Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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32216 Publications
Cyclotron resonance absorption of 2D holes in strained InGaAs/GaAs quantum wells under high magnetic fields
Drachenko, O.; Kozlov, D.; Gavrilenko, V.; Maremyanin, K.; Ikonnikov, A.; Zvonkov, B.; Goiran, M.; Leotin, L.; Fasching, G.; Winnerl, S.; Schneider, H.; Wosnitza, J.; Helm, M.;
We report a systematic study of the cyclotron resonance (CR) absorption of two dimensional (2D) holes in strained InGaAs/GaAs quantum wells (QWs) in the quantum limit. The energies of CR transitions are traced as a function of magnetic field up to 55 T. A remarkable CR line splitting was evidenced when the resonant field exceeds 20 T. We analyze our date with a 4x4 Luttinger Hamiltonian including strain and QW potentials and find excellent agreement in the positions of the resonances. On the other hand, the spectral weight distribution of the split components suggests an inverted position of the two first Landau levels compared to the theoretical model.
Keywords: cyclotron resonance, strain, 2D holes, quantum wells
  • Poster
    Workshop of GDR-E "Semiconductor sources and detectors of THz frequencies", 26.-27.09.2008, Paris, France

Publ.-Id: 12302 - Permalink


On the accuracy of range determination from in-beam PET data
Fiedler, F.; Shakirin, G.; Skowron, J.; Braess, H.; Crespo, P.; Kunath, D.; Pawelke, J.; Pönisch, F.; Enghardt, W.;
no abstract available
Keywords: in-beam PET
  • Contribution to external collection
    in: GSI Scientific Report 2008, Darmstadt: GSI, 2009

Publ.-Id: 12301 - Permalink


Advanced laser driven accelerator concepts at the FZD
Schramm, U.;
Summary of laser acceleration projects to be performed at FZD
Keywords: laser particle acceleration, ELBE
  • Lecture (others)
    Laser Physics Seminar Univ. Twente, NL, 28.01.2009, Enschede, Niederlande

Publ.-Id: 12299 - Permalink


Laser-accelerated ion beams for future medical applications
Kraft, S.;
Recent success in laser-driven particle acceleration has increased interest in laser-generated “accelerator-quality” beams, for example, protons and ions have been produced with up to several tens of MeV per nucleon, and with extremely low emittance (<0.01 mm mrad, normalized). Compact, high-gradient laser-accelerators are therefore now being discussed as a potentially viable technology for a host of particle-beam applications, including future compact medical accelerators for medical diagnostics and therapy. After commissioning of a 150 TW laser system at the FZD, a joint research center for radiation therapy with laser-accelerator ions is being established together with the OncoRay Center for Radiation Research in Oncology, and the University Clinic of the Technical University of Dresden. The present status and future plans of the center, and the results from first proton acceleration experiments at FZD will be presented.
  • Lecture (Conference)
    Second Internatioanl Symposium on Laser-Driven Relativistic Plasma Applied to Science, Industry and Medicine, 19.-23.01.2009, Kyoto, Japan

Publ.-Id: 12298 - Permalink


Physikalisch- technische Vorbereitung von Zellbestrahlungen am intensiven Channeling-Röntgenstrahl der Strahlungsquelle ELBE
Zeil, K.;
Derzeit erfolgt im Forschungszentrum Dresden-Rossendorf (FZD) die schrittweise Inbetriebnahme und Erprobung der Strahlungsquelle ELBE, welche unter anderem intensive quasimonochromatische und in der Energie durchstimmbare Röntgenstrahlung durch Channeling relativistischer Elektronen in Diamantkristallen erzeugt. Im Rahmen strahlenbiologischer invitro Experimente soll diese zur Bestimmung der relativen biologischen Wirksamkeit (RBW) von Photonenstrahlung in Abhängigkeit von der Photonenenergie eingesetzt werden. Die hierzu notwendige Durchführung strahlenbiologischer Experimente und die Bestimmung von Dosis-Effekt-Kurven unter Berücksichtigung der Diversität lebender Zellen erfordern die Bestrahlung einer größeren Anzahl von Zellproben mit verschiedenen vorgegebenen Dosiswerten (ca. 0, 5 − 10 Gy) und für praktikable Bestrahlungsdauern eine Dosisleistung von 1 Gy/min. Gleichzeitig muss die auf die Zellproben übertragene Dosis exakt bestimmt und ihre räumliche sowie spektrale Verteilung charakterisiert werden. ...
  • Diploma thesis
    HU Berlin, 2007
    100 Seiten

Publ.-Id: 12297 - Permalink


Oncoray Retreat 2008: Laserteilchenbeschleunigung
Zeil, K.;
Presentation der Aktivitäten der Gruppe Laserteilchenbeschleunigung am FZD.
  • Invited lecture (Conferences)
    Oncoray Retreat 2009, 15.1.2009, Bautzen, Deutschland

Publ.-Id: 12296 - Permalink


Detector response to ps electron bunches with high bunch charge
Zeil, K.;
Presentation of the scientific program of the Laser Particle Acceleration Group at the FZD as well as the status of the Laser lab. Then the major topic of the talk are measurements of detector response calibration to ps - pulses from the ELBE electron source with different electron bunch charges.
  • Invited lecture (Conferences)
    Radiation Protection Workshop, 16.12.2008, Chamonix, France

Publ.-Id: 12295 - Permalink


In-Medium QCD Sum Rules for omega Meson, Nucleon and D Meson
Thomas, R.;
The modifications of hadronic properties caused by an ambient nuclear medium are investigated within the scope of QCD sum rules. This is exemplified for the cases of the ω meson, the nucleon and the D meson. By virtue of the sum rules, integrated spectral densities of these hadrons are linked to properties of the QCD ground state, quantified in condensates. For the cases of the ω meson and the nucleon it is discussed how the sum rules allow a restriction of the parameter range of poorly known four-quark condensates by a comparison of experimental and theoretical knowledge. The catalog of independent four-quark condensates is covered and relations among these condensates are revealed. The behavior of four-quark condensates under the chiral symmetry group and the relation to order parameters of spontaneous chiral symmetry breaking are outlined. In this respect, also the QCD condensates appearing in differences of sum rules of chiral partners are investigated. Finally, the effects of an ambient nuclear medium on the D meson are discussed and relevant condensates are identified.
  • Other report
    Dresden: Technische Universität Dresden, 2008
    105 Seiten

Publ.-Id: 12294 - Permalink


QCD equation of state of hot deconfined matter at finite baryon density - A quasiparticle perspective
Bluhm, M.;
The quasiparticle model, based on quark and gluon degrees of freedom, has been developed for the description of the thermodynamics of a hot plasma of strongly interacting matter which is of enormous relevance in astrophysics, cosmology and for relativistic heavy-ion collisions as well. In the present work, this phenomenological model is extended into the realm of imaginary chemical potential and towards including, in general, different and independent quark flavour chemical potentials. In this way, nonzero net baryon-density effects in the equation of state are selfconsistently attainable. Furthermore, a chain of proximations based on formal mathematical manipulations is presented which outlines the connection of the quasiparticle model with the underlying gauge field theory of strong interactions, QCD, putting the model on firmer ground.
A comparison of quasiparticle model results with available lattice QCD data for, e. g., basic bulk thermodynamic quantities and various susceptibilities such as
diagonal and off-diagonal susceptibilities, which provide a rich and sensitive testing ground, is found to be successful. Furthermore, different thermodynamic quantities and the phase diagram for imaginary chemical potential are faithfully described. Thus, the applicability of the model to extrapolate the equation of state known from lattice QCD at zero baryon density to nonzero baryon densities is shown. In addition, the ability of the model to extrapolate results to the chiral limit and to asymptotically large temperatures is illustrated by confrontation with available first-principle lattice QCD results. These extrapolations demonstrate the predictive power of the model.
Basing on these successful comparisons supporting the idea that the hot deconfined phase can be described in a consistent picture by dressed quark and gluon degrees of freedom, a reliable QCD equation of state is constructed and baryon-density effects are examined, also along isentropic evolutionary paths. Scaling properties of the equation of state with fundamental QCD parameters such as the number of active quark flavour degrees of freedom, the entering quark mass parameters or the numerical value of the deconfinement transition temperature are discussed, and the robustness of the equation of state in the regions of small and large energy densities is shown. Uncertainties arising in the transition region are taken into account by constructing a family of equations of state whose members differ from each other in the specific interpolation prescription between large energy density region and a realistic hadron resonance gas equation of state at low energy densities.
The obtained family of equations of state is applied in hydrodynamic simulations, and the implications of variations in the transition region are discussed by considering transverse momentum spectra and differential elliptic flow of directly emitted hadrons, in particular of strange baryons, for both, RHIC top energy and LHC conditions. Finally, with regard to FAIR physics, implications of the possible presence of a QCD critical point on the equation of state are outlined both, in an exemplary toy model and for an extended quasiparticle model.
  • Other report
    Dissertation: Technische Universität Dresden, 2008
    155 Seiten

Publ.-Id: 12293 - Permalink


Uran(VI)-Sorption an Ton in An- und Abwesenheit von Huminsäure
Joseph, C.; Schmeide, K.; Sachs, S.; Bernhard, G.;
Die Endlagerung radioaktiver Abfälle steht im Mittelpunkt vieler politischer Debatten. Neben Salzstöcken (Gorleben, Asse) kommen in Deutschland auch Ton und Granit als Wirtsgestein für ein Endlager in Frage. Ton und Salz werden favorisiert und für eine bessere Entscheidungsfindung werden die Untersuchungen am Ton derzeit intensiviert. Schwerpunkt unserer Untersuchungen ist die Wechselwirkung von Uran(VI) mit Ton (Referenzton: Kaolinit; natürlicher Ton: Opalinuston, Mont Terri, Schweiz). Natürliche Tone können organische Substanzen, wie z.B. Humin- und Fulvinsäuren, enthalten. Aufgrund dessen wird in unseren Versuchen der Einfluss von Huminsäure auf die Uran(VI)-Ton-Wechselwirkung untersucht.

Zunächst wurde der Einfluss des Elektrolyten auf die Uran(VI)-Sorption an Kaolinit erforscht. Neben dem bisher in unseren Experimenten verwendeten NaClO4 [1], wurde synthetisches Opalinustonporenwasser (I = 0.42 M, pH 7.6) [2] untersucht. Es zeigte sich, dass bei Verwendung von Opalinustonporenwasser weniger Uran(VI) an Kaolinit sorbiert. Dieses Verhalten kann mit der Uran(VI)-Speziation erklärt werden. Der im Opalinustonporenwasser bei pH 7.6 vorliegende neutrale Ca2UO2(CO3)3-Komplex sorbiert schlechter als die in 0.42 M NaClO4-Lösung gebildeten geladenen Uranspezies UO2(CO3)34-, (UO2)2CO3(OH)3- und UO2(CO3)22-. Bei Anwesenheit von Huminsäure wird weniger Uran(VI) im NaClO4-System sorbiert, da es durch die Bildung von Uran(VI)-Humat-Komplexen mobilisiert wird und die Huminsäure mit dem Uran(VI) um Bindungsplätze auf dem Ton konkurriert. Durch Huminsäuresorption auf dem Ton stehen wiederum zusätzliche Uran(VI)-Bindungsstellen zur Verfügung und die Menge an sorbiertem Uran(VI) steigt mit steigender Huminsäurekonzentration. Im Opalinustonporenwassersystem ist jedoch kein signifikanter Einfluss von Huminsäure auf die Menge an sorbiertem Uran(VI) zu beobachten, da die Huminsäure keinen Einfluss auf die Uranspeziation in Opalinustonporenwasser bei pH 7.6 nimmt. Weiterhin wurden Kaolinit und Opalinuston hinsichtlich ihres Uran(VI)-Sorptionsvermögens in Opalinustonporenwasser verglichen. Es zeigt sich, dass mehr Uran(VI) an Kaolinit (2.8 ± 0.2 µg/m2) sorbiert als an Opalinuston (0.049 ± 0.002 µg/m2). Dieses Ergebnis ist unerwartet, da Opalinuston einerseits eine größere spezifische Oberfläche als Kaolinit besitzt, andererseits mehr Eisenminerale enthält, die sehr gut Uran(VI) sorbieren [3] können (Opalinuston: BET = 42 m2/g, 5 Gew.-% Fe; Kaolinit: BET = 11.7 m2/g, 0.27 Gew.-% Fe [1]). Der Grund für diesen Unterschied scheint somit im Anteil an Uran(VI) schlecht sorbierenden Mineralen im Opalinuston zu liegen, möglicherweise an Quarz [3].

[1] A. Křepelová et al., Radiochim. Acta 2007, 94, 825. [2] F.J. Pearson, PSI Internal Report TM-44-98-07 1998, Paul Scherrer Institut, Villigen, Schweiz. [3] K. Schmeide et al., Radiochim. Acta 2000, 88, 723.
Keywords: uranium(VI), clay, kaolinite, opalinus clay, sorption, speciation, opalinus clay pore water, humic acid
  • Lecture (Conference)
    Fachgruppentagung der GDCh-Fachgruppe Nuklearchemie, 30.08.-02.09.2009, Frankfurt/Main, Deutschland

Publ.-Id: 12290 - Permalink


Komplexierung von Curium(III) und Europium(III) mit organischen Liganden unter physiologischen Bedingungen – erste Hinweise auf ihre Speziation in Biofluiden
Heller, A.; Barkleit, A.; Bernhard, G.;
Curium und Europium sind zwei f-Elemente, deren Metabolismus im Biosystem bis heute nicht vollständig geklärt ist. Um diese Wissenslücke zu schließen, wurde das Komplexbildungsverhalten beider Metalle mit relevanten organischen Substanzen unter physiologischen Bedingungen bestimmt. Außerdem wurde die Speziation beider Ele-mente im menschlichen Urin untersucht.
Da Curium innerhalb des Kernbrennstoffzyklus gebildet wird und nur radioaktive Isotope aufweist, stellt es im Falle einer Kontamination oder unfallbedingter Freisetzung in die Umwelt eine ernste Gefahr für die Gesundheit dar. Um mögliche Dekontaminationsmittel zu erforschen, müssen daher sein Metabolismus und die Bindungsform in Biofluiden bekannt sein. Im Gegensatz dazu ist Europium nicht radioaktiv und gewinnt in der Medizin immer mehr an Bedeutung als Bestandteil von Kontrastmitteln in der bildgebenden Diagnostik. Trotz seiner wachsenden Applikation ist auch der Metabolismus dieses Metalls bisher unbekannt.
Beide Elemente weisen ähnliche Eigenschaften auf, da sie in Form ihrer dreiwertigen Ionen vergleichbare Elektronenkonfigurationen besitzen. Aufgrund seiner besseren Handhabbarkeit wird Europium daher oft als Analogon für Curium verwendet. Darüber hinaus weisen beide Elemente einzigartige Fluoreszenzeigenschaften auf. Dies erlaubt Untersuchungen mittels zeitaufgelöster laserinduzierter Fluoreszenzspektroskopie im Spurenkonzentrationsbereich.
Urin ist das Hauptausscheidungsmedium im menschlichen Körper und besteht zu über 90 % aus Harnstoff. Mögliche Reaktionen mit dieser Matrixkomponente wurden daher zuerst untersucht. Beide Metalle bilden Komplexe vom Typ ML 3+ und MLOH 2+, was zu signifikanten Änderungen in den Lumineszenzspektren führt, allerdings nur bei sehr hohem Harnstoffüberschuss Dies spricht ebenso für schwache Komplexe wie die sehr niedrigen Komplexbildungskonstanten.
Ein weiterer biologisch relevanter, organischer Ligand ist Citronensäure. Auch hier führte die Bildung verschiedener Komplexe vom Typ MLH2 2+, MLH +, ML2H 2- und ML bei beiden Elementen zu deutlichen Veränderungen im Lumineszenzspektrum, im Gegensatz zu Harnstoff aber schon bei der kleinsten Ligandkonzentration. Berücksichtigt man, dass Citronensäure in der Biosphäre weitverbreitet ist, spricht dies zusammen mit den hohen Komplexbildungskonstanten dafür, dass Citronensäure eine Hauptrolle bei der Curium- und Europiumspeziation in Biofluiden spielt.
Erste Aufnahmen von Lumineszenzspektren natürlicher, menschlicher Urinproben, die in vitro mit einem der beiden Elemente versetzt wurden, zeigen, dass bei niedrigeren pH-Werten Komplexe mit Citronensäure die Speziation dominieren. Im Gegensatz dazu scheinen bei höheren pH-Werten Komplexe mit anorganischen Liganden, die noch näher untersucht werden müssen, vorzuherrschen. Allgemein weisen Curium und Europium ähnliche Komplexbildung und Speziation auf, wobei das Lanthanid aber etwas stärkere Komplexe bildet als das Actinid.
Keywords: curium(III), europium(III), TRLFS, complexation, human biofluids, heavy metal speciation
  • Lecture (Conference)
    GDCh-Wissenschaftsforum Chemie 2009, 30.08.-02.09.2009, Frankfurt am Main, Deutschland

Publ.-Id: 12289 - Permalink


Total neutron cross section measurements at nELBE
Junghans, A. R.; Altstadt, E.; Bemmerer, D.; Beyer, R.; Galindo, V.; Grosse, E.; Hannaske, R.; Marta, M.; Matic, A.; Nair, C.; Naumann, B.; Schilling, K. D.; Schneider, S.; Schlenk, R.; Schwengner, R.; Wagner, A.; Weiss, F.-P.; Mosconi, M.; Nolte, R.; Röttger, S.;
Total neutron cross section measurements at nELBE
  • Lecture (Conference)
    EFNUDAT progress and general assembly meeting, 01.-03.10.2008, Uppsala, Schweden

Publ.-Id: 12288 - Permalink


The fate of uraniumin phosphate-rich soils
Read, D.; Black, S.; Beddow, H.; Trueman, E.; Arnold, T.; Baumann, N.;
A number of industrial processes concentrate natural radionuclides to levels that cannot be disregarded on health or environmental grounds. These activites include mining of metalliferous and non-metalliferous ores; ore processing; oil and gas extraction; metal smelting and power production from coal (IAEA 2003; Ceccarello et al. 2004; Read et al. 2004). The phosphate industry, which encompasses fertilizer production, is another. Concern has been raised that the radiological consequences of such processes have been underestimated. While this is undoubtedly true in many cases, there is considerable debate as to whether the widespread application of fertilizer has any significant effect on human exposure or the broader environment. This paper adds to the debate by addressing the likely fate of uranium in phosphate-rich soil media.
  • Contribution to external collection
    L. J. De Kok, E. Schnug: Loads and Fate of Fertilizer-derived Uranium, AH Leiden: Backhuys Publishers BV, 2009, 978-90-5782-193-6, 65-71

Publ.-Id: 12287 - Permalink


P0703 - Verfahren zur Messung von lokalen Strömungsgeschwindigkeiten in flüssigen Schmelzen
Eckert, S.; Gerbeth, G.; Gundrum, T.;
Die Erfindung betrifft ein Verfahren zur Messung der Strömungsgeschwindigkeit in flüssigen Schmelzen in einem Temperaturbereich oberhalb von 200°C mit einem Ultraschallgenerator sowie zugehörigem Ultraschall-Wellenleiter nach dem Ultraschall-Doppler-Verfahren.
Mit der Erfindung soll eine gute Signalein- und -auskopplung gewährleistet werden. Erreicht wird das durch Herstellen der Benetzbarkeit der Stirnfläche des Ultraschallwellenleiters vor dem Messvorgang, anschließendes direktes Einkoppeln von Ultraschall-Messsignalen in die Schmelze unter einem Winkel verschieden von 90°, indem zumindest die Stirnfläche des Ultraschallwellenleiters in die Schmelze eingetaucht wird, und Auskoppeln der in der Schmelze reflektierten Ultraschallsignale über die Stirnfläche des Ultraschallwellenleiters und Weiterleitung derselben an eine Auswerteschaltung. Die Herstellung der Benetzbarkeit erfolgt durch mechanisches und chemisches Reinigen der Stirnfläche und nachfolgendes Beschichten derselben mit einem geeigneten Material.
  • Patent
    DE 10 2007 027 392 B3 - 2009.01.15
  • Patent
    WO 00 2008 152 025 A2 - 2008.12.18
  • Patent
    US 7950293 B2 - 31.05.2011
  • Patent
    KR101196407B1 - 25.10.2012

Publ.-Id: 12286 - Permalink


Inverse Compton backscattering source driven by the multi-10 TW laser installed at Daresbury
Priebe, G.; Laundy, D.; Macdonald, M.; Diakun, G.; Jamison, S.; Jones, L.; Holder, D.; Smith, S.; Phillips, P.; Fell, B.; Sheehy, B.; Naumova, N.; Sokolov, I.; Ter-Avetisyan, S.; Spohr, K.; Krafft, G.; Rosenzweig, J.; Schramm, U.; Gruner, F.; Hirst, G.; Collier, J.; Chattopadhyay, S.; Seddon, E.;
Inverse Compton scattering is a promising method to implement a high brightness, ultra-short, energy tunable X-ray source at accelerator facilities. We have developed an inverse Compton backscattering X-ray source driven by the multi-10 TW laser installed at Daresbury. Hard X-rays, with spectral peaks ranging from 15 to 30 keV, depending on the scattering geometry, will be generated through the interaction of laser pulses with electron bunches delivered by the energy recovery linac machine, initially known as energy recovery linac prototype and subsequently renamed accelerators and lasers in combined experiments. X-ray pulses containing 9 × 107 photons per pulse will be created from head-on collisions, with a pulse duration comparable to the incoming electron bunch length. For transverse collisions 8 × 106 photons per pulse will be generated, where the laser pulse transit time defines the X-ray pulse duration. The peak spectral brightness is predicted to be ~1021 photons/(s mm2 mrad2 0.1% Δλ/λ).
Keywords: ALICE; Compton scattering; Compton synchrotron radiation; Energy recovery linac; ERLP; Laser Compton scattering; Laser synchrotron radiation; Thomson scattering; Ultra-short X-ray pulses; X-ray source

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Publ.-Id: 12285 - Permalink


S-Layer basierte Forschungsarbeiten zur Eliminierung von Organika in Wasser
Raff, J.; Pollmann, K.;
Vorstellung der S-Layer basierten Forschungsarbeiten am Institut für Radiochemie zur Eliminierung von Organika in Wasser über fotokatalytische Verfahren
  • Lecture (others)
    Vortrag im Rahmen des Besuchs der IBL Umwelt- und Biotechnik GmbH, 21.01.2009, Heidelberg, Deutschland

Publ.-Id: 12284 - Permalink


Anisotropic ion-enhanced diffusion during ion nitriding of single-crystalline austenitic stainless steel
Martinavicius, A.; Abrasonis, G.; Möller, W.; Templier, C.; Riviere, J. P.; Declemy, A.; Chumlyakov, Y.;
Nitrogen diffusion is investigated in single crystalline austenitic stainless steel AISI 316L (ASS) during ion beam nitriding and subsequent annealing at different crystalline orientations. After nitriding at 400ºC and ion energy of 1 keV, the N penetration depth depends significantly on the crystalline orientation, with the highest penetration depth for (001) orientation. The experimental observations are quantitatively reproduced by fitting using the model of diffusion under the influence of traps. During subsequent isothermal annealing, the N diffusion becomes significantly slower than during nitriding and independent of the orientation. Possible mechanisms of the anisotropic ion enhanced N diffusion are discussed.
Keywords: Stainless steel, Ion nitriding, AISI316L single crystal
  • Journal of Applied Physics 105(2009)9, 093502

Publ.-Id: 12283 - Permalink


Native Sn-Pb droplets in a zeolitic amygdale (Isle of Mull, Inner Hebrides)
Dekov, V. M.; Hålenius, U.; Billström, K.; Kamenov, G. D.; Munnik, F.; Eriksson, L.; Dyer, A.; Schmidt, M.; Botz, R.;
Despite the particular scientific interest in the elements with high affinity to S and O2, but found in zero-valence state in nature, the origin of these native minerals has been little explored and remains obscure. Here we describe unique Sn-Pb droplets found in a closed analcime-calcite amygdale collected from a basaltic unit cropping out at Carsaig Bay (Isle of Mull, Inner Hebrides). The droplets consist of intimate intergrowths of nearly pure Sn0 and Pb0 domains in proportion 88:12 and are enveloped in a thin, brownish, amber-like film of organic composition, which gives the impression of metallic “embryos” in organic “placenta”. The occurrence of the Sn-Pb droplets in a closed amygdale, their relationship with the host analcime+calcite and their Pb isotope composition (which does not match any known anthropogenic Pb source) rule out the possibility of anthropogenic contamination and support the natural origin of the Sn-Pb alloy.
The variable isotope (Pb, Sr, Nd) compositions in different members of the host basaltic sequence suggest that a parent basaltic magma was modified by crustal assimilation and post-emplacement alteration processes. Considering all possible scenarios, it appears that the most likely source of Pb for the Sn-Pb alloy is a discrete basaltic unit with an isotopic composition comparable to the Antrim basalts (Northern Ireland). The amygdale phases, on the other hand, show isotopic evidence for incorporation of elements from both local basaltic and sedimentary units. The apparent isotopic disequilibrium between Sn-Pb droplets and amygdale phases indicates a complex, multi-stage fluid evolution. The occurrence of Sn-Pb droplets in organic capsules suggests that the droplets and the enveloping organic substances are co-precipitates. This implies that the transportation and deposition of Sn and Pb might have occurred through organometallic compounds. We assume interaction of seawater fluids carrying metals leached from basaltic rocks with hydrocarbons from sedimentary units as a prerequisite for the formation of the organometallic complexes. The zeolites lining the basaltic vesicles might have destabilized the migrating organo- Sn and Pb compounds causing their breakdown and precipitation of Sn-Pb alloy.
Keywords: Sn-Pb alloy; organometallic compounds; Isle of Mull; Inner Hebrides

Publ.-Id: 12282 - Permalink


Tracked megawatt PV plants: Operation results 2008 in Germany and Spain
Rindelhardt, U.; Dietrich, A.; Rösner, C.;
An increasing number of 2-axis tracked Megawatt PV plants have been put into operation during the last years. The higher final yield of such plants (compared to plants with fixed generator orientation) must be paid with higher plant costs and larger area consumption. The absolute yield is determined by the insolation conditions at the sites. The paper compares design and operation results of four 2-axis tracked plants operating in Germany and Spain in 2008, which are representative PV sites in Europe.

The plant locations are distributed between 37 and 50 degrees northern latitude (Fig.1), in South Spain and Central Germany. Some technical features of the investigated plants are given in the table below.

plant total power /MW tracker Plant area/m² module supplier
Borna 3.44 Solon 210000 Solon
Penig 0,2 Deger 22000 Sanyo,Sharp,SunLink
Alqueria 1.02 Solon 125000 Solon
Ventanas 1.01 Solon 102000 Solon

The used tracker systems differ in their construction and in the applied tracking principle. Whereas the Solon mover (Fig. 2) follows every 10 minutes the astronomic sun path, the Deger tracker (Fig. 3) tries to find the optimal generator position also at cloudy conditions. The tracker distance varies between the both used tracker types and the sites. The most plants started their operation in 2007. The operation of the plants was monitored by the owners or by professional service providers.

The operation results of the year 2008 are exemplarily presented. The solar irradiance in 2008 in Germany was higher than the long year average, similar to the years before. The final yield of the both plants is about 1300 kWh/kW (Fig. 4), with an advantage of 8 % for the plant using Deger trackers. The annual performance ratio was fond to be 82 %.
The yields of the Spain plants exceed the yield of the German plants with 2250 kWh/kW by more than 70 %. Only in one month (May) the yield of the German reaches the yield of the Spain plants due to the extraordinary insolation in Germany (high) and Spain (low), respectively. The performance ratios of the Spain plants were also about 82 %.
A number of operation details will be given.
Finally a long term estimation of the yield for the different plants will be given.
Keywords: PV plants, tracked systems, performance
  • Lecture (Conference)
    24th European Photovoltaic Solar Energy Conference and Exhibition, 21.-25.09.2009, Hamburg, Deutschland
  • Contribution to proceedings
    24th European Photovoltaic Solar Energy Conference and Exhibition, 21.-25.09.2009, Hamburg, Deutschland
    Proceedings CD-ROM, contribution 5AO.8.5, 3-936338-25-6

Publ.-Id: 12281 - Permalink


Beltline welding seam and base metal investigations of a WWER-440/230 reactor pressure vessel from the former Greifswald NPP
Rindelhardt, U.; Schuhknecht, J.; Viehrig, H.-W.;
Nuclear plants operators must demonstrate that the structural integrity of the nuclear reactor pressure vessel (RPV) is assured during routine operations or under postulated accident conditions. Russian type WWER reactors are operated in Russia and many other European countries like Ukraine, Finland, Czech Republic and Hungary. Surveillance specimens programmes for inspection of aging of the RPV materials were implemented for the second generation (213) of WWER-440 reactors.
The paper presents results of the circumferential core weld SN0.1.4 and the base metal ring 0.3.1 of the RPV from the unit 1 of the Greifswald WWER-440/230. The investigated trepans represent the irradiated-annealed-re-irradiated (IAI) condition. The working program is focussed on the characterisation of the RPV steels through the RPV wall. The key part of the testing is aimed at the determination of the reference temperature T0 following the ASTM Test Standard E1921-05 to determine the fracture toughness in different thickness locations. It is shown that the Master Curve approach as adopted in ASTM E1921 is applicable to the investigated original WWER-440 weld and base metal.
The evaluated T0 varies through the thickness of the welding seam. The lowest T0 value was measured in the root region of the welding seam representing a uniform fine grain ferritic structure. The highest T0 of the weld seam was not measured at the inner wall surface. This is important for the assessment of ductile-to-brittle temperatures measured on sub size Charpy specimens made of weld metal compact samples removed from the inner RPV wall. Our findings imply that these samples may not represent the most conservative condition. The Charpy transition temperature TT41J estimated with results of sub size specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens. The evaluated transition temperature of 51°C is close to the estimated critical embitterment temperature for the initial condition TK0 of the welding seam SN0.1.4.
The T0 from the trepan 1-4 of base metal ring 0.3.1 varies through the thickness of the welding seam. T0 decreases from -124°C at the inner surface to -90°C at a distance of 33 mm from it and again to -113°C at the outer RPV wall. The KJc values generally follow the course of the MC, although the scatter is large. The re-embrittlement during 2 campaigns operation can be assumed to be low. Hence, the variation of T0 measured through the thickness of the base metal ring 0.3.1 results basically from differences in the structure. With metallographic characterization the scatter of the MC will be investigated.
The Charpy transition temperature TT41J estimated with results of sub size specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens.
Keywords: Russian WWER-type reactor, WWER, reactor pressure vessel steel, weld metal, trepans, fracture toughness, Master Curve.
  • Lecture (Conference)
    6th International Scientific and Technical Conference “Safety Assurance of NPP with WWER”, 26.-29.05.2009, Podolsk, Russian Federation
  • Contribution to proceedings
    6th International Scientific and Technical Conference “Safety Assurance of NPP with WWER”, 26.-29.05.2009, Podolsk, Russian Federation
    Conference CD, Podolsk

Publ.-Id: 12280 - Permalink


Neutron fluence calculations for embrittlement surveillance specimens in VVER-1000
Konheiser, J.; Mittag, S.; Zaritsky, S.;
Neutron fluence spectrum calculations have been performed for the reactor pressure vessel of a VVER-1000, applying the Monte Carlo code TRAMO. Activities measured earlier in Balakovo-1 by fluence monitors, placed in special Charpy surveillance containers, are compared to TRAMO results. The average deviation from the measurements is about 5 %. A good agreement of the fluence spectra near the RPV inner side, at the height of the core beltline, to the spectra at the Charpy probe positions on top of the radial reflector has been demonstrated.
Keywords: Neutron Fluence Calculation; Surveillance specimens; VVER-1000; Monte-Carlo; TRAMO
  • Annals of Nuclear Energy 36(2009)8, 1235-1241

Publ.-Id: 12279 - Permalink


High pressure materials for energy storage. The case of V2O5
Arroyo-De Dompablo, M. E.; Amador, U.; Gallardo–Amores, J. M.; Baehtz, C.; Biskup, N.; Morán, E.;
The high pressure polymorph of V2O5 is investigated as example of a high-pressure material (HP-V2O5) with potential applications in electrochemical devices, such as lithium batteries. HP-V2O5 reversibly intercalates up to 2 lithium ions down to 1 Volt vs Li+/Li. The typical voltage-composition profile of HP-V2O5 shows distinct features than that of the ambient pressure polymorph, AP-V2O5. Remarkably, the specific capacity retention with cycling of HP-V2O5 // Li cells (250 Ah/Kg at a C/3.5 rate) is comparable to that of the ambient pressure polymorph. Furthermore, the measured resistivities at room temperature (10000 Ωcm in AP and 400 Ωcm in HP) reveal that HP-V2O5 is a better electronic conductor than AP-V2O5. The enhanced electronic conductivity of HP-V2O5 is an advantage for electrochemical applications.
Keywords: in-situ diffraction, lithium ion battery, synchrothron

Publ.-Id: 12278 - Permalink


Thermal “order-disorder” behaviour in (Na1-xKx)4B8O14 solid solutions investigated by X-ray powder diffraction
Georgievskaya, M.; Albert, B.; Bubnova, R.; Cordier, G.; Baehtz, C.; Filatov, S.;
In the potassium-rich part of the binary system Na4B8O14-K4B8O14 solid solutions have been found that can be described with the formula (Na1-xKx)4B8O14 with 0.45 ≤ x < 1.0. The crystal structures of (Na0.25K0.75)4B8O14 and (Na0.45K0.55)4B8O14 were refined at room temperature by the Rietveld method. The solid solutions crystallize like K4B8O14 in the triclinic crystal system, space group P-1, with K partially substituted for Na.
An ordered distribution of the alkali atoms over the four cation sites at room temperature has been discovered. The structure of (Na0.25K0.75)4B8O14 was also refined for data collected at 300 and 500°C. The refinements show that sodium and potassium atoms are less ordered at higher temperatures.
Keywords: borates, solid solutions, Rietveld refinement, structure refinement, high temperatures

Publ.-Id: 12277 - Permalink


TOPFLOW hot leg model experiments: Overview, examples, status of data analysis and future work
Vallee, C.; Seidel, T.; Lucas, D.;
The presentation gives an overview about the experiments performed in the hot leg model built in in the pressure vessel of the TOPFLOW facility.
These experiments were conducted in a flat test-section representing a model of the hot leg of a pressurised water reactor. The region of the elbow and of the steam generator inlet chamber is equipped with glass side walls in order to allow high-speed video observations of the two-phase flow in this region. The used fluids were air and water at ambient temperature and pressures up to 0.5 MPa as well as steam and saturated water at pressures up to 5.0 MPa and temperatures up to 264°C. Four types of experiments were performed: experiments without water circulation, co-current flow experiments, steady counter-current flow experiments and counter-current flow limitation (CCFL) experiments. The test procedures, detailed test matrices and selected examples of the measurements are shown.
The current status of data analysis is presented. Data sheets were arranged in order to give an overview of the 191 runs. The water level measured during co-current flow experiments was analysed over probability distributions. Furthermore, the flooding characteristics of the hot leg model was determined and a new parameter is proposed to correlate the data. Finally, a first approach for the interface detection in high-speed camera images was presented.
In the next future, the acquired data will be compared with CFD calculations for validation purposes.
Keywords: hot leg, pressurised water reactor, PWR, two-phase flow, counter-current flow, counter-current flow limitation, CCFL
  • Lecture (others)
    15th Meeting of the German CFD Network, 21.-22.01.2009, Garching, Germany

Publ.-Id: 12276 - Permalink


High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS
Trots, D. M.; Senyshyn, A.; Mikhailova, D. A.; Knapp, M.; Baehtz, C.; Hoelzel, M.; Fuess, H.;
Results of simultaneous thermal analysis, synchrotron and neutron powder diffraction in the range from room temperature up to the melting point at 936 K on non-superionic orthorhombic β-AgCuS as well as on superionic hexagonal α- and cubic δ-AgCuS are reported. On heating the sample is only stable in argon. The following phase transitions occur in AgCuS at elevated temperatures: β 361 K −→ α 399 K −→ α + δ 439 K −→ δ. The volume changes at the superionic β −→ α and α −→ δ phase transitions are about 2.3 and 0.6%. The volume thermal expansion coefficients are 26 × 10−6, 130 × 10−6 and 85 × 10−6 K−1 for the pure β-, α-and δ-phases, respectively. Models forthe average structures of α-and δ-AgCuS are proposed and discussed. Ionic conductivity in δ-AgCuS may originate from cation jumps in ‘skewed’ (100) directions between nearest-neighbour tetrahedral sites via the peripheries of the octahedral cavities. A correlation between the temperature dependence of the cation redistribution in δ-AgCuS and the temperature dependence of the ionic conductivity is assumed. A two-dimensional nature of the ionic conductivity due to cation jumps in slabs perpendicular to the c-direction is supposed for α-AgCuS. There is no evidence for ionic diffusion through the (1/2, 1/2, 1/2) site in (111) directions in either superionic α-or δ-phases.
Keywords: XRD phase transition AgCuS

Publ.-Id: 12275 - Permalink


Annual Report 2007 - Institute of Radiation Physics
Kämpfer, B.;
activities etc. in line of previous reports. In 2007, the various research directions were organized and performed in four departments: radiation physics, biophysics (both belonging to the program Life Science), nuclear physics and hadron physics (both belonging to Structure of Matter). A substantial part of the institute’s tasks is the performance and further development of the radiation source ELBE, for which a fifth department is responsible. Besides providing secondary beams for radiation physics and biology, nuclear and hadron physics, ELBE is used by groups from other institutes of the Forschungszentrum Dresden-Rossendorf, too in parts in common projects and by external users. Beamtime is used extensively by outside users while all beam time requests have been rated by an international advisory committee.
Some highlights in 2007 related to ELBE have been: first electron beam from superconducting HF gun, first pulsed fast neutron beams from nELBE, and first experiments with single electron pulses of high bunch charge (cell irradiation for radiobiological studies). These achievements are not yet documented in this report.
  • Article, self-published (no contribution to HZDR-Annual report)
    Forschungszentrum Rossendorf 2008
    72 Seiten

Downloads:

Publ.-Id: 12274 - Permalink


Labeling of peptides and proteins with 18F via click chemistry using a novel prosthetic group 4-[18F]fluoro-N-methyl-N-(prop-2-ynyl)benzenesulfonamide
Ramenda, T.; Knieß, T.; Steinbach, J.; Wüst, F.;
Ziel/Aim:
The radiolabeling of peptides or proteins with the short-lived positron emitter 18F requires rapid and mild reaction conditions compatible with the structural and functional integrity of these biopolymers. Over the last two years several approaches have been published focusing on the application of copper(I)-mediated 1,3-dipolar [3+2]cycloaddition of azides and alkynes for labeling peptides with 18F. The peptides were functionalized with an azide- or alkyne group to be reacted with an appropriately 18F-labeled azide or alkyne, respectively. We report on the radiosynthesis of a novel alkine containing 18F-labeled prosthetic group having the advantage of a stable aromatic 18F-label and low lipophilicity caused from the sulfonamide backbone. First applications for click chemistry by labeling azide-functionalized phosphopeptides and human serum albumin (HSA) are demonstrated.

Methodik/Methods:
Two labeling precursors containing different leaving groups (nitro- and trimethylammoniumtriflate) and the reference substance were prepared by the reaction of N methylpropargylamine with the corresponding sulfonic acid chlorides. Radiofluorination was performed in a single step on an automated synthesizer. After purification on semi-preparative HPLC click reaction was performed with a phosphopeptide and the HSA protein. Peptide and protein have been modified with an azide linker. Click reaction occurs in the presence of copper(I) salts and in combination with different copper-chelating ligand systems.

Ergebnisse/Results:
The radiolabeled sulfonamide can be obtained in radiochemical yields of 19 % (d. c.) in high radiochemical purity of > 99 % after HPLC purification within 84 min. First promising results in labeling an azide modified phosphopeptide and protein via click chemistry gave labeling yields about 42 % for posphopeptides after semi-preparative HPLC and about 31 % for HSA after size exclusion chromatography.

Schlussfolgerungen/Conclusions:
The novel prosthetic group 4-[18F]fluoro-N-methyl-N-(prop-2-ynyl)benzenesulfonamide for peptide and protein labeling with 18F via click chemistry can be prepared in reasonable radiochemical yields and high radiochemical purity. Moreover, by this method for the first time click chemistry was successfully applied to the 18F-labeling of a phosphopeptide and a protein. The radiopharmacological investigation of the 18F-labeled phoshopeptides and HSA including metabolic stability, biodistribution and cell uptake studies is in progress.
  • Lecture (Conference)
    47. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 22.-25.04.2009, Leipzig, Deutschland
  • Abstract in refereed journal
    Nuklearmedizin 48(2009)2, A38

Publ.-Id: 12273 - Permalink


Die Relevanz der Borflüchtigkeit bei Langzeittransienten in einem mit Bor vergifteten Siedewasserreaktor
Laczko, G.; Böhlke, S.; Ohlmeyer, H.; Schuster, C.; Hurtado, A.;
Die Analyse der Reaktivitätswirksamkeit der Boreinspeisung am SWR erfolgt im Rahmen einer sich im Abschluss befindlichen Dissertation an der Technischen Universität Dresden. Die Finanzierung dieses Vorhabens nahm Vattenfall Europe Nuclear Energy (VENE) GmbH über den Kompetenzverbund Kerntechnik wahr. Innerhalb dieses Projektes wurde die Flüchtigkeit des Bors aus Boratlösungen in Abhängigkeit der Einflussgrößen Borkonzentration, Temperatur, pH-Wert und Volumendampfgehalt aus Zweiphasenströmungen experimentell bestimmt. Aus den Messwerten erfolgte die Ableitung empirischer Funktionen, welche für Simulationsrechnungen mit System-Codes und einfache Abschätzungen nutzbar sind [BoB08].
Keywords: Boreinspeisung am SWR, Zweiphasenströmung, Simulationsrechnung
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2009, 12.-14.05.2009, Dresden, Deutschland
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2009, 12.-14.05.2009, Dresden, Deutschland
    Tagungsband der Jahrestagung Kerntechnik 2009, paper 311, Berlin: INFORUM GmbH

Publ.-Id: 12272 - Permalink


Im Kern - Energie
Weiß, F.-P.; Hurtado, A.;
Weltweit sind derzeit 439 Kernkraftwerke in Betrieb, in Deutschland waren es noch 17 Anlagen. Diese 17 Anlagen haben im Jahre 2007 22,1% des gesamten in Deutschland erzeugten Stromes geliefert. An der Grundlast macht der Strom aus Kernenergie sogar 45% aus.
Die Bundesregierung hat den Ausstieg aus der Nutzung der Kernenergie zum Zwecke der Stromerzeugung beschlossen, weltweit zeichnet sich jedoch ein erheblicher Ausbau der Kernenergie ab. Im Oktober 2008 waren 36 Anlagen im Bau und 99 weitere in Planung.
Vor diesem Hintergrund geht der Vortrag auf die physikalischen und technischen Grundlagen der friedlichen Nutzung der Kernenergie, der Sicherheitsprinzipien sowie auf die mit dem Betrieb von Kernkraftwerken verbundenen Risiken im Vergleich zu anderen Formen der Stromerzeugung ein. Dabei wird auch der Beitrag der Kernenergie zu CO2-Vermeidung dargestellt. Darüber hinaus werden Aspekte der Brennstoffversorgung, insbesondere der Reichweiter des Urans, und der Abfallentsorgung beleuchtet.
Keywords: Strom aus Kernenergie, Brennstoffversorgung, CO2-Vermeidung, Abfallentsorgung
  • Invited lecture (Conferences)
    Im Kern - Energie Veranstaltungsreihe der Katholischen Akademie, 11.11.2008, Katholische Akademie Dresden, Deutschland

Publ.-Id: 12271 - Permalink


Impossibility to describe repulsion with contact interaction
Morawetz, K.; Maennel, M.;
Contact interactions always lead to attractive behaviour. Arguments are presented to show why a repulsive interacting system, e.g. Bose gases, cannot be described by contact interactions and corresponding treatments are possibly obscured by the appearance of bound states.

Publ.-Id: 12270 - Permalink


Application of a step-wise verification and validation procedure to the 3D neutron kinetics code DYN3D within the European NURESIM project
Rohde, U.; Mittag, S.; Grundmann, U.; Petkov, P.; Hadek, J.;
The generic strategy of core physics codes benchmarking which has been elaborated within the European NURESIM code platform development was applied to benchmarking of the 3D neutron kinetics code DYN3D for applications to VVER-type reactors. Numerical and experimental benchmark problems were considered for code verification and validation.
Mathematical problems with given cross sections are used for the verification of the mathematical methods applied e.g. in nodal codes against finite difference solutions.
After minimisation of numerical errors, modelling errors have to be considered. Diffusion approximation and homogenisation error are due to simplified physical approaches and can be estimated by comparing diffusion solutions with more accurate Monte Carlo or deterministic transport solutions.
A series of 2D whole core benchmarks for different core loadings and operational conditions for VVER-1000 reactors was defined for this purpose. Reference transport solutions were calculated by the MARIKO and APOLLO codes based on Method of Characteristics. Homogenised two-group and few-group diffusion parameters were derived from the reference solutions and used as cross section data for the nodal diffusion code DYN3D. The DYN3D solutions were compared to the reference solution. It was shown that the homogenisation error can be significantly reduced, if Assembly Discontinuity Factors (ADF) and Reference Discontinuity Factors (RDF) which are obtained from the transport solution by applying equivalence theory are used.
A study using the multi-group version of DYN3D has shown that increasing the number of groups in the considered cases has only a small effect in comparison with homogenisation error.
Experimental problems are used for code validation. Experimental data for VVER reactors, which were used for the benchmarking of the DYN3D code within NURESIM, are power distribution measurements at the full-size (VVER-1000) experimental facility V-1000, which have been well documented within the EC project VALCO, and kinetic experiments at the LR-0 zero power reactor in NRI Řež.
The code DYN3D has proved to be an effective tool for steady-state and kinetics core calculations. The high accuracy of the code is based on the advanced nodal method “HEXNEM2”, multi-group approach, applying discontinuity factors, and intra-nodal flux reconstruction.
Keywords: reactor physics, neutron kinetics, verification, validation, benchmarking, diffusion theory, homogenisation
  • Lecture (Conference)
    17th International Conference on Nuclear Engineering ICONE17, 12.-17.07.2009, Brussels, Belgium
  • Contribution to proceedings
    17th International Conference on Nuclear Engineering ICONE-17, 12.-16.07.2009, Brussels, Belgium
    CD-ROM paper 75446

Publ.-Id: 12269 - Permalink


Switching Ti Valence in SrTiO3 by a dc Electric Field
Leisegang, T.; Stöcker, H.; Levin, A. A.; Weißbach, T.; Zschornak, M.; Gutmann, E.; Rickers, K.; Gemming, S.; Meyer, D. C.;
A (001) SrTiO3 wafer has been investigated in situ at room temperature under application of a static electric field of varying polarity by the fluorescence X-ray Absorption Near Edge Structure (XANES) analysis at the Sr-K and Ti-K absorption edges. The XANES spectra show a clear shift of the Ti-K absorption edge energy. The shift is attributed to a change of the Ti valence state in a volume invoked by diffusion of the oxygen ions and vacancies. No shift was observed for the Sr-K absorption edge energy. Theoretical calculations support these findings.
Keywords: functional oxide, density-functional, XANES, electric field, strontium titanate

Publ.-Id: 12268 - Permalink


On the effect of spatial discretization in integral transport calculations with HELIOS 1.9
Merk, B.; Weiß, F. P.;
In this study the consequences of the discretization effect is investigated for the full calculation chain starting with the steady state calculation continuing with the burnup calculations and finishing with the evaluation of the safety coefficients. The investigation is based on Mixed Oxide (MOX) Fuel with reactor grade Plutonium. Detailed evaluation of the convergence behavior, the influence of the discretization on the neutron spectrum and the isotopic composition during burnup is given. Finally the influence on the few group cross section preparation and an estimation of the influence of discretization on the safety coefficients is shown.
Keywords: Cell- and Lattice calculation, cross section preparation, HELIOS, Discretization, Burnup calculation, Depletion, Safety coefficients
  • Contribution to proceedings
    XXI International Conference on Transport Theory, 12.-17.07.2009, Torino, Italy

Publ.-Id: 12267 - Permalink


A three scale expansion solution for the Telegrapher’s equation with external source: development and first application
Merk, B.; Glivici, V.; Weiß, F. P.;
This work presents a improved onset for the analysis of experiments by the development of an analytical approximation solution for a space-time dependent P1 neutron transport problem in a one dimensional system consisting of homogenized medium with a central external source with Green's functions. The delayed neutron production is implemented in two additional time scales with the multiple scale expansion method. The approximation solutions are developed for the switch off of the source. First applications are shown for the analysis of the YALINA Booster experiment.
Keywords: Time dependet neutron transport, Accelerator driven system, Experimental analysis, Green's funtion expansion, YALINA experiment
  • Contribution to proceedings
    XXI International Conference on Transport Theory, 12.-17.07.2009, Torino, Italy
  • Lecture (Conference)
    XXI International Conference on Transport Theory, 12.-17.07.2009, Torino, Italy

Publ.-Id: 12266 - Permalink


ATWS analysis for PWR using the coupled code system DYN3D/ATHLET
Kliem, S.; Mittag, S.; Rohde, U.; Weiß, F.-P.;
The ATWS transient “Loss of main feed water supply” in a generic four-loop PWR at the nominal power of 3750 MW was analyzed using the coupled code system DYN3D/ATHLET. A variation of the MOX-fuel-assembly portion in the core has an effect on the reactivity coefficients of the fuel temperature and the moderator density. These two parameters mainly influence the behaviour of the coolant pressure, which is safety-relevant. It has been demonstrated that the pressure maximum decreases with an increasing portion of MOX. For all core loadings considered, both primary-circuit mechanical integrity and sufficient core cooling are guaranteed.
Keywords: reactor safety; MOX, reactivity; temperature-feedback; thermal-hydraulics; transient

Publ.-Id: 12265 - Permalink


Evaluation leistungsbezogener Budgetierungsmodelle
Gilge, B.; Joehnk, P.;
Wird die an öffentlich finanzierten außeruniversitären Forschungseinrichtungen zunehmend wichtiger werdende Programmbudgetierung durch eine leistungsbezogene Budgetierung ergänzt, kann die durch das Neue Steuerungsmodell geforderte Wirkungsorientierung der Ressourcenallokation forciert werden. Darüber hinaus ermöglicht die Übernahme von Kriterien der externen Evaluierung in die budgetierungsrelevanten Leistungsindikatoren eine Verknüpfung zwischen externen Anforderungen der Träger der Einrichtungen und internen Leistungsanreizen. Mit dem vorliegenden Beitrag wird eine Evaluationskonzeption vorgestellt, mit welcher das leistungsbezogene Budgetierungsmodell einer öffentlich finanzierten außeruniversitären Forschungseinrichtung bewertet sowie verbessert werden kann.
  • Wissenschaftsmanagement 4(2008), 12-19

Publ.-Id: 12264 - Permalink


Preparatory Grants for Collaboratory European Research Projects
Joehnk, P.;
  • Lecture (Conference)
    Bioingteh - The exploratory Workshop on Advanced Materials & Technologies in Biology and Medicine, 18.-20.09.2008, Poiana Brasov, Romania

Publ.-Id: 12263 - Permalink


High-resolution hydrogen profiling in AlGaN/GaN heterostructures grown by different epitaxial methods
González-Posada Flores, F.; Redondo-Cubero, A.; Gago, R.; Bengoechea, A.; Jiménez, A.; Grambole, D.; Braña, A. F.; Muñoz, E.;
Hydrogen (H) incorporation into AlGaN/GaN heterostructures used in high electron mobility transistors, grown by different methods, is studied by high-resolution depth profiling. Samples grown on sapphire and Si(1 1 1) substrates by molecular-beam epitaxy and metal–organic vapour phase epitaxy; involving H-free and H-containing precursors, were analysed to evaluate the eventual incorporation of H into the wafer. The amount of H was measured by means of nuclear reaction analysis (NRA) using the 1H(15N,αγ )12C reaction up to a depth of ∼110 nm into the heterostructures. Interestingly, the H profiles are similar in all the samples analysed, with an increasing H content towards the surface and a negligible H incorporation into the GaN layer (0.24 ± 0.08 at%) or at the AlGaN/GaN interface. Therefore, NRA shows that H uptake is not related to the growth process or technique employed and that H contamination may be due to external sources after growth. The eventual correlation between topographical defects on the AlGaN surface and the H concentration are also discussed. (Some figures in this article are in colour only in the electronic version)
Keywords: PACS: GaN, AlGaN, Hydrogen, NRA, HEMT, AFM, MOCVD, MBE

Publ.-Id: 12262 - Permalink


Experimental studies and CFD calculations for buoyancy driven mixing phenomena
Da Silva, M. J.; Thiele, S.; Höhne, T.; Vaibar, R.; Hampel, U.;
In nuclear reactor safety the mixing of borated and deborated water is a critical issue that needs investigation, assessment and prediction. Such mixing is buoyancy driven and numerical codes must correctly model momentum transfer between components of different density. To assess and develop CFD models for buoyancy driven mixing we set up a simple vertical mixing test facility (VeMix) and equipped it with a newly developed planar electrical imaging sensor. This imaging sensor acquires conductivity images of the liquid at the rear channel wall with a speed of 2,500 frames per second. By adding NaCl tracer to the denser component we were able to visualize the mixing process in high spatial and temporal detail. Furthermore, an image processing algorithm based on the optical flow concept was implemented and tested which allows the measurement of flow pattern velocities. Selected experiments at different Richardson numbers were run with two components of different density (pure water and glucose-water mixture) simulating borated and deborated water in a light water reactor scenario. These experiments were compared to CFD calculations using standard turbulence models. Good agreement between experimental data and first CFD simulations was found.
Keywords: buoyancy driven flow, mixing, deborated water, flow visualization, CFD, simulation, planar array sensor
  • Nuclear Engineering and Design 240(2010)9, 2185-2193

Publ.-Id: 12261 - Permalink


Collisional Energy Loss: A Welcoming Component for Jet Quenching Phenomenology in Heavy-Ion Collisions
Mustafa, M.;
  • Lecture (others)
    Universität Gießen, 10.09.2008, Gießen, Deutschland
  • Lecture (others)
    Seminar am Max-Planck-Institut fuer extraterrestrische Physik, 11.09.2008, Garching, Deutschland

Publ.-Id: 12260 - Permalink


Strongly Coupled QGP - Equation of State
Bluhm, M.;
  • Lecture (Conference)
    Workshop of the European Network SIM, 08.-12.09.2008, Villasimius, Italien

Publ.-Id: 12259 - Permalink


Nuclear data needs for transmutation of nuclear waste
Ignatyuk, A.;
  • Lecture (others)
    Seminar FWK, 10.04.2008, Dresden, Deutschland

Publ.-Id: 12258 - Permalink


Quantal Rotation: Molecular view on nuclei
Frauendorf, S.;
  • Lecture (others)
    Seminar FWK, 30.04.2008, Dresden, Deutschland

Publ.-Id: 12257 - Permalink


Exotic modes of rotation
Frauendorf, S.;
  • Lecture (others)
    Seminar FWK, 04.06.2008, Dresden, Deutschland

Publ.-Id: 12256 - Permalink


Raman Spectrometer for monitoring Isotope Exchange Reactions and Energy Transfer in Low Temperature Plasmas
Borysow, J.;
One of the major elements in tritium processing systems is hydrogen isotopes identification and separation. Work with multiple hydrogen isotopes at the is often accompanied by isotopic mixing. Maintaining isotopic purity of tritium is one of the major tasks in new generation Texas Neutrino Mass Experiment (NEXTEX). We developed unique Raman Spectrometer capable of detecting hydrogen isotopes T2, HT, H2, D2, TD and H2 at pressures near 10 Pa with signal-to-noise ratio better than 2 during minutes long observations. This spectrometer is capable of distinguishing traces of numerous isotopomers at partial concentration as low as 1:4000 and can be also used as a medical diagnostic tool. Additionally I will discuss some aspect of our Coherent Raman Spectrometer and its ability to measure molecular kinetics in low temperatures plasmas.
  • Lecture (others)
    Seminar Institut für Strahlenphysik, 01.07.2008, Dresden, Deutschland

Publ.-Id: 12255 - Permalink


Ultra-sensitive in-beam g-ray spectroscopy deep underground
Caciolli, A.;
Ultra-sensitive in-beam γ-ray spectroscopy studies for nuclear astrophysics are performed at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400 kV accelerator, deep underground in Italy's Gran Sasso laboratory. By virtue of a specially constructed passive shield, the laboratory γ-ray background for Eγ < 3 MeV at LUNA has been reduced to levels comparable to those experienced in dedicated offline underground γ-counting setups. The γ-ray background induced by
an incident α-beam has been studied. The data are used to evaluate the feasibility of sensitive inbeam experiments at LUNA and, by extension, at similar proposed facilities.
  • Lecture (others)
    Seminar Institut für Strahlenphysik, 05.08.2008, Dresden, Deutschland

Publ.-Id: 12254 - Permalink


Influence of system and neutron-kinetic parameter variations on an anticipated transient without SCRAM in a PWR
Kliem, S.; Mittag, S.; Rohde, U.; Weiß, F.-P.;
The complete failure of the reactor scram system upon request during an operational transient is called anticipated transient without scram (ATWS). According to the German regulatory guidelines, postulated ATWS events have to be analyzed with regard to their consequences on the safety of nuclear power plants.
Since the course of ATWS transients is determined by a strong interaction of the neutron kinetics with the thermal hydraulics of the system, coupled 3D neutron kinetic/thermal hydraulic code systems are adequate tools for the analysis of such transients. The coupled code system DYN3D/ATHLET developed at FZD is applied to the analysis of an ATWS transient. The objective of the present work is to perform a best-estimate analysis with consequent use of a 3D neutron kinetic code (DYN3D) in combination with an advanced thermal hydraulic system code (ATHLET) together with a quantification of differences in the course and the results of transients, which arise from the uncertainties of thermal hydraulic and neutron-physical conditions.
Typically, the complete failure of the main feed water supply is assumed to be the bounding ATWS event with regard to the maximum primary coolant pressure, which can be reached during the transient. The limitation of the coolant pressure is a pre-condition for the integrity of the primary circuit. The situation is aggravated if the main coolant pumps remain in operation.
For this particular transient, the influence of different thermal hydraulic and neutron-physical conditions on the course of the transient was analyzed.
In a number of code runs all systems which have an influence on the course of the transient were varied. These are the auxiliary boration system and the auxiliary feed water supply. Further, the influence of the modeling of the pressurizer safety and relief valves as well as the steam bypass system on the secondary side was assessed. The variation of the pressurizer relief and safety valve behavior has the biggest influence on the primary circuit coolant pressure.
In the second part, two different core loading patterns were generated for the analyses by varying the number of MOX (mixed oxide) fuel assemblies (FA) in the core. The basic core loading contains 64 MOX FA. All these MOX FA were replaced by standard uranium oxide FA. The presence of MOX in the core has a remarkable influence on the reactivity coefficients of the fuel temperature and the moderator density. These two parameters mainly influence the behavior of the coolant pressure in the first part of the transient. It has been demonstrated that the pressure maximum decreases with growing MOX portion in the core.
The maximum pressure determined in the calculations with variation of system and neutron-physical boundary conditions does not reach the allowed limit for the primary circuit.
  • Contribution to proceedings
    17th International Conference on Nuclear Engineering, 12.-16.07.2009, Brussels, Belgium
    Proceedings of the 17th International Conference on Nuclear Engineering, CDROM, paper 75569: ASME
  • Lecture (Conference)
    17th International Conference on Nuclear Engineering, 12.-16.07.2009, Brussels, Belgium

Publ.-Id: 12253 - Permalink


Instantaneous Shape Sampling for Calculation of the Electromagnetic Dipole Strength
Zhang, S.;
Electromagnetic dipole absorption cross-sections of transitional nuclei with large-amplitude shape fluctuations are calculated in a microscopic way by introducing the concept of Instantaneous Shape Sampling, which is based on the slow shape dynamics as compared to the dipole vibrations. The dipole strength is calculated by means of RPA for the instantaneous shapes, the probability of which is obtained by means of IBA-1. Very good agreement with the experimental absorption cross sections near the nucleon emission threshold is obtained. The dipole strength in this energy region is controlled by the Landau fragmentation.
  • Lecture (others)
    Seminar Institut für Strahlenphysik, 11.08.2008, Dresden, Deutschland

Publ.-Id: 12252 - Permalink


Radiation of electromagnetically and strongly interacting plasmas
Mustafa, M.;
  • Lecture (others)
    Seminar Institut für Strahlenphysik, 05.09.2008, Dresden, Deutschland

Publ.-Id: 12251 - Permalink


Photoneutron measurement of Se-80, La-139: implications for the nucleosynthesis
Makinaga, A.;
  • Lecture (others)
    Seminar Institut für Strahlenphysik, 08.09.2008, Dresden, Deutschland

Publ.-Id: 12249 - Permalink


phi production in hadronic processes and phi mesons in nuclear matter
Kämpfer, B.;
  • Invited lecture (Conferences)
    Donnersberg Workshop 2008 - A1 Collaboration, 31.03.-03.04.2008, Donnersberg, Germany

Publ.-Id: 12248 - Permalink


Bremsstrahlung
Kämpfer, B.;
Hadron masses; If we would have a theory; Modelling, parametrizing, guessing
  • Lecture (Conference)
    HADES Collaboration Meeting XIX, 05.07.2008, Darmstadt, Deutschland
  • Lecture (others)
    Seminar an der TU München, 28.01.208, München, Deutschland
  • Lecture (Conference)
    Workshop on Virtual Bremsstrahlung and HADES, 12.08.2009, Frankfurt am Main, Deutschland

Publ.-Id: 12247 - Permalink


eta, eta' meson production in NN collisions
Kämpfer, B.;
eta, eta' meson production in NN collisions
  • Lecture (Conference)
    Symposium on Meson Physics, 01.-04.10.2008, Krakow, Poland

Publ.-Id: 12246 - Permalink


Equation of state above T_c
Kämpfer, B.;
  • Invited lecture (Conferences)
    Erice School on Nuclear Physics, 20.-25.09.2008, Erice, Italy

Publ.-Id: 12245 - Permalink


Hot 1-2 Loop QCD
Kämpfer, B.;
  • Invited lecture (Conferences)
    Workshop of the European SIM Network, 08.-12.09.2008, Villasimius, Italy

Publ.-Id: 12244 - Permalink


Chiral Symmetry and Medium-Modifications of Hadrons
Kämpfer, B.;
Chiral Symmetry and Medium-Modifications of Hadrons
  • Lecture (Conference)
    Hot and Dense Matter: the next few years, 17.11.2008, Rehovot, Israel

Publ.-Id: 12243 - Permalink


Medium-Modifications of Hadrons
Kämpfer, B.;
  • Invited lecture (Conferences)
    International Symposium on Heavy Ion Physics 2008 (ISHIP2008), 17.-20.11.2008, Darmstadt, Germany

Publ.-Id: 12242 - Permalink


Naturwissenschaftliches Arbeiten am Forschungszentrum Dresden-Rossendorf.
Bussmann, M.;
Der Vortrag soll Schülern einen Einblick in die Arbeit eines Naturwissenschaftlers geben und Ihnen helfen, sich für Ihr anstehendes Studium zu orientieren.
Keywords: physics, natural science, work, student, pupil, school
  • Lecture (others)
    Podiumsdiskussion des Gymnasiums Radeberg, 24.11.2008, Radeberg, Deutschland

Publ.-Id: 12241 - Permalink


Lasers and Particle Beams - From the Ultracold to the Ultrafast
Bussmann, M.;
The Creation and Manipulation of Particle Beams using Lasers opens new Paths towards compact, ultrabright Radiation Sources. With the advent of high-intensity, ultrashort Laser Sources it has become possible to accelerate Electrons and Ions with table top Laser Systems in the Laboratory. Moreover, Lasers can be used to cool Ion Beams to millikelvin Temperatures. In my talk I will focus on the Study of Laser-Matter Interaction by realistic large-scale Particle Simulations which can give insight into the complex Plasma Phenomena leading to the Creation of ultrabrilliant Particle Beams. I will introduce the numerical Methods used in these Computer Experiments and draw the Connection towards recent and future Experiments planned at FZD and GSI.
Keywords: laser acceleration, electron beam, ion beam, laser cooling, molecular dynamics, simulation, strong coupling, plasma, highly charged ions, particle-in-cell, md, pic
  • Invited lecture (Conferences)
    Seminar "Materialwissenschaft/Materials Science", 16.09.2008, Dresden Rossendorf, Deutschland

Publ.-Id: 12240 - Permalink


Kompakte Laserbeschleuniger und ihre Anwendungen
Bussmann, M.;
In diesem Vortrag werden die Prinzipien der Laserteilchenbeschleunigung sowie wichtige Anwendungen der dabei erzeugten Teilchenstrahlen vorgestellt.
Keywords: laser, particle, acceleration
  • Lecture (others)
    FZD-Vortrag für Besucher des Abendgymnasiums Bautzen, 08.07.2008, Dresden Rossendorf, Deutschland

Publ.-Id: 12239 - Permalink


Thermal and Chemical Freeze-out in Spectator Fragmentation
Trautmann, W.; Bassini, R.; Begemann-Blaich, M.; Ferrero, A.; Fritz, S.; Gaff-Ejakov, S. J.; Groß, C.; Imme, G.; Iori, I.; Kleinevoß, U.; Kunde, G. J.; Kunze, W. D.; Le Fevre, A.; Lindenstruth, V.; Lukasik, J.; Lynen, U.; Maddalena, V.; Mahi, M.; Möhlenkamp, T.; Moroni, A.; Müller, W. F. J.; Nociforo, C.; Ocker, B.; Odeh, T.; Orth, H.; Petruzzelli, F.; Pochodzalla, J.; Raciti, G.; Riccobene, G.; Romano, F. P.; Rubehn, T.; Saija, A.; Sann, H.; Schnittker, M.; Schüttauf, A.; Schwarz, C.; Seidel, W.; Serfling, V.; Sfienti, C.; Trzcinski, A.; Tucholski, A.; Verde, G.; Wörner, A.; Hongfei, X.; Zwieglinski, B.;
Isotope temperatures from double ratios of hydrogen, helium, lithium, beryllium, and carbon isotopic yields, and excited-state temperatures from yield ratios of particle-unstable resonances in 4He, 5Li, and 8Be, were determined for spectator fragmentation, following collisions of 197Au with targets ranging from C to Au at incident energies of 600 and 1000 MeV per nucleon. A deviation of the isotopic from the excited-state temperatures is observed which coincides with the transition from residue formation to multi-fragment production, suggesting a chemical freeze-out prior to thermal freeze-out in bulk disintegrations.
  • Physical Review C 76(2007), 064606

Publ.-Id: 12238 - Permalink


Nuclear Astrophysics with real photons at ELBE
Nair, C.; Junghans, A. R.; Erhard, M.; Bemmerer, D.; Beyer, R.; Grosse, E.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.;
The neutron deficient p-nuclei thought to be produced in explosive stellar environments through chains of photodisintegration reactions on heavy seed nuclei. The modelling of the nucleosynthesis for the p-nuclei is mainly based on statistical model calculations and the knowledge of the experimental cross sections for the prediction of the p-nuclei abundances is of crucial importance. To forward in this direction we have started and experimental program at the bremsstrahlung facility of the superconducting electron accelerator ELBE of FZ Dresden-Rossendorf . Photodisintegration measurements on the astrophysically relevant p-nuclei 92Mo and 144Sm have been performed via photoactivation technique with bremsstrahlung end-point energies from 10.0 to 16.5 MeV. In particular the (gamma,alpha) reactions of the mentioned nuclei were studied for the first time at different endpoint energies above and close to the threshold. The activation yields from all measurements are compared with calculations using cross sections from recent Hauser-Feshbach models .
Keywords: p-nuclei, photoactivation, bremsstrahlung
  • Invited lecture (Conferences)
    Seminar at the National Superconducting Cyclotron Laboratory, Michigan State University as a JINA (Joint Institute of Nuclear Astrophysics) visitor, 04.08.2008, Michigan, United States of America

Publ.-Id: 12237 - Permalink


Photoactivation studies on astrophysically relevant nuclei: measuring techniques for activated samples
Nair, C.; Junghans, A. R.; Erhard, M.; Bemmerer, D.; Degering, D.; Beyer, R.; Grosse, E.; Koehler, M.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Wagner, A.; Schwengner, R.;
For studying the neutron deficient p-nuclei experimentally, we have started and experimental program at the bremsstrahlung facility of the superconducting electron accelerator ELBE of FZ Dresden-Rossendorf . Photodisintegration measurements on the astrophysically relevant p-nuclei 92Mo and 144Sm have been performed via photoactivation technique with bremsstrahlung end-point energies from 10.0 to 16.5 MeV. In particular the (gamma,alpha) reactions of the mentioned nuclei were studied for the first time at different endpoint energies above and close to the threshold. The activation yields from all measurements are compared with calculations using cross sections from recent Hauser-Feshbach models. The radioactive decay of irradiated targets with very low counting statistics was studied at the low-background underground laboratory "Felsenkeller" in Dresden.
Keywords: photoactivation, p-nuclei, underground laboratory 'felsenkeller'
  • Poster
    IEEE Nuclear Science Symposium, 20.-24.10.2008, Dresden, Germany

Publ.-Id: 12236 - Permalink


Experimental and numerical investigations of natural circulation phenomena in passive safety systems for decay heat removal in large pools
Krepper, E.; Beyer, M.;
Modern concepts of nuclear power reactor systems are equipped with passive systems for decay heat removal. Examples are the pool of the emergency condenser (BWR-1000) or the pool of the ESBWR. These systems operate without active influence from outside. The questions arise: How reliable are the based physical mechanisms? Are they understood completely? Are actual models able to describe the phenomena?
In different passive systems the energy is transferred by natural circulation into large pools which are considered as infinite heat sink. The paper deals with experiments and with CFD simulations to investigate the capability of actual CFD codes to describe these phenomena. In the FZ Dresden-Rossendorf at the facility TOPFLOW heating up tests of an emergency condenser were performed. During these tests also the temperature courses on the secondary side of the pool were recorded. The data recording comprises periods starting from single phase liquid until steam on the secondary pool side was found. During these experiments temperature stratification phenomena were observed, which were found in earlier small scale tests. In the paper also these small scale experiments are described. A detailed CFD analysis of these experiments was performed. An explanation of the observed phenomena on the basis of the small scale tests and the CFD simulations is presented.
Keywords: Passive safety systems, Experiments, CFD, natural circulation
  • Contribution to proceedings
    17th International Conference on Nuclear Engineering, ICONE-17, 12.-16.07.2009, Brussels, Belgium
  • Lecture (Conference)
    17th International Conference on Nuclear Engineering, ICONE-17, 12.-16.07.2009, Brussels, Belgium
  • Nuclear Engineering and Design 240(2010), 3170-3177
    DOI: 10.1016/j.nucengdes.2010.05.050

Publ.-Id: 12235 - Permalink


Surfing the plasma wake - particle acceleration with laser light
Schramm, U.;
Modern short-pulse high-power lasers can, for a few optical cycles, generate electrical field strengths strong enough to accelerate electrons to relativistic energies. Rectifying these fields by means of a laser plasma can lead to acceleration gradients that exceed conventional rf-based technology by many orders of magnitude. Recent results in this field will be discussed as well as potential applications of laser accelerated particle pulses.
Keywords: laser plasma acceleration
  • Invited lecture (Conferences)
    Tata Institute of Fundamental Research, Institute Seminar, 12.1.2009, Mumbai, India
  • Invited lecture (Conferences)
    Institute of plasma research, Seminar, 13.1.2009, Ahmenabad, India

Publ.-Id: 12234 - Permalink


Prospects of high intensity laser driven radiation sources
Schramm, U.;
Recent development in table-top high-power lasers of the 100 Terawatt class combined with an improved understanding of relativistic laser matter interaction now allows for the discussion of applications of laser accelerated particle beams and secondary radiation sources. In this presentation, an introduction covering the underlying mechanisms will be given followed by a presentation of the novel combined laser-accelerator facility at FZD and its goals as, e.g., laser driven proton oncology.
Keywords: laser particle acceleration, secondary sources
  • Invited lecture (Conferences)
    Eighth DAE-BRNS National Laser Symposium (NLS-08), 07.-10.1.2009, Delhi, India
  • Invited lecture (Conferences)
    Lecture Laser and Neutron Physics Section of BARC, 14.1.2009, Mumbai, India

Publ.-Id: 12233 - Permalink


Structural investigations of ZnO thin films grown by reactive pulsed magnetron sputtering at different substrate temperatures
Redondo-Cubero, A.; Vinnichenko, M.; Krause, M.; Gago, R.;
Zinc oxide (ZnO) is a promising material for electronic and optical applications [1]. As in the case of other wide bandgap compounds (i.e. GaN) grown in heteroepitaxy conditions, the final electrical properties of the film are affected by its crystal quality. Rutherford backscattering spectrometry (RBS) in channeling mode (RBS/C) is a well proved method to obtain this physical information in such structures, with the additional advantage of in-depth information [2]. In this work, we report RBS/C and Raman characterization of ZnO thin films grown onto (0001) oriented sapphire [3] by reactive pulsed magnetron sputtering at substrate temperatures (Ts) spanning from 22ºC to 550ºC .
Random and RBS/C measurements were performed along the and axes of the wurtzite lattice (P63mc) of ZnO [1] with a 3.035 MeV He+ beam. The sample position was controlled by a 3-axis goniometer. The micro-Raman spectra were collected at an excitation wavelength of 532 nm. The influence of substrate temperature onto low- and high-frequency E2 modes of the resulting film was monitored. The low-frequency E2 mode is associated with the vibration of the heavy Zn sublattice, while the high-frequency E2 mode involves only the oxygen atoms.
Stoichiometry of the oxide layer was determined from the random RBS spectra, which showed a constant composition except for an O-rich interface (associated with Zn in-diffusion). RBS/C angular scans along the axis revealed a progressive enhancement of crystal quality of wurtzite ZnO with substrate temperature, with a <0001> textured growth even for low substrate temperatures (100ºC). The film crystallinity is greatly increased for substrate temperatures above 400ºC, a behaviour also confirmed by Raman measurements. The latter shows significant decrease of the line width which in the case of low-frequency E2 mode at Ts>400 °C approaches and even becomes smaller than the values of reference single crystal sample. Also, the Raman peak positions do not change for the films grown at temperatures above 400°C. Further RBS/C analysis along the oblique axis was carried out to determine the possible influence of strain. The angular scan showed no-shift among different ZnO depths, revealing a non-strained film under the technique limits. From these measurements, it can be concluded that epitaxial ZnO films can be grown by pulsed reactive magnetron sputtering without appreciable strain on sapphire substrates at Ts ~550ºC.

References:
1. Ü. Özgür, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Dogan, V. Avrutin, S.-J. Cho, and H. Morkoc, J. Appl. Phys. 98, 041301 (2005).
2. L.C. Feldman, J.W. Mayer and S.T. Picraux, Material analysis by ion channeling, NY, Academic Press (1982).
3. M. Vinnichenko, N. Shevchenko, A. Rogozin, R. Grötzschel, A. Mücklich, A. Kolitsch and W. Möller, J. Appl. Phys. 102, 113505 (2007)
Keywords: ZnO, epitaxial growth, reactive pulsed magnetron sputtering
  • Poster
    Charged and neutral particles channeling phenomena (Channeling 2008), 25.10.-01.11.2008, Erice, Italy

Publ.-Id: 12232 - Permalink


Experiments on nuclear rotation
Schwengner, R.; Keywords: Nuclear structure, gamma-ray spectroscopy, collective rotation, magnetic rotation, cranking model, shell model
  • Lecture (others)
    Institutsseminar des Instituts für Strahlenphysik, 20.08.2008, Dresden-Rossendorf, Deutschland

Publ.-Id: 12231 - Permalink


Flavonoids – organic compounds with strong interactions towards uranium
Geipel, G.; Viehweger, K.; Bernhard, G.;
Flavonoids belong to a class of secondary plant metabolites. They are most commonly known for their antioxidant activity. Next to chlorophyll flavonoids are the most important group of visible plant pigments.
We studied by use of spectrophotometric techniques the interaction of several flavonoids with uranium. The change in the spectral properties of the flavonoids was used to determine the stability constants. Spectra were evaluated with the factor analysis program Specfit. All spectra of flavonoids show strong change with increasing uranium concentration at constant pH. Stability constants were derived for quercetin, hesperetin, hesperidin, the aglycon of hesperetin. Hesperetin was obtained by hydrolytic splitting of the glycoside hesperidin.
The overall structure Isosbestic points in the absorption spectra indicate a clear interaction between the flavonoids and uranium(VI).
The most strong interaction was found for quercetin. The derived stability constant was assigned to be log β131 = 41.4 ± 0.4 at an ionic strength of 0.1 M for the reaction

UO22+ + C15H5O75- + 3 H+ → UO2C15H8O7 (1)

Hesperidin and hesperetin show much lower stability constants. For example the stability constant for the hesperetin complex at 0.1 M ionic strength was determined to be log β121 = 31.0 ± 0.6.
We assume that the complex formation occur by a ring formation, whereas quercitin forms a 6-membered ring between a phenolic group and the ketone oxygen in the benzopyran-4-one ring whereas hesperidin and hesperetin form 5-membered rings.
Keywords: Uranium, Flavonoids
  • Lecture (Conference)
    Actinides 2009, 12.-17.07.2009, San Francisco, USA

Publ.-Id: 12230 - Permalink


An U accumulating plant – a suitable tool for remediation?
Viehweger, K.; Geipel, G.; Bernhard, G.;
Abstract. Large areas were disturbed in the southern “Erzgebirge”, Germany, due to former uranium mining activities. Great efforts were done for the remediation and restoration during the last decade. Nevertheless there are some small areas, which are not yet rehabilitated and therefore possess exalted uranium soil contents.
The first step was the evaluation of different former U mining sites. Reconstructed areas contain considerable less amounts of U compared with a leaved stock pile near Johanngeorgenstadt. To get more reliable data on the bioavailability of U in this distinct soil, a sequential chemical soil fractionation procedure was accomplished. The bioavailable U were recovered from the first 3 extraction steps (~ 30 mg*Kg-1).
Fortunately we could identify the well known heavy metal hyperaccumulator Arabidopsis halleri (also known as Cardaminopsis halleri) in this U contaminated area. A basic tool for the characterisation of metal mobility within the soil-plant system is the soil-to-plant transfer factor or accumulation factor. Arabidopsis plants growing on the mining dump achieved accumulation factors around 2.6 for roots and 1.1 for shoots, respectively.
To get more insight in mechanisms underlying plant U uptake and accumulation, a hydroponic grow system under laboratory conditions was developed. The accumulation factors in this system were around 1670 for roots and 625 for shoots. It is obvious that U is clear more bioavailable for plants in hydroponic solution than in the soil from the former mining side.
Despite this enormous U accumulation it is mandatory to evaluate the U tolerance and toxicity under hydroponic conditions. The classical root-elongation test was used for estimation of the tolerance index (TI). Plants growing permanent with U could increase their TI within 7 weeks. Nevertheless U had a negative impact on the plant fitness indicated by a significant decrease of chlorophyll a/b ratio during the growth period. Additionally, spectroscopic measurements of leaves and chlorophyll extracts revealed some disturbances of chlorophyll biosynthesis and proper function of photosystem I, respectively.
We could identify a U accumulating plant, which is able to take up enormous amounts of U in hydroponic solution. To make this plant suitable for remediation processes it is crucial getting a deeper insight in uptake, sequestration and U tolerance pathways. The described hydroponic system could be useful tool for this purpose.
Keywords: Plants, uranium
  • Lecture (Conference)
    Actinides 2009, 12.-17.07.2009, San Francisco, USA

Publ.-Id: 12229 - Permalink


Dipole strength in 89Y and 90Zr up to the neutron-separation energy
Schwengner, R.; Keywords: Nuclear structure, nuclear spectroscopy, photon scattering, gamma-ray strength functions, photoabsorption cross section, random-phase approximation
  • Lecture (Conference)
    DPG Frühjahrstagung, 10.-14.03.2008, Darmstadt, Germany

Publ.-Id: 12228 - Permalink


Strength-function measurements
Schwengner, R.; Keywords: Nuclear structure, gamma-ray spectroscopy, photon scattering, strength functions, absorption cross sections, random-phase approximation
  • Lecture (Conference)
    Workshop on Modern Methods Using Fast Neutrons for Research Related to the Transmutation of Nuclear Waste, 13.-15.02.2008, Dresden, Germany

Publ.-Id: 12227 - Permalink


NeuLAND MRPC Prototype construction and testing at Electron Linear Accelerator (ELBE)
Bemmerer, D.; Yakorev, D.; Stach, D.; Wagner, A.;
Different prototypes of Multigap resistive plate chamber detector (MRPC) for the future NeuLAND detector were built and tested at the ELBE electron beam in FZD. Results and future plans are discussed.
Keywords: MRPC, RPC, Multigap resistive plate chamber, Resistive plate chamber, NeuLAND, FAIR, gas chamber, ELBE
  • Lecture (Conference)
    NeuLAND Working Group Meeting, 24.-26.09.2008, Sinaia, Romania

Publ.-Id: 12226 - Permalink


Room-temperature ferromagneticlike behavior in Mn-implanted and postannealed InAs layers deposited by Molecular Beam Epitaxy
González-Arrabal, R.; González, Y.; González, L.; García-Hernández, M.; Munnik, F.; Martín-González, M. S.;
We report on the magnetic and structural properties of Ar- and Mn-implanted InAs epitaxial films grown on GaAs (100) by Molecular Beam Epitaxy (MBE) and the effect of Rapid Thermal Annealing (RTA) for 30 s at 750 °C. Channelling Particle Induced X- ray Emission (PIXE) experiments reveal that after Mn implantation almost all Mn atoms are subsbtitutional in the In site of the InAs lattice, like in a diluted magnetic semiconductor (DMS). All of these samples show diamagnetic behavior. However, after RTA treatment the Mn–InAs films exhibit room-temperature magnetism. According to PIXE measurements the Mn atoms are no longer substitutional. When the same set of experiments was performed with Ar as implantation ion, all of the layers present diamagnetism without exception. This indicates that the appearance of room-temperature ferromagneticlike behavior in the Mn–InAs-RTA layer is not related to lattice disorder produced during implantation but to a Mn reaction produced after a short thermal treatment. X-ray diffraction patterns and Rutherford backscattering measurements evidence the segregation of an oxygen-deficient MnO2 phase (nominally MnO1.94) in the Mn–InAs-RTA epitaxial layers which might be the origin of the room-temperature ferromagneticlike response observed.
Keywords: DMS, InMnAs, room temperature magnetism, PIXE, implantation, III-V semiconductors

Publ.-Id: 12225 - Permalink


Fast Digitizing and Digital Signal Processing of Detector Signals
Hannaske, R.;
A fast-digitizer data acquisition system recently installed at the neutron time-of-flight experiment nELBE, which is located at the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf, is tested with two different detector types. Preamplifier signals from a high-purity germanium detector are digitized, stored and finally processed. For a precise determination of the energy of the detected radiation, the moving-window deconvolution algorithm is used to compensate the ballistic deficit and different shaping algorithms are applied. The energy resolution is determined in an experiment with γ-rays from a 22Na source and is compared to the energy resolution achieved with analogously processed signals. On the other hand, signals from the photomultipliers of barium fluoride and plastic scintillation detectors are digitized. These signals have risetimes of a few nanoseconds only. The moment of interaction of the radiation with the detector is determined by methods of digital signal processing. Therefore, different timing algorithms are implemented and tested with data from an experiment at nELBE. The time resolutions achieved with these algorithms are compared to each other as well as to reference values coming from analog signal processing. In addition to these experiments, some properties of the digitizing hardware are measured and a program for the analysis of stored, digitized data is developed. The analysis of the signals shows that the energy resolution achieved with the 10-bit digitizer system used here is not competitive to a 14-bit peak-sensing ADC, although the ballistic deficit can be fully corrected. However, digital methods give better result in sub-ns timing than analog signal processing.
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Dresden-Rossendorf; FZD-510 2009
  • Poster
    Graduate Students Seminars, 27.-29.08.2008, Limbach-Oberfrohna, Deutschland
  • Lecture (others)
    IKTP Institutsseminar, 20.11.2008, Dresden, Deutschland

Downloads:

Publ.-Id: 12224 - Permalink


Progress of the EPOS project: Gamma-Induced Positron Spectroscopy (GiPS)
Krause-Rehberg, R.; Anwand, W.; Brauer, G.; Butterling, M.; Cowan, T.; Jungmann, M.; Krille, A.; Schwengner, R.; Wagner, A.;
Gamma-induced positron generation has been performed using the superconducting electron accelerator ELBE at the Research Center Dresden-Rossendorf.
  • Contribution to proceedings
    The XVth International Conference on Positron Annihilation (ICPA-15), 18.-23.01.2009, Kolkata, India
    Progress of the EPOS Project: Gamma-Induced Positron Spectroscopy (GiPS)
  • Lecture (Conference)
    The XVth International Conference on Positron Annihilation (ICPA-15), 18.-23.01.2009, Kolkata, India
  • Physica Status Solidi (C) 6(2009)11, 2451-2455
    DOI: 10.1002/pssc.200982076

Publ.-Id: 12223 - Permalink


Structural and electrochemical studies on uranyl(VI) complex with pentadentate Schiff base ligand: A guide to stable uranyl(V)
Takao, K.; Kato, M.; Takao, S.; Nagasawa, A.; Scheinost, A. C.; Bernhard, G.; Hennig, C.; Ikeda, Y.;
Uranium(V) is normally instable in solution because of its disproportionation. On the other hand, U(V) has one unpaired electron in the 5f orbital, i.e., 5f1 configuration., and hence chemistry of U(V) is essential for the systematic understanding of actinide chemistry. Previously, we studied electrochemical behavior of U(VI) complexes in non-aqueous solvents, and obtained insight that multidentate ligands may stabilize U(V).1 From this point of view, we have found that two stable U(V) complexes [UVO2(salophen)DMSO]– (salophen = N,N’-disalicylidene-o-phenylenediaminate) and [UVO2(dbm)2DMSO]– (dbm = dibenzoylmethanate) are stable in DMSO.1-4 However, dissociation of a unidentate ligand (L) such as DMSO in [UVO2(salophen)L]– was also observed at lower L concentration. This prevents preparation and observation of a “pure” U(V) complex. On the basis of this knowledge, we obtained a hint that it is better to exclude L from a U(V) complex for its stability. Normally, U(VI) (UO22+) has 3–6 coordination sites in its equatorial plane, and probably most prefers 5 even in a bulky ligand.5 In this study, we selected N,N’-disalicylidenediethylenetriaminate (saldien2–)6 as a pentadentate ligand to satisfy this request. The U(VI) complex with saldien2– was characterized by single crystal X-ray analysis and X-ray absorption fine structure (XAFS) spectroscopy, and its electrochemical behavior in DMSO and N,N-dimethylformamide (DMF) was studied.
The obtained U(VI)-saldien2– complex recrystallized from DMSO was identified as orthorhombic UVIO2(saldien)•DMSO by single crystal X-ray analysis (Fig. 1). It should be noted that all coordination sites in the equatorial plane of UO22+ are occupied by saldien2–, and that any unidentate ligands are excluded as desired. A DMF solution of UVIO2(saldien) shows k3-weighted U LIII-edge EXAFS spectrum similar to that in solid state, indicating that the structure of UVIO2(saldien) remains even in the solution. This is supported by structural parameters from EXAFS curve fit.
Redox behavior of UVIO2(saldien) in DMSO and DMF was studied by using cyclic voltammetry. As a result, quasi-reversible redox waves were observed around E°’ = –1.582 ± 0.005 V vs. Fc/Fc+ (Ep = 0.080–0.170 V at v = 0.010–0.500 V•s–1) in DMSO and E°’ = –1.632 ± 0.003 V vs. Fc/Fc+ (Ep = 0.076–0.141 V at v = 0.010–0.500 V•s–1) in DMF. UV-Vis-NIR absorption spectral changes with the electrochemical reduction of UVIO2(saldien) were recorded using the spectroelectrochemical technique.1,4 The result of the DMSO solution is shown in Fig. 2. From the absorbance change, the electron stoichiometry in the reduction of UVIO2(saldien) was determined as 0.92 in DMSO and 0.82 in DMF using the Nernstian relationship. This quantity close to unity reveals that the following reaction occurs in both solutions.

UVIO2(saldien) + e– = [UVO2(saldien)]–

As we expected, it was found that UVIO2(saldien) without unidentate ligands results in the stable U(V) complex, [UVO2(saldien)]–, in DMSO and DMF. This U(V) species also shows the characteristic absorption bands of U(V) at 620, 700, 830, 1390, and 1890 nm as well as other U(V) species, [UVO2(salophen)DMSO]– and [UVO2(dbm)2DMSO]–.1,4
Keywords: U(V), Structure, Stability, Electrochemistry, Absorption Spectrum
  • Lecture (Conference)
    ACTINIDES 2009, 12.-17.07.2009, San Francisco, USA

Publ.-Id: 12222 - Permalink


X-ray absorption fine structures of uranyl(V) complexes in non-aqueous solutions
Takao, K.; Tsushima, S.; Takao, S.; Scheinost, A. C.; Bernhard, G.; Ikeda, Y.; Hennig, C.;
Actinide elements at oxidation states +5 and +6 exist as actinyl ions (AnO2n+, An = U, Np, Pu, Am) with typical trans-dioxo arrangement. Among them U(V) is quite instable due to the disproportionation. Recently, U(V) attracts special interest, because this field of actinides has been little explored despite its importance in the nuclear engineering. Especially, the U(V) solution chemistry is quite important in nuclear fuel reprocessing and environmental risks with long-term storage of radioactive waste. Structure of U(V) species is one of the essential parts of its chemistry. Actually, several crystal structures of U(V) compounds were reported previously. On the other hand, structure of U(V) species in solutions are not investigated so far except for EXAFS studies of UVO2(CO3)35– in an aqueous system.1,2 In this study, we report the structure determination of two U(V) complexes, [UVO2(salophen)DMSO]– (1V, salophen = N,N’-disalicylidene-o-phenylenediaminate) and [UVO2(dbm)2DMSO]– (2V, dbm = dibenzoylmethanate), in DMSO.3-6
The k3-weighted EXAFS spectra of 1V, 1VI, 2V, and 2VI and their Fourier transforms (FTs) are shown in Fig. 1. The structures of these U(V) and U(VI) complexes in DMSO solutions were determined by the EXAFS curve fits on the basis of the molecular structures of 1VI and 2VI from single crystal X-ray analyses.5,6 The best fit curve for each EXAFS spectrum and FTs are also displayed in Fig. 1. As a result, the interatomic distances between U and axial O (Oax) were determined as 1.84 Å for 1V and 1.85 Å for 2V, which are comparable with other U(V) complexes in crystal structures. On the other hand, the U–Oax distances of 1VI and 2VI are evaluated 1.80 and 1.78 Å, respectively. The lengthening of the U–Oax distance of 0.04–0.07 Å with the reduction of U(VI) to U(V) corroborates our previous estimation from IR spectra for 1V/1VI and 2V/2VI couples.4,5 The interatomic distances between U and coordinating atoms of salophen2– and dbm– are also lengthened 0.04–0.14 Å with the reduction from U(VI) to U(V). It should be noted that a long interatomic distance between U and O of DMSO (U–ODMSO; ca. 2.90 Å) was found in both 1V and 2V. Although these U–ODMSO distances seem unusual, those are still shorter than the sum of van der Waals radii of U and O (1.86 + 1.52 = 3.38 Å),9 indicating that such a long U–ODMSO interaction is still possible. The long U–ODMSO distance implies the very weak coordination of DMSO to U(V) in 1V and 2V. Actually, we previously observed that 1V may release DMSO at lower DMSO concentration.1 The week coordination of the unidentate ligand (L) such as DMSO might be a reason why U(V) solvates (UVO2(L)5+) is instable even in L,10,11 and provides an insight that strong multidentate ligand is required for stabilization of U(V).
Keywords: XAFS, U(V), Solution Chemistry, Structure, Stability
  • Lecture (Conference)
    Actinides 2009, 12.-17.07.2009, San Francisco, USA
  • Inorganic Chemistry 48(2009)20, 9602-9604

Publ.-Id: 12221 - Permalink


The time-of-flight setup for inelastic scattering measurements at nELBE
Beyer, R.; Grosse, E.; Hannaske, R.; Junghans, A. R.; Matic, A.; Nolte, R.; Schilling, K.-D.; Schwengner, R.; Wagner, A.;
At the nELBE facility at Forschungszentrum Dresden-Rossendorf fast neutrons with kinetic energies of 0.1 to 10 MeV will be used to deliver nuclear data on neutron induced reactions.
First experiments on neutron scattering on Fe-56 were performed using a double time-of-flight setup. This setup is based on proton recoil detectors and an array of 42 Barium-Flouride crystals. Emitted photons and neutrons are detected in coincidence to determine the inelastic neutron scattering cross section.
Keywords: nELBE, inelastic neutron scattering, double time-of-flight
  • Lecture (Conference)
    EFNUDAT progress and general assembly meeting, 01.-03.10.2008, Uppsala, Sverige

Publ.-Id: 12220 - Permalink


Transmutation with fast neutrons
Beyer, R.;
Nuclear Transmutation is one way to reduce the amount nuclear waste that has to be disposed for hundred thousands of years. The idea is to convert long lived isotopes in to short lived ones by nuclear interaction with fast neutrons. This procedure will take place in future types of nuclear facilities, like generation IV reactors or accelerator driven systems. At the neutron time-of-flight setup nELBE at Forschungszentrum Dresden-Rossendorf experiments will be performed to obtain neutron induced reaction cross sections which are necessary to develop and construct such facilities.
Keywords: nuclear transmutation, nELBE, neutron time-of-flight
  • Lecture (others)
    3rd FZD Graduate Students Seminar, 27.-29.08.2008, Limbach-Oberfrohna, Deutschland

Publ.-Id: 12219 - Permalink


Experimental investigation of the residues produced in the 136Xe+Pb and 124Xe+Pb fragmentation reactions at 1A GeV
Henzlova, D.; Schmidt, K. H.; Ricciardi, M. V.; Kelic, A.; Henzl, V.; Napolitani, P.; Audouin, L.; Benlliure, J.; Boudard, A.; Casarejos, E.; Ducret, J. E.; Enqvist, T.; Heinz, A.; Junghans, A. R.; Jurado, B.; Krasa, A.; Kurtukian, T.; Leray, S.; Ordonez, M. F.; Pereira, J.; Pleskac, R.; Rejmund, F.; Schmitt, C.; Stephan, C.; Tassan-Got, L.; Villagrasa, C.; Volant, C.; Wagner, A.; Yordanov, O.;
The nuclide cross sections and longitudinal velocity distributions of residues produced in the reactions of 136Xe and 124Xe at 1A GeV in a lead target were measured at the high-resolution magnetic spectrometer, the fragment separator (FRS) of GSI. The data cover a broad range of isotopes of the elements between Z=3 and Z=56 for 136Xe and between Z=5 and Z=55 for 124Xe, reaching down to cross sections of a few microbarns. The velocity distributions exhibit a Gaussian shape for masses above A=20, while more complex behavior is observed for lighter masses. The isotopic distributions for both reactions preserve a memory on the projectile N/Z ratio over the whole residue mass range.
Keywords: cross section residue high-resolution magnetic spectrometer fragment separator FRS GSI

Publ.-Id: 12218 - Permalink


Ultra-low-energy ion-beam-synthesis of Ge nanocrystals in thin ALD Al2O3 layers for memory applications
Dimitrakis, P.; Mouti, A.; Bonafos, C.; Schamm, S.; Ben Assayag, G.; Ioannou, V.; Schmidt, B.; Becker, J.; Normand, P.;
Structural and electrical properties of ALD-grown 5 and 7 nm-thick Al2O3 layers before and after implantation of Ge ions (1 keV, 0.5–1 x 1016 cm-2) and thermal annealing at temperatures in the 700–1050°C range are reported. Transmission Electron Microscopy reveals the development of a 1 nm-thick SiO2-rich layer at the Al2O3/Si substrate interface as well as the formation of Ge nanocrystals with a mean diameter of ca. 5 nm inside the implanted Al2O3 layers after annealing at 800 °C for 20 min. Electrical measurements performed on metal–insulator–semiconductor capacitors using Ge-implanted and annealed Al2O3 layers reveal charge storage at low-electric fields mainly due to location of the Ge nanocrystals at a tunnelling distance from the substrate and their spatial dispersion inside the Al2O3 layers.
Keywords: Ion implantation, Ge nanocrystals, nanocrystal memory
  • Lecture (Conference)
    16th biannual conference of Insulating Films on Semiconductors, 29.06.-01.07.2009, Cambridge, United Kingdom
  • Microelectronic Engineering 86(2009), 1838-1841
    DOI: 10.1016/j.mee.2009.03.074

Downloads:

Publ.-Id: 12217 - Permalink


Prospects of Laser Cooling of Ion Beams at CSR
Bussmann, M.;
This talk focuses on the prospects of laser cooling of ion beams at the storage rings CSRe and CSRm located at the Institute of Modern Physics in Lanzhou, China.
Keywords: laser cooling, ion beams, relativistic energies, storage ring, CSR, CSRe, CSRm
  • Invited lecture (Conferences)
    Seminar of the Institute of Modern Physics, CAS, 19.11.2008, Lanzhou, China

Publ.-Id: 12216 - Permalink


Laser Cooling of Ion Beams at PALLAS and ESR
Bussmann, M.;
Recent experiments at the ESR storage ring at GSI have shown that it is possible to cool relativistics ions beams using table top laser systems. We present results from these experiments including precision laser spectroscopy measurements of the 2S1/2-2P1/2 and 2S1/2-2P3/2 transition in C3+. We compare the prospects of future laser cooling experiments at GSI and FAIR with experiments on crystalline ion beams caried out at the table top storage ring PALLAS.
Keywords: laser, laser cooling, ion beam, storage ring, PALLAS, ESR, GSI, C3+, laser spectroscopy, VUV, x-ray
  • Invited lecture (Conferences)
    Seminar of the Institute of Modern Physics, CAS, 18.11.2008, Lanzhou, China

Publ.-Id: 12215 - Permalink


Laser Cooling of Ions in Traps and Storage Rings
Bussmann, M.;
Laser Cooling of Ions is an established technique for providing ultracold ions for precision experiments in traps. In this talk I will present the prospects of laser cooling of ion beams in storage rings, showing both the similarities and differences of this new cooling scheme compared to traditional in-trap laser cooling.
Keywords: laser cooling, ion beam, PALLAS, Paul trap, storage ring, ion, laser
  • Invited lecture (Conferences)
    Seminar of the Institute for Modern Physics, CAS, 17.11.2008, Lanzhou, China

Publ.-Id: 12214 - Permalink


Cooling of Ions
Bussmann, M.;
Measuring the properties of heavy ions with high accuracy demands precise control of their
motional degrees of freedom in an isolated environment. Such a situation can be achieved by
combining modern cooling techniques with new means to trap and store the ions of interest. The first lecture will provide an overview of current state-of-the-art techniques to trap and store ions, including a comparison of the ion dynamics in the two most common types of ion traps, Penning and Paul traps, with the ion dynamics in storage rings.
This overview will be followed by an introduction to some widely used cooling techniques, focusing on sympathetic cooling and laser cooling. Based on this introduction the second lecture will give inside to current high accuracy experiments with ions in traps and storage rings with emphasis on sympathetic cooling of highly charged ions and laser cooling of ion beams. I will conclude with an outlook on future high accuracy measurements of heavy, unstable nuclei and accurate laser X-ray spectroscopy of Li-like and Na-like electronic transitions in heavy ions at future storage ring facilities.
Keywords: laser cooling, Paul trap, Penning trap, storage ring, ion beam, crystalline ion beam, phase transition, laser spectroscopy, x-ray, VUV
  • Invited lecture (Conferences)
    International WE-Heraeus Summer School: Atomic Properties of the Heaviest Elements, 24.08.-06.09.2008, Wittenberg, Deutschland

Publ.-Id: 12213 - Permalink


Laseraktivitäten am FZD in Rossendorf
Bussmann, M.;
In this talk we present the scientific program of the Laser Particle Acceleration Group and the status of the DRACO laser system.
Keywords: laser, particle acceleration, ion beam, electron beam, DRACO
  • Invited lecture (Conferences)
    Gruppenseminar des Lehrstuhls für Experimentelle Kernphysik der Ludwig-Maximilians-Universität München, 16.05.2008, München, Deutschland

Publ.-Id: 12212 - Permalink


Laser-Cooling of Ion Beams at Relativistic Energies
Bussmann, M.;
Recent Experiments at the Experimental Storage Ring at GSI have seen the successful application of laser cooling of bunched C3+ ion beams at relativistic energies of 122 MeV per nucleon. Major results of these experiments include the attainment of space-charge dominated beams, evidence for collective ion motion, three-dimensional cold beams and precision laser spectroscopy in the deep UV spectral range. The talk will review these results, showing that measurements of important beam properties such as momentum spread and bunch length are currently limited by the beam diagnostics available. Several solutions to better resolve the beam momentum spread will be presented, which can be easily included in future experiments. These experimental efforts are supplemented by extensive computer simulations of laser-cooled bunched ion beams which can provide insight into the ion-dynamics on the single-particle level. The talk will conclude with an outlook to the exciting possibilities for laser cooling of ion beams at FAIR.
Keywords: laser cooling, ion beam, crystalline beam, FAIR, ESR, GSI, laser spectroscopy, VUV, X-ray
  • Invited lecture (Conferences)
    Atomphysik-Seminar, 14.05.2008, Darmstadt, Deutschland

Publ.-Id: 12211 - Permalink


Commissioning of the double Penning trap system MLLTRAP
Kolhinen, V. S.; Bussmann, M.; Gartzke, E.; Habs, D.; Neumayr, J. B.; Schürmann, C.; Szerypo, J.; Thirolf, P. G.;
A cylindrical double Penning trap system has been installed and commissioned at the Maier-Leibnitz-Laboratory (MLL) in Garching. This trap system has been designed to isobarically purify low-energy ion beams and perform highly accurate mass measurements. Technical details of the device and the first results of the commissioning measurements will be presented. The mass resolving power achieved in the first trap for 119Rb ions is R=139(2)×103, while a relative mass uncertainty of δm/m=2.9×10−8 was reached with the second trap (no analysis of systematic uncertainties included) when using 87Rb as a reference ion for 85Rb.
Keywords: Penning trap; Mass measurement; Mass separation; Buffer gas cooling

Publ.-Id: 12210 - Permalink


Criteria for system solution in Particle Therapy Positron Emission Tomography
Shakirin, G.;
Image processing in Particle Therapy Positron Emission Tomography (PT-PET) differs significantly from one in conventional nuclear medicine PET. The evaluation of dose delivery in particle therapy requires specific tasks to be solved during the analysis of the PT-PET images. Therefore, dedicated image quality criteria have been developed for PT-PET. These criteria together with a 3D configuration tool allow to construct an optimum PT-PET system for a given particle therapy facility and PET components supplier.
Keywords: in-beam PET, radiation therapy
  • Invited lecture (Conferences)
    Conference on Clinical and Experimental Research in Radiation Oncology (CERRO), 17.-24.01.2009, Les Menuires, France

Publ.-Id: 12209 - Permalink


Ion Bombardment of Solids - unified simulation of damage formation and thermally activated relaxation
Liedke, B.; Heinig, K.-H.; Facsko, S.; Möller, W.;
Till now, damage formation and thermally activated relaxation are calculated by different atomistic methods like Binary Collision Approximation (BCA, TRIM code) and kinetic Monte Carlo (kMC), respectively. However, frequently damage formation and relaxation happens simultaneously. Molecular Dynamics (MD), which treats both processes, can not describe them on experimental spatiotemporal scales due to insufficient computer power. Here, an unified TRIM-kMC simulation method will be presented and applied to ion-induced nanopatterning of surfaces as well as mixing and phase separation of intermetallic compounds.
Keywords: ion implantation, TRIM, Kinetic Monte-Carlo, unified description, nanopatterninig, interface mixing, phase separation
  • Lecture (others)
    Seminar at MFA of KFKI of Budapest, 11.11.2008, Budapest, Hungary

Publ.-Id: 12208 - Permalink


Simulation of defects and composition after irradiation of ultrathin Pt/Co/Pt film with Ga+
Liedke, B.; Facsko, S.; Fassbender, J.ORC; Jaworowicz, J.; Ferre, J.; Maziewski, A.; Vernier, N.; Möller, W.
Spin reorientation transition from in-plane to out-of-plane state has been observed experimentally in Pt/tCo/Pt film (tCo=3nm) after ion irradiation with 30 keV Ga+ [1]. Theoretical studies of the collision intermixing and defects creation processes of irradiated are presented. By means of TRIDYN simulations the dependence of composition and sputtering yield on ion fluence in the range of 1014 to 5 · 1016 ions/cm2 is elucidated. Simulations show that ion fluence plays non-neglectable role in case of erosion and intermixing of the interface (which likely gives a certain strain to the system), which give rise to the new phenomena, the so-called swelling effect. On the other hand the swelling effect can relax the strain in the film and give rise to an increase of the magnetic anisotropy. However, the strain relaxation can be strongly non-uniform on the full square area providing a mixture of patches with in-plane or out-of-plane anisotropy. The presence of relatively large and quasi-uniform perpendicular anisotropy partially comes from peculiar strain states at the interface. Simulated compositions are compared with experimentally observed irradiation induced phenomena.
Keywords: TRIDYN, implantation, Monte-Carlo simulation, intermixing, swelling
  • Poster
    PHYSICS OF MAGNETISM 2008, 24.-27.06.2008, Poznan, Poland

Publ.-Id: 12206 - Permalink


Fluorescence properties of a uranyl(V)-carbonate species [U(V)O2(CO3)3]5− at low temperature
Großmann, K.; Arnold, T.; Ikeda, A.; Steudtner, R.; Geipel, G.; Bernhard, G.;
Fluorescence properties of a uranyl(V)-carbonate species in solution are reported for the first time. The fluorescence characteristics of the stable aqueous uranyl(V)-carbonate complex [U(V)O2(CO3)3]5− was determined in a frozen solution (T = 153 K) of 0.5mM uranium and 1.5M Na2CO3 at pH 11.8 by time resolved laser-induced fluorescence spectroscopy (TRLFS). Two different wavelengths of 255nm and 408 nm, respectivelywere used to independently of each other excite the uranyl(V)-carbonate species. The resulting U(V) fluorescence emission bandswere detected between 380nmand 440 nm, with a maxima at 404.7nm (excitation with 255 nm) and 413.3nm (excitation with 408 nm), respectively. It was found that by using an excitation wavelength of 255nm the corresponding extinction coefficient was much higher and the fluorescence spectrum better structured than the ones excited at 408 nm. The fluorescence lifetime of the uranyl(V)-carbonate species was determined at 153K as 120s. TRLFS investigations at room temperature, however, showed no fluorescence signal at all.
Keywords: U(V) Uranyl(V)-carbonate Fluorescence Laser fluorescence spectroscopy

Publ.-Id: 12205 - Permalink


Boltwoodite [K(UO2)(SiO3OH)(H2O)1.5] and Compreignacite K2[(UO2)3O2(OH)3]2 • 7 H2O Characterized by Laser Fluorescence Spectroscopy
Arnold, T.; Baumann, N.;
Synthetically prepared boltwoodite and compreignacite were characterized with time-resolved laser-induced fluorescence spectroscopy (TRLFS). The obtained TRLFS emission spectra of both synthesized uranium minerals differ from each other in their positions of the vibronic peak maxima and in their fluorescence lifetimes. Also, the shapes of the spectra and their respective intensities are different. The TRLFS–spectrum of boltwoodite showed well-resolved sharp vibronic peaks at 485.1, 501.5, 521.2, 543.0, 567.4, and 591.4 nm with deep notches between them and compreignacite is characterized by two broad peaks with various shoulders. Here five emission bands were identified at 500.7, 516.1, 532.4, 554.3, and 579.6 nm. The shape of the TRLFS spectra of compreignacite is typical for uranium in a hydroxide coordination environment. For both minerals two fluorescence lifetimes were extracted. The two species of boltwoodite and compreignacite, respectively, showed the same positions of the peak maxima showing that the coordination environments are similar, but differ in the chemistry and number of possible quenchers, e.g. water molecules and hydroxide groups. For boltwoodite fluorescence lifetimes of 382 and 2130 ns, and for compreignacite shorter ones of 202 and 914 ns, respectively, were determined. The spectroscopic signatures of the two uranyl minerals reported here could be useful for identifying uranyl(VI) mineral species as colloids, as thin coatings on minerals, as minor component in soils, or as alteration products of nuclear waste.
Keywords: Boltwoodite, Compreignacite, Uranium(VI), Time-resolved Laser-induced Fluorescence Spectroscopy (TRLFS)

Publ.-Id: 12204 - Permalink


Precision measurements of the reconstructed image resolution for different PET and PET/CT scanners with the NEMA phantom.
Mix, M.; Weber, W. A.; van den Hoff, J.;
Objectives:
For multicenter PET studies robust techniques are required to measure the reconstructed image resolution of different PET systems. The aim of this study was to determine the reconstructed image resolution (RIR) using a NEMA phantom as a function of count statistics and image contrast.

Methods:
Measurements with the NEMA whole-body (WB) phantom at 7 scanner systems at different signal-to-noise levels and different target to background (T/BG) ratios were analyzed. Images were reconstructed iteratively using the default scanner WB reconstruction protocol. For each sphere, the image data were transformed to spherical coordinates relative to the center of the respective sphere yielding radial profiles. The RIR was then determined by fitting the convolution of a Gaussian point spread function with the object function (sphere+wall+BG) to these profiles.

Results:
With the presented procedure the RIR can be determined easily with a high statistical accuracy (average accuracy in 593 spheres 2.8+/-0.1%). For all scanners the RIR was distinctly lower than the scanner resolution according to NEMA. Image resolution was independent from counting statistic but deteriorated with decreasing target to BG (T/BG) ratios. The average resolution degradation in relation to the background free case was ~30% for a 6:1 T/BG ratio, over 50% for 3:1 and ~80% for 1.5:1. The degradation of RIR with decreasing contrast differed between the studied scanners.

Conclusions:
The presented algorithm is a robust approach for precise measuring reconstructed image resolution (RIR). The marked contrast ratio dependence of the RIR should be considered for quantitative PET studies in a multicenter setting.
  • Lecture (Conference)
    SNM 56th Annual Meeting, 13.-17.06.2009, Toronto, Canada

Publ.-Id: 12203 - Permalink


Diffusion suppression etc. during electrical activation in implanted Ge and Si-SOI
Skorupa, W.;
Recent results on diffusion suppression, electrical activation and related problems in implanted Ge and Si-SOI were reported. A prospect regarding millisecond thermal processing of high k dielectrics was given.
  • Invited lecture (Conferences)
    24. Nutzertreffen Kurzzeittemperung, 23.10.2008, Dortmund, Deutschland

Publ.-Id: 12202 - Permalink


Rare Earth Ion Beam Processing for Silicon Photonics
Skorupa, W.; Rebohle, L.; Prucnal, S.; Cherkouk, C.; Helm, M.;
Combining silicon-based electronic circuits with optoelectronic functionality is one of the key challenges for the future semiconductor technology. Such work must not only be devoted to the “telecommunication” wavelength of 1.54 µm because there are much more applications requiring light sources from the UV to IR wavelength range. In our work we employed ion beam processing to embed different rare earth (RE) luminescent centers (Gd, Ce, Tm, Tb, Eu, Er) into the silicon dioxide layer of purpose-designed Metal-Oxide-Silicon-based Light Emitting Devices (MOSLEDs) with advanced electrical performance. Efficient electroluminescence was obtained from UV to infrared with a transparent top electrode made of indium-tin oxide. Several developments for improving the device stability will be proposed related to charge compensation and the elimination of defects in SiO2. The electrical and electroluminescence properties of these devices are discussed and evaluated in respect of possible applications for biosensing applications. As an example our recent effort to detect estrogens in drinking water will be discussed.
  • Invited lecture (Conferences)
    2008 MRS Fall Meeting, Symposium D: Rare-Earth Doping of Advanced Materials for Photonic Applications, 01.-05.12.2008, Boston MA, USA

Publ.-Id: 12201 - Permalink


Casting experiments and materials studies for restoring lead pipes in historical organs
Skorupa, W.; Rossner, M.; Werner, H.; Eule, A.-C.; Schucknecht, T.; Rafaja, D.; Hausmann, U.; Wegscheider, K.;
We will report on a new casting technique basing on old recipes from the 17. and 18. century to produce new pipes approaching the quality of the old ones. Materials studies of old and new metal probes were performed by metallography and other methods. Different casting variants as well as the influence of hammering the casted metal plates onto the microstructure were investigated. In the course of these studies special consideration was devoted to the restoration projects at Borgentreich/Westfalen (Eule) and Stralsund/Vorpommern (Wegscheider).
  • Invited lecture (Conferences)
    25. Congress of the International Society of Organbuilders (ISO), 21.-26.09.2008, Danzig-Stralsund, Polen-Deutschland

Publ.-Id: 12200 - Permalink


A short review on Flash Lamp Annealing
Skorupa, W.;
A short review on Flash Lamp Annealing
  • Invited lecture (Conferences)
    Industrie-Projekttreffen mit BASF und Zentrum für Sonnenenergie-& Wasserstoff-Forschung Baden-Württemberg (ZSW), 18.11.2008, Stuttgart, Germany

Publ.-Id: 12199 - Permalink


Old Physics for Modern Nanotechnologies - Studies of Nano-Scale Ordering by Simulations and Experiments
Heinig, K.-H.;
Shaping and ordering of nanostructures is mandatory for many applications. However, top-down approaches like electron lithography have their limits and are expensive. Here, we present some bottom-up approaches like self-ordering and alignment at interfaces, which are driven by well-known thermodynamic processes like phase separation and surface energy minimization. The reaction pathways are studied by atomistic computer simulations and verified by experiments. The relevance for some applications, e.g. FLASH memories and Si-based light emitters, will be demonstrated.
Keywords: nanostructure formation, nanostructure shaping, ion irradiation, self-organisation, kinetic Monte Carlo simulation
  • Invited lecture (Conferences)
    Fizikai és Anyagtudományi Kutatóintézet Tanácstermében, 21.05.2008, Budapest, Hungary

Publ.-Id: 12198 - Permalink


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