schäfer, T.; Bieberle, A.; Neumann, M.; Hampel, U.

In this work, gas-liquid distributions in an industrial centrifugal pump operated at various steady state conditions have been quantitatively determined. Therefore, high-resolution gamma-ray computed tomography (HireCT) has been applied, operated in time-averaging rotation-synchronized CT scanning mode. Detailed studies have been performed on a hydraulic test facility providing authentic operating conditions for industrial centrifugal pumps. The gas distribution in the centrifugal pump has been studied at defined inlet gas volumetric flow rates between 0% and 5% and for two different inlet flow regimes, namely disperse and swirling gas-liquid two-phase flow. In this way, the influence of the inlet flow boundary conditions on the performance as well as gas fraction distributions and gas holdup distribution within the impeller region could be successfully determined.

Keywords: gamma-ray computed tomography; centrifugal pump; gas entrainment; two-phase flow

Publ.-Id: 21225

Obtaining magnitude-cumulative frequency curves from rockfall scar size distribution using cosmogenic chlorine-36 in the Montsec area (Eastern Pyrenees, Spain)

Domènech, G.; Mavrouli, O.; Corominas, J.; Abellán, A.; Merchel, S.; Pavetich, S.; Rugel, G.

Magnitude-cumulative frequency (MCF) relations are commonly used components for assessing the rockfall hazard using databases of recorded events. However, in some cases, data are lacking or incomplete. To overcome this restriction, the volume distribution of the rockfall scars has been used instead. The latter may yield the temporal probability of occurrence if the time span required to generate the scars is known.
The Montsec range, located in the Eastern Pyrenees, Spain, was chosen as a pilot study area for investigating MCF distributions. This cliff, which is composed of limestones from Upper Cretaceous age, shows distinct evidences of rockfall activity, including large recent rockfall scars. These areas are identifiable by their orange colour, which contrasts in front of the greyish old stable (reference) surface of the cliff face. We present a procedure to obtain the MCF of the rockfall scars by dating an old reference cliff surface and measuring the total volume released since then. The reference cliff surface was dated using the terrestrial cosmogenic nuclide (TCN) chlorine-36 (Merchel et al., 2013). We used the Rockfall Scar Size Distribution (RSSD) obtained in Domènech et al. (2014) that considers several rockfall pattern scenarios. Scenario 1 allows for, mostly, large rockfall scar volumes, scenario 2 considers smaller occurrences and scenario 3 suggests that rockfall scars can be the result of one or several rockfall events, and thus contemplating a wider range of scar volumes.
The main steps of the methodology are: a) Obtaining the RSSD, b) Volume calculation of material lost, c) Calculation of time (T0) elapsed for the cliff to retreat (age of the old reference surface), and d) generation of the MCF curve from the RSSD. A total volume of material lost of 78900 m3 was obtained as well as an elapsed period of time of 15350 years.
The MCF curves for different rockfall scenarios are found to be well fitted by a power law with exponents -1.7, -1.1 and -1 for scenarios 1, 2 and 3, respectively. Frequencies about 0.17, 0.43 and 0.27 events/year were calculated for scenario 1, 2 and 3, respectively, considering rockfall scar volumes greater - or equal to - 0.5 m3.
Domènech G., Mavrouli O., Corominas J. and Abellán A. (2014): Calculation of the rockfall scar volume distribution using a Terrestrial Laser Scanner in the Montsec Area (Eastern Pyrenees, Spain). Geophysical Research Abstracts 16. EGU General Assembly. Vienna.
Merchel S., Braucher R., Alfimov V., Bichler M., Bourlès D.L., Reitner J.M. (2013): The potential of historic rock avalanches and man-made structures as chlorine-36 production rate calibration sites. Quat. Geochron. 18, 54-62.

Keywords: AMS; TCN; cosmogenic nuclide; hazard; rockfall

Related publications

  • Lecture (Conference)
    European Geosciences Union (EGU) General Assembly, 12.-17.04.2015, Wien, Österreich

Publ.-Id: 21224

Neutron-induced fission measurements at the time-of-flight facility nELBE

Kögler, T.; Beyer, R.; Junghans, A. R.; Massarczyk, R.; Schwengner, R.; Wagner, A.

Neutron-induced fission of 242 Pu was studied at the photoneutron source nELBE. The fast neutron fission cross section was determined using actinide fission chambers in a time-of-flight experiment. Whereas the absolute normalization is missing so far, a good agreement to the present nuclear data and evaluations has been achieved in the range of 100 keV to 10 MeV.

Keywords: Neutron-induced fission; parallel plate fission ionization chambers

Related publications

  • Invited lecture (Conferences)
    Scientific Workshop on Nuclear Fission dynmaics and the Emission of Prompt Neutrons and Gamma Rays, THEORY-3, 16.-18.09.2014, Opatija, Kroatien
  • Open Access Logo Contribution to proceedings
    Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma-Rays, THEORY-3, 16.-18.09.2014, Opatija, Kroatien
    Physics Procedia, Amsterdam: Elsevier, 150-155
    DOI: 10.1016/j.phpro.2015.04.020
    Cited 2 times in Scopus

Publ.-Id: 21223

3d cfd simulation of flashing flows in a converging-diverging nozzle

Liao, Y.; Lucas, D.

Flashing of initially sub-cooled water in a converging-diverging nozzle is simulated with two-fluid model incorporating drag and non-drag forces. Phase change is assumed to be induced by interphase heat transfer. Comparison with experimental data is performed for 14 test runs under different temperature and pressure conditions. Good agreement is achieved for mass flow rate and cross-section averaged parameters. The reliability of the CFD predictions is obviously better than the ones obtained in 1D code. The transversal (radial) distribution of void fraction is however not satisfyingly reproduced. It is mainly caused by the neglect of nucleation as well as other uncertainties related to the prediction of mean bubble diameter. A poly-disperse approach with consideration of all relevant bubble dynamics is recommended for further work. For this purpose, reliable closure models and experimental data of bubble size information is required. In addition, cases characterised with large pressure-undershoot exhibit significant mechanical non-equilibrium.

Keywords: Flashing; Nozzle Flow; CFD Simulation; Two-Fluid Model

Publ.-Id: 21222

P1313 - Magnetisierbare Halbleiter und Oxide mit permanenter Magnetisierung, deren Herstellung und Verwendung

Schmidt, H.; Kaspar, T.; Bürger, D.; Skorupa, I.; Fiedler, J.

Die Erfindung beschreibt die Herstellung und den Aufbau einer Anordnung mit mindestens einer Raumladungszone, bei der sich im Bereich der Raumladungszone magnetische Polaronen stabil ausbilden. Weiterhin beschreibt die Erfindung, die Integration und die Verwendung der Anordnung in einem Spin-FET, in einem Spin-Ventil und in einer Spin-LED.

Related publications

  • Patent
    DE102013209278 - Offenlegung 20.11.2014, Erteilung 18.02.2016, Nachanmeldung: WO

Publ.-Id: 21221

Baseline model for bubbly flows: Simulation of monodisperse flow in pipes of different diameters

Kriebitzsch, S.; Rzehak, R.

CFD simulations of the multiphase flow in technical equipment can provide a detailed insight into the local flow field and hence potentially be a valuable optimisation and design tool. Such simulations are feasible within the framework of interpenetrating continua, the so-called two-fluid modelling. Within this framework the interfacial transfer processes need to be modelled by suitable closure relations, many of which have been proposed in the literature. Predictions with multiphase CFD are only possible if a fixed set of closures is available that has been validated for a wide range of flow conditions and can therefore reliably be used also for unknown flow problems. To this end, a baseline model, which is applicable for adiabatic bubbly flow, has been specified recently (e.g. Rzehak and Krepper, 2013) and has been implemented into OpenFOAM (Rzehak and Kriebitzsch, 2015).
In this work we compare simulation results obtained using the baseline model with three different sets of experimental data for dispersed gas-liquid pipe flow given by Liu (1998), Shawkat et al. (2008), and Hosokawa and Tomiyama (2009). Air and water under similar flow conditions have been used in the different experiments, so that the main difference between the experiments is the variation of the pipe diameter from 25 mm to 200 mm. Overall all three experimental data sets are reasonably well reproduced by the simulation results, in particular in the bulk of the flow. The need for improved modelling of multiphase turbulence as well as wall effects manifests itself through larger differences with the experimental data in the near-wall region of the pipes.

Keywords: dispersed gas liquid multiphase flow; Euler-Euler two-fluid model; closure relations; CFD simulation; model validation; OpenFOAM

Publ.-Id: 21220

Plasma Dynamics in ultra-short relativistic laser-solid matter interactions and synthetic diagnostics using XFELs

Huang, L. G.; Bussmann, M.; Kluge, T.; Cowan, T. E.

Abundant and complex plasma dynamics are triggered by optical ultra-short high power lasers interacting on solid targets: such as atomic ionization, hot electron generation and transportation, collisions between the charged particles, return current, bulk electron heating, ion heating and acceleration, instabilities and so on. Controlling the relative dynamic processes requires modelling of transient, non-equilibrium processes on the atomic scale. We present particle-in-cell simulations which studied enhanced ion heating in buried layer targets [1], ionization dynamics and instabilities. In order to connect the plasma dynamics seen in simulations with experiments we will discuss the role of in-situ synthetic diagnostics that mimic experimental diagnostics. As one key example we propose to use X-Ray Free Electron Lasers for probing laser-driven solid-density plasmas by small angle X-ray scattering [2] which allows for femtosecond and nanometer resolution of transient plasma processes. With these techniques, probing fundamental plasma properties will allow for direct comparison to simulations, challenging state of the art theoretical modeling of collisions, ionization, radiation transport and atomic processes.

Keywords: Plasma dynamics; ion heating; ionization; instability; XFEL probing

  • Poster
    Radiative Properties of Hot Dense Matter, 29.09.-03.10.2014, Vienna, Austria

Publ.-Id: 21219

PolCarr® - Smart carriers for advanced manufacturing in biotechnology.

Wiesenhütter, K.; Urban, B.; Müller, M.; Müller, A.-D.; Skorupa, I.; Rüb, M.; Skorupa, W.; Schmidt, O. G.; Schmidt, H.

We propose a novel concept for functionalization of carriers (PolCarr®) by surface-near electrostatic forces for diverse applications in biotechnology. PolCarr® consists of a locally doped Si wafer with an ultra-thin insulating top layer and a characteristic pattern of surface near electrostatic forces (SNEF). The selective binding of the electrically polarizable material is purely driven by SNEF. By varying the type and concentration of the dopant ions, the strength and direction of surface-near electrostatic forces can be controlled. Further on, by attaching a structured bottom electrode to PolCarr® and bias altering, SNEF can be modulated precisely in the nm-µm-mm range, permitting transport and release of the target biomaterial.

Keywords: functionalization of carriers; biotechnology; surface-near electrostatic forces; semiconductor doping; biosensors; tissue engineering

Related publications

  • Lecture (others)
    Innovation Days 2014 München, Research Meets Business, 01.-02.12.2014, München, Deutschland

Publ.-Id: 21218

PolCarr: Smart carriers for advanced manufacturing in biotechnology.

Wiesenhütter, K.; Urban, B.; Müller, M.; Müller, A.-D.; Skorupa, I.; Rüb, M.; Skorupa, W.; Schmidt, O. G.; Schmidt, H.

Further development of intelligent, highly-efficient and low-cost concepts in biosensors is a prime drive of the dynamically expanding biotechnology industry. As majority of the available market for biosensors is based on the functionalization of substrates, new approaches offering carriers with superior performance i.e. with easy-to-control immobilization, modification, transport and detection of the target analytes are strongly required. Consequently, herein we propose a novel, promising concept for fabrication of the smart carriers (PolCarr) for diverse applications in biotechnology. The PolCarr substrate consists of a doped Si wafer with an ultra-thin insulating top layer and a characteristic pattern of surface near electrostatic forces (SNEF) [Baumgart 2009]. The selective binding and release of the electrically polarizable molecules onto the PolCarr medium is purely driven by SNEF [Schmidt 2013]. Though, chemical-covalent and biological immobilization mechanisms are widely used by conventional biotechnology industry, they suffer from limited control. In stark contrast, the physical interaction via SNEF offers an excellent degree of control on the mm-nm scale. By attaching a structured bottom electrode to a locally doped Si wafer and voltage altering, SNEF can be precisely modulated in the nm range. Since SNEF are characterized by excellent environmental stability, the PolCarr carriers can be successfully utilized under a broad-spectrum of environmental conditions i.e. temperature, pH and humidity. The exceptional functionality of PolCarr makes it a suitable medium for typical biotechnology processing e.g. autoclaving for sterilization, incubation for cell growth, and for cryogenic applications for shock freezing, where conventional substrates may undergo critical failure. Finally, as the PolCarr technology originates from a standard, well-established semiconductor manufacture [Skorupa and Schmidt Springer 2014], the exceptionally facile carrier processing allows for realization of significant throughput and overall cost-reduction. Based on the highly-desirable and unique features of the PolCarr technology presented above, we strongly believe that our concept constitutes a high-value solution to the challenges faced by state-of-the-art biotechnology industry and may have a decisive impact on design and development of carriers for biotechnological manufacturing [Müller in preparation].
To protect the valuable IP, patent applications were filed in 2011 and 2012. To commercialize the PolCarr technology, a spin-off company is planned.

Keywords: biotechnology; biomaterials immobilization; carrier materials; biosensors; tissue engineering; doped Si-wafer; surface-near electrostatic forces; semiconductor industry

Related publications

  • Lecture (others)
    Bionection Partnering Conference for Technology Transfer in Life Sciences, 09.-10.10.2014, Dresden, Deutschland

Publ.-Id: 21217

Advanced ms-annealing concepts for semiconducting oxides for PV applications.

Wiesenhuetter, K.; Lindberg, P.; Bregolin, F. L.; Prucnal, S.; Vines, L.; Mathey, A.; Wiesenhuetter, U.; Monakhov, E. V.; Svensson, B. G.; Skorupa, W.

The demand for high performance PV devices has led to vast advances in novel concepts for highly efficient PV products to be realized. Transparent conductive oxides (TCO) is one of the materials with a great potential towards PV applications and their indium tin oxide (ITO) is an industry viable option. The excellent set of properties demonstrated by ITO are stipled by its high cost and as a result given impetus to scientists to research for cheaper materials as an alternative. Consequently, Al- and Ga-doped ZnO (AZO and GZO) were identified as attractive candidates to replace the ITO-based PV components. However, to simultaneously ensure a higher conversion of solar energy to electricity and a significant reduction of the processing costs, further improvements of the AZO characteristics need to be achieved. Herein the authors propose application of advanced, millisecond annealing technologies e.g. flash lamp annealing (FLA) for the fabrication of the enhanced quality AZO for PV industry. As it will be shown, FLA offers effective recrystallization of the as-processed AZO films, activation of the Al dopants and creation of a defect-depleted AZO/c-Si interface. Superior opto-electrical response of the fabricated semiconductor heterostructures is achieved as a result. The application of ultra-short annealing times and selective heating option lead to an extraordinary time and energy conservation, opening up novel and low cost fabrication strategies for innovative PV products.

Keywords: transparent conductive oxide; thin-films; Al-doped ZnO; millisecond flash lamp annealing; interface; PV applications

Related publications

  • Invited lecture (Conferences)
    E-MRS Fall Meeting 2014, 15.-18.09.2014, Warszawa, Polska

Publ.-Id: 21216

PolCarr®: Smart carriers for advanced nano-sensors and tissue engineering applications.

Wiesenhütter, K.; Urban, B.; Müller, M.; Müller, A.-D.; Skorupa, I.; Rüb, M.; Skorupa, W.; Schmidt, O. G.; Schmidt, H.

Further development of intelligent, highly-efficient and low-cost concepts in biosensors is a prime drive of the dynamically expanding biotechnology industry. As majority of the available market for biosensors is based on the functionalization of substrates, new approaches offering carriers with superior performance i.e. with easy-to-control immobilization, modification, transport and detection of the target analytes are required. Consequently, herein we propose a novel concept for fabrication of the smart carriers (PolCarr®) for diverse applications in biotechnology e.g. nano-sensors. The PolCarr® substrate consists of a doped Si wafer with an ultra-thin insulating top layer and a characteristic pattern of surface near electrostatic forces (SNEF). The selective binding and release of the electrically polarizable molecules onto the PolCarr® medium is purely driven by SNEF. Due to the excellent control degree at both the nm- and µm-range and the superb inertness of SNEF to environmental conditions, the PolCarr® carriers are very attractive candidates for tissue engineering and regenerative medicine, as they allow for directed cell growth. The exceptional functionality of PolCarr® makes it a suitable medium for typical biotechnology processing e.g. autoclaving for sterilization. As the PolCarr® technology originates from a standard semiconductor manufacture, the exceptionally facile carrier processing offers realization of significant throughput and overall cost-reduction.

Keywords: biotechnology; biosensors; controlled cell growth; carriers; biomaterials immobilization; doped-Si wafer; semiconductors manufacturing; surface-near electrostatic forces

Related publications

  • Lecture (Conference)
    E-MRS Fall Meeting 2014, 15.-18.09.2014, Warszawa, Polska

Publ.-Id: 21215

Surface solid and liquid phase processing in the ms-range using flash lamp annealing.

Wiesenhütter, K.; Schumann, T.; Prucnal, S.; Bregolin, F.; Wutzler, R.; Reichel, D.; Mathey, A.; Zichner, R.; Lindberg, P.; Vines, L.; Wiesenhütter, U.; Svensson, B. G.; Skorupa, W.

Annealing is one of the oldest methods utilized by mankind for the manufacture of materials. Over the past millennium, thermal processing has evolved from its simple form to a highly sophisticated, mature technology. However, to meet modern requirements for novel, high performance products and to respond to dynamic progress in technology, new concepts in heat treatment that allow realization of innovative materials structures with superior functionality are required. Consequently, herein we demonstrate a successful application of ultra-short millisecond flash lamp annealing (for short FLA) for surface solid and liquid phase processing of advanced materials fabricated in the form of bulk, thin-films or complex nano-heterostructures [1]. Overall principles of FLA, the state-of-the-art facilities as well as selected FLA-applications developed at the HZDR will be presented. The ms-range FLA has already proven to be a highly promising alternative to standard heating technologies e.g. furnace annealing, which cannot meet the material-manufacture-property requirements imposed by modern devices e.g. large-area electronics printed on flexible, low-thermal budget media. As FLA enables a selective surface-near high temperature heating in ultra-short cycles, the high processing efficiencies with a substantial drop of the overall fabrication costs can be achieved. The numerous advantages of ms-range FLA are already widely exploited in the semiconductor industry. However, we believe there is still plenty of room for novel innovative applications of the ms-FLA to be identified and be successfully developed.
1. W. Skorupa and H. Schmidt, Springer Series in Materials Science, 192 (2014)

Keywords: millisecond flash lamp annealing; liquid phase processing; large-area electronics; thin-films; transparent conducting oxides; Al-doped ZnO; photovoltaics

Related publications

  • Poster
    4th International Conference on Advances in Solidification Processes (ICASP-4), 08.-11.07.2014, Beaumont Estates, Old Windsor, United Kingdom

Publ.-Id: 21214

Functionalization of Printed Metal-Particle Suspensions by Millisecond Thermal Processing.

Wiesenhütter, K.; Schumann, T.; Zichner, R.; Gebel, T.; Wiesenhütter, U.; Skorupa, W.

The global quest towards novel, flexible and low-cost electronic products with functionality far beyond that offered by conventional size-restricted and rigid semiconductor devices, demands a rapid development of advanced material and deposition technology concepts. One of the most promising pathways to realize this ambitious goal is printed flexible electronics (PFE). Over the past years, printing has successfully demonstrated its potential for manufacture of manifold electronic products such as flexible displays, thin-film solar cells, large-area sensors etc. Importantly, by employing bendable, inexpensive media (e.g.: polymer foils, paper-like substrates) and high-throughput roll-to-roll (R2R) processing, a significant reduction of the overall costs associated with electronic device fabrication has been achieved.
Herein, we report on a successful application of ultra-fast millisecond flash lamp annealing (FLA) as a highly-attractive technique for the functionalization of Ag- and Cu-layers screen printed on low-thermal budget PET and paper-like media for e.g. antenna applications. The effect of the FLA parameters (i.e. pulse duration and energy density), on the substrate behavior as well as on the microstructure and electrical response of the as-flashed films was studied. A significant drop of the sheet resistance of the FL-treated layers as compared to the as-printed films was observed for the selected samples. As ms-FLA permits selective, near-surface heating, a damage of the sensitive substrates was avoided. Being highly-efficient (ultra-short), “non-destructive” (suitable for low-thermal tolerance flexible media) and compatible with R2R processing, FLA offers the realization of advanced PFE products.

Keywords: printed electronics; flash lamp annealing; roll-to-roll; flexible inexpensive substrates; Ag- and Cu-based inks

  • Poster
    E-MRS Spring Meeting 2014, 26.-30.05.2014, Lille, France

Publ.-Id: 21213

Advanced AZO processing via flash lamp annealing.

Bregolin, F. L.; Lindberg, P.; Wiesenhütter, K.; Vines, L.; Prucnal, S.; Svensson, B.; Skorupa, W.

Currently, indium tin oxide (ITO) is the most widely used transparent conductive oxide due to its outstanding properties. However, because of its high cost, several alternatives are being sought to replace it. Among them, the aluminum-doped zinc oxide (AZO) films are one of the most promising candidates for PV applications due their low resistivity, high transparency and most of all, their relative low cost of fabrication.
In this work, AZO films were deposited over Si wafers via r.f. magnetron sputtering and subsequently treated by millisecond-range flash lamp annealing (FLA). The fabricated layers were then characterized by sheet resistance, photoluminescence spectroscopy, X-ray diffraction and Hall effect measurements. The influence of the deposition temperature and FLA parameters on the microstructure and optoelectronic response of the AZO layers was studied in detail. It was demonstrated that the FLA technique significantly improves the electrical conductivity of the as-deposited AZO layers due to the Al activation, the increase in crystallinity as well as the passivation of defects and grain boundaries. In particular, the room temperature sputtered AZO films subsequently treated by FLA have shown performance characteristics similar to those sputtered at 400 ºC, opening the possibility for further cost reductions in the fabrication process. The FLA technique is a cost-effective and high-throughput alternative for the processing of Si-based heterojunction solar cells.

Keywords: Transparent Conductive Oxides; Al-doped ZnO; Flash Lamp Annealig; Photovoltaics

Related publications

  • Poster
    E-MRS Spring Meeting 2014, 26.-30.05.2014, Lille, France

Publ.-Id: 21212

PolCarr - Smarte Trägermaterialien für die Biotechnologie

Schmidt, H.; Wiesenhütter, K.; Teichmann, D.

Das smarte Trägermaterial PolCarr® besteht aus dotiertem Silizium und umfasst eine isolierende Deckschicht sowie eine strukturierte Rückseitenelektrode. Die Dotierung des Siliziums verursacht die Ausbildung oberflächennaher, elektrostatischer Kräfte, deren Stärke und Richtung durch die Konzentration und Spezies der implantierten Ionen auf der Nanometer- bis Millimeterlängenskale kontrolliert eingestellt wird. Elektrisch polarisierbare Zellen oder Moleküle können an PolCarr® angezogen, ausgerichtet und immobilisiert werden.

Keywords: Trägermaterialien; Biosensoren; Zellwachstumsplatten

Related publications

  • Lecture (others)
    Cross Cluster Cooperation-Projekt „C3-Saxony“, IDEA CALL zum 9. Silicon Saxony Day, 03.07.2014, Dresden, Deutschland
  • Lecture (others)
    Cross Cluster Cooperation-Projekt „C3-Saxony“ IDEA CALL zum 9. Silicon Saxony Day, 03.07.2014, Dresden, Deutschland

Publ.-Id: 21211

Smart carriers for advanced nano-sensors and tissue engineering applications.

Wiesenhütter, K.; Skorupa, I.; Rüb, M.; Müller, M.; Skorupa, W.; Schmidt, O. G.; Schmidt, H.

A paramount drive of the rapidly growing biotechnology sector is the further development of intelligent, highly-efficient and inexpensive concepts for biosensors. As the key component of a biochip platform, biosensors hold a responsibility for immobilization, modification, transport and detection of a variety of biological analytes broadly utilized in health care, food industry and environmental monitoring. To augment the overall biosensor performance, much effort has been dedicated to designate the new, superior carrier materials, which permit easy-to-control immobilization of the target analytes. Consequently, herein we do propose a novel, promising concept for the smart carriers’ fabrication which is named PolCarr. PolCarr consists of doped silicon wafers and ultra-thin insulating top layers and exploits surface-near electrostatic forces (SNEF) [1-2] for the selective adsorption of electrically polarizable bioanalytes and functionalized polymers [3]. The binding and release of molecules onto the PolCarr substrate is purely driven by SNEF. By attaching a structured bottom electrode to locally doped silicon wafers and by a careful voltage altering, the SNEF can precisely be controlled on the nm-length scale, enabling realization of new, advanced products for manifold medical applications (for instance: nano-sensors). Further on, the excellent control degree at both the nm- and µm-range and the superb inertness of SNEF to environmental influences make PolCarr carriers very attractive candidates for tissue engineering and regenerative medicine, as they allow the growth of the target cells in a highly-desirable ordered manner. As PolCarr permits exceptionally facile manufacture by ion implantation and thermal dopant activation [4] and as PolCarr is compatible with well-developed standard semiconductor processing, the significant throughput and overall cost-reduction associated with the entire carrier’s production and its subsequent use as an integral part of a medical device (e.g.: biochip), can be achieved. Considering the whole benefits offered by our smart carriers, we strongly believe that the PolCarr concept can thoroughly transform traditional biosensor- and tissue engineering-oriented technologies [5]. Finally, the unique selling points of the innovative and proprietary technology offer from our point of view a high value proposition compared to state of the art technology. In order to protect the valuable intellectual property, patent applications were filed in 2011 and 2012. For the future commercialization of the technology a spin-off company is planned. The start-up team is formed by an experienced business developer and key scientists. Cooperations for the biochip development are already established. In addition, the team is supported by technology transfer partners of the Helmholtz Zentrum Dresden Rossendorf. [1] Quantitative dopant profiling in semiconductors: A Kelvin probe force microscopy model, C. Baumgart, M. Helm, H. Schmidt, Phys. Rev. B 80 (2009) 085305. [2] Kelvin probe force microscopy in the presence of intrinsic local electric fields, C. Baumgart, A.-D. Müller, F. Müller, H. Schmidt, Phys. Stat. Sol. (A) 208 (2011) 777–789. [3] Kelvin probe force microscopy for characterizing doped semiconductors for future sensor applications in nano- and biotechnology, H. Schmidt, S. Habicht, S. Feste, A.D. Müller, O.G. Schmidt, Appl. Surf. Sci. 281 (2013) 24-29 (invited). [4] Subsecond Annealing of Advanced Materials Annealing by Lasers, Flash Lamps and Swift Heavy Ions (Eds.: Wolfgang Skorupa, Heidemarie Schmidt), Springer-Verlag, ISBN: 978-3-319-03130-9 (2014). [5] Selective polyelectrolyte adsorption at novel charge patterned carrier materials for future biosensor applications, M. Müller, B. Urban, A.-D. Müller, M. Rüb, K. Wiesenhütter, I. Skorupa, O.G. Schmidt, H. Schmidt, Materials (2014), in preparation (invited).

Keywords: Biotechnology; biosensors; tissue engineering; carriers; doped Si-wafers; Surface-Near Electrostatic Forces

Related publications

  • Poster
    Saxon Biotechnology Symposium 2014, Dresden, 19.03.2014, Dresden, Deutschland

Publ.-Id: 21210

Pressure-induced shift of energy levels and structural phase transition in CdSe/ZnS quantum dots

Tauch, J.; Braun, J. M.; Keller, J.; Hinz, C.; Haase, J.; Seletskiy, D. V.; Leitenstorfer, A.; Pashkin, A.

Electronic band structure of CdSe/ZnS quantum dots under high pressures is studied using fluorescence spectroscopy. We observe a strong blue shift of about 50 meV/GPa for the emission line at 655 nm. At moderate pressures (below 3 GPa) this shift is linear and it is dominated by increase of the fundamental band gap of CdSe under pressure [1]. In contrast to bulk CdSe where the fluorescence is quenched above 3 GPa as a results of the phase transition into the rock-salt structure, the CdSe/ZnS quantum dots remain structurally stable up to 6.5 GPa. The shift of the fluorescence line below this pressure is strongly nonlinear with tendency to saturation. This behavior can be well described using the Murnaghan equation of state giving the deformation potential value of -3.5 eV.
The remarkably high pressure of the structural phase transition in the studied CdSe/ZnS quantum dots exceeds previously reported values for CdSe nanocrystals [2] and bulk CdSe [1]. Presumably, the wurtzite structure of the quantum dots is stabilized by the ZnS shell. This structural robustness together with the high fluorescence yield and the large pressure coefficient of the wavelength shift make CdSe quantum dots a promising alternative to bulk ruby crystals for precise pressure calibration at moderate pressures.

[1] W. Shan et al., Appl. Phys. Lett. 84, 67 (2004).
[2] S. H. Tolbert and A. P. Alivisatos, J. Chem. Phys. 102, 4642 (1995).

Keywords: quantum dots; high pressure; structural phase transition

  • Poster
    Pressure and Strain Effects in Correlated Electron Materials, 06.-10.10.2014, Dresden, Germany

Publ.-Id: 21209

Above Room Temperature Ferromagnetism in Co- and V-Doped TiO2 — Revealing the Different Contributions of Defects and Impurities

Semisalova, A. S.; Mikhailovsky, Yu. O.; Smekhova, A.; Orlov, A. F.; Perov, N. S.; Gan’shina, E. A.; Lashkul, A.; Lahderanta, E.; Potzger, K.; Yildirim, O.; Aronzon, B.; Granovsky, A. B.

We report recent experimental results on themagnetic, magnetotransport, and magneto-optical properties of Co- and V-doped TiO2−δ magnetic oxides at the doping level around 1 at. %. The samples were prepared using rf magnetron sputtering in identical conditions that allows to compare the mechanisms of above-room-temperature ferromagnetism observed in both cases of doping. In spite of the comparable values of magnetic moment around 1 ÷ 2.5 μB per 3d impurity derived from macroscopic magnetic measurements for both systems, the magneto-optical response of TiO2−δ :V was at least 2 orders of magnitude weaker. The anomalous Hall effect was absent in V-doped TiO2−δ, and no appreciable magnetic moment on V impurities was found by X-ray magnetic circular dichroism (XMCD) technique in contrast to Co-doped TiO2−δ. The obtained experimental data indicate dissimilar origin of intrinsic ferromagnetismin TiO2−δ:Co and TiO2−δ:V.

Keywords: Doped TiO2; Magnetic semiconductors; Oxygen vacancy; Defect-induced ferromagnetism

Related publications

Publ.-Id: 21207

Ultrafast dynamics in CeTe3 across the pressure-induced charge-density-wave transition

Tauch, J.; Schäfer, H.; Obergfell, M.; Demsar, J.; Giraldo, P.; Fisher, I. R.; Pashkin, A.

Time-resolved optical spectroscopy is a powerful tool for studying ultrafast dynamics of quasiparticles and phonons in strongly correlated electronic systems. In particular, this technique has been efficiently utilized for investigation of charge-density-wave (CDW) compounds [1-3]. In all these studies the system has been tuned across the boundary of the CDW phase by temperature variation. However, application of external (or chemical) pressure can also lead to a suppression of a CDW state caused by an impairment of the Fermi surface nesting [4].
Here, we combine femtosecond time-resolved optical spectroscopy and a diamond anvil cell technology to study the electron and lattice dynamics in tri-telluride compound CeTe3. The optical pump-probe measurements (400 nm pump and 800 nm probe wavelength, respectively) are performed on single crystals mounted inside the pressure cell. CsI has been used as a pressure transmitting medium. Around pressures of 4 GPa we observe a gradual vanishing of the relaxation process related to the recombination of the photoexcited quasiparticles. The coherent oscillations of the phonon modes coupled to the CDW order parameter demonstrate even more dramatic suppression with increasing pressure . These observations clearly indicate a transition into the metallic state of CeTe3 induced by the external pressure.

[1] J. Demsar et al., Phys. Rev. Lett. 83, 800 (1999).
[2] J. Demsar et al., Phys. Rev. B 66, 041101 (2002).
[3] R.V. Yusupov et al., Phys. Rev. Lett. 101, 246402 (2008).
[4] A. Sacchetti et al., Phys. Rev. Lett. 98, 026401 (2007).

Keywords: Time-resolved optical spectroscopy; high pressure; charge-density-waves

  • Poster
    Pressure and Strain Effects in Correlated Electron Materials, 06.-10.10.2014, Dresden, Germany

Publ.-Id: 21206

Simulation and Experimental Verification of Prompt Gamma-ray Emissions during Proton Irradiation

Schumann, A.; Petzoldt, J.; Dendooven, P.; Enghardt, W.; Golnik, C.; Hueso-González, F.; Kormoll, T.; Pausch, G.; Roemer, K.; Fiedler, F.

Irradiation with protons and light ions offers new possibilities for tumor therapy but has a strong need for novel imaging modalities for treatment verification. The development of new detector systems, which can provide an in vivo range assessment or dosimetry, requires an accurate knowledge of the secondary radiation field and reliable Monte Carlo simulations. This paper presents multiple measurements to characterize the prompt γ-ray emissions during proton irradiation and benchmarks the latest Geant4 code against the experimental findings. Within the scope of this work, the total photon yield for different target materials, the energy spectra as well as the γ-ray depth profile were assessed. Experiments were performed at the superconducting AGOR cyclotron at KVI-CART, University of Groningen. Properties of the γ-ray emissions were experimentally determined. The prompt γ-ray emissions were measured utilizing a conventional HPGe detector system (Clover) and quantitatively compared to simulations. With the selected physics list QGSP BIC HP, Geant4 strongly verestimates the photon yield in most cases, sometimes up to 50 %. The shape of the spectrum and qualitative occurrence of discrete γ lines is reproduced accurately. A sliced phantom was designed to determine the depth profile of the photons. The position of the distal fall-off in the simulations agrees with the measurements, albeit the peak height is also overestimated. Hence, Geant4 simulations of prompt γ-ray emissions from irradiation with protons are currently not as reliable as simulating electromagnetic processes. Deviations from experimental findings were observed and quantified. Although there has been a constant improvement of Geant4 in the hadronic sector, there still remains a gap to close.

Keywords: proton therapy; prompt gamma imaging; Geant4

Publ.-Id: 21205

HADES results in elementary reactions

Ramstein, B.; Adamczewski-Musch, J.; Arnold, O.; Atomssa, E. T.; Behnke, C.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Deveaux, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gill, K.; Golubeva, M.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Kardan, K.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krebs, E.; Kuc, H.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petousis, V.; Pietraszko, J.; Przygoda, W.; Rehnisch, L.; Reshetin, A.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmidt-Sommerfeld, K.; Schuldes, H.; Sellheim, P.; Siebenson, J.; Silva, L.; Sobolev, Y. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Wendisch, C.; Wirth, J.; Wüstenfeld, J.; Zanevsky, Y.; Zumbruch, P.

Recent results obtained with the HADES experimental set-up at GSI are presented with a focus on dielectron production and strangeness in pp and quasi-free np reactions. Perspectives related to the very recent experiment using the pion beam at GSI are also discussed.

Publ.-Id: 21204

Transmutation von Transuranen unter den Randbedingungen des Kernenergieausstiegs – Ist das technisch machbar?

Merk, B.; Rohde, U.

Die deutsche Regierung hat den Ausstieg aus der Kernenergie beschlossen, aber der Umgang mit den hochradioaktiven Abfällen ist noch nicht geklärt. Partitionierung und Transmutation (P&T) kann als technologische Option im Prozess des Umgangs mit hochradioaktiven Abfällen betrachtet werden, dazu wurde eine umfangreiche Studie durchgeführt. In diesem Rahmen wurden auch Ziele für P&T unter der Maßgabe des Kernenergieausstiegs diskutiert. In den vorliegenden Simulationsrechnungen wird analysiert inwieweit diese Ziele unter dem Einsatz von Salzschmelzenreaktoren mit schnellem Neutronenspektrum erreicht werden können. Er wird gezeigt, dass eine effiziente Transmutation aller in Deutschland zum Abschaltzeitpunkt existierenden Transurane mit 3 bis 4 Anlagen in 45 bis 60 Jahren machbar wäre. Ferner wird eine detaillierte Bilanzierung verschiedener Inventare zum tieferen Verständnis der Vorgänge in der Transmutation präsentiert.
The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P&T) could be considered as a technological option in the process of management of highly radioactive waste management, therefore a wide study has been conducted. In this group objectives for P&T und the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed using simulations of molten salt reactors with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible in 3 to 4 reactors in a time frame of 45 to 60 years. Further on a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation.

Keywords: nuclear; nuclear reactor; molten salt; molten salt reactor; transmutation; nuclear waste management; nuclear phase out

  • Contribution to proceedings
    Jahrestagung Kerntechnik, 05.05.2015, Berlin, Deutschland

Publ.-Id: 21203

Two-dimensional and tubular structures of misfit compounds: Structural and electronic properties

Lorenz, T.; Joswig, J.-O.; Seifert, G.

Misfit layer compounds are structures that consist of two sublattices differing in at least one of their lattice constants. The two different layers are stacked either an alternating or in a more complex series resulting in mono- or multi-layer misfit compounds. To date, planar and bent misfit structures, such as tubes, scrolls or nanoparticles, have been synthesized and interesting magnetic and physical properties have been observed as a result of their special structures. Based on these observations, we present an overview of such misfit systems and summarize and discuss their electronic structure as well as the interlayer bonding behaviour, which is not completely understood yet. Furthermore, a more detailed insight into the SnS–SnS2 system is given, which was the first tubular misfit compound that has been synthesized and extensively investigated.

Keywords: 2D layered materials; misfit layer compounds

Related publications

Publ.-Id: 21202

Optical properties of triangular molybdenum disulfide nanoflakes

Wendumu, T. B.; Seifert, G.; Lorenz, T.; Joswig, J.-O.; Enyashin, A.

The results from calculations of optical and electronic properties of triangular MoS2 nanoflakes with edge lengths ranging from 1.6 to 10.4 nm are presented. The optical spectra were calculated using the time-dependent extension of the density-functional tight-binding method (TD-DFTB). The size effect in the optical absorption spectra is clearly visible. With decreasing length of the nanoflakes edges, the long-wavelength absorption in the range of visible light is shifted toward short-wavelength absorption, confirming a quantum-confinement-like behavior of these flakes. In contrast, the edges of the nanoflakes exhibit a distinct metallic-like behavior. The relation of the absorption properties to the observed photoluminescence of MoS2 nanoflakes is discussed in a qualitative manner.

Keywords: Molybdenum disulfide; Nano-flakes

Related publications

Publ.-Id: 21201

Linear thermal expansion, thermal diffusivity and melting temperature of Am-MOX and Np-MOX

Prieur, D.; Belin, R. C.; Manara, D.; Staicu, D.; Richaud, J.-C.; Vigier, J.-F.; Scheinost, A. C.; Somers, J.; Martin, P.

The thermal properties of Np- and Am-MOX solid solutions were investigated. The linear thermal expansion was investigated with high temperature X-ray diffraction from room temperature to 1973 K. No significant difference was observed between the Np and the Am doped MOX. The thermal conductivity of Am-MOX is about 10% higher than that of Np-MOX. The melting temperatures of Np-MOX and Am-MOX were measured using a laser heating setup and are equal to 3020 ± 30 K and 3005 ± 30 K, respectively.

Keywords: Transmutation; minor actinides; MOX; XANES; XRD; thermal conductivity; laser melting

Related publications

Publ.-Id: 21200

Drag and turbulence modelling for free surface flows within the two-fluid Euler-Euler framework

Porombka, P.; Höhne, T.

Two-phase flows are regularly involved in the heat and mass transfer in industrial processes. To ensure the safety and efficiency of such processes, an accurate prediction of the flow field and phase distribution by means of Computational Fluid Dynamics (CFD) is required. Nowadays, Direct numerical simulations (DNS) of large-scale two-phase flow problems are not feasible due to the computational costs involved. Therefore the Euler-Euler framework is often employed for large-scale simulations which involves macro-scale modelling of turbulence, mass and momentum transfer. The research activities at Helmholtz-Zentrum Dresden - Rossendorf (HZDR) focus on general closure models for multiphase flows that are closer to physics and include less empiricism. As part of this effort an Algebraic Interfacial Area Density model (AIAD) is developed for the morphology detection in the two-fluid Euler-Euler approach. Drag models for free surface flows are often based on experimental correlations, their applicability thus being limited to certain flow regimes. In this paper a modified free-surface drag model based on local shear stress is investigated that avoids this limitation. For this purpose the algebraic morphology detection mechanism of the AIAD model is revised. In DNS of free surface flow a dampening of the gas side turbulent fluctuations in the near surface region was found by previous investigators. This effect has also been accounted for in Euler-Euler simulations by means of dampening functions. In this work the significance of turbulence dampening in case of free surface flows is examined quantitatively for the k-omega turbulence model. For this purpose steady-state simulations of countercurrent stratified air-water flow have been performed using the commercial CFD code ANSYS CFX. The results are here presented and compared to experimental data. The revised morphology detection mechanism is seen as an improvement with respect to the detection of sharp interfaces. Satisfactory quantitative agreement is achieved for the modified free surface drag model based on experimental pressure difference, liquid levels and interfacial shear stress. Furthermore, it is demonstrated that turbulence dampening has to be accounted for in the k-omega model to qualitatively reproduce the mean flow and turbulence quantities from the experiment. More CFD grade experimental data is required for further model validation.

Keywords: CFD; two-phase flow; drag modelling; free surface; turbulence dampening; AIAD

Publ.-Id: 21199

Closures for simulation of gas-liquid flows in solid foam structures

Subramanian, K.; Baldota, R.; Schubert, M.; Lucas, D.; Hampel, U.

Ceramic foam packings are promising alternatives for packing internals used in chemical engineering processes due to their high porosity and high specific surface area, which results in low pressure drop and high catalytically utilization of the packing. The aim of this work is to perform three-dimensional Computational Fluid Dynamics (CFD) simulations of the evolving gas-liquid flow patterns considering ceramic foams as column internals and to validate them with experimental X-ray tomographic studies. The closures from trickle bed studies are modified according to the ceramic foam specifications considering the flow domain as porous.

Keywords: Multiphase flow; CFD; Ceramic foams; X-ray tomography

  • Lecture (Conference)
    ISCRE 23 & APCRE 7, 07.-10.09.2014, Bangkok, Thailand

Publ.-Id: 21198

Speciation of uranium in compartments of living cells

Geipel, G.; Viehweger, K.

Depleted uranium used a ammunition corrodes in the environment forming mineral phases and then dissolved uranium species like uranium carbonates (Schimmack et al. 2007) and hydroxides. These hydroxide species were contacted with plant cells (canola). After 24 h contact time the cells were fractionated and the uranium speciation in the fraction was determined by TRLFS (time resolved laser-induced fluorescence spectroscopy) at room temperature as well at 150K. It could be shown that the uranium speciation in the fractions is different to that in the nutrient solution. Comparison of the emission bands with literature data allows assignment of the uranium binding forms.

Keywords: Uranium; plant cells; Spectroscopy


Publ.-Id: 21197

Evolution of Spin Wave Modes in Periodically Perturbed Thin Films

Langer, M.; Gallardo, R.; Banholzer, A.; Jansen, A.; Schneider, T.; Wagner, K.; Demidov, V.; Demokritov, S. O.; Landeros, P.; Lenz, K.; Lindner, J.; Fassbender, J.

Periodic perturbations of a magnetic thin film lead to a dipolar contribution proportional to –k (for ultrathin films: k•d << 1) in the dispersion relation of backward volume spin waves additional to the exchange term, which goes quadratically with k. If the scattering condition is fulfilled, meaning the k-vector matches a multiple of the reciprocal lattice vector g0 = 2π/a0, spin waves can scatter into excited magnonic states. This process is referred to as two-magnon scattering (TMS).
In this work, TMS is investigated by introducing periodic defects by Cr+ ion beam irradiation on the surface of a d = 30 nm thick permalloy (Ni80Fe20) film. Patterning was achieved using a PMMA mask, which was pre-structured by electron beam lithography (EBL) and subsequently exposed to a low energy Cr ion beam. Selecting ion energy and fluence, the effective depth of such perturbations can be controlled to investigate the transition from a surface perturbed thin film towards a full magnonic crystal.
The FMR spectra f(H) (see Fig.1) of different samples with varying perturbation depth h and a periodicity a0 ranging from 200 nm to 400 nm have been measured showing mode splitting at each crossing point of higher spin wave modes with the uniform mode due to TMS. Moreover, brillouin light scattering (BLS) measurements have been performed to directly measure the dispersion relation of such periodically perturbed film.
In a further experiment, the evolution of FMR mode splitting dependent on the perturbation depth h was investigated performing multi-step reactive Ar+ ion beam etching (RIBE) of surface steps on a 30 nm permalloy film.
Theoretical calculations based on a perturbation theory[1,2] are accompanied and reveal a good agreement of experiment and theory (see Fig.1). Amongst that, numerical simulations of the FMR spectra were carried out using the MuMax3 code allowing for deeper understanding of the micromagnetic structure of the observed magnonic modes, such as the visualization of the dynamic magnetization.
This work has been supported by DFG grant no. LE2443/5-1.
[1] P. Landeros and D. L. Mills, Phys. Rev. B 85, 054424 (2012).
[2] R. A. Gallardo, A. Banholzer, K. Wagner, M. Körner, K. Lenz, M. Farle, J. Lindner, J. Fassbender and P. Landeros, New J. Phys 16, 023015 (2013).
[3] M. Körner, K. Lenz, R. A. Gallardo, M. Fritzsche, A. Mücklich, S. Facsko, J. Lindner and J. Fassbender, Phys. Rev. B 88, 054405 (2103).

Keywords: Spin Waves; Magnons; Manonics; Magnetization Dynamics; Ferromagnetic Resonance; FMR; Ion Irradiation; Micromagnetic Simulation

Related publications

  • Lecture (Conference)
    59th Annual Magnetism and Magnetic Materials Conference (MMM) 2014, 03.-07.11.2014, Honolulu, Hawaii, USA

Publ.-Id: 21196

Underground nuclear astrophysics for the Sun, and for the Big Bang (updated)

Bemmerer, D.

After the resolution of the solar neutrino problem in 2002, the study of the Sun has now entered a precision era, and an entirely new dilemma has come up: New elemental abundance data from Fraunhofer line analyses are in contradiction with helioseismological observables. Observations of 13N and 15O neutrinos from the Sun may address this so-called solar abundance problem, but their interpretation will require precise nuclear reaction data. Due to the low cross sections involved, such data can only be provided by experiments in an underground low-background setting. Work at the world's only underground accelerator, the 0.4 MV LUNA machine in Gran Sasso (Italy), on solar fusion reactions and on the Big Bang production of lithium-6 and -7 will be reviewed. In addition, some surface-based data on radiative capture reactions on 12C, 14N, and 40Ca will be shown. The status and working program of the planned higher-energy underground accelerator at the Dresden Felsenkeller in Germany will be discussed.

Keywords: Felsenkeller; Underground nuclear astrophysics; Big Bang nucleosynthesis

Related publications

  • Invited lecture (Conferences)
    Joint Institute for Nuclear Astrophysics Seminar, 10.11.2014, South Bend, Indiana, USA
  • Lecture (others)
    Seminar, 14.11.2014, Seattle, Washington, USA

Publ.-Id: 21195

A new study of the 22Ne(p,γ)23Na reaction deep underground: Feasibility, setup, and first observation of the 186 keV resonance

Cavanna, F.; Depalo, R.; Menzel, M.-L.; Aliotta, M.; Anders, M.; Bemmerer, D.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Corvisiero, P.; Davinson, T.; Di Leva, A.; Elekes, Z.; Ferraro, F.; Formicola, A.; Fülöp, Z.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, G.; Imbriani, G.; Junker, M.; Menegazzo, R.; Prati, P.; Rossi Alvarez, C.; Scott, D. A.; Somorjai, E.; Straniero, O.; Strieder, F.; Szücs, T.; Trezzi, D.

The 22Ne(p,γ)23Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the 22Ne(p,γ)23Na cross section directly at the astrophysically relevant energies are needed. In the present work, a feasibility study for a 22Ne(p,γ)23Na experiment at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400\,kV accelerator deep underground in the Gran Sasso laboratory, Italy, is reported. The ion beam induced γ-ray background has been studied. The feasibility study led to the first observation of the Ep = 186\,keV resonance in a direct experiment. An experimental lower limit of 0.12\,×\,10−6\,eV has been obtained for the resonance strength. Informed by the feasibility study, a dedicated experimental setup for the 22Ne(p,γ)23Na experiment has been developed. The new setup has been characterized by a study of the temperature and pressure profiles. The beam heating effect that reduces the effective neon gas density due to the heating by the incident proton beam has been studied using the resonance scan technique, and the size of this effect has been determined for a neon gas target.

Keywords: LUNA; underground nuclear astrophysics; asymptotic giant branch stars; novae

Publ.-Id: 21194

Process-based forward numerical ecological modelling for carbonate sedimentary basins

Clavera-Gispert, R.; Carmona, A.; Gratacós, O.; Tolosana-Delgado, R.

Nowadays, numerical modelling is a significant tool used both by researchers and the industry in the study of sedimentary basins, since it allows to quantify the simulated processes and to determine interactions among them. One of such programs is SIMSAFADIM-CLASTIC, a 3D forward-model process-based code to simulate the sedimentation in a marine basin at geological scale. It models the fluid flow, siliciclastic transport and sedimentation, and carbonate production. In this article, we present the last improvements in carbonate production, in particular the usage of Generalized Lotka-Volterra equations, that include logistic growth and interaction among species. Logistic growth is linked to environment parameters such as water depth, energy of the medium, and slope to the model the growing of species. The environmental parameters are factorized and combined to obtain an environment parameter that is applied to compute the modelled species development. The interaction among species is quantified using the community matrix that captures the beneficial or detrimental effects of the presence of each species on the other. A theoretical example of a carbonate ramp is computed to model the interaction among carbonate and siliciclastic sediment, the affection of environmental parameters to the modelled species, and the interaction among species. The distribution of the modelled species associations in the theoretical example is compared with Asmari Formation in Iran and Ragusa Platform in Italy.

Keywords: Forward-Model; process-based; sedimentary basin; ecological model; carbonate production; SIMSAFADIM-CLASTIC

Publ.-Id: 21193

Measurement of the analysing power in proton-proton elastic scattering at small angles

Bagdasarian, Z.; Chiladze, D.; Dymov, S.; Kacharava, A.; Macharashvili, G.; Barsov, S.; Gebel, R.; Gou, B.; Hartmann, M.; Keshelashvili, I.; Khoukaz, A.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Lomidze, N.; Lorentz, B.; Maier, R.; Mchedlishvili, D.; Merzliakov, S.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Papenbrock, M.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Shmakova, V.; Stassen, R.; Stockhorst, H.; Strakovsky, I. I.; Ströher, H.; Tabidze, M.; Täschner, A.; Trusov, S.; Tsirkov, D.; Uzikov, Y.; Valdau, Y.; Wilkin, C.; Workman, R. L.

The proton analysing power in p→p elastic scattering has been measured at small angles at COSY-ANKE at 796 MeV and five other beam energies between 1.6 and 2.4 GeV using a polarised proton beam. The asymmetries obtained by detecting the fast proton in the ANKE forward detector or the slow recoil proton in a silicon tracking telescope are completely consistent. Although the analysing power results agree well with the many published data at 796 MeV, and also with the most recent partial wave solution at this energy, the ANKE data at the higher energies lie well above the predictions of this solution at small angles. An updated phase shift analysis that uses the ANKE results together with the World data leads to a much better description of these new measurements.

Publ.-Id: 21192

High-performance QWIPs and time-resolved terahertz spectroscopy with a free-electron laser

Schneider, H.

There is no abstract.

Related publications

  • Lecture (others)
    Seminar, Kunming Institute of Physics, 17.10.2014, Kunming, China

Publ.-Id: 21190

Microstructural changes in highly irradiated 15Kh2MFA steel

Gillemot, F.; Horváth, A.; Horváth, M.; Kovács, A.; Radiguet, B.; Cammelli, S.; Pareige, P.; Hernandez-Mayoral, M.; Ulbricht, A.; Kresz, N.; Oszwald, F.; Török, G.

15Kh2MFA-type steel forgings were irradiated in an accelerated surveillance position of a power reactor, up to about 1 × 1021 n/cm2, E> 1 MeV with medium flux. This steel is a Cr-Mo-V-type low-copper reactor pressure vessel material. 15Kh2MFA was microstructurally tested as received and in three different irradiation states within the frame of the LONGLIFE project. The following microstructural tests were performed: metallography, fractography, transmission electron microscopy, small angle neutron scattering, and atom-probe tomography. The aim of the current paper is to summarize the results that were evaluated by the six European institutes performing the study. The SANS tests show that the cluster volume fraction growth is nearly linear as a function of the fluence, and atom-probe tomography concludes that vanadium carbide precipitations were already originally present in the as-received steel. During irradiation these precipitates are enriched with Mo, Cu, and Cr. At the highest dose Mn, Si, and Ni are also attached to these clusters.

Keywords: Clusters; Dislocations; Irradiation; Microstructural testing; Precipitations

  • Contribution to proceedings
    26th International Symposium - Effects of Radiation on Nuclear Materials, 12.-13.06.2013, Indianapolis, US
    Effects of Radiation on Nuclear Materials: 26th Volume, ASTM STP 1572, West Conshohocken, PA, USA: ASTM International, 978-0-8031-7589-1, 45-56
    DOI: 10.1520/STP157220130098
    Cited 4 times in Scopus

Publ.-Id: 21189

Quantitative differentiation of sulfur in different oxidation states (-II and +VI) by WD-XRF

Uhlig, S.; Möckel, R.; Pleßow, A.

Sulfur is one of the most abundant non-metals in the Earth’s crust and a key component of sulfidic ores. A number of methods for the determination of the total sulfur content in geochemical samples are available in the literature. However, sulfur appears in numerous oxidation states. Sulfide (-II) and sulfate (+VI) are the most common ones, but options for a analytical chemical differentiation between them are quite limited. This distinction could be achieved by combustion with stepwise adjustable decomposition temperatures (Brumsack 1981) or by classical wet-chemical methods (e.g., Kokkonen et al. 1987), but these methods require special efforts and can not be implemented during high throughput routine analyses.
Selective separation of different oxidation states by WD-XRF has been reported for sulfur (Perino et al. 2002), aluminium and silicon (Perino et al. 2002), iron (Finkelshtein and Chubarov 2010), and chromium (Malherbe and Claverie 2013). Referring to these known methods, two techniques for the quantitative differentiation between the most common sulfur species were developed, respectively improved that are based on a routine WD-XRF measurement. The first method is predicated on the exact position of the Kα1,2 peak in the XRF spectra, depending on the sulfide and sulfate content. The second option is based on the Kβ’/Kβ-ratio. As opposed to sulfides, sulfates show a Kβ’ satellite peak and its area and height depend on the sulfate concentration.
Both methods provide simple and time-saving options to differentiate between sulfide and sulfate, because the separation of the different oxidation states can be done during a routine WD-XRF measurement without any special efforts. Furthermore, samples with high amounts of fluorine, which could cause damages of technical devices, can be measured without any problems in the vacuum of the spectrometer. We aware that our research results may have two limitations. The first relates to the sulfur content. The method can not be used for samples with concentrations of the sulfatic and/or sulfatic component smaller than 10 g kg-1. The second one is the overlap of the lead (Pb) Mβ peak and the sulfur Kβ’ satellite peak. Samples with detectable lead amounts can only be investigated by the so-called Kα method.
We are currently in the process of a validation of our results by a second, independent method to further advance our investigations. Samples from Saxon mining dump drill holes appear suitable. Their total sulfur content and sulfide and sulfate concentration vary with depth. Suitable applications of these techniques are the high throughput routine analyses of samples that contain or consist of sulfidic ores.
Brumsack, H.-J., 1981. A Simple Method for the Determination of Sulfide- and Sulfate-Sulfur in Geological Materials by Using Different Temperatures of Decomposition. Fresenius' Journal of Analytical Chemistry, 307, 206.
Finkelshtein, A.L. and Chubarov, V.M., 2010. X-ray fluorescence determination of the FeO/Fe2O3tot ratio in igneous rocks. X-Ray Spectrometry, 39 (1), 17–21.
Kokkonen, P., Palko, M., and Lajunen, Lauri H. J., 1987. Indirect determination of sulfate and sulfide by flame atomic absorption spectrometry. Atomic Spectroscopy, 8 (3), 98–100.
Malherbe, J. and Claverie, F., 2013. Toward chromium speciation in solids using wavelength dispersive X-ray fluorescence spectrometry Cr Kbeta lines. Analytica Chimica Acta (773), 37–44.
Perino, E., et al., 2002. Determination of oxidation states of aluminium, silicon and sulfur. X-Ray Spectrometry, 31 (2), 115–119.

Keywords: sulfur oxidation state; WD-XRF

  • Lecture (Conference)
    CANAS - Colloquium Analytische Atomspektroskopie, 08.-10.03.2015, Leipzig, Deutschland

Publ.-Id: 21188

P1315 - Energiespeicheranordnung, deren Verwendung und Energiespeicherzellenanordnung

Galindo, V.; Gerbeth, G.; Stefani, F.; Weber, N.; Weier, T.

Gemäß verschiedenen Ausführungsformen wird eine Energiespeicheranordnung bereitgestellt, wobei diese Folgendes aufweisen kann: mindestens eine elektrochemische Zelle, wobei die mindestens eine elektrochemische Zelle eine im Betrieb flüssige Anode, einen im Betrieb flüssigen Elektrolyten und eine im Betrieb flüssige Kathode aufweist; eine außerhalb der mindestens einen elektrochemischen Zelle angeordnete Magnetfelderzeugungsstruktur zum Erzeugen eines Magnetfeldes, wobei die Magnetfelderzeugungsstruktur derart eingerichtet ist, dass das erzeugte Magnetfeld die mindestens eine elektrochemische Zelle durchdringt.

  • Patent
    DE102013112555 - Erteilung 06.11.2014, Nachanmeldung: WO, CN, EP, US

Publ.-Id: 21187

Level-set reconstruction algorithm for ultrafast limited angle X-ray computed tomography of two-phase flows

Bieberle, M.; Hampel, U.

Tomographic image reconstruction is based on recovering an object distribution from its projections, which have been acquired from all angular views around the object. If the angular range is limited to less than 180° of parallel projections, typical reconstruction artefacts arise when using standard algorithms. To compensate for this, specialized algorithms using a priori information about the object need to be applied.
The application behind this work is ultrafast limited angle X-ray computed tomography of two-phase flows. Here, only a binary distribution of the two phases needs to be reconstructed, which reduces the complexity of the inverse problem. To solve it, a new reconstruction algorithm (LSR) based on the level set method is proposed. It includes one force function term accounting for matching the projection data and one incorporating a curvature dependent smoothing of the phase boundary. The algorithm has been validated using simulated as well as measured projections of known structures and its performance has been compared to the algebraic reconstruction technique (ART) and a binary derivative of it. The validation as well as the application of the level set reconstruction on a dynamic two-phase flow demonstrated its applicability and its advantages over other reconstruction algorithms.

Keywords: Level set method; X-ray CT; image reconstruction; two-phase flow; ultrafast

Publ.-Id: 21186

X-ray Absorption Spectroscopy of Nuclear Materials at the Rossendorf Beamline, ESRF

Scheinost, A. C.; Prieur, D.; Smith, A.; Martin, P. M.; Lebreton, F.; Belin, R. C.

The Rossendorf Beamline is a dedicated X-ray absorption spectroscopy beamline for research on actinides. Embedded in the Helmholtz research program Safety of Nuclear Waste Disposal, inhouse research deals with the chemical behavior of actinides and fission products in the context of nuclear waste disposal, encompassing both near-field and far-field retention mechanisms. In the framework of European research programs, e.g. ACTINET, TALISMAN, ESRF, there is also a vivid body of research conducted on nuclear materials in the context of GenIV fuels, minor actinide transmutation, and the behavior of fuels under operational and accident conditions. In this talk I will focus on the latter aspect, presenting results from collaborations with CEA and ITU on a variety of topics including the oxidation state and local structure of Am in uranium dioxide and MOX fuels, self-irradiation effects of minor actinides in fuel matrices, and structure and oxidation state of U in sodium uranates.

Keywords: ROBL; XANES; Actinet; Talisman; Nuclear fuel

Related publications

  • Invited lecture (Conferences)
    NES Colloquium, 19.11.2014, Villigen, Schweiz

Publ.-Id: 21185

Characterizing intra-exciton Coulomb scattering in terahertz excitations

Zybell, S.; Bhattacharyya, J.; Winnerl, S.; Eßer, F.; Helm, M.; Schneider, H.; Schneebeli, L.; Böttge, C. N.; Kira, M.; Koch, S. W.; Andrews, A. M.; Strasser, G.

An intense terahertz field is applied to excite semiconductor quantum wells yielding strong non-equilibrium exciton distributions. Even though the relaxation channels involve a complicated quantum kinetics of Coulomb and phonon effects, distinct relaxation signatures of Coulomb scattering are identified within time-resolved photoluminescence by comparing the experiment with a reduced model that contains all relevant microscopic processes. The analysis uncovers a unique time scale for the Coulomb scattering directly from experiments and reveals the influence of phonon relaxation as well as radiative decay.

Keywords: Exciton dynamics; GaAs quantum well; terahertz; intra-exciton transition; Coulomb scattering

Related publications

Publ.-Id: 21184

Uranyl(VI) binding by bis(2-hydroxyaryl)diimine and bis(2-hydroxyaryl)diamine ligand derivatives. Synthetic, X-ray, DFT and solvent extraction studies

Jeazet, H. B. T.; Gloe, K.; Doert, T.; Mizera, J.; Kataeva, O. N.; Tsushima, S.; Bernhard, G.; Weigand, J. J.; Lindoy, L. F.; Gloe, K.

The interaction of uranyl(VI) nitrate with a series of bis(2-hydroxyaryl)imine and bis(2-hydroxyaryl)amine derivatives (H2L1- H2L7) incorporating 1,3-dimethylenebenzene or 1,3-dimethylenecyclohexane bridges between nitrogen sites is reported. Crystalline complexes of type [UO2(H2L)(NO3)2] (where H2L is H2L1 -H2L4) were isolated from methanol. X-ray structures of the complexes of H2L1, H2L2 and H2L4 show that each of these neutral ligands bind to their respective UO2 2+ centres in a bidentate fashion in which coordination only occurs via each ligand's hydroxy functions. Two bidentate nitrate anions complete the metal's coordination sphere in each complex to yield hexagonal bipyramidal coordination geometries. A DFT investigation of [UO2(H2L1)(NO3)2] in a simulated methanol environment is in accord with this complex maintaining its solid state conformation in solution. Solvent extraction experiments (water/chloroform) employing H2L1 - H2L7 in the organic phase and uranyl(VI) nitrate in the aqueous phase showed that both amine derivatives, H2L8 and H2L9, yielded enhanced extraction of UO2 2+ over the corresponding imine derivatives, H2L1 and H2L2. These results were further compared with those obtained for the corresponding Schiff bases incorporating 1,2-phenylene and 1,2-cyclohexane bridged ligands, H2L6 and H2L7; these more rigid systems also yielded enhanced extraction of UO2 2+ relative to the more flexible Schiff bases H2L1 - H2L5. A very significant synergistic enhancement of the extraction of UO2 2+ by H2L1‐H2L4 and H2L7 was observed in the presence of a 10-fold excess of octanoic acid; the influence of pH on extraction efficiency was also investigated. A parallel set of experiments employing H2L1 - H2L9 as extractants for europium(III) nitrate indicated a clear uptake preference for UO2 2+ over Eu3+ in all cases; separation of the uranyl ion from the rare earths is important in mineral processing;

Keywords: Uranyl(VI); Schiff base; Europium(III); X-ray; Solvent extraction; Density functional theory

Publ.-Id: 21183

Dual-modality Impedance Wire-Mesh Sensor for Investigation of Multiphase Flows

Dos Santos, E. N.; Da Silva, M. J.; Morales, R. E.; Reinecke, S.; Schleicher, E.; Hampel, U.

For the investigation of multiphase flows, i.e. in oil production, there are only few suitable measuring techniques. For this reason, in this paper a new multichannel complex impedance measuring system using wire-mesh sensors is presented. The novel system measures amplitude and phase components of impedance (at single frequency) and is thus able to evaluate simultaneously the conductive and the capacitive parts of a fluid (complex permittivity). In the future this system can be employed for the investigation of dynamic processes in multiphase flow. The performance in measuring amplitude and phase of a signal is evaluated. First promising results for the three-phase flow are presented.

Keywords: Complex impedance measurement; multiphase flow; wire-mesh sensor

  • Lecture (Conference)
    International Conference on Imaging Systems and Techniques (IST), 14-17.10.2014, Santorini, Greece, 14.-17.10.2014, Santorini, Griechenland
  • Contribution to proceedings
    International Conference on Imaging Systems and Techniques (IST), 14-17.10.2014, Santorini, Greece, 14.-17.10.2014, Santorini, Griechenland
    Proceedings of International Conference on Imaging Systems and Techniques (IST), 14-17.10.2014, Santorini, Greece, 9781479952199, 316-319

Publ.-Id: 21181

Configurational anisotropy effects in 90 degree domain wall imprinted thin films - statics and dynamics

Trützschler, J.; Sentosun, K.; Langer, M.; Mattheis, R.; Fassbender, J.; McCord, J.

The dynamic magnetic behavior of magnetic films has gained increased attention due to the use of magnetic films for high frequency inductors and their application as microwave filters. Moreover, the excitation and modification of spin waves has led to considerable interest in the field of magnonic crystals[1]. In general, the high frequency behavior of magnetic film stacks is determined by the material’s magnetic properties and by structural patterning. Yet, dynamic magnetization modes are not only inherent to the physical structure of magnetic films, but are also strongly influenced by e.g. ripplelike magnetic domain states[2] and as well as the pure existence of domain walls (DW)[3] in magnetic films. One way to introduce DWs in a controlled way in thin films is by local ion-irradiation[4,5,6].
In order to introduce a periodic DW pattern, extended Ni19Fe81(50nm)/Ir23Mn77(7nm) films with an initial unidirectional anisotropy are patterned by local He-ion irradiation into stripe-like twodimensional structures with periodically alternating directions of exchange bias. Magnetization patterns with zigzag oriented exchange bias directions are obtained. The influence of the DW density on static and dynamic magnetization properties is investigated for a stripe period (stripe width) from 12 μm (6 μm) down to 1 μm (500 nm). By this, exactly oriented and magnetically charged 90 N´eel-type domain walls with a DW density up to 2x103/mm are imprinted in the film.
Static and dynamic magnetization properties of the thin films are analyzed by complementary methods.
In Figure 1 (a) and (c) exemplary magnetization loops are presented for a stripe period of 2 μm. Perpendicular to the stripe axis an effective exchange bias field, which is caused by the magnetic interaction of the individual exchanged biased stripes, results in a net exchange bias direction. Due to DW interactions with increasing stripe period the samples correspondingly exhibit a decrease of remanent magnetization. Applying the external magnetic field parallel to the stripe axis, a two staged reversal loop is obtained. Even down to low stripe periods and despite of the straightening of magnetization the two step magnetization process remains for low stripe widths.
The corresponding change of high frequency permeability maps (up to 5 GHz) with bias fields in accordance with the shown magnetization reversal loops are displayed in Fig. 1 (b) and (d). Increasing the external magnetic field perpendicular to the stripes two distinct precessional frequencies, corresponding to an acoustic and an optical dynamic mode, are exhibited over the whole field range (Fig. 1(b)). Applying the field parallel to the stripe axis, in the central plateaued region (Fig. 1(d)) a bi-modal dynamic behavior is observed, that transforms into a single mode with higher permeability outside the plateau region. With increasing stripe period, the precessional frequencies at zero magnetic field decrease.
The occurring magnetic configurations are verified by high resolution Kerr microscopy in the longitudinal mode, examples of which are given in Fig. 2. The displayed images for different applied field values match the situation in Fig. 1 (c) and (d). The domain imaging data proves the existence of a pronounced magnetic modulation with high stability to magnetic fields even for a highly remanent state. The domain states, shown in Fig. 2 (b, c, d), exist in a magnetic field range, which is in accordance with the plateau in the magnetization loop and the change in the permeability spectrum around zero field.
Quasi-static and dynamic behavior are explained in terms of an increased domain wall mediated configurational magnetic anisotropy that results from variable magnetic charges at the imprinted domain walls due to the zigzagged alignment of magnetization. The magnetic charges increase with the rotational magnetization process. The DW stabilization induced effect has also significant influence on the dynamic magnetic characteristics. The effect of DW orientation relative to the alignment of exchange bias will be discussed. The controlled introduction of high density and locked micromagnetic objects opens new ways to control the static and dynamic magnetic properties of continuous magnetic thin films.
Funding from the German Science Foundation DFG through the grants MC9/7-2, FA314/3-2, and the Heisenberg programme of the DFG (MC9/9-1) is highly acknowledged.
[1] A. V. Chumak, A. A. Serga, B. Hillebrands, M. P. Kostylev, Appl. Phys. Lett. 93, 022508 (2008)
[2] C. Patschureck, K. Lenz, M. O. Liedke, M. U. Lutz, T. Strache, I. M¨onch, R. Sch¨afer, L. Schultz, and J. McCord, Phys. Rev. B 86, 054426 (2012)
[3] U. Queitsch, J. McCord, A. Neudert, R. Sch¨afer, L. Schultz, K. Rott, H. Br¨uckl, J. Appl. Phys. 100, 093911 (2006)
[4] J. Fassbender, J. McCord, J. Magn. Magn. Mater. 320, 579 (2008)
[5]C. Hamann, R. Mattheis, I. M¨onch, J. Fassbender, L. Schultz, J. McCord, Magnetization dynamics of magnetic domain wall imprinted magnetic films, submitted
[6] J. Tr¨utzschler, K. Sentosun, M. Langer, I. M¨onch, R. Mattheis, J. Fassbender, J. McCord, Magnetoresistive and domain investigations of zigzag folded magnetization structures, submitted

Keywords: Magnetic Domains; Anisotropic Magneto-Resistance; Kerr-Microscopy; Ferromagnetic Resonance

Related publications

  • Lecture (Conference)
    IEEE Internation Magnetics Conference - Intermag Dresden 2014, 04.-08.05.2014, Dresden, Deutschland

Publ.-Id: 21180

P1211 - Verfahren und System zur Abtrennung von Schwermetallen

Lütke, L.; Moll, H.

Die Erfindung betrifft das Gebiet der Aufreinigung schwermetallbelasteter Gewässer, sowie den Nachweis von Schwermetallen in Lösungen. Der Erfindung liegt die Aufgabe zugrunde, eine effektive Abtrennung von Uran (Schwermetallen allgemein) durch mikrobielle Zellen ohne einen zusätzlichen Immobilisierungsschritt zu erzielen. Die Lösung der Aufgabe erfolgt durch ein erfindungsgemäßes Verfahren zur Abtrennung von Schwermetallen, enthaltend die folgenden Schritte: a. Bereitstellen einer Lösung enthaltend ein Minimalmedium und metabolisch aktive Biomasse aus gramnegativen Bakterien, b. Inkontaktbringen dieser Lösung mit einer Lösung enthaltend Schwermetalle, c. Einstellen der Phosphatkonzentration auf, 0,05 mmol/l bis 0,1 mol/l, bevorzugt 0,2 mmol/l bis 0,5 mmol/l, wobei die Schritte b und c in beliebiger Reihenfolge erfolgen können. Ebenfalls erfindungsgemäß ist ein System zur Abtrennung von Schwermetallen, enthaltend ein Minimalmedium, metabolisch aktive Biomasse aus gramnegativen Bakterien und Phosphat in einer Konzentration von 0,05 mM bis 0,1 M, bevorzugt 0,2 mM bis 0,5 mM. Ebenfalls erfindungsgemäß ist die Verwendung des erfindungsgemäßen Verfahrens oder des erfindungsgemäßen Systems zur Aufreinigung schwermetallbelasteter Gewässer oder zum Nachweis von Schwermetallen in Gewässern.

  • Patent
    DE102013207197 - Offenlegung 23.10.2014

Publ.-Id: 21179

Tomographie an technischen Anlagen – für effizientere Prozesse in der Chemie- und Verfahrenstechnik

Bieberle, M.; Bieberle, A.; Hampel, U.

Tomographie an technischen Anlagen – für effizientere Prozesse in der Chemie- und Verfahrenstechnik

Keywords: tomography

  • Lecture (others)
    Vortrags-/Besichtigungsprogramm für Besuchergruppen, 02.07.2014, Dresden, Deutschland

Publ.-Id: 21178

Ultrafast X-ray computed tomography for the analysis of multiphase flows

Bieberle, M.; Hampel, U.

This presentation addresses the question, why tomographic imaging of multiphase flows is needed and explains the principle of computed tomography as well as the ultrafast X-ray computed tomography system. Examples of application are presented as well as present developments.

Keywords: X-ray computed tomography; ultrafast

  • Lecture (others)
    summer school MIMENIMA, 18.09.2014, Dresden, Deutschland

Publ.-Id: 21177

Np-237 sorption onto montmorillonite and corundum

Elo, O.; Huittinen, N.; Müller, K.; Heim, K.; Hölttä, P.; Lehto, J.

The bentonite buffer in Engineered Barrier Systems (EBS), planned for spent nuclear fuel (SNF) repositories, consists mainly of the clay mineral montmorillonite. Montmorillonite and other aluminosilicates are known to retain radionuclides found in the SNF, thus, contributing to the retention or immobilization of these metal ions in the environment. The neptunyl cation, NpO2+, is rather soluble, poorly sorbed, and readily mobile under environmental conditions making it highly relevant for research concerning SNF repository safety. In the present study we have investigated the sorption of neptunium on the clay mineral montmorillonite under carbonate free, but environmentally relevant conditions. The interaction of neptunium with α-Al2O3 (corundum) has also been investigated in order to study the aluminol surface sites present on clay minerals, which are regarded as the main adsorption sites for radionuclide attachment. We have performed batch sorption studies both as a function of pH and as a function of neptunium concentration 5×10-10 M-5×10-6 M. The NpO2+ uptake on the two different minerals is rather weak. Sorption on the mineral surfaces begins at pH 7, and at pH 8 which is the pH-value expected to prevail in the deep underground in Olkiluoto, Finland, the final disposal site for the Finnish SNF, only ~ 10% of the actinyl ion is retained. To gain insight into the surface speciation of neptunium on the two minerals, we performed in situ ATR-FT-IR spectroscopic investigations at pH 9 and 10. Upon NpO2+ sorption onto corundum and montmorillonite we observe a shift of the antisymmetric stretch vibration of the neptunyl ion from 818 cm-1 obtained for the free aquo ion to 790 cm-1. The large shift of the asymmetric stretch vibration indicates the formation of an inner-sphere bound neptunium com-plex on the mineral surface. A similar shift has previously been observed by Gückel et al. (2013) for NpO2+ sorption onto gibbsite (α-Al(OH)3). In contrast to the results obtained in Gückel et al., where neptunium desorption could not be observed after flushing the mineral film on the ATR crystal, we see a high reversibility of the sorption on both corundum and montmorillonite. This high reversibility of the sorption process speaks for a weaker bonding to the surface. In upcoming EXAFS (Extended X-ray Absorption Fine Structure) measurements, we hope to be able to find an explanation for the deviating desporption behaviour of NpO2+ on montmorillonite and corundum in comparison to gibbsite. In addition, information on structural parameters and the complexation mechanism of neptunium sorption onto montmorillonite and corundum will be obtained.

Keywords: neptunium; sorption; in situ ATR-FT-IR; montmorillonite; corundum

  • Poster
    Advanced Techniques in Actinide Spectroscopy 2014 (ATAS 2014), 03.-07.11.2014, Dresden, Germany

Publ.-Id: 21176

Site-selective TRLFS of Eu(III) doped rare earth phosphates for conditioning of radioactive wastes

Huittinen, N.; Arinicheva, Y.; Holthausen, J.; Neumeier, S.; Stumpf, T.

Crystalline ceramic materials show promise as potential waste forms for immobilization of high-level radioactive wastes. Rare earth (RE) phosphate ceramics have been found to be extremely stable over geological time scales and they show good tolerance to high radiation doses. These ceramics are able to incorporate radionuclides in well-defined atomic positions within the crystal lattice up to high (~25%) loadings, which will reduce the volume of waste in the radionuclide conditioning process. The dehydrated RE phosphates are known to crystallize in two distinct structures, depending on the ionic radius of the cation: the larger lanthanides from La3+ to Gd3+ crystallize in the nine-fold coordinated monazite structure, while the smaller lanthanides such as Lu3+ form eight-fold coordinated xenotime structures.
In the present work we have used site-selective time-resolved laser fluorescence spectroscopy (TRLFS) to investigate the structural incorporation of Eu3+, an analogue for the actinides Pu3+, Am3+ and Cm3+, in rare earth phosphate ceramics. The very narrow excitation spectra of LaPO4 and GdPO4 monazites doped with 500 ppm Eu3+ indicate that Eu3+ is fully incorporated on the host cation sites in the highly ordered ceramic materials independent of the ionic radii of the host cations. The LuPO4 xenotime phase, however, shows a very low incorporation of the Eu3+ ion within the crystal lattice. The majority of the signal in the Eu3+-LuPO4 excitation spectrum could be assigned to partly hydrated europium in the LuPO4 ceramic. In experiments where we increased the dopant concentration up to 50 % in the xenotime host matrix, a larger amount of Eu3+ incorporation within the crystal structure in relation to the hydrated species could be seen. A similar increase of the dopant concentration in the monazite phases caused a broadening of the excitation spectra as a result of local disordering of the crystal structures. This disordering, however, had no influence on the Ln3+ site symmetry in the monazites.
Our site-selective TRLFS investigations have shown that the host cation size in the monazites has very little influence on the Eu3+ incorporation into these materials. The structure of the ceramic, however, seems to play a decisive role in how well the dopant is substituted within the crystal lattice.

Keywords: rare earth phosphate ceramics; incorporation; Eu(III); site-selective TRLFS

  • Lecture (Conference)
    Advanced Techniques in Actinide Spectroscopy 2014 (ATAS 2014), 03.-07.11.2014, Dresden, Germany

Publ.-Id: 21175

A few remarks on the structure of PT quantum mechanics

Günther, U.

In the first part of the talk, starting from a historical discussion of the 2-dimensional Ising model, the Yang-Lee analysis of the zeros of the corresponding partition function and the occurrence of the Yang-Lee edge singularities the structural origin of the quantum mechanical toy model Hamiltonian with ix^3 potential is elucidated. The close relationship of this Hamiltonian to the Landau theory of phase transitions and conformal field theories (CFTs) is sketched what provides an intuitive explanation for the operator-theoretic difficulties in treating a conjectured Hermitian structure of the ix^3 model in full depth.
In the second part of the talk, the Krein space and Hilbert space metric structures of quasi-Hermitian PT-symmetric matrix models are discussed with emphasis on the underlying general Lie group structures of these metric operators. The Cartan decomposition into compact and noncompact metric components is used to show the existence of an underlying Lie triple system and its relation to the curvature of homogeneous coset spaces.
Finally, several extension schemes from finite-dimensional Lie groups toward ∞−dimensional Lie groups and Hilbert-Schmidt Lie groups are sketched.

Keywords: Yang-Lee model; Yang-Lee edge singularity; Ising model; Landau theory of phase transitions; conformal field theory; PT quantum mechanics; metric operator; Krein space; Lie groups; Cartan decomposition; Lie triple systems; homogeneous coset spaces; Hilbert-Schmidt Lie groups

  • Invited lecture (Conferences)
    14th International Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physics, 05.-10.09.2014, Setif, Algeria

Publ.-Id: 21174

Validierung der Nutzbarkeit eines zweikanaligen Heißfilmanemometers in Mehrphasenströmungen durch Vergleichsmessungen mittels Particle Imaging Velocimetry

Chi, B.

Die Bestimmung der Geschwindigkeitskomponenten zur Validierung von CFD-Simulation zählt zu den elementarsten Messaufgaben in einer Blasensäule. Während besonders in einphasigen Strömungen Particle Imaging Velocimetry (PIV) und Constant Temperature Anemometry (CTA) etabliert sind, ist deren Einsatz in Zweiphasenströmung deutlich durch die auftretenden Phasenwechsel gestört.
Während der Einsatz eines PIV-Systems bereits bei geringen Gasanteilen durch fehlende optische Zugänglichkeit nicht mehr möglich ist, besteht bei CTA-Systemen, bedingt durch ihr Messprinzip, die Möglichkeit auch bei höheren Gasdurchsätzen zu messen.
Im Rahmen der Diplomarbeit sind systematische Studien zur Validierung der Nutzbarkeit eines Flüssigkeits-CTA-Systems in Mehrphasenströmung mit verschiedenen Gasgehalten durchzuführen. Die Validierung erfolgt hierbei durch parallele, zeitgemittelte Vermessung lokaler Strömungsgeschwindigkeiten mittels PIV. Um der Verfälschung von Flüssigkeits-Messdaten des CTA-Systems durch Phasenwechsel vorzubeugen, ist das Messsystem mit einer HZDR-eigenen Nadelsonde zu koppeln und entsprechend verfälschte Daten zu maskieren. Zudem ist eine vorherige Kalibrierung des CTA-Systems vorzunehmen.

Keywords: hot film anemometry; multiphase velocimetry; particle imaging velocimetry

  • Diploma thesis
    TU Dresden, 2014
    Mentor: Zalucky, J., Hampel, U.

Publ.-Id: 21173

Hydrodynamics and transport processes in structured reactor devices: Project status report

Zalucky, J.; Wagner, M.; Rabha, S. S.; Schubert, M.; Bieberle, M.; Hampel, U.

On the occasion of half-annual project status report, work package progress is presented. The first part covers the presentation of pre-liminary experiments in the x-ray investigation of multiphase hydrodynamics in solid foam packed fixed bed and packed bubble column reactors. The second part reports on pre-liminary actions in mass transfer investigations. The presentation concludes with the planed project schedule and upcoming milestones.

Keywords: ultrafast x-ray CT; solid foam reactors; multiphase hydrodynamics; mass transfer investigations

  • Lecture (others)
    Helmholtz-Energie-Allianz EECMP: Half-annular project meeting, 03.-04.04.2014, Dresden, Deutschland

Publ.-Id: 21172

Advances in multiphase hydrodynamic characterization of solid foams and cubic cell structures - Project status report

Zalucky, J.; Wagner, M.

On the occasion of annual project status report, work package progress is presented. The first part includes conventionally measured hydrodynamic characteristics such as static liquid holdup, flow maps and pressure drop measurements. Second part includes deeper data mining on ultrafast x-ray computed tomography measurements. The second part is related to actions in mass transfer investigations and reports progress and upcoming investigations with the electrochemical method.

Keywords: project status report; ultrafast x-ray computed tomography; liquid-solid mass transfer; multiphase hydrodynamics

  • Lecture (others)
    Jahrestreffen Helmholtz-Energie-Allianz "Energieeffiziente chemische Mehrphasenprozesse", 08.-09.10.2014, Hamburg, Deutschland

Publ.-Id: 21171

Pulse dynamic visualization in foam packed reactors - flow path evolution

Zalucky, J.; Rabha, S. S.; Schubert, M.; Hampel, U.

In co-currently downward operated packed bed reactors, pulse flow is well known for its performance enhancing effects. Though suffering from a lot higher pressure drop than trickle flow, it offers the high advantage of continuous re-wetting, liquid flow re-routing and enhanced mass transfer due to higher, liquid induced shear stress. In our contribution, the evolution of liquid flow is addressed and visualized by the used of our ultrafast X-ray computed tomography system. As novel catalyst internal, foam blocks made of silicon infiltrated silicon carbide (SiSiC) were investigated.

Keywords: Pulse flow visualization; co-current downward flow; ceramic foams; ultrafast x-ray computed tomography

  • Poster
    ProcessNET Jahrestagung, 29.09.-02.10.2014, Aachen, Deutschland

Publ.-Id: 21170

Advances in application of the limiting current technique for solid-liquid mass transfer investigations

Zalucky, J.; Rabha, S. S.; Schubert, M.; Hampel, U.

The limiting current technique has widely been used to study liquid-solid mass transfer in various reactor configurations. In the present contribution several underlying physical aspects have been investigated in order to improve the design of mass transfer experiments. Experimentally, the significant influence of electrolyte composition and hydrodynamic conditions have been studied and quantified to ensure conditions of high reproducibility. In the course of single phase COMSOL simulations, different electrode configurations have been examined with emphasis on concentration fields and electric current distribution showing a large sensitivity of the experimental configuration on the absolute current values.

Keywords: Liquid-solid mass transfer; limiting current technique; electric field simulation; ceramic solid foams

  • Poster
    2nd International Symposium on Multiscale Multiphase Process Engineering, 24.-27.09.2014, Hamburg, Deutschland
  • Contribution to proceedings
    2nd International Symposium on Multiscale Multiphase Process Engineering, 24.-27.09.2014, Hamburg, Deutschland
    Book of full-length manuscript, Fr: DECHEMA/VDI, 313-318

Publ.-Id: 21169

The Bubbles Breakup and Coalescence Rates in Bubble Columns

Azizi, S.; Schubert, M.

Bubble size distribution has important role in bubble columns in point view of available interfacial area for interphase exchange phenomena. The difficulty in determining of bubble size is due to uncertain breakup and coalescence models for using in population balance equations. Variety of mechanism and coefficients for the each of the models prevents to generalize them. Furthermore, measurement of each rate individually is not possible except for single bubble trajectory in transparent systems (mostly air-water dispersions) that some of the existing models based on it. Here, a novel algorithm demonstrated to calculate breakup and coalescence rates using the bubble size distribution, bubble rise velocity, and hold-up profiles along the bubble column.

Keywords: Bubble Column; Bubbles Breakup and Coalescence; Mechanisms; Experimental Study; Population Balance

  • Poster
    HZDR Annual PhD Seminar, 06.-08.10.2014, Altenberg, Germany

Publ.-Id: 21168

Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.]