Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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38996 Publications

Temporal evolution of dot patterns during ion sputtering

Bobek, T.; Facsko, S.; Kurz, H.; Dekorsy, T.; Xu, M.; Teichert, C.

The temporal evolution of the morphology of GaSb surfaces induced by ion bombardment is investigated.
The erosion process with normal incident argon ions forms a regular dot pattern that shows an increase of
ordering among the dots with increasing sputtering time. The pattern stabilizes to a highly uniform, hexagonally
ordered dot pattern for very long times. The degree of ordering is determined by quantitative analysis of
the surface roughness and the power spectral density of the surface pattern using atomic force microscopy. A
comparison of the experimental results with numerical integrations of the unstabilized Kuramoto-Sivashinsky
equation shows that this equation cannot reproduce essential details of the experimental pattern observed.

Keywords: ion sputtering; pattern formation; continuum equations; Kuramoto-Sivashinsky equation

  • Physical Review B 68 (2003) 085324

Publ.-Id: 5753

Status of the ELBE accelerator - a driver for different radiation sources

Michel, P.; Gabriel, F.; Grosse, E.

At the Forschungszentrum Rossendorf (FZR) the new facility ELBE for research with various kinds of radiation (IR from FEL´s, quasi-monochomatic channeling X-rays, bremsstrahlung in the MeV range, neutrons) is presently under construction. ELBE is centered around a superconducting Electron Linac which will produce quasi-continuous beams of high Brilliance and low Emittance. Electron beams with variable bunch charges up to 80 pC and variable repetition rates up to 260 MHz are produced in a pulsed thermionic DC gun followed by a two-stage RF bunching system. Two cryomodules each containing two 9-cell RF-cavities (1.3 Gz) accelerate the electrons t 40 MeV. At present the 250 keV injector has been installed and tested. The accelerator is planned to deliver a 20 MeV beam at the end of 2000. First results of beam parameter measurements at the 250 keV injector will be shown. Detailed transverse emittance studies by multi-slit techniques and investigations concerning the longitudinal phase space will be discussed

  • Lecture (Conference)
    FEL-Conferenz 2000

Publ.-Id: 5752

An internal friction working model to advance the understanding of effects of radiation and thermal ageing on reactor pressure-vessel steel

van Ouytsel, K.; de Batist, R.; Schaller, R.

Temperature- and amplitude-dependent internal-friction measurements have been carried out on JRQ A533B Cl. 1 steel, in order to investigate the influence of neutron irradiation and thermal ageing on this material. Neutron irradiation decreases the internal friction maximum observed in the vicinity of 315 K; this decrease is attributed to a reduction in the dislocation mobility by copper-rich clustering. Thermal ageing (3 years, 300 °C) clearly influences the internal friction highlighting the sensitivity of the technique.
A new working model - referred to as the new interpretation, based on a linear combination of seven dislocation-related relaxations - is introduced to provide a basis from which to explain more in detail the qualitative effects of thermal ageing and irradiation.
Amplitude-dependent results provide a measure of the yield stress which is compared with static tensile data and with a model for the yield stress comprising long- and short-range interactions. Neutron irradiation results in an athermal increase in the yield stress, while thermal ageing influences only the thermally activated part of the yield stress. The model is refined to explain the effects of thermal ageing and irradiation.

Keywords: Pressure vessel stee; Neutron irradiation; Thermal ageing, Dislocations, Embrittlement; Internal friction

  • International Journal of Pressure Vessels and Piping 80 (2003) 275-284

Publ.-Id: 5751

Development of Ti based coatings using plasma immersion ion implantation assisted deposition techniques and their properties

Mukherjee, S.; Richter, E.; Pham, M. T.; Maitz, M. F.; Prokert, F.; Möller, W.

Various Ti based coatings have been produced by plasma immersion ion implantation assisted deposition (PIIIAD) technique on a wide variety of substrates. In PIIIAD, the substrate is exposed to cathodic arc plasma comprising of metallic ions corresponding to the cathode composition, and the substrate is biased pulsed negative. The pulsed bias of the substrate gives alternate phases of deposition (during the bias off time) and implantation and deposition (during bias on time). Thus the deposition temperature can be controlled and simultaneously the compressive stress can be reduced, enhancing adhesion of the coating with the substrate. The deposition has been carried out in a neutral as well as reactive nitrogen environment, which leads to nitrogen bearing coatings. The coatings investigated are Ti, TiN, TiAl, TiAlN. It has been observed that the TiAl composition on the substrate depends on the bias and is different from the cathode composition. TiN and TiAlN coatings are hard coatings and show an enhanced wear resistance. All the coatings are tested for their suitability as biocompatible coatings on stainless steel substrates, and hence the adherence of osteoblast progenitor cells to these coatings was investigated in correlation with deposition parameters and surface morphology. The results indicate that these coatings can suitably be used as inert wear resistant coatings for orthopaedic implants.

Keywords: Biocompatibility; Cell adhesion; Titanium; coating; Titanium nitride

  • Lecture (Conference)
    XIIIth International Conference on Surface Modification of Materials by Ion Beams (SMMIB), San Antonio, Texas, 21.-26.09.2003

Publ.-Id: 5750

r0meson production in the pp->ppp+p-reaction at 3.67 GeV/c

Balestra, F.; Bedfer, Y.; Bertini, R.; Bland, L. C.; Brenschede, A.; Brochard, F.; Bussa, M. P.; Seon-Ho, C.; Colantoni, M. L.; Dressler, R.; Dzemidzic, M.; Faivre, J. C.; Ferrero, A.; Ferrero, L.; Foryciarz, J.; Frohlich, I.; Frolov, V.; Garfagnini, R.; Grasso, A.; Heinz, S.; Jacobs, W. W.; Kuhn, W.; Maggiora, A.; Maggiora, M.; Manara, A.; Panzieri, D.; Pfaff, H. W.; Piragino, G.; Popov, A.; Ritman, J.; Salabura, P.; Tchalyshev, V.; Tosello, F.; Vigdor, S. E.; Zosi, G.

kein Abstract

  • Physical Review Letters 89 (2002) 092001

Publ.-Id: 5749

Surface properties of NiTi alloy modified by plasma immersion ion implantation

Shevchenko, N.; Pham, M. T.; Maitz, M. F.

The titanium-nickel NiTi alloys is already in use in medical applications due to a good combination of shape memory or superelastic characteristics, biocompatibility and corrosion resistance. However, there are still concerns because of the high nickel content and a possible release of nickel ions, where toxicity and allergic hazards are well documented and carcinogenicity is under discussion. At present the influence of nickel on biocompatibility of the titanium - nickel alloys is an actual and open question for biomedical applications.

The aim of this work is to investigate surface modifications of nickel-titanium alloys and its influence on a biocompatibility and corrosion resistance.

Ar+ and/or N+ implantation in superelastic NiTi alloy with energy of 20-40 keV and fluences of (3-5) x 1017 cm-2 by means of plasma immersion ion implantation was performed.
The near surface layers were studied by grazing incidence X-ray diffraction analysis, Auger electron spectroscopy (AES), scanning electron microscopy and an analysis of the biocompatibility and corrosion resistance of these layers were performed.

The AES analysis of the implanted NiTi showed a reduced Ni content in the near surface (approx. 100 nm). Due to preferential sputtering of Ni and a Ni diffusion in the deeper layers a nickel depleted surface layer was produced, which was sealed by formation of a TiN layer. The deeper layers with a high Ni concentration contain mainly the Ni3Ti or Ni4Ti3 phases. Electrochemical corrosion experiments showed a significantly improved corrosion stability of the ion implanted surfaces.

Bone forming cells grown on untreated NiTi showed in several cases a disturbed cytoskeleton organisation as it was found also on pure nickel. As the effect could not be completely reproduced by nickel ions in the solution, it seems to be a surface effect. On the ion implanted surfaces the cell adherence always was undisturbed.

The results show that by Ar and N ion implantation the corrosion stability and biocompatibility of NiTi can be further improved.

Keywords: Nitinol; Plasmaimmersionsionenimplantation; PIII; Stickstoff

  • Lecture (Conference)
    XIIIth International Conference on Surface Modification of Materials by Ion Beams (SMMIB), San Antonio, Texas, 21.-26.09.2003

Publ.-Id: 5748

Forward K+ Production in Subthreshold pA Collisions at 1.0 GeV

Zolnierczuk, P.; Zwoll, K.; Zychor, I.; Debowski, M.; Müller, H.; Prietzschk, B.; Rimarzig, B.; Schneider, C.; Schneider, H.; Schneider, A.; Schleichert, R.; Schug, G.

kein Abstract

  • Phys. Rev. Lett. 87(2001)022301

Publ.-Id: 5747

Time-resolved dynamics of ta-C film deposition as predicted by molecular-dynamics simulations

Jäger, H. U.; Belov, A. Y.

The temporal pattern for ion beam deposition of amorphous carbon films is presented on the basis of molecular-dynamics simulations. An analytic interatomic potential of Brenner was adopted, but with an increased C-C interaction range. Deposition of films with a thickness of up to 10 nm was simulated for ion energies Eion =10-80 eV and for substrate temperatures Ts =100-900 K. The approach used describes quite accurately the properties (including sp2 clustering) of highly tetrahedral amorphous carbon (ta-C) films, overestimating, however, density of graphitic films, since the potential does not account for the long-range repulsion between non-bonded pi-orbitals.

A time-resolved analysis of atomic trajectories from the film deposition simulations revealed a short-term temperature-dependent relaxation stage (t~70-1000 fs), where the film formation is considerably influenced byTs . During this stage, depending on Ts , the carbon atoms at metastable highly coordinated sites can relax into either three- or fourfold coordinated positions. In agreement with experiment the molecular-dynamics simulations predict a sharp (within the range of about 50 K) transition from ta-C to graphitic carbon as Ts exceeds a critical temperature Tc . The behaviour of the sp3 content, density and the film stress near the transition temperature is discussed. For super-critical substrate temperatures (Ts > Tc ), the kinetic energy of the atoms is high enough to overcome the barrier in cohesive energy between a diamond-like and graphite-like film region. As a result, the relaxation processes lead finally to the energetically more favoured graphitic amorphous network. The diamond-like network remains stable in the case of deposition at sub-critical substrate temperatures (Ts <Tc ).

Keywords: diamond-like carbon; deposition simulations; substrate temperature; critical temperature

  • Lecture (Conference)
    14th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes, Nitrides & Silicon Carbide, 7-12 Sept. 2003, Salzburg, Austria

Publ.-Id: 5746

Titanium Oxide Layers prepared by Metal Plasma Immersion Ion Implantation and Deposition (MePIID) as Hemocompatible Surfaces

Tsyganov, I.; Wieser, E.; Prokert, F.; Richter, E.; Rogozin, A.; Maitz, M. F.

BACKGROUND: Titanium oxide is known for a good bio- and hemocompatibility, but this has not yet been correlated with crystal structure or electronic properties of this semiconductor. These physical features may be interesting because surface charges interact with charges of the protein and induce conformational changes of the protein with a change of function. Also chemical oxidation of proteins on the surface is under discussion for blood clotting activation.
METHOD: For this study Titanium oxide layers were deposited on oxidised Si as model substrate from a plasma produced by cathodic arc evaporation under addition of oxygen to the ambient near the substrate. The redox state of amorphous titanium oxide was additionally changed by ion implantation of Chromium, the electronic prop-erties of rutile TiO2 were changed by low dose implantation of the n-doping element Phosphorous. Both types of ion implantation should prevent an electron transfer from the protein to the surface. Blood platelet adherence and activation as well as clotting time were determined as parameters of hemocompatibility.
RESULTS: In dependence of the deposition parameters amorphous and nanocrystal-line structures, crystalline layers composed of anatase and brookite as well as layers dominated by the rutile phase have been obtained. The activation of the plasmatic clotting cascade was only minimally influenced by the crystal size and the crystallite structure of the titanium oxide films. As a trend, amorphous, nanocrystalline and fine-grained layers showed higher clotting times than well crystallized rutile films. Ion im-plantation of Cr or P strongly prolongated the clotting time, indicating a lower clotting activation. Only for P+-doped rutile both, enhanced clotting time and improved platelet adhesion, are observed. Contrasting tendencies in the dependence of clotting time and platelet adhesion on the Cr implanted Ti oxide have been stated.
CONCLUSION: Low dose P+ implantation into TiO2 can improve its blood compatibility, but it has to be worked out whether this effect really is due to modifications in the electronic properties of the TiO2 or due to biochemical effects. There was almost no effect of the crystal structure on the blood compatibility.

Keywords: Blutkompatibilität; Titanoxyd; Kristallstruktur; Dotierung

  • Poster
    XIIIth International Conference on Surface Modification of Materials by Ion Beams (SMMIB), San Antonio (Texas), 21.-26.09.2003
  • Contribution to proceedings
    XIIIth International Conference on Surface Modification of Materials by Ion Beams (SMMIB), San Antonio (Texas), 21.-26.09.2003

Publ.-Id: 5745

Proton beam examination of glass – an analytical contribution for preventive conservation

Mäder, M.; Neelmeijer, C.

Historic glass objects belong to the valuable artistic and cultural heritage that suffers a progressive deterioration due to atmospheric effects. For predicting the chemical stability of a glass object showing no visible alteration or corrosion damage, the three ion beam techniques PIGE, PIXE and RBS have been combined in simultaneous measurements at the Rossendorf external proton beam. Non-destructive determination of the glass bulk composition despite a thin corrosion layer on the glass surface facilitate the identification of glasses which are sensitive to environmental degradation, hence require specific storage conditions. The complete analytical reproduction of the chemical composition of unaffected glass using the combination of PIGE and PIXE is also discussed.

Keywords: glass corrosion; ion beam analysis; external beam; PIGE; PIXE; RBS; conservation; preservation

Publ.-Id: 5744

Electrochemical behaviour of bimetallic Ni-Ti surface generated by ion implantation

Pham, M. T.; Maitz, M. F.; Richter, E.; Reuther, H.; Prokert, F.; Mücklich, A.

Ni was surface-alloyed with Cu, Ti or Cu + Ti by ion implantation. The redox and catalytic activity of the materials was studied in NaOH by cyclic voltammetry. The surface was characterized by X-ray photoelectron spectroscopy, X-ray and electron diffraction, and electron and atomic force microscopy. All three materials exhibited a unique voltammetric response of Ni and were shown to stabilize the ß modification of the Ni oxide/hydroxide. Cu modified the anodic oxidation of glucose and the oxygen evolution to a higher degree than Ti. The morphology and microstructure differed from those of bulk materials.

  • Journal of Materials Science 19(2004)2, 439-446

Publ.-Id: 5741

Iridescent Art Nouveau glass - IBA and XPS for the characterisation of thin iridescent layers

Jembrih, D.; Neelmeijer, C.; Schreiner, M.; Mäder, M.; Ebel, M.; Svagera, R.; Peev, M.

The external proton beam of the Tandem accelerator on the research Centre in Rossendorf/Germany was used to carry out non-destructive particle-induced X-ray emission (PIXE) particle-induced gamma-ray emission (PIGE) and Rutherford backscattering (RBS) measurements simultaneously on Art Nouveau artefacts produced around 1900 by Tiffany/USA and Loetz/Austria. These studies should proof the technology of producing an iridescent layer on a glass surface. By means of the yield ratio Y(Si-K)/g(Si-g) of both characteristic X-radiation (Si-K) and g-radiation (Si-g) of the element silicon it could be shown that a thin top layer is present on the glass surface due to the treatment of the heated artefacts (about 500°C) with an alcoholic solution of SnCl2 [1]. Combined evaluation of the PIXE and RBS spectra resulted in a thickness of 20-300 nm for this top layer. In addition, a transition region between the iridescent layer and the bulk glass was obtained by RUMP simulations. XPS studies showed that the outermost layer consists of SnO2. The formation of other Sn compounds in the outermost near-surface region based on Sn-Si-O during the manufacturing process can be excluded.

Keywords: IBA; XPS; iridescent layers; Art Nouveau glass; Tiffany; Loetz

  • Nuclear Instruments and Methods in Physics Research B 181 (2001) 698-702

Publ.-Id: 5739

Comissioning of the ELBE Superconducting Electron Linac

Michel, P.; Büchner, A.; Evtushenko, P.; Gabriel, F.; Lehnert, U.; Teichert, J.; Voigtländer, J.

The radiation source ELBE at Forschungszentrum Rossendorf is based on a superconducting linear accelerator that produces a cw electron beam up to 40 MeV and 1 mA. In 2001 first stage of the ELBE-linac was put into operation. The main electron beam parameters like energy, energy spread, transverse emittance and bunch length were specified and several online diagnostic tools for ELBE routine high-power operation were tested, such as λ/4-stripline monitors and beam-loss detectors.

  • Lecture (Conference)
    EPAC 2002, Paris, Frankreich, 03.06. - 07.06.2002
  • Contribution to proceedings
    EPAC 2002, 03.-07.06.2002, Paris, Frankreich
    Proceedings of EPAC 2002

Publ.-Id: 5738

Zerstörungsfreie Röntgenfluoreszenzanalyse von Kunstwerken

Schreiner, M.; Mantler, M.; Neelmeijer, C.

Für die zerstörungsfreie Analyse von Kunstwerken ist die Messdatenerfassung an Luft erforderlich. RFA liefert hohe Signalintensitäten hauptsächlich für die schwereren und mittelschweren Elemente im PSE. Die geringe Nachweisempfindlichkeit für leichte Elemente, z. B. Si, wird durch starke Schwächung der niederenergetischen Röntgenstrahlung in Luft noch weiter herabgesetzt. Eine spezielle Messdüse mit Heliumdurchfluss verhindert diesen Effekt und macht den Nachweis leichter Elemente für RFA an Atmosphäre zugänglich.

Keywords: RFA; RFA an Luft; zerstörungsfreie Analyse; Kunstwerke

  • Contribution to proceedings
    Archäometrie und Denkmalpflege 2000, Jahrestagung der Arbeitskreise: deutscher Chemiker, deutsche mineralogische Gesellschaft, Landesamt für archäologie Dresden, Kurzberichte 2000, S. 201-204

Publ.-Id: 5737

Irisierende Jugendstilgläser - mit Röntgenfluoreszenz- und Ionenstrahlmethoden auf der Spur ihrer Geheimnisse

Jembrih, D.; Schreiner, M.; Neelmeijer, C.; Mäder, M.; Peev, M.; Krejsa, P.; Clausen, C.

Irisierende Jugendstilgläser zählen heute zu sehr kostbaren und beliebten Sammelobjekten zahlreicher Museen und Privatsammler. Die Geheimnisse der Herstellungstechnologie, die nur wenige Glasmanufakturen wie Tiffany (USA) und Lötz (Österreich-Ungarn) bis zu deren Perfektion entwickelt haben, beschäftigen heute viele Kunsthistoriker und Wissenschaftler, da die bekannten Patente oft Lücken enthalten. Auch die steigende Zahl der Fälschungen solcher Glasobjekte kommt immer mehr zum Tragen und dadurch wird häufig die Frage nach der eindeutigen Identifizierung sowie der Zuordnung der irisierenden Jugendstilgläser gestellt.

Keywords: Jugendstilgläser; Irisierung; zerstörungsfreie Identifizierung; Herstellungstechnologie; Tiffany; Lötz; RFA; PIGE; PIXE; RBS

  • Contribution to proceedings
    Archäometrie und Denkmalpflege, Jahrestagung der Arbeitskreise Achäometrie: deutsche Chemiker, deutsche Mineralogen, Landesamt für Archäologie Dresden, Kurzberichte (2000) pp. 116-119

Publ.-Id: 5736

Welche Ursachen haben die Schäden an Emailkunstwerken?

Müller, W.; Adam, K.; Neelmeijer, C.; Mäder, M.

Emails bestehen aus dem „Materialverbund“ Edelmetalllegierung und als dünne Schicht aufgebrachter farbiger Glasfluss. Thermomechanische Eigenschaften, chemische Zusammensetzung, Herstellungsprozess, aber auch die Geometrie der Objekte bestimmen die Schadensursachen.

Keywords: Email; Kunstwerke; Schäden; Ursachen; zerstörungsfreie Analyse

  • Restauro 6 (2000) pp. 414-418

Publ.-Id: 5735

Non-destructive characterisation of degraded glass objects and enamels

Schreiner, M.; Mäder, M.; Neelmeijer, C.

The aim of this interdisciplinary research project is the non-destructive analysis of glass/enamel objects of the Medieval and Baroque periods. For medieval stained glass, medieval goblets decorated with émail en ronde bosse, and artefacts of the baroque gold work, which are highly endangered by environmental effects, specific storage conditions shall be recommended in order to avoid further degeneration processes. The analytical procedure can be applied to museum objects as well as in situ artefacts with initial corrosion phenomena.

Keywords: art objects of glass; art objects of enamel; glass; enamel; non-destructive analysis; ion beam analysis; PIGE; PIXE RBS

  • Book (Authorship)
    Ion beam study of art and archaeological objects, ed. by G. Demortier and M. Adriaens, European Commission, Brussels, ISBN 92-828-7652-7 (2000) pp. 45-49

Publ.-Id: 5734

Paint layers - depth resolved analysis at the particle accelerator

Neelmeijer, C.; Mäder, M.; Schramm, H.-P.

PIXE, proton induced X-ray emission, is a proven method for non-destructive substantial analysis of art objects. By varying the proton energy this technique succeeds also in the non-destructive identification of layer sequences. Very thin surface layers can be characterised by simultaneous RBS, the detection of backscattered protons.

Keywords: paint layers; layer sequences; non-destructive analysis; ion beam analysis; depth resolved analysis; PIXE; RBS

  • Book (Authorship)
    Ion beam study of art and archaeological objects, ed. by G. Demortier and M. Adriaens, European Commission, Brussels, ISBN 92-828-7652-7 (2000), pp. 15-20

Publ.-Id: 5733

Johann Gregorius Höroldt fecit?

Neelmeijer, C.; Mäder, M.; Pietsch, U.; Ulbricht, H.; Walcha, H.-M.

Pigment studies on porcelain painting may help to support the attribution of a special artefact made from porcelain to a certain artist. Examinations of a variety of decoration details allow a representative image of the paint materials used. Non-destructive substantial analysis is guaranteed by X-ray (PIXE) and gamma-ray (PIGE) emission plus particle backscattering (RBS), induced by the proton beam at atmospheric pressure.

Keywords: porcelain painting; non-destructive analysis; ion beam analysis; PIXE; PIGE; RBS

  • Book (Authorship)
    Ion beam study of art and archaeological objects, ed. by G. Demortier and A. Adriaens, European Commission, Brussels, ISBN 92-828-7652-7 (2000), 54-59

Publ.-Id: 5732

Spectroscopic ellipsometry investigation of amorphous carbon films with different fraction of sp3 bonds: relation with protein adsorption

Vinnichenko, M.; Gago, R.; Huang, N.; Leng, Y. X.; Sun, H.; Kreissig, U.; Kulish, M. P.; Maitz, M.

Diamond like carbon (DLC) is known to posses high mechanical hardness and chemical inertness along with good bloodcompatibility. The latter is determined by protein - DLC surface interaction that is not properly addressed in the literature. These properties of DLC are determined to a large extent by sp3 bonds fraction and hydrogen content. Therefore, DLC films with different sp3 content have been produced by Ion Beam Assisted Deposition (IBAD) (low sp3) and Filtered Cathodic Vacuum Arc (FCVA) (high sp3) by changing deposition parameters.
The films were characterized by spectrocopic ellipsometry (SE) within the wavelength range l=300-1700 nm after deposition. The spectral dependences of ellipsometric parameters, D and Y, were acquired in autoretarder mode of VASE spectroscopic ellipsometer (J.A. Woolam Co., Inc., USA). To improve the quality of SE data reduction, multiple sample analysis was carried out for set of different thickness DLC samples produced by IBAD at the same deposition parameters on different substrates. The optical constants of DLC both with low and high content of sp3 bonds were parameterized in semiconductor model approach [2]. The SE data reduction yielded refraction and absorption index values, film thickness, band gap values of the DLC and surface roughness. Relation of SE results for samples produced by FCVA with Raman scattering data, which demonstrate D and G bands displacements, allowed proper characterization of the bonding structure of DLCs and estimation of sp3/sp2 fraction ratio. By using film thickness from SE results DLC film densities were estimated due to elastic recoil detection analysis (ERDA). ERDA also demonstrated only low amount of hydrogen mainly near film-substrate interface in DCLs produced by FCVA technique. Thus, it demonstrates that DLC properties modification is due to sp3/sp2 ratio variation and are not caused by variation of hydrogen content.
Deposition of human serum albumin labeled by fluorescein on DLC layers with different sp3 fraction was investigated. Selective binding of polyclonal antibody to the adsorbed albumin was quantified. The ratio of antibody binding to total adsorbed protein as measured by florescence gives the information about availability of epitopes and protein deformation.

Keywords: Ellipsometrie; Protein; Adsorption; Diamant-artiger Kohlenstoff

  • Poster
    3rd International Conference on Spectroscopic Ellipsometry, ICSE-3, 6-11 July, 2003, University Vienna, Austria, Presentation ThP F62
  • Contribution to proceedings
    3rd International Conference on Spectroscopic Ellipsometry, ICSE-3, 6-11 July, 2003, University Vienna, Austria, Presentation ThP F62

Publ.-Id: 5731

Native extracellular matrix coating on Ti surfaces

Pham, M. T.; Reuther, H.; Maitz, M. F.

Osteoblast-like SAOS-2 cells were allowed to synthesize and assemble their extracellular matrix (ECM) on titanium surfaces. After the selective removal of cells, Ti coated with a native ECM was obtained (ECM-Ti). The responses of SAOS-2 cells to ECM-Ti compared with those to peptide sequence RGDS- or fibronectin-immobilized Ti were examined,
demonstrating the compositional and structural effects needed to trigger the native cell behavior.

Keywords: Titan; Extracelluläre Matrix; Osteoblasten; Zelladhäsion

  • Journal of Biomedical Materials Research 66A (2003) 310-316

Publ.-Id: 5730

Blood Compatibility of Titanium-Based Coatings Prepared by Metal Plasma Immersion Ion Implantation and Deposition

Tsyganov, I.; Maitz, M. F.; Wieser, E.

Titanium with its natural oxide is known to be generally good biocompatible; and therefore, the suitability of some Ti-based coatings as coating for blood-contacting implants is analyzed. Layers of pure Ti, Ti oxynitrides (TiN1-xOx with x = 0.25, 0.50, and 0.75), and Ti oxides were deposited on oxidized Si from a plasma produced by cathodic arc evaporation under addition of N-2 and/or O-2 to the ambient near the substrate. The oxynitrides are crystalline with the fcc structure of TiN up to x = 0.25. For x = 0.5, a two-phase system of fcc TiN and fcc TiO has been found. In dependence on the deposition parameters, amorphous and crystalline layers (anatase + brookite or rutile) of TiO2 have been obtained. The rutile layers were doped by implantation of P. The amorphous TiO2 layers were implanted with Cr. To study the correlation between structure of the coating and blood compatibility, the clotting time of blood plasma as well as the adhesion and activation of blood platelets o! n the surface was investigated. TiN and oxynitrides showed the longest clotting time compared to rutile. Minimum platelet adhesion has been observed for pure TiO2. Contrasting tendencies in the dependence of clotting time and platelet adhesion on the microstructure have been stated. However, for P+-doped rutile, both enhanced clotting time and improved platelet adhesion were observed. Platelet adherence and activation always showed similar trends. (C) 2004 Elsevier B.V. All rights reserved.

Keywords: Blood compatibility; biomaterials; titanium oxide; TiO2; titanium oxynitride

  • Poster
    Abstracts of the 8 European Vacuum Congress EVC-8, Berlin, 23-26 June 2003. Berlin, Germany, 2003. P.93-94.
  • Applied Surface Science 235(2004), 156-163
    DOI: 10.1016/j.apsusc.2004.05.134
    Cited 73 times in Scopus
  • Contribution to proceedings
    Abstracts of the 8 European Vacuum Congress EVC-8, Berlin, 23-26 June 2003. Berlin, Germany, 2003. P.93-94.

Publ.-Id: 5729

Paintings - a challenge for XRF and PIXE analysis

Neelmeijer, C.; Brissaud, I.; Calligaro, T.; Demortier, G.; Hautojärvi, A.; Mäder, M.; Martinot, L.; Schreiner, M.; Tuurnala, T.; Weber, G.

Conventional pigment analysis of paintings requires the removal of micro-samples followed by the preparation of cross-sections. There are also requirements for investigating several locations within a painting in order to obtain information about dating and provenance or the reason for aesthetic impressions of the paint materials. The need to carry out such work without removing samples prompted the present project, in which the authors aimed to examine the possibility of applying XRF and PIXE methods in a complementary manner. The ion beam techniques of external PIXE plus Rutherford backscattering could distinguish painting techniques, i.e. paint layer arrangements and pigment admixtures, whereas portable XRF represents a valuable tool for preselecting the objects of interest which could be transported to the ion beam laboratory. This procedure was tested using samples of prepared paint layers. It is shown that it is possible to distinguish between two or three layers. The situation would be more difficult for more complex paint layer arrangements.

Keywords: Paint layers; non-destructive analysis; XRF; PIXE; RBS; x-ray fluorescence analysis; ion-beam analysis; paint layer identification

  • X-Ray Spectrometry, 29, 2000, pp. 101 - 110

Publ.-Id: 5727

Diagnose von Kunstwerken am Teilchenbeschleuniger

Neelmeijer, C.; Mäder, M.; Wagner, W.; Sandner, I.; Schramm, H.-P.

Die zerstörungsfreie Identifizierung von Malschichten mittels Protonenstrahlen an Luft wird exemplarisch an der Torgauer Tafel "14 Nothelfer" (Lucas Cranach der Ältere) vorgestellt. Durch Variation der Protonenenergie lassen sich Abfolgen von Malschichten sichtbar machen.

Keywords: Ionenstrahlanalyse; zerstörungsfreie Analyse; Malschichten; PIXE

  • Other report
    Einsatz neuer Technologien in den Geisteswissenschaften, 1997, S. 28 - 30 BEO: Projektträger Biologie, Energie, Ökologie des BMBF

Publ.-Id: 5726

Diagnose von Kunstwerken am Teilchenbeschleuniger

Neelmeijer, C.; Wagner, W.; Schramm, H.-P.

Externe PIXE, protoneninduzierte Röntgenemission an Luft, hat sich als zerstörungsfreie Methode zur Substanzanalyse von Kunstwerken bewährt. Durch Variation der Protonenenergie gelingt es jetzt auch, Schichtenabfolgen zerstörungsfrei zu identifizieren. Extrem dünne Oberflächenschichten können durch RBS, die Detektion der rückgestreuten Protonen, charakterisiert werden.

Keywords: Ionenstrahlanalyse an Luft; zerstörungsfreie Analyse; PIXE; RBS; Malschichten

  • Restauro 5 (1995) pp. 326 - 329

Publ.-Id: 5725

Nondestructive pigment analysis in paint layers using ion-beam methodes on air

Neelmeijer, C.; Wagner, W.

Restorers, art scientists and criminalogists are interested in the material composition of historic paintings. The substantial and structural analysis of details of paint layers are helpful and necessary to distinguish originals from forgeries, to decide on original states and later additives, to support statements on age and provenance and to understand aging phenomena. The basic idea of non-destructive paint layer analysis is demonstrated using PIXE at different proton energies.

Keywords: ion beam analysis; non-destructive analysis; PIXE; pigment analysis; paintings; paint layers

  • Naturwissenschaften 81, 553 - 554 (1994)

Publ.-Id: 5724

Das Servatius-Reliquienkästchen aus dem Quedlinburger Schatz

Wendt, C.; Neelmeijer, C.

An dem Reliquienkästchen aus der Stiftskirche in Quedlinburg, das derzeit im Berliner Kunstgewerbemuseum ausgestellt ist, wurde für die Untersuchung von Metall die zerstörungsfreie Röntgendiagnostik am Teilchenbeschleuniger (PIXE) gewählt. Sie soll Aufschluss über die zeitliche Einordnung der verschiedenen Fassungen geben. Die hohe Bedeutung und Einmaligkeit des Objekts rechtfertigte den apparativen und finanziellen Aufwand dieser Methode. Ein Bericht über die Restaurierung des Kästchens wird folgen.

Keywords: Ionenstrahlanalyse; Protonenstrahl an Luft; zerstörungsfreie Analyse; PIXE; Gold; Analysen an Kunstwerken

  • Restauro 2 (1993) pp. 93 - 98

Publ.-Id: 5723

Verfahren zur schmelzmetallurgischen Herstellung von Magnetlegierungen auf Nd-Fe-B-Basis

Hermann, R.; Gerbeth, G.; Filip, O.; Priede, J.

Der a-Fe-Volumenanteil in den Magnetlegierungen auf Nd-Fe-B-Basis wird reduziert.

  • Patent
    DE 103 31 152 A1
  • Patent
    WO 2005/003396 A1

Publ.-Id: 5722

Analyse non-destructive par faisceaux d'ions du panneau provenant du retable des Quatorze Intercesseurs de Lucas Cranach l'Ancien

Neelmeijer, C.

Les résultats analytiques par faisceaux des protons à pression atmosphérique et par la combination PIXE-RBS sont presentées pour charactériser la stratification des pigments sur le retable "Quatorze Intercesseurs" de Lucas cranach l'Ancien.

Keywords: PIXE; PIGE; l'analyse par faiseaux d'ions; l'analyse non-destructive; la stratification des pigments

  • Dossier de la Commission Royale des Monumnts, Sites et Fouilles, 10, p. 107

Publ.-Id: 5721

P0311 - Verfahren und Vorrichtung zur schmelzmetallurgischen Herstellung von Magnetlegierungen auf Nd-Fe-B-Basis

Hermann, R.; Gerbeth, G.; Filip, O.; Priede, J.; Schultz, L.

Es wird der a-Fe-Volumenanteil in den Magnetlegierungen auf Nd-Fe-B-Basis reduziert.

  • Patent
    DE 103 28 618 A 1
  • Patent
    WO 2004/112993 A1
  • Patent
    DE 103 28 618 B4 - 24 / 04/ 2008

Publ.-Id: 5720

Intravasal lipid transfer in impaired glucose tolerance (IGT): role of the cholesterol ester transfer protein (CETP)

Julius, U.; Kirschner, E.; Pietzsch, J.

  • Poster
    63rd Scientific Session of the American Diabetes Association (ADA), New Orleans, USA, 13-17 June 2003
  • Lecture (Conference)
    In: Proceedings of the 21th International Symposium on Diabetes and Nutrition - Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD), Bruges, Belgium, 19-22 June 2003
  • Abstract in refereed journal
    Diabetes 52(2004)suppl. 1, A211-A212

Publ.-Id: 5719

Verfahren und Vorrichtung zum Ziehen von Einkristallen durch Zonenziehen

Priede, J.; Gerbeth, G.; Hermann, R.; Behr, G.; Schultz, L.; Uhlemann, H.-J.

Es wird die verbesserte Stabilität des Züchtungsprozesses und eine verbesserte Qualität des Einkristalls erreicht.

  • Patent
    DE 103 28 859 A 1
  • Patent
    WO 2004/113596 A1
  • Patent
    DE 103 28 859 B4 - 27. Sept. 2007

Publ.-Id: 5718

Biodistribution and catabolism of [18F]fluorobenzoylated amino acids, peptides and proteins

Bergmann, R.; Pawelke, B.; Hultsch, C.; Pietzsch, J.; Wüst, F.; Henle, T.; Johannsen, B.

  • Contribution to proceedings
    In: Cancer Biotherapy & Radiopharmaceuticals (2003) 18: 280-281; 16th International Meeting of the International Research Group in Immunoscintigraphy and Immunotherapy (IRIST), Capri, Italy, 8-10 May 2003
  • Poster
    16th International Meeting of the International Research Group in Immunoscintigraphy and Immunotherapy (IRIST), Capri, Italy, 8-10 May 2003

Publ.-Id: 5715

Verfahren zur Herstellung einer nickelarmen Oberfläche auf Nitinol

Shevchenko, N.; Maitz, M.; Pham, M. T.

Die Nitinol-Oberfläche wird so modifiziert, dass sie durch Nickel-Armut oder -freiheit gut biovertäglich ist, ohne die gewünschten mechanischen Eigenschaften des Materials an sich zu verändern. Die Oberflächen-Schicht ist mechanisch stabil, kratzunempfindlich und fest haftend.

  • Patent
    Offenlegungsschrift 103 25 410 A1 2004
  • Patent
    WO 2004/108983 A2

Publ.-Id: 5714

Anordnung zur Bestimmung der Phasenverteilung in strömenden Mehrphasenmedien und Verfahren zur Auswertung der mit der Anordnung gewonnenen Messsignale

Zschau, J.

Es wird die Phasenverteilung des Strömungsmediums mit Hilfe von Sender-Empfangsstrecken ohne tomographische Nachberechnung mit hoher örtlicher, zeitlicher und stofflicher Auflösung für mehrphasige Medien auch nichtleitender Art zweidimensional bestimmt.

  • Patent
    Offenlegungsschrift 103 18 548.8 A1 2004
  • Patent
    WO 2004/095010 A1
  • Patent
    DE 103 18 548 B4 - 08. Febr. 2007

Publ.-Id: 5713

Technetiummarkierte Fettsäuren und deren Verwendung für die Myokarddiagnostik sowie Verfahren zur Herstellung der technetiummarkierten Fettsäuren

Spies, H.; Pietzsch, H.-J.; Jung, C.

Es werden Substanzen vorgeschlagen, die nach Applikation in den Körper metabolisch stabil hinsichtlich des Chelats sind und vom Herzmuskel aufgenommen werden. Die Herstellung der Substanzen wird angegeben.

  • Patent
    Patentanmeldung 103 16 965.2
  • Patent
    Offenlegungsschrift 103 16 965 A1 2004
  • Patent
    WO 2004/092184 A1

Publ.-Id: 5712

Analysis of non-protein amino acids as specific markers of protein oxidation: the use of N(O,S)-ethoxycarbonyltrifluoroethyl ester derivatives and GC-MS

Pietzsch, J.

Oxidative modification of proteins can interfere with critical cellular functions, and is widely regarded as a crucial event in the pathogenesis of various diseases ranging from rheumatoid arthritis to atherosclerosis and cancer. The mechanisms of formation and the nature of the altered amino acid side chain residues formed on proteins subjected to oxidant attack are reviewed. In this line, a new GC-MS method using N(O,S)-ethoxycarbonyltrifluoroethyl amino acid esters (ECEE-F3) for rapid and sensitive determination of 3-chlorotyrosine, 5-hydroxy-2-aminovaleric acid (HAVA), and 6-hydroxy-2-aminocaproic acid (HACA) in proteins is discussed. 3-Chlorotyrosine is a highly specific marker of myeloperoxidase-catalyzed protein oxidation, whereas HAVA and HACA are specifically formed by metal-catalyzed oxidation processes. ECEE-F3 derivatives are formed by the unlabored reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. The key steps of the methodology employed are i) enzymatic hydrolysis of target proteins to prevent decomposition of oxidation products during hydrolysis and ii) an uniquely rapid derivatization of amino acids completing sample preparation for GC within a few minutes in aqueous solution at room temperature. Femtomole levels of 3-chlorotyrosine, HAVA, and HACA can be reproducible measured in different protein preparations subjected to oxidative damage in vitro. Furthermore, the use of these stable products of protein amino acid side chain oxidation as potential markers for assessing oxidative damage in patients with inflammatory and metabolic disorders ex vivo and in vivo is demonstrated. Evidence is presented to show that the pattern of products detected may yield information as to the nature of the original oxidative insult.

  • Abstract in refereed journal
    In: Proceedings of the 2nd International Conference on Biomedical Spectroscopy, London, UK 5-8 July 2003
  • Lecture (Conference)
    2nd International Conference on Biomedical Spectroscopy, London, UK, 5-8 July 2003

Publ.-Id: 5711

Verfahren zur Behandlung Silizium-basierter Lichtemitter

Skorupa, W.; Nazarov, A.; Yankov, R.; Gebel, T.; Rebohle, L.

Die Oxiddegradation wird vermindert.

  • Patent
    Patentanmeldung 103 13 727.0
  • Patent
    Offenlegungsschrift 103 13 727 A1 2004

Publ.-Id: 5710

In situ Verfahren zur Filmoptimierung bei der ITO-Abscheidung

Rogozin, A.; Vinnichenko, M.; Kolitsch, A.

Es wird der Messaufwand für die Bestimmung der elektrischen Parameter bei der ITO-Abscheidung gesenkt.

  • Patent
    Patentanmeldung 103 12 593.0
  • Patent
    DE 103 12 593 A1

Publ.-Id: 5708

Measurement of 5-hydroxy-2-aminovaleric acid as a specific marker of iron-mediated oxidation of proline and arginine residues of low density lipoprotein aplipoprotein B-100 in human atherosclerotic lesions

Pietzsch, J.; Bergmann, R.

Gamma-Glutamyl-semialdehyde (Gamma-GSA) is a major product of the metal catalysed oxidation of apolipoprotein B-100 (apoB-100) proline and arginine residues. On reduction, Gamma-GSA forms 5-hydroxy-2-aminovaleric acid (HAVA). This report describes the application of HAVA measurement to characterise the formation of Gamma-GSA in low density lipoprotein (LDL) recovered from human atherosclerotic lesions. HAVA concentrations were greatly increased in LDL from early (mean, 10.25; SD, 3.49 mol/mol apoB-100; p < 0.01), intermediate (mean, 11.18; SD, 2.37 mol/mol apoB-100; p < 0.01), and advanced (mean, 9.91; SD, 2.15 mol/mol apoB-100; p < 0.01) lesions, when compared with LDL from normal aortic tissue (mean, 0.05; SD, 0.01 mol/mol apoB-100). These findings support the hypothesis that pathways involving metal catalysed oxidation of LDL apoB-100 are of pathological importance in atherogenesis. LDL apoB-100 recovered from human aortic vascular lesions. These observations provide quantitative chemical evidence for metal catalysed oxidative processes in the human artery wall.

  • J Clin Pathol (2003) 56: 622-623

Publ.-Id: 5706

Flavonoide: Wirkmechanismen und neue Anwendungsmöglichkeiten (Teil 2)

Pietzsch, J.; Bergmann, R.; Wüst, F.

Die in Nahrungspflanzen enthaltenen Flavonoide umfassen eine sehr umfangreiche Gruppe von Molekülen, die über verschiedene Wirkmechanismen einen Einfluss auf die Entstehung und Progression von Tumoren, die Atherogenese und andere chronische Erkrankungen nehmen können (BIOforum 5/2003, S. 289-291). Die zugrundeliegenden zellulären Prozesse sind bisher nur ansatzweise geklärt und wurden erst für wenige ausgewählte Verbindungen dieser umfangreichen Stoffgruppe untersucht.
Noch ist man vorsichtig mit Aussagen über klinische Wirkungen der Flavonoide, da viele Studien rein experimentell sind bzw. nur an Tiermodellen durchgeführt wurden. Einige epidemiologische Studien (Copenhagen City Heart Study, Physician´s Health Study, Nancy Study, Mainzer Weinstudie, u. a.) lassen aber bereits annehmen, dass durch die Aufnahme von Flavonoiden Herz-Kreislauf-Krankheiten und vermutlich auch anderen chronischen Krankheiten vorgebeugt werden kann [1,6]. Ob die Befunde dieser zuletzt genannten Studien tatsächlich auf der Wirkung bestimmter Flayonoide beruhen, erfordert detailliertere Untersuchungen über das Flavonoidspektrum in verschiedenen Lebensmitteln und Lebensmittelzubereitungen, ihre Bioverfügbarkeit im menschlichen Organismus und ihre spezifischen zellulären Wechselwirkungen.

  • Bioforum (2003) 6:384-385

Publ.-Id: 5704

Flavonoide: Wirkmechanismen und neue Anwendungsmöglichkeiten (Teil 1)

Pietzsch, J.; Bergmann, R.; Wüst, F.

Flavonoide sind polyphenolische Verbindungen mit ubiquitärem Vorkommen in Lebensmitteln pflanzlicher Herkunft. Sie sind in allen höheren Landpflanzen die mengenmäßig am häufigsten auftretenden sekundären Pflanzeninhaltsstoffe und stellen innerhalb der Polyphenole eine Substanzgruppe mit sehr großer Strukturvielfalt dar.
Sekundärmetabolite galten lange als "Abfallprodukte" des pflanzlichen Stoffwechsels. In den letzten Jahrzehnten wurde allerdings deutlich, dass solche Verbindungen eine entscheidende Bedeutung bei der Anpassung von Pflanzen an biotische und abiotische Stressfaktoren haben. Besonders hervorzuheben ist ihre Funktion als Abwehrwaffe gegen Fressfeinde, Parasiten und Pathogene. Neuere experimentelle Erkenntnisse an Zellen und Tiermodellen sowie erste epidemiologische Untersuchungen beim Menschen belegen das breite Spektrum biologischer Wirkungen von Flavonoiden und rücken diese vielseitigen Naturstoffe damit in den Mittelpunkt des wissenschaftlichen Interesses.

  • Bioforum (2003) 5: 289-291

Publ.-Id: 5703

Spezifische Glukoseverstärkung der Hämin-(Fe3+)-katalysierten LDL-Oxidation in vitro und in vivo

Julius, U.; Pietzsch, J.

  • Contribution to proceedings
    In: Heinle H, Schulte H, Hahmann H. (Hrsg.) Geschlechtsspezifische Mechanismen der Arteriosklerose; 16. Jahrestagung der Deutschen Gesellschaft für Arterioskleroseforschung; Köhler Druck, Tübingen, (2003) 70-74

Publ.-Id: 5702

Thermodynamic Sorption Models: Derivation of Recommended Data Sets and Application to Performance Assessment

Brendler, V.; Richter, A.; Arnold, T.; Bernhard, G.

This paper integrally addresses three topics: the general predictive capabilities of Surface Complexation Models (SCM) for radionuclide migration modeling, their current state of parametrization based on a respective database, and the application for performance assessment (PA).

The SCM concept is mineral-specific and can therefore also be used for additive models of more complex solid phases such as rocks or soils. It properly takes into account the physico-chemical phenomena governing the contamination source term development in time and space. One major aspect there is the substitution of conventional distribution coefficients (KD-values) for the empirical description of sorption processes, most often applied in risk assessment studies so far. Thus, the framework of a "Smart KD" is developed for complex scenarios with a detailed explanation of the underlying assumptions and theories. It helps to identify essential processes and the associated most critical parameters, easing further experimental refinement studies.

As to the knowledge of the authors, so far there is no digital thermodynamic database for surface complexation equilibria existent world-wide, despite the vast amount of available data. Therefore, the "Rossendorf Expert System for Surface and Sorption Thermodynamics" (RES³T) was developed [1]. Originally implemented as a stand-alone relational database under MS Access on a PC, now RES³T is also connected to the WWW and accessible through commonly used web browser interfaces. An integrated user interface allows to easily access selected mineral and sorption data, to convert parameter units, to extract internally consistent data sets for sorption modeling, and to export them into formats suitable for other modeling software. Data records comprise of mineral properties, specific surface area values, characteristics of surface binding sites and their protolysis, sorption ligand information, and surface complexation reactions. All relevant submodels are already implemented, extensions to other variants are straightforward. An extensive bibliography is attached, providing links not only to the above listed data items, but also to background information concerning surface complexation model theories, related software for data processing and modeling, sorption experiment techniques, and independent spectroscopic evidence of surface species. RES³T assists the identification of critical data gaps, the evaluation of existing parameter sets, consistency tests and the establishment of selected reference data sets.

High-quality experimemtal sorption data sets as provided by Phase II of the NEA Sorption Project for its fitting assessment efforts were used. The systems covered are Np(V) sorption onto hematite, U(VI) sorption onto quartz and Se sorption onto goethite. To keep the number of parameters at a minimum, the Diffuse Double Layer model was selected to account for electrostatics. All calculations were performed with the FITEQL code, version 3.2 [2]. Based on the information in the sorption database RES³T for the above minerals and chemically similar phases, first a set of relevant species was formed. Then respective surface complexation parameters were taken from RES³T: the binding site density for the minerals, the surface protolysis constants, and the brutto stability constants for all relevant surface complexes. To be able to compare and average thermodynamic constants originating from different sources, the normalization concept as introduced by Kulik [3] was applied. Lacking data was substituted by estimates exploiting chemical analogy. The only system-specific parameters directly going into the computations were the solid-liquid ratio and the specific surface area. The model prediction almost always represented the experimental values for the sorbed amount of Np, U and Se, expressed as conventional distribution coefficients KD as required by PA software, within one order of magnitude or better, provid...

  • Lecture (Conference)
    Waste Management Conference 2004, Topic 6, Tucson, Ariz., United States
  • Contribution to proceedings
    Waste Management Conference 2004, 29.02.-04.03.2004, Tucson, Ariz., United States

Publ.-Id: 5701

First results from subthreshold K+ production measurements with ANKE

Barsov, S.; Bechstedt, U.; Borchert, G.; Borgs, W.; Büscher, M.; Debowski, M.; Drochner, M.; Erven, W.; Eüer, R.; Fedorets, P.; Gotta, D.; Hartmann, M.; Junghans, H.; Kacharava, A.; Kamys, B.; Klehr, F.; Koch, H. R.; Komarov, V. I.; Koptev, V.; Kulessa, P.; Kulikov, A.; Kurbatov, V.; Macharashvili, G.; Maier, R.; Mikirtichyants, S.; Merzliakov, S.; Müller, H.; Mussgiler, A.; Nioradze, M.; Ohm, H.; Petrus, A.; Prasuhn, D.; Pysz, K.; Rathmann, F.; Rimarzig, B.; Rudy, Z.; Schleichert, R.; Schneider, C.; Schult, O. W. B.; Seyfahrt, H.; Sistemich, K.; Stein, H. J.; Ströher, H.; Wüstner, P.

The new spectrometer ANKE has been put into operation at the accelerator COSY of the Forschungszentrum Jfilich. An initial scientific goal is to study K+-production in pA collisions at subthreshold energies below the free NN-threshold of T = 1.58 GeV. First measurements of double differential cross sections in p12C collisions at emission angles around 0° have been performed at T = 1.0,1.2 and 2.0 GeV. The challenge is to identify the kaons in a huge background of pions and protons, since the signal to background ratio decreases to about 10-6 at T = 1.0 GeV. For background suppression detectors and a trigger system based on energy-loss and time-of-flight measurements have been developed.
In the analysis the decay of kaons (τ = 12.4 ns) stopped in the detection system into π+ and μ+ is exploited as well as the track information from the wire chambers.

  • Nucl. Phys. A675 (2000) 230c-233c

Publ.-Id: 5700

The ANKE spectrometer at COSY-Jülich and studies of the subthreshold K+ production

Barsov, S.; Bechstedt, U.; Borchert, G.; Borgs, W.; Büscher, M.; Debowski, M.; Erven, W.; Eüer, R.; Fedorets, P.; Gotta, D.; Junghans, H.; Kacharava, A.; Kamys, B.; Klehr, F.; Koch, H. R.; Komarov, V. I.; Koptev, V.; Kulessa, P.; Kulikov, A.; Kurbatov, V.; Macharashvili, G.; Maier, R.; Mikirtichyants, S.; Merzliakow, S.; Müller, H.; Mussgiller, A.; Nioradze, M.; Ohm, H.; Petrus, A.; Prasuhn, D.; Pysz, K.; Rathmann, F.; Rimarzig, B.; Rudy, Z.

kein Abstract

  • Nucl. Phys. A 663 (2000) 1107

Publ.-Id: 5699

Intraindividual comparison of [11C]acetate and [11C]choline PET for detection of metastases of prostate cancer

Kotzerke, J.; Volkmer, B. G.; Glatting, G.; van den Hoff, J.; Gschwend, J. E.; Messer, P.; Reske, S. N.; Neumaier, B.

In a pilot trial we investigated whether significant differences in prostate cancer (PCA) imaging would be observed using [11C]acetate and [11C]choline positron emission tomography (PET).
Methods: Twelve patients were studied with both radiotracers. Whole body PET without attenuation correction was performed after injection of 0.95 ± 0.15 GBq [11C]acetate and 0.84 ± 0.13 GBq [11C]choline, respectively, from 5 to 60 min p. i. Focally increased uptake in bone, below the urinary bladder or in a lymph node region was considered as tumour. Primary tumour, lymph node involvement, bone metastases, local recurrence; and no evidence of disease were known in 2, 4, 2, 2; and 2 patients, respectively.
Results: [11C]acetate uptake was highest in spleen and pancreas while [11C]choline uptake was predominant in liver and kidney parenchyma. However, interindividual variation was high. The potential of both radiotracers to detect known bone lesions, lymph node metastases, and imaging of the primary tumour was identical. However, both failed to detect a small local recurrence in two patients as well as to demonstrate lymph node involvement in one patient, which was confirmed by surgery.
Conclusion: In this preliminary study, uptake of both radiotracers in prostate cancer or its metastases was nearly identical and none of them should be favoured. At present, both radiotracers influence patient management by detection of local recurrence, lymph node, or bone metastases of PCA.

Keywords: acetate; choline; positron emission tomography; prostate cancer

  • Nuklearmedizin (2003); 42 (1): 25-30

Publ.-Id: 5698

Application of autocathode in a superconducting electron RF injector for the industry acclerator

Janssen, D.; Volkov, V. N.; Konstantinov, S. G.; Kudryavtsev, A. M.; Myskin, O. K.; Petrov, V. M.; Tribendis, A. G.

Recently, publications on the development of cold field emission cathodes with current high density at rather low voltage applied are very broadly spread [1,2]. In the work presented here, the computer simulation has been performed for one of the versions of application of such cathodes in a superconducting RF cavity of the electron injector designed for the industrial accelerator.

  • Lecture (Conference)
    APAC01, September 17-21, 2001, Beijing, China

Publ.-Id: 5697

Infrared characterization of environmental samples by photothermal beam deflection using a free electron laser

Seidel, W.; Foerstendorf, H.; Heise, K.-H.; Ortega, J.-M.; Glotin, F.; Prazeres, R.

The low concentration of toxic radioactive metals in environmental samples often limits the interpretation of results of infrared studies investigating the interaction processes between the metal ions and environmental compartments. For the first time, we could show that photothermal infrared spectroscopy performed with a pulsed free-electron laser can provide reliable infrared spectra throughout a distinct spectral range of interest. In this model investigation, we provide vibrational absorption spectra of a rare earth metal salt dissolved in a KBr matrix and a natural calcite sample obtained by thermal beam deflection technique and FT-IR spectroscopy, respectively. General agreement was found between all spectra of the different recording techniques.

Keywords: Keine

  • Poster
    Proc. 25th Int. Conf. on Free Electron Laser, and the 10th FEL User Workshop, Tsukuba, Ibaraki, Japan, 8 - 12 September 2003, (North-Holland, Amsterdam, 2004) ed. (eingereicht)
  • Contribution to proceedings
    Proceedings. of the 25th International. Conference on Free Electron Laser, and the 10th FEL User Workshop,08.-12.09.2003 Tsukuba, Ibaraki, Japan, (North-Holland, Amsterdam, 2004)

Publ.-Id: 5696

The optical resonator of the IR-FEL at ELBE

Seidel, W.; Evtushenko, P.; Gippner, P.; Grosse, E.; Jainsch, R.; Oepts, D.; Sobiella, M.; Wohlfarth, D.; Wolf, A.; Wolf, U.; Wünsch, R.; Wustmann, B.

To allow first lasing at the ELBE FEL at the end of 2003 various efforts have been made. In particular, the optical resonator including the system which controls and stabilizes its length and alignment has been installed and tested. The resonator length is controlled by means of an interferometer beam passing diagonally from one side of the upstream mirror to a retroreflector on the opposite side of the downstream mirror.
To avoid temperature effects the mirror holders have been equiped with a special heating and cooling system which stabilizes the mirror temperature. Simulating maximum laser power the cavity detuning due to temperature changes has not exceeded 1micron.
The alignment of the resonator axis is controlled by the overlap of two He-Ne laser beams entering the resonator from each side. To predict the outcoupled laser power and the upper wavelength limit we have modeled the IR-beam propagation in the optical resonator. In particular, the vacuum chamber in the undulator, which is 10 mm high, and the outcoupling hole affect the beam power and profile significantly; respective results will be presented.

Keywords: Keine

  • Poster
    25th Int. Conf. on Free Electron Laser, Tsukuba, Ibaraki, Japan, 8 - 12 September 2003
  • Nuclear Instruments and Methods in Physics Research A 528(2004)1-2, 199-202

Publ.-Id: 5695

Infrared characterization of environmental samples by pulsed photothermal spectroscopy

Seidel, W.; Foerstendorf, H.; Heise, K.-H.; Nicolai, R.; Dekorsy, T.; Ortega, J.-M.; Glotin, F.; Prazeres, R.

The low concentration of toxic radioactive metals in environmental samples often limits the interpretation of results of infrared studies investigating the interaction processes between the metal ions and environmental compartments. For the first time, we could show that photothermal infrared spectroscopy performed with a pulsed free-electron laser can provide reliable infrared spectra throughout a distinct spectral range of interest. In this model investigation, we provide vibrational absorption spectra of a rare earth metal salt dissolved in a KBr matrix and a natural calcite sample obtained by thermal beam deflection technique and FT-IR spectroscopy, respectively. General agreement was found between all spectra of the different recording techniques. Spectral deviations were observed with samples containing low concentration of the rare earth metal salt indicating a lower detection limit of the photothermal method as compared to conventional FT-IR spectroscopy. Furthermore, the photothermal method provide spatial information of a sample surface. This may result in a microspectrometric technique for determining the distribution of metal species on mineral surfaces. First experiments exploring the spatial resolution of photothermal spectroscopy were carried out by scanning the surface of a germanium substrate showing a localized region where O-ions were implanted. The border range of this region was investigated by recording time curves of the deflection signal at distinct positions of the substrate surface with a constant free-electron laser wavelength of 11.6 micrometer.

Keywords: Laser spectroscopy; thermooptical and photothermal effects

  • Poster
    International Workshop on Infrared Microscopy and Spectroscopy with Accelerator Based Sources, July 8-11, 2003, lake Tahoe, CA, USA
  • Contribution to proceedings
    International Workshop on Infrared Microscopy and Spectroscopy with Accelerator Based Sources, July 8-11, 2003, lake Tahoe, CA, USA

Publ.-Id: 5694

Spatial distribution of cavities in silicon formed by ion implantation generated excess vacancies

Peeva, A.; Kögler, R.; Skorupa, W.; Kuznetsov, A.; Christensen, J.

Spatial distribution of nano-sized cavities in silicon formed by high energy Ge ion implantation and annealing was determined. The cavities were directly observed by transmission electron microscopy without any decoration. The cavities are shown to be the agglomerates of implantation-induced excess vacancies. The concentration depth profile of the vacancies bound in the cavities agrees well with the excess vacancy profile calculated for the implantation process. Almost all the generated excess vacancies agglomerate in cavities after annealing at 900 °C for 30 s. The vacancy profile coincides with the depth profile of Cu that was intentionally introduced in the cavity region. The perfect match of vacancy and Cu distribution indicates that the cavities are the determining gettering centres for Cu atoms.

Keywords: Defects in silicon; Implantation defects; Vacancies; Cavities; Gettering

Publ.-Id: 5693

Improved Statistical Power of the Multilinear Reference Tissue Approach to the Quantification of Neuroreceptor Ligand Binding by Regularization

Buchert, R.; Wilke, F.; van den Hoff, J.; Mester, J.

A multilinear reference tissue approach has been widely used recently for the assessment of neuroreceptor-ligand interactions with positron emission tomography. The authors analyzed this "multilinear method" with respect to its sensitivity to statistical noise, and propose regularization procedures that reduce the effects of statistical noise. Computer simulations and singular value decomposition of its operational equation were used to investigate the sensitivity of the multilinear method to statistical noise. Regularization was performed by truncated singular value decomposition, Tikhonov-Phillips regularization, and by imposing boundary constraints on the rate constants. There was a significant underestimation of distribution volume ratios. Singular value decomposition showed that the bias was caused by statistical noise. The regularization procedures significantly increased the test-retest stability. The bias could be reduced by applying linear constraints on the rate constants based on their normal range. Underestimation of distribution volume ratios by the multilinear method is caused by its sensitivity to statistical noise. Statistical power in the discrimination of different groups of subjects can be significantly improve by regularization procedures without introducing additional bias. Correct distribution volume ratios can be obtained by imposing physiologic constraints on the rate constants.

Keywords: PET; modeling; linear regression; reference tissue method; regularization

  • Journal of Cerebral Blood Flow and Metabolism (2003) 23: 612-620

Publ.-Id: 5692

Experiments at COSY

Schult, O. W. B.; Bisplinghoff, J.; Müller, H.; u. a.

A cooler synchrotron, COSY, has been built in the Research Center Jülich for the acceleration of protons to any energy between 38 and 2500 MeV and for the preparation of cooled beams for experiments, which use the circulating beam with ideal thin targets in the ring, or which benefit from smal spots of the extracted beam. At present, the accelerator is in the phase of conditioning. Internal and extracted beams have been used for testing and calibration of detectors and data acquisition systems. Production runs of physical data are expected in the very near future.

  • Contribution to proceedings
    Proceedings of the 7th international conference on nuclear reaction mechanisms, varenna, june 6-11, 1994, Milano

Publ.-Id: 5691

Study of medium modifications with the new spectrometer ANKE at COSY - Jülich

Barsov, S.; Koptev, V.; Mikirtychiants, S.; Bechstedt, U.; Borchert, G.; Borgs, W.; Buescher, M.; Erven, W.; Gotta, D.; Hartmann, M.; Junghans, H.; Klehr, F.; Koch, H. R.; Kulessa, P.; Maier, R.; Ohm, H.; Prasuhn, D.; Schleichert, R.; Schneider, H.; Schult, O. W. B.; Seyfahrt, H.; Sistemich, K.; Stroeher, H. J.; Debowski, M.; Müller, H.; Rimarzig, B.; Schneider, C.; Rathmann, F.; Mussgiller, A.; Kamys, B.; Pysz, K.; Rudy, Z.; Zychor, I.; Kacharava, A.; Komarov, V. I.; Kulikov, A.; Kurbatov, V.; Macharashvili, G.; Merzliakov, S.; Petrus, A.; Fedorets, P.; Nioradze, M.

kein Abstrakt

  • Acta Phys. Pol. B31 (2000) 357

Publ.-Id: 5690

A Quark Model for Hadron Production

Müller, H.

Hadron production in nucleon-nucleon, nucleon-nucleus and nucleus-nucleus interactions is considered in the framework of the Rossendorf collision model, which aims at describing simultaneously all reaction channels in a wide energy region. An empirical matrix element based on the partonic picture of hadrons is combined with the concept of intermediate subsystems and the calculation of modified statistical weights of the various final states. In case of nuclear reactions the Glauber concept is used to calculate the partial cross sections for the interaction of various numbers of participants. It is demonstrated that a large variety of experimental data can be satisfactorile reproduced. Predictions for proposed missing-mass measurements are discussed.

  • Acta Physica Polonica B, No 11, Vol. 27 (1996)

Publ.-Id: 5689

Study of medium modifications with the new spectrometer ANKE at COSY - Jülich

Barsov, S.; Koptev, V.; Mikirtychiants, S.; Bechstedt, U.; Borchert, G.; Borgs, W.; Buescher, M.; Erven, W.; Gotta, D.; Hartmann, M.

kein Abstrakt

  • Acta Phys. Pol. B31 (2000) 357

Publ.-Id: 5688

Kaon and antikaon production in proton nucleus collisions

Scheinast, W.

kein Abstract

  • Acta Phys. Pol. B31 (2000) 2305

Publ.-Id: 5687

A Dedicated 0° Facility for Threshold Particle Production Studies at COSY

Büscher, M.; Sistemich, K.; Abaev, V.; Bechstedt, U.; Birien, P.; Borgs, W.; Cassing, W.; Dienel, S.; Dombrowski, H.; Dshemuchadze, S. V.; Ernst, J.; Müller, H.

A universal facility is in preparation for the study of particle production in proton-nucleus reactions below the nucleon-nucleon threshold. The device will be located at the internal target position TP2 at COSY-Jülich and will consist of three dipole magnets. This 0° 'Facility will separate ejectile from the circulating proton beam and allow momentum and angle analysis both for positively and negatively charged particles. A major goal of the experimental program is the investigation of the K+-meson production at projectile energies below the NN threshold. The detector concept for these studies is described and also an overview over further planned experiments is given.

  • Physica Scripta, Vol. 48, 50-53, 1993

Publ.-Id: 5686

Photon Radiation from expanding gluon rich plasma

Kämpfer, B.; Pavlenko, O. P.

Photon production in an expanding gluon plasma with initially little quark admixture is considered. Photons are created by lowest α5 order processes which include quarks. Chemical equilibration of the quarks in turn is followed by rate equations which rely on lowest α5 order gg<=>qq processes. Expansion slows down the quark cooking. Compared with the standard local qquilibrium estimates we find a drestic reduction of medium-energy photons if the initial quark admixture is below 20 % of the chemical saturation density. Higher initial temperatures increase significantly the high-energy photon yield and overcompensate this reduction.

  • Phys. Atom. Nucl. 58, 1995, 2144-2149; Yad. Fiz. 58, 1995, 2260

Publ.-Id: 5685

Accurate determination of metabolic rates from dynamic positron emission tomography data with very-low temporal resolution

Buchert, R.; van den Hoff, J.; Mester, J.

Purpose: The graphical approach is widely used for the pixelwise determination of local metabolic rate of glucose from dynamic positron emission tomography (PET) data. In its conventional implementation, measured integrals over time frames are used to approximate instantaneous tracer concentrations at midframe times ("midframe approach"). This is justified in case of high temporal resolution of the PET measurement; that is, if scan protocols with a large number of short frames are used. This requires fast data handling and large amounts of memory. Cardiac gating and three-dimensional (3D) acquisition of dynamic studies is hardly possible with this approach. Therefore, a new variant of the graphical method is proposed which can be used with a very low number of rather long frames.
Methods: An operational equation of the graphical method was derived which uses measured time integrals only and, thus, avoids the systematic errors of the midframe approximation. This "integral approach" was evaluated in computer simulations based on experimental data.
Results: The integral approach enables the use of protocols with 3 frame only without compromising accuracy of the derived metabolic rates whereas the midframe approach leads to bias of about 10 % to 20 % for these protocols. Furthermore, test-retest stability can significantly be improved when using the integral approach.
Conclusion: The integral approach to the graphical evaluation of dynamic PET data yields accurate and precise results using scan protocols with down to only 3 frames. This can be relevant to gating and/or 3D acquisition of dynamic studies. The integral approach is applied most naturally whenever the input function is derived from the dynamic PET data.

Keywords: graphical analysis; positron emission tomography; sampling schedule; tracer kinetic modeling

  • Journal of Computer Assisted Tomography (2003) 27 (4): 597-605

Publ.-Id: 5684

Lifetime study of particle-hole excitations in the semimagig nucleus 93TC

Hausmann, M.; Jungclaus, A.; Galindo, E.; Lieb, K. P.; Yordanov, O.; Johnstone, I. P.; Schwengner, R.; Dewald, A.; Fitzler, A.; Möller, O.; de Angelis, G.; Gadea, A.; Martinez, T.; Napoli, D. R.; Ur, C.

The recoil-distance Doppler-shift technique was employed for determining lifetimes of high-spin states in the semimagic nucleus 93Tc. The nuclei were populated using the reaction 64Zn(35Cl,b1;2p) at a beam energy of 135 MeV, and the g radiation from their decay was detected in the GASP spectrometer. A total of 26 reduced transition probabilities and limits for 19 further transitions were extracted and compared to large scale shell model calculations, considering different configuration spaces and residual interactions. The information deduced about transition strengths turned out to be essential for the correct assignment of the calculated to the experimental excited states.

  • Physical Review C68, 024309 (2003)

Publ.-Id: 5683

Charged hadron tumour therapy monitoring by means of PET

Enghardt, W.; Crespo, P.; Fiedler, F.; Hinz, R.; Parodi, K.; Pawelke, J.; Pönisch, F.

Positron emission tomography (PET) imaging of radioactivity distributions induced by therapeutic irradiation is at present the only feasible method for an in-situ and non-invasive monitoring of radiooncology treatments with ion beams. Therefore, at the experimental carbon ion therapy facility at the Gesellschaft für Schwerionenforschung Darmstadt, Germany (GSI) a PET-scanner has been completely integrated into the treatment site for a quality assurance monitoring simultaneously to the therapeutic irradiation. Although the device has been assembled from components of positron emission tomographs developed for nuclear medicine applications, substantial modifications had to be made for meeting the requirements of ion therapy monitoring. these changes regard the geometrical detector configuration as well as the data acquisition and processing. Since 1997 this technique has been applied to monitoring the fractionated irradiation of more than 180 patients predominantly suffering from tumours in the head neck region. It could be demonstrated that this new PET technique is capable of assesing parameters being relevant for quality assurance of carbon ion therapy, i. e. the particle range in tissue, the position of the irradiated volume with respect to anatomical landmarks and local deviations between the planned and the applied dose distributions.

Keywords: Positron emission tomography; charged hadron therapy; ion therapy

Publ.-Id: 5682

Synthesis of a 11C-labelled Taxane Derivative by [1-11C]Acetylation

Mäding, P.; Zessin, J.; Pleiß, U.; Wüst, F.

Taxans are an important class of antitumor agents. These compounds bind to the microtubuli and inhibit their depolymerization into tubulin. Subsequently, the mitosis is disrupted and the cells are not able to divide into daughter cells. Investigations with positron emission tomography (PET) are an important tool to determine the in vivo distribution and the pharmacokinetics of such drugs if they are labelled with positron-emitting radionuclides. This report describes the 11C-labelling of a taxan derivative as a new potent anticancer drug 1.
The acetyl moiety of 1 in position 10 was chosen to introduce carbon-11, because it is considered to be stable with respect to drug metabolism. For synthesis of the required precursor 2 the taxan 1 was selectively deacetylated in position 10 by treatment with sodium hydrogencarbonate and hydrogen peroxide. To avoid the known epimerization of the hydroxy group in position 7 and to stabilize the ester function in position 13 the 2’ and 7 hydroxy groups were protected with triethylsilyl moieties yielding the precursor 2.
[11C]1 was synthesized in a multi-step procedure according to the Scheme using an automated syn-thesis module. The capability of this module includes the radiosynthesis of [1﷓11C]acetyl chloride (3) and its conversion with the precursor 2 to an intermediate, which was hydrolysed to [11C]1, the HPLC purification of the final product, its solid phase extraction and formulation.
The used module was a commercially available module for 11C methylation from GE Medical Sys-tems (former Nuclear Interface), Münster, Germany.
[1﷓11C]Acetyl chloride (3) was synthesized by conversion of [11C]carbon dioxide with methyl-magnesium bromide in diethyl ether followed by quenching the resulting [11C]acetate solution with phthaloyl dichloride. After evaporation of the solvent, 3 was driven into a cooled THF solution of 2 and lithium hexamethyldisilazide. The [11C]acetylation took place at room temperature within 6 min. The solvent was evaporated and the residue was treated with a solution of hydrochloric acid in MeOH/dioxane for cleavage of the triethylsilyl protecting groups at room temperature. The crude product was purified by semipreparative RP HPLC and solid phase extraction at an RP﷓18-cartridge. The resulting ethanolic solution of [11C]1 and a saline solution was transferred succes-sively through a sterile filter to obtain the final formulation of [11C]1. The decay-corrected radio-chemical yields were in the range of 6 to 19 % (related to [11C]CO2) within a synthesis time of 45-50 min. The radiochemical purity exceeded 96 %, the chemical purity was in the range of 80-99 %.
The specific radioactivity of the final product was up to 18 GBq/µmol at 11 successful attempts with starting radioactivities of 26 GBq.

Keywords: taxan; anticancer drug; [1-11C11]acetyl chloride; automated module synthesis; PET

  • Lecture (Conference)
    11th Conference of the Central European Division e. V. of the International Isotope Society, Bad Soden, 25.-26.09.2003
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals 47(2004), 263-265

Publ.-Id: 5681

Carbon-11 Labelled Compounds in the Development of Pharmaceuticals

Wüst, F.

Positron emission tomography (PET) is a powerful non-invasive clinical and research imaging technique which allows in vivo measurements and quantification of biochemical processes at the molecular level. Besides the success story of PET as valuable diagnostic tool in oncology, neutrology and cardiology, PET technology has also emerged the process of drug research and development. Its strength stems from the ability to obtain directly quantitative knowledge of the distribution and bioavailability of drugs and their therapeutic and toxic effects on living systems. The direct assessment of pharmacokinetic and pharmacodynamic events in humans and animals combined with the new generation of high-resolution PET cameras place PET in a unique position to contribute significantly to the process of drug development and evaluation. PET helps to understand the molecular mechanism underlying drug action while addressing some very practical questions such as determining effective drug doses, determining the duration of drug action and examining potential drug interactions. To fully exploit PET technology in drug development, appropriately labeled compounds are needed. The drug usually must be labeled with carbon-11 (t1/2 = 20 min) to aviod changing the characteristics of the parent compound. Alternatively, fluorine-18 (t1/2 = 110 min) can be used if the drug contains a fluorine atom. The short half lives of 11C and 18F require rapid and selective labelling techniques, since time dominates all aspects of PET. In this connection the extensive performance of organic radiochemistry using 11C and 18F is fundamental but also a special challenge. This presentation will address the recent developments of organic PET radiochemistry in the synthesis of PET radiotracers with sprecial focus on the potential role of 11C-labelled compounds in the design, development and evaluation of pharmaceuticals.

  • Lecture (Conference)
    11th Conference of the International Isotope Society, Bad Soden, 25.-26.09.2003
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmceuticals 47(2004), 261-262

Publ.-Id: 5680

Embrittlement of Reactor Pressure Vessel Steel A508: A Look on Mesoscopic Levels

Borodin, V. A.; Böhmert, J.

We present the results of fractographic study of standard V-notch Charpy specimens of US steel A508, tested at different temperatures ranging from the lower to upper shelf. The same fracture cross sections were studied at progressively increasing magnifications from x10 up to x20000, using both stereo optical microscopy and scanning electron microscopy. The results demonstrate that test conditions at mesoscopic and macroscopic length scale levels are important factors influencing the crack propagation.

Keywords: Fracture; steels; fractography; embrittlement

  • Lecture (Conference)
    13. International Conference on Strength of Material, 25.-30.08.2003, Budapest, Hungary, Book of Abstracts, p. 113
  • Contribution to proceedings
    13. International Conference on Strength of Material, 25.-30.08.2003, Budapest, Hungary, Book of Abstracts, p. 113

Publ.-Id: 5679

Generation of sub-picosecond electron bunches from superconducting 5.3 cell RF gun and coherent wiggler radiation

Volkov, V. N.; Janssen, D.; Wünsch, R.

In this paper we discuss the possibility to gernerate subpicosecond electron bunches with a small emittance directly from the superconducting 5.3 cell rf gun by illuminating a photo-cathode in the rf cavity with a phaselocked 3 ps laser pulses. The bunch length compression caused by the RF force take place in the first TESLA cell of the rf gun. Numerical simulations of the beam dynamics in the rf gun and of the radiation of the corresponding electron bunch in a wiggler predict a coherent enhancement of radiaton for wavelength smaller than 100 micron.

  • Lecture (Conference)
    PAC 2001, June 18-22, 2001 Chicago, Illinois, USA
  • Contribution to external collection
    PAC 2001, June 18-22, 2001 Chicago, Illinois, USA

Publ.-Id: 5678

First operation of a superconducting RF-Gun

Janssen, D.; Büttig, H.; Evtushenko, P.; Freitag, M.; Lehnert, U.; Hartmann, B.; Michel, P.; Reppe, B.; Schamlott, A.; Schneider, C.; Schurig, R.; Teichert, J.; Gabriel, F.; Möller, K.; Quast, T.; Konstantinov, S.; Kruchkov, S.; Kudryavtsev, A.; Myskin, O.; Petrov, V.; Tribendis, A.; Volkov, V.; Sandner, W.; Will, I.; Matheisen, A.; Moeller, W.; Pekeler, M.; von Stein, P.; Haberstroh, C.

For the first time, a superconducting RF gun where a photo cathode is inside a superconducting cavity has been working stably over a periode of seven weeks. The gun with a half cell cavity has been operated in the cryostat at 4.2K. A maximal field strength of 22MV/m in the cavity and maximal beam energy of 900keV have been obtained. Measurements of beam current, transmission, energy spread and transverse emittance are presented.

Publ.-Id: 5677

Interaction of Polyoxotungstates with Aminosaccharides

Jelínek, L.; Matejka, Z.; Novotná, M.; Burda, R.; Sawatzki, A.-K.; Stephan, H.

Owing to their antiviral and antitumoral properties polyoxometalates (POMs) are gaining in importance in the development of therapeutic agents. Such cluster molecules possessing a multitude of metal atoms might be took advantage in view of cancer treatment by photon activation therapy (PAT). In this nexus it is necessary to meet some requirements. So, POMs must have sufficient stability under physiological conditions. Furthermore, highly efficient transportation into cells, and finally the interaction with DNA is essential. The encapsulation of POMs by aminosaccharides seems to be a promising way to achieve that. In our previous study we reported about the possibility conditions to form complexes between various metal-oxoanions and sorbents having different diol-ligands. Now, we want to report the binding and sorption behavior of selected aminosaccharides towards polyoxotungstates.

  • Contribution to proceedings
    XVIIIth International Symposium "Ars Separatoria 2003", Z. Potok (Polen), 2003, 74-76
  • Lecture (Conference)
    XVIIIth International Symposium "Ars Separatoria 2003", Z. Potok (Polen), 02.-05.06.2003

Publ.-Id: 5676

A New Beam Loss Measurement System For ELBE

Schurig, R.; Evtushenko, P.; Lehnert, U.; Michel, P.; Teichert, J.

During the commissioning of the first accelerator stage of ELBE, beam loss was measured with photomultipliers and self-testing integrating electronics. While the electronics worked flawless, the correct positioning of the monitors and finding a good trade off between sensitivity and saturation of the photomultipliers were a problem. A new BLM system, consisting of ionization chambers, acquisition electronics and monitoring software is now under construction. Coaxial cable with air dielectricum, normally used in high power applications, makes the ionization chamber and will be installed along the beamline. The outer conducter of the cable is subsectioned, the inner conductor not. The current on the inner conductor represents the total beam loss. The current from each outer conductor segment to ground is measured separately, providing position resolution of the beam loss. On each section, a RISC microcontroller (Slave) with built in ADC is used for data acquisition and continuous average calculation. One microcontroller (Master) handles the communication with the slaves via RS-485 bus and acts as an interface to a PC running monitoring software. First test have been done successfully.

  • Poster
    Beam Instrumentation Workshop 2002,Brookhaven National Laboratore, Poster Session

Publ.-Id: 5675

A Beam Loss Measurement System with Longitudinal Resolution

Schurig, R.; Michel, P.

At ELBE, beamloss is measured in two different ways. Long ionization chambers (LIC) made from coaxial cable and having an air dielectric are used to detect beam loss at critical sites of the machine. In the second system, beam current is measured at three different locations. The sum signals from two stripline beam position monitors and the nuclear physics beam dump current are compared. A difference in current at these points indicates that portions of the electron beam are lost somewhere. Above a certain level the interlock is triggered and the beam is switched off. Both kinds of measurement are described in detail elsewhere in this annual report.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-375 April 2003
    ISSN: 1437-322X

Publ.-Id: 5674

A Resonant Beam Current Monitor for ELBE

Schurig, R.; Büttig, H.; Büchner, A.

During the first stages of commissioning ELBE, the beam current could be measured directly at the gun, the macropulser aperture and at the beam dump. Later, a package consisting of a resonant beam current monitor (RBCM) and a resonant beam position monitor was added. The result of the RBCM test are described in this paper.

  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; FZR-341 April 2002, 15-15
    ISSN: 1437-322X

Publ.-Id: 5673

Application of the Normalization Method to Various Fracture Toughness Specimens

Dzugan, J.; Viehrig, H.-W.

The objective of this paper is the evaluation of the normalization method performance compared to the conventional standard method for a broad spectrum of different materials and specimen geometries. The normalization method based critical J-integral values were summarized and compared with the results of the unloading compliance tests. The results point out the applicability of the normalization method for the J-R curve determination for the investigated materials. The normalization method provided results with up to 15 % deviation from the values obtained with the unloading compliance method.

Keywords: fracture mechanics; fracture toughness; normalization method; unloading compliance

  • Poster
    13. International Conference on the Strength of Materials, 25.-30.08.2003, Budapest, Hungary

Publ.-Id: 5672

A Small Angle X-ray Scattering Method to Investigate the Crack Tip in Metals

van Ouytsel, K.; Böhmert, J.; Müller, G.

The work in this report, financed by the European Union through the Marie Curie Fellowship Association, was carried out at the FZ-Rossendorf. The subject of the research was to develop a method to investigate the damage, the high defect gradients at the tip of a ductile crack by means of Small Angle X-ray Scattering. The work explains the objectives and entails a brief introduction and background; it portrays and discusses the results which can be summarized as follows. Different damage parameters were investigated: the integral intensity, the total intensity on the detector, the anisotropy parameter and the fractal dimension. Of these, the anisotropy parameter is the most robust and most clearly depicts a damage region and the fractal dimension provides an idea of the structure of the scattering defect. The integral and total intensity provide comparable results only in some cases and are therefore not reliable.
From supportive investigations: Scanning and Transmission Electron Microscopy (S-TEM), Finite Element Analysis and X-Ray Diffraction, it is suggested that the scatterer created after deformation is related to large oriented dislocation networks.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-388 August 2003
    ISSN: 1437-322X


Publ.-Id: 5671

Maßnahmen zur Sicherung der Betriebsdauer des Reaktordruckbehälters

Viehrig, H.-W.; Boehmert, J.

Die uneingeschränkte Nutzung eines RDB bis zum Ende der Betriebsdauer des KKWs auf einem unverändert hohen Sicherheitsniveau ist nur durch ein ganzheitliches und umfassendes Programm von Maßnahmen und Instrumentarien zu gewährleisten. Entscheidend werden dafür die Weichen bereits bei der Auslegung gestellt, indem hochzähe, strahlenversprödungsresistente Werkstoffe verwendet werden, die Neutronenbelastung durch einen ausreichend breiten Wasserspalt redu-ziert wird, die fortschreitende Materialalterung durch ein gut konzipiertes repräsentatives Überwachungsprogramm erfasst und Herstellung und Konstruktion gute Prüfbarkeit ebenso wie die Vermeidung von Spannungsdiskontinuitäten absichern. Betriebliche Maßnahmen können die Bean-spruchung bei Betrieb oder im Störfall reduzieren (Transientenregime, Einspeisung von vorge-wärmten Notkühlwasser), die Neutronenflussdichte durch ein geeignetes Beladeregime senken oder mit aktualisierten Überwachungsprogrammen die Charakterisierung des Materialzustandes verbessern. Als ultimo ratio steht die Ausheilglühung zur Verfügung, deren Praktikabilität inzwi-schen bereits erwiesen ist.
Schließlich erweist sich nicht zuletzt die Einführung neuer Konzepte zur Sprödbruchsicherheitsanalyse als wertvoll. Als ein hinsichtlich seiner Einführung bereits fortgeschrittenes Beispiel dieser Art wurde das Master-Curve-Konzept vorgestellt. Dieses Konzept wird gegenwärtig zur Bestimmung einer bruchmechanisch definierten Übergangstemperatur be-nutzt, mit der die KIc-Universalkurve der Regelwerke materialspezifisch auf der Temperaturachse positioniert werden kann. Die so ermittelten Referenztemperaturen liegen ca. 40 - 60 K niedriger als die bisher verwendeten Referenztemperaturen, die auf den NDT- oder den Charpy-V-Übergangstemperaturen beruhen. Auf diese Weise kann eine unnötige Konservativität der Bewertung abgebaut werden. Das wurde bereits in realen Anwendungsfällen zweifelsfrei nachgewiesen. Langfristig könnte die statistisch definierte MC selbst als Bruchzähigkeitskurve verwendet werden. Damit erfolgt die Bestimmung der Materialparameter nach einem durchgehend physikalisch defi-nierten Konzept, welches Aussagen zur Versagenswahrscheinlichkeit ermöglicht.

Keywords: Kernreaktor; Reaktordruckbehälter; Betriebsdauer; Sprödbruchsicherheitsnachweis; Thermo-schock; Bruchzähigkeit; Referenzkurve; Master-Curve-Konzept; Neutronenversprödung; Versprödungsüberwachungsprogramm; Trendkurve; Alterung; thermische Ausheilung

  • Lecture (Conference)
    Vertiefungskurs der Schweizerischen Vereinigung für Atomenergie, Betriebsdauermanagement der Kernkraftwerke, 27. und 28. November 2003, Winterthur, Schweiz.
  • Contribution to external collection
    Vertiefungskurs der Schweizerischen Vereinigung für Atomenergie, Betriebsdauermanagement der Kernkraftwerke, 27. und 28. November 2003, Winterthur, Schweiz.

Publ.-Id: 5670

Washout measurement of radioisotope implanted by radioactive beams in the rabbit.

Mizuno, H.; Tomitani, T.; Kanazawa, M.; Kitagawa, A.; Pawelke, J.; Iseki, Y.; Urakabe, E.; Suda, M.; Kawano, A.; Iritani, R.; Matsushita, S.; Inaniwa, T.; Nishio, T.; Furukawa, S.; Ando, K.; Nakamura, Y. K.; Kanai, T.; Ishii, K.

Washout of 10C and 11C implanted by radioactive beams in brain and thigh muscle of rabbits was studied. The biological washout effect in a living body is important in the range verification system or three-dimensional volume imaging in heavy ion therapy. Positron emitter beams were implanted in the rabbit and the annihilation gamma-rays were measured by an in situ positron camera which consisted of a pair of scintillation cameras set on either side of the target. The ROI (region of interest) was set as a two-dimensional position distribution and the time-activity curve of the ROI was measured. Experiments were done under two conditions: live and dead. By comparing the two sets of measurement data, it was deduced that there are at least three components in the washout process. Time-activity curves of both brain and thigh muscle were clearly explained by the three-component model analysis. The three components ratios (and washout half-lives) were 35% (2.0 s), 30% (140 s) and 35% (10191 s) for brain and 30% (10 s), 19% (195 s) and 52% (3175 s) for thigh muscle. The washout effect must be taken into account for the verification of treatment plans by means of positron camera measurements.

  • Physics in Medicine and Biology 48 (2003) 2269-2281

Publ.-Id: 5669

Möglichkeiten und Trends in Diagnostik und Therapie

Johannsen, B.

Radiopharmaka werden in der nuklearmedizinischen Diagnostik und Therapie eingesetzt. Diagnostisches Ziel ist es, möglichst viele biochemische Prozesse ohne Eingriff in diese Abläufe bildgestützt zu analysieren. Der menschliche Körper soll somit biochemisch transparent werden. Trotz allen Fortschritts sind noch viele neue, spezifische, radioaktive Sondenmoleküle, sogenannte Radiotracer, nötig.

  • Pharm. Zeitg. 148, 2003, 2884-2893


Publ.-Id: 5668

Arbeiten zur Simulation prototypischer In-Vessel-Retention-Szenarien auf Basis von Vergleichsrechnungen mit mittelskaligen Experimenten

Altstadt, E.; Willschütz, H.-G.

Bezüglich eines hypothetischen Kernschmelzeszenarios in einem Leichtwasserreaktor ist es notwendig, mögliche Versagensformen des Reaktordruckbehälters sowie Versagenszeiträume zu untersuchen, um die Belastung für das Containment bestimmen zu können. Es wurden weltweit bereits eine Reihe von Experimenten durchgeführt, welche Erkenntnisse hierüber liefern sollen. Begleitend wurden in Einzelversuchen Materialeigenschaften ermittelt, sowie theoretische und numerische Arbeiten durchgeführt.
Für die Simulation von Experimenten zum Versagen der Bodenkalotte, wie OLHF oder FOREVER, ist es notwendig, Kriechen und Plastizität zu berücksichtigen. Gleichzeitig müssen geeignete Modelle das Temperaturfeld in der Behälterwand für die mechanischen Rechnungen bereitstellen. Vom Institut für Sicherheitsforschung des FZR wird ein Finite-Elemente-Modell erstellt, das sowohl die Temperaturfeldberechnung für die Wand als auch die elasto-plastische Mechanik der Behälterwand modelliert.
Am FZR wurde ein Finite Elemente Model entwickelt, das die Verwendung von einfachen Kriechgesetzen, die mit ihren angepassten Konstanten nur für begrenzte Spannungs- und Temperaturbereiche gültig sind, umgeht. Stattdessen wird eine numerische Kriechdatenbasis angelegt, in der die Kriechdehnrate in Abhängigkeit von der Gesamtdehnung, der Temperatur und der Vergleichsspannung abgelegt ist. Eine wesentliche Aufgabe für diese Vorgehensweise besteht in der Generierung und Validierung der Kriechdatenbasis. Zusätzlich wurden alle relevanten temperaturabhängigen Materialeigenschaften mit entsprechenden Modellen in den Code eingegeben. Für die Bestimmung der Versagenszeit wurde ein Schädigungsmodel nach einem Vorschlag von Lemaitre implementiert.
Die Validierung des numerischen Models erfolgte durch die Simulation von und den Vergleich mit den skalierten Integralexperimenten der FOREVER-Reihe, in denen die Bodenkalotte eines Druckwasserreaktors mit ihrer halbkugelförmigen Geometrie wiedergegeben wird. In Zusammenarbeit mit den Experimentatoren an der KTH in Stockholm wurden Pre- und Posttest-Rechnungen für diese bisher einzigartigen Experimente durchgeführt, deren Ergebnisse qualitativ und quantitativ sehr zufriedenstellend sind.
Ausgehend von diesen Arbeiten wird die Simulation prototypischer Szenarien angestrebt, welche im Vergleich zu FOREVER um den Faktor 10 größere Abmessungen aufweisen. Hierzu sind noch Modellerweiterungen notwendig, die daraus resultieren, dass eine vollständige einheitliche Skalierung aller thermischen und mechanischen Einflussgrößen nicht möglich ist.

Keywords: Kernschmelzerückhaltung; FE-Modellierung; 2D- und 3D-Experimente

  • Lecture (Conference)
    3. Workshop KOMPETENZVERBUND KERNTECHNIK am 8.10.2003, MPA, Stuttgart, Proceedings-CD
  • Contribution to proceedings
    3. Workshop KOMPETENZVERBUND KERNTECHNIK am 8.10.2003, MPA, Stuttgart, Proceedings-CD

Publ.-Id: 5667

RF System and Measurements at the Superconducting RF Gun

Büttig, H.; Schurig, R.; Tribendis, A.

The paper gives an overview on the RF-system developed for the Superconducting Photo RF Gun at FZ-Rossendorf and a brief discussion an RF-measurements at the superconducting gun-cavity.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-375 April 2002, 49
    ISSN: 1437-322X

Publ.-Id: 5666

The ELBE- RF-Coupler

Büttig, H.

The power-point presentation gives an overview on RF-coupler development, operational experience at the ELBE-Linac and the coupler test-equipment used at FZ-Rossendorf.

  • Lecture (Conference)
    Proc. of Workshop an 1.3 GHz couplers for cw operation at power levels between 10 and 100 kW ACCEL Instr. GmbH 09.04.2002

Publ.-Id: 5665

Optimizing the Antenna Tip-Length of the ELBE Main RF Coupler

Büttig, H.

The ELBE LINAC is equipped with superconducting TESLA 9-cell cavity resonators. Its RF-coax coupler antennas are designed to operate each cavity withe 8...10 kW beam power. The paper describes a procedure on optimising the antenna- length of the RF-coupler at room temprature.

  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; FZR-341 April 2002, 8-9
    ISSN: 1437-322X

Publ.-Id: 5664

Photothermal Beam Deflection Using a Free Electron Laser For Infrared Characterization of Environmental Samples

Foerstendorf, H.; Seidel, W.; Heise, K.-H.; Ortega, J.-M.; Glotin, F.; Prazeres, R.

The low concentration of toxic radioactive metals in environmental samples often limits the interpretation of results of infrared studies investigating the interaction processes between the metal ions and environmental compartments. For the first time, we could show that photothermal infrared spectroscopy performed with a pulsed free-electron laser can provide reliable infrared spectra throughout a distinct spectral range of interest. In this model investigation, we provide vibrational absorption spectra of a rare earth metal salt dissolved in a KBr matrix and a natural calcite sample obtained by thermal beam deflection technique and FT-IR spectroscopy, respectively. General agreement was found between all spectra of the different recording techniques. Spectral deviations were observed with samples containing low concentration of the rare earth metal salt indicating a lower detection limit of the photothermal method as compared to conventional FT-IR spectroscopy. Furthermore, the photothermal method provide spatial information of a sample surface. This may result in a microspectrometric technique for determining the distribution of metal species on mineral surfaces. First experiments exploring the spatial resolution of photothermal spectroscopy were carried out by scanning the surface of a germanium substrate showing a localised region where O+-ions were implanted. The border range of this region was investigated by recording time curves of the deflection signal at distinct positions of the substrate surface with a constant free-electron laser wavelength of 11.6 micrometer.

  • Poster
    The 2nd International Conference on Advanced Vibrational Spectroscopy (ICAVS-2), Nottingham, U.K.

Publ.-Id: 5663

The growth of Ti(Al)N thin films studied by synchrotron radiation

Beckers, M.; Schell, N.; Möller, W.

  • Lecture (Conference)
    DGK workshop "Characterization of thin films by x-ray scattering", Uckley, 21.-23.05.2003

Publ.-Id: 5662

Evolution of microstructure and preferred orientation in TiAlN thin films - an in-situ study

Beckers, M.; Schell, N.; Möller, W.

  • Lecture (Conference)
    Frühjahrstagung der DPG, Dresden, 24.-28.03.2003

Publ.-Id: 5661

In-situ growth characterization of magnetron sputtered thin films by synchrotron radiation

Beckers, M.; Schell, N.; Möller, W.

  • Lecture (Conference)
    36th IUVSTA workshop, Plzen, Czech republic, 20.-24.10.2002

Publ.-Id: 5660

Calculation of the Scattering Factor from the Shell Model of Nanoscale Defects

Gokhman, A.; Böhmert, J.; Ulbricht, A.

Theoretical and experimental investigations have pointed out the formation of dilute polydisperse system of spherical particles with diffusion zones embedded in matrix in the nucleation and growth evolution stages due to quenching, irradiation and other special kinds of treatment of multicomponent materials. Small-angle neutron and X-ray scattering provide information about the chemical composition as well as about the size distribution of the nanoscale defects.
Unlike to the case of homogeneously structurized scattering objects the analytical solution for heterogeneous scattering objects has not yet well-established. The paper states that the present approaches do not account in full measure the interference between the scattering intensities from the core and shell. Therefore, a more accurate procedure to calculate the scattering factor from heterogeneous objects is worked out. It bases on the formalism of the pair distribution function and the Porod' formula.
The suggested approach is verified on homogeneous scattering objects and then is applied to the set of shell models with different parameters of structure. For the calculation a Visual-Fortran programme is worked out. It is found that the homogeneous model and shell models produce the same scattering factor.
Model of the polydisperse nanoscale defects in neutron irradiated reactor steel is considered as composites of iron core and vacancy enriched shell with different sizes. The fitting procedure to determine the parameters of the size distribution function of irradiation induced precipitates from the magnetic part of small-angle neutron scattering is worked out. The results well agree with results of investigation by other methods for VVER steels with small Cu-content.

  • Lecture (Conference)
    XV International Conference on X-ray Diffraction & Crystal Chemistry of Minerals, St. Petersburg, 15.-19.09.2003
  • Contribution to proceedings
    XV International Conference on X-ray Diffraction & Crystal Chemistry of Minerals, St. Petersburg, 15.-19.09.2003

Publ.-Id: 5659

Validierung des gekoppelten neutronenkinetischen-thermohydraulischen Codes ATHLET/DYN3D mit Hilfe von Messdaten des OECD Turbine Trip Benchmarks

Grundmann, U.; Kliem, S.

Das Vorhaben bestand in der Validierung des gekoppelten neutronenkinetisch-thermohydraulischen Programmkomplexes ATHLET/DYN3D für Siedewasserreaktoren durch Teilnahme an dem OECD/NRC Benchmark zum Turbinenschnellschluss. Das von der OECD und der amerikanischen NRC definierte Benchmark basiert auf einem Experiment mit Schließens des Turbinenschnellschlussventils, das 1977 im Rahmen einer Serie von 3 Experimenten im Kernkraftwerk Peach Bottom 2 durchgeführt wurde. Im Experiment erzeugte das Schließen des Ventils eine Druckwelle, die sich unter Abschwächung bis in den Reaktorkern ausbreitete. Die durch den Druckanstieg bewirkte Kondensation von Dampf im Reaktorkern führte zu einem positiven Reaktivitätseintrag. Der folgende Anstieg der Reaktorleistung wurde durch die Rückkopplung und das Einfahren der Regelstäbe begrenzt. Im Rahmen des Benchmarks konnten die Rechenprogramme durch Vergleiche mit den Messergebnissen und den Ergebnissen der anderen Teilnehmer an dem Benchmark validiert werden.

Das Benchmark wurde in 3 Phasen oder Exercises eingeteilt. Die Phase I diente der Überprüfung des thermohydraulischen Modells für das System bei vorgegebener Leistungsfreisetzung im Kern. In der Phase II wurden 3-dimensionale Berechnungen des Reaktorkerns für vorgegebene thermohydraulische Randbedingungen durchgeführt. Die gekoppelten Rechnungen für das ausgewählte Experiment und für 4 extreme Szenarien erfolgten in der Phase III. Im Rahmen des Projekts nahm FZR an Phase II und Phase III des Benchmarks teil. Die Rechnungen für Phase II erfolgten mit dem Kernmodell DYN3D unter Berücksichtigung der Heterogenitätsfaktoren und mit 764 thermohydraulischen Kanälen (1 Kanal/Brennelement). Der ATHLET-Eingabedatensatz für die Reaktoranlage wurde von der Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) übernommen und für die Rechnungen zu Phase III, die mit der parallelen Kopplung von ATHLET mit DYN3D erfolgten, geringfügig modifiziert.

Für räumlich gemittelte Parameter wurde eine gute Übereinstimmung mit den Messergebnissen und den Resultaten anderer Codes erzielt. Der Einfluss der Modellunterschiede wurde mit Hilfe von Variantenrechnungen zu Phase II untersucht. So können Unterschiede in der Leistungs- und Voidverteilung in einzelnen Brennelementen auf die unterschiedliche neutronenkinetische und thermohydraulische Modellierung des Reaktorkerns zurückgeführt werden.

Vergleiche zwischen ATHLET/DYN3D (parallele Kopplung) und ATHLET/QUABOX-CUBBOX (interne Kopplung) zeigen für räumlich gemittelte Parameter nur geringe Unterschiede. Abweichungen in den lokalen Parametern können im wesentlichen mit der unterschiedlichen Modellierung des Reaktorkerns erklärt werden (geringere Anzahl von modellierten Kühlkanälen, keine Berücksichtigung der Heterogenitätsfaktoren und ein anderes Siedemodell in der Rechnung mit ATHLET/QUABOX-CUBBOX).

Die Rechnungen für die extremen Szenarien von Phase III zeigen die Anwendbarkeit des gekoppelten Programms ATHLET/DYN3D für die Bedingungen bei Störfällen, die weit über das Experiment hinausgehen.

Keywords: nuclear reactors; transients; neutron kinetics; three-dimesional; thermal hydraulics; coupled codes; validation; benchmark; boiling water reactors; turbine trip

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-384 Dezember 2003
    ISSN: 1437-322X


Publ.-Id: 5658

Impact of the QCD four-quark condensate on in-medium spectral changes of light vector mesons

Zschocke, S.; Pavlenko, O. P.; Kämpfer, B.

Within the Borel QCD sum rule approach at finite baryon density we study the role of the four-quark condensates % such as langle(overline{q} gamma_{mu} lambda^a)^2rangle_n , for the modifications of the vector mesons rho, omega and phi in nuclear matter.
We find that in-medium modifications of the rho and omega mesons are essentially dominated by the dependence of the 4-quark condensate on the nucleon density. In particular, the numerical value of a parameter (kappa_N), which describes the strength of the density dependence of the 4-quark condensate beyond the mean-field approximation, governs the decrease of the rho mass as a function of the density. For the omega meson the sign of the in-medium mass shift is changed by variations of kappa_N. To study consistently the in-medium broadening of the light vector mesons we employ rho N and omega N scattering amplitudes derived recently from a covariant unitary coupled channel approach adjusted to pion- and photo-induced reactions. In contrast to the rho and omega mesons, the in-medium mass of the phi meson is directly related to the chiral (strange) quark condensate. Measurements of the vector meson spectral change in heavy-ion collisions with HADES can shed light on the yet unknown density dependence of the 4-quark condensate.

Keywords: medium modifications; vector mesons; condensates

  • hep-ph/0308070

Publ.-Id: 5657

Kleinwasserkraftnutzung am Grenzfluss Lausitzer Neiße

Rindelhardt, U.; Grzelak, K.

An der Lausitzer Neiße wird seit 100 Jahren die Wasserkraft zur Stromerzeugung genutzt. Im vorliegenden Beitrag werden - ausgehend von den hydrologischen Bedingungen und der historischen Entwicklung - der heutige Stand der Wasserkraftnutzung am Grenzfluss Lausitzer Neiße sowie mögliche Perspektiven dargestellt.

Keywords: Wasserkraft; Neiße

  • Elektrizitätswirtschaft Heft 22 (2003), S. 58

Publ.-Id: 5656

Origin of anomalous temperature dependence and high efficiency of silicon light-emitting diodes

Sun, J. M.; Dekorsy, T.; Skorupa, W.; Schmidt, B.; Helm, M.

Efficient electroluminescence with power efficiency up to 0.12 % is observed from silicon pn diodes prepared by boron implantation with boron concentrations above the solubility limit at the post-implantation annealing temperature. The electroluminescence spectra exhibit a transition from two bound-exciton bands towards the free electron-hole pair recombination with an anomalous increase in the total intensity with increasing temperature. The implantation dose and temperature dependences of the relative peak intensities provide evidence for the relevance of excitonic traps as a supply for free electron-hole pairs and thus the origin of the enhanced electroluminescence at elevated temperatures.

Keywords: Electroluminescence; silicon; pn junction; implantation; boron; bound excitons

Publ.-Id: 5655

Slow positron beam investigations of defects caused by B implantation into epitaxial 6H-SiC

Anwand, W.; Brauer, G.; Kuriplach, J.; Skorupa, W.

B+ implantation into epitaxial 6H-SiC has been carried out in order to create a laterally structured p-doped layer. The defects caused by the ion implantation should be minimized by implantation at higher substrate temperatures and post implantation annealing. Using Slow Positron Implantation Spectroscopy (SPIS), the distribution of vacancy-type defects after ion implantation could be evaluated and the efficiency of the annealing could be demonstrated. Furthermore, first results about the boron distribution after annealing are shown.

Keywords: 6H-SiC; B+ implantation; vacancy-type defects; defect annealing; Slow Positron Implantation Spectroscopy

  • Materials Science Forum 445-446(2004), 60-62

Publ.-Id: 5654

A no-go theorem for isospectral alpha^2-dynamos

Günther, U.; Stefani, F.; Gerbeth, G.

The data analysis of current dynamo experiments and the design of new experiments led to an increasing interest in the spectral properties of MHD dynamos. In particular, the huge amount of multichannel data measured with high spectral resolution at large magnetic sensor arrays outside the liquid sodium facilities calls for the development of tomographic methods for these experiments. In general, such methods would allow for a rough reconstruction of velocity and alpha profiles inside a facility from the magnetic field data measured outside the facility. Due to the fact that viable tomographic methods are crucially based on a correct interpretation of the measured data, one has first to deeply understand the spectral properties of the experimental setup and to clarify the uniqueness of the corresponding inverse problem.

As step in this direction and in order to keep the calculations at the beginning as simple as possible, in [1] the uniqueness of spectral data was studied numerically for the toy model of a spherically symmetric alpha^2-dynamo. The results, which were obtained by combining a spectral forward solver with an inverse problem solver, indicated a possibly existing isospectrality of spherically symmetric alpha^2-dynamos with different alpha-profiles alpha_1(r) and alpha_2(r) and a corresponding non-uniqueness of the inverse problem.

The present contribution is based on Ref. [2] and reports analytical results on the isospectrality problem of spherically symmetric alpha^2-dynamo operators. First, it is shown that the 2 x 2 operator matrix of the alpha^2-dynamo possesses a fundamental (canonical) symmetry J, so that the operator itself can be naturally described as J-pseudo-Hermitian operator in a Krein space (a Hilbert space with an additional indefinite inner product structure). Then this symmetry is used to extend the operator intertwining techniques of supersymmetric quantum mechanics to the operator matrix of the alpha^2-dynamo. The intertwiners are assumed as first-order matrix differential operators with coefficients which are highly constrained by a system of nonlinear matrix differential equations. The (hidden) symmetries of this equation system are analyzed by transforming it into a set of constrained and interlinked matrix Riccati equations. As next step, the structure of the spherically symmetric alpha^2-dynamo operator is tested on its compatibility with the considered intertwining ansatz and a no-go theorem is derived which states that the structure is not compatible with an intertwining ansatz based on first-order differential operators as intertwiners. This implies, that other, more powerful techniques should be used for a clarification of the isospectrality and uniqueness problem of the dynamo operator. Finally, the linear eigenvalue problem for the 2 x 2 dynamo operator matrix is transformed to the equivalent eigenvalue problem for the associated quadratic operator pencil. From this quadratic pencil a general functional equation is derived, which will be useful in future research (extending [3]) for discriminating oscillating dynamo regimes from non-oscillating regimes and for localizing the degenerate spectral intersection points where transitions from one regime to the other occur.

[1] F. Stefani and G. Gerbeth, Astron. Nachr. 321, (2000), 235, astro-ph/0010090; Phys. Earth Planet. Inter. 128, (2001), 109.

[2] U. Günther and F. Stefani, J. Math. Phys. 44, (2003), 3097, math-ph/0208012.

[3] F. Stefani and G. Gerbeth, Phys. Rev. E 67, (2003), 027302, astro-ph/0210412.

  • Poster
    Mathematical Aspects of Natural Dynamos, Caramulo, Portugal, August 31 - September 6, 2003.

Publ.-Id: 5653

New Results in the Riga Dynamo Experiment

Gailitis, A.; Lielausis, O.; Platacis, E.; Gerbeth, G.; Stefani, F.

It is widely believed that almost all magnetic fields in a natural environment are the result of the dynamo process - the field generation in a moving nearly homogeneous electroconducting fluid in the depth of celestial bodies such as Earth, most of the planets, Sun, other stars and even galaxies.
We are not going to model in the laboratory any particular celestial body. Our aim is to demonstrate the very idea that the intense motion in the large volume of a good electroconducting liquid creates a magnetic field. As the working fluid serve 2 m^3 of molten sodium, which is the best electroconducting liquid available. It is filled in a 3 m long and 0.8 m thick cylinder. By means of two thin stainless steel internal walls the cylinder is divided into three coaxial channels. The swirling sodium circulation within the two central channels is produced by a propeller at the top of the cylinder powered by two 100 kW motors. When the circulation is fast enough the magnetic field appears. The field pattern slowly rotates around the axis of the cylinder hence any field sensor produces an AC signal.
The first results were reported in the third and fifth MHD days. In the present meeting we will touch upon such details as the radial profiles of field pattern, the turbulent spectra of field, the field produced motions in sodium etc.

  • Abstract in refereed journal
    Astronomische Nachichten 324 (2003), Suppl. Issue 3, 78-79
  • Lecture (Conference)
    Jahrestagung der Astronomischen Gesellschaft, 15-20 September 2003 in Freiburg im Breisgau

Publ.-Id: 5652

Micro-PIXE study of gold archaeological objects

Bugoi, R.; Cojocaru, V.; Constantinescu, B.; Constantin, D.; Grambole, D.; Herrmann, F.

Several fragments of ancient gold objects coming from an Eneolithic hoard and from Pietroasa .Clo#ca cu Puii de Aur. (.The Golden Brood Hen with Its Chickens.) hoard, unearthed on Romanian territory, and two Romanian native gold nuggets samples were analyzed using micro-PIXE technique. The purpose of the study was to clarify the metal provenance. Trace and minor elements (Cu, Te, Sn, Pb, Ti, Cr, V, Mn, Ta) and platinum group elements (PGE) concentrations were estimated. The presence of inclusions (micrometer size areas of composition different from the surroundings) was investigated. We found Si and Ca inclusions on two Eneolithic samples, and Ta inclusions on two samples from Pietroasa hoard. The measurements suggested an alluvial origin of gold for the Eneolithic samples and give indications for the possible gold ore sources of Pietroasa hoard.

Keywords: keine

  • Journal of Radioanalytical and Nuclear Chemistry,257 (2003) 375

Publ.-Id: 5651

Diamond formation by carbon implantation into cubic silicon carbide

Weishart, H.; Heera, V.; Eichhorn, F.; Pécz, B.; Toth, L.; Skorupa, W.

Cubic SiC is implanted with carbon ions at 600, 900, 1100 and 1200 °C. X-ray diffraction and transmission electron microscopy revealed the influence of implantation temperature and dose rate on the formation of graphite and diamond precipitates, respectively. The high dose carbon implantation at 600 °C yields graphite already in a textured form. Spherical diamond grains, which are always epitaxial to the SiC, are found in samples implanted at 900 °C or higher. Increasing the dose rate leads to formation of graphite instead of diamond at 900 oC as well. Hence, a critical temperature for diamond evolution exists, which depends on dose rate. Size and shape of the formed diamond precipitates is not influenced by dose rate within the investigated range. Increasing the fluence results in bigger diamond nanocrystals, which are bordered by facets.

Keywords: silicon carbide (SiC); diamond crystal; ion bombardment; microstructure

  • Poster
    Diamond and Related Materials Vol 13/4-8 (2004) pp 627-632
  • Diamond and Related Materials 13(2004)4-8, 627-632

Publ.-Id: 5650

Time-resolved laser fluorescence spectroscopy study on the interaction of Cm(III) with Desulfovibrio äspöensis DSM 10631T

Moll, H.; Stumpf, T.; Merroun, M.; Rossberg, A.; Selenska-Pobell, S.; Bernhard, G.

The influence of microorganisms on migration processes of actinides has to be taken into account for the assessment of potential high level nuclear waste disposal sites. Therefore it is necessary to characterize the actinide-bacteria species formed and to elucidate the reaction mechanisms involved. This work is focused on the sulfate-reducing bacterial (SRB) strain Desulfovibrio äspöensis DSM 10631T which frequently occurs in the deep granitic rock aquifers at the Äspö Hard Rock Laboratory (Äspö HRL), Sweden. We chose Cm(III) due to its high fluorescence spectroscopic sensitivity as a model system for exploring the interactions of trivalent actinides with D. äspöensis in the trace concentration range of 3 x 10-7 mol/L. A time-resolved laser fluorescence spectroscopy (TRLFS) study has been carried out in the pH range from 3.00 to 7.55 in 0.154 mol/L NaCl. We interpret the pH dependence of the emission spectra with a biosorption forming an inner-sphere surface complex of Cm(III) onto the D. äspöensis cell wall. This Cm(III)-D. äspöensis-surface complex is characterized by its emission spectrum (peak maximum at 600.1 nm) and its fluorescence lifetime (162 ± 5 µs). No evidence was found for incorporation of Cm(III) into the cells.

Keywords: Curium; Bacteria; Desulfovibrio äspöensis; TRLFS; Surface complexation

Publ.-Id: 5649

Corrected procedure for crack lengths calculation by the unloading compliance technique for Charpy size specimens

Dzugan, J.

The problems with the crack length determination by the unloading compliance method are well known for Charpy size specimens. The final crack lengths calculated for bent specimens do not fulfill ASTM 1820 accuracy requirements. Some investigations have been performed to resolve this problem by correcting the compliance value, but satisfying results were not obtained. In the presented work the measured specimen compliance was taken as a correct value and the calculation procedure was modified. On the basis of experimentally obtained compliances of bent specimens and optically measured crack lengths a calculation procedure enabling accurate crack length calculation up to 5 mm of plastic deflection was developed. Applying the new procedure to a sample of 238 measured crack lengths, more than 80% of the values fulfilled the ASTM 1820 accuracy requirement, while presently used procedure provided only about 30% of valid results. The newly proposed procedure can be also prospectively used in modified form for specimens of a size being different from Charpy size.

Keywords: Unloading compliance; fracture toughness; Charpy specimen; J-R curve

  • Journal of Testing and Evaluation 33(2005)6, 433-438

Publ.-Id: 5648

Quadrupole correlations and inertial properties of rotating nuclei

Almehed, D.; Dönau, F.; Nazmitdinov, R. G.

The contribution of quantum shape fluctuations to inertial properties of rotating nuclei has been analysed for QQ-nuclear interaction using the random phase approximation (RPA). The different recipes to treat the cranking mean field plus RPA problem are considered. The effects of the dN = 2 quadrupole matrix elements and the role of the volume conservation condition are discussed.

  • J.Phys. G: Nucl. Part. Phys. 29 (9): 2193-2206 SEP 2003

Publ.-Id: 5646

Microstructural Characterization and Engineering of Defects in Silicon

Peeva, A.

no abstract

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-387 Juli 2003
    ISSN: 1437-322X


Publ.-Id: 5645

Uranium(VI) separation from aqueous solution by calix[6]arene modified textiles

Schmeide, K.; Heise, K.-H.; Bernhard, G.; Keil, D.; Jansen, K.; Praschak, D.

The separation of uranium(VI) from aqueous solution by textile bound uranophile calix[6]arenes was studied as a function of pH value and uranium concentration in the absence and presence of competing ions by means of batch experiments. Furthermore, the kinetics of the uranium binding was studied as well as the possibility for remobilization of the bound uranium by solutions of various pH values.
The results showed that calixarene modified textiles are suitable for the separation of uranium from aqueous solution at pH values higher than 4. The applicability in the acidic pH range is limited. Maximal 7.6x10-7 mol uranium per 1 g of the calixarene modified textile is bound at pH 5. The influence of competing ions (sodium, potassium, calcium, magnesium, carbonate and sulfate) on the uranium separation at pH 5 is very small. However, at pH 7 in carbonate rich waters calcium ions have a competing effect due to the formation of the Ca2UO2(CO3)3 (aq) complex.
Under environmentally relevant pH conditions (near-neutral pH range) the uranium is strongly bound to the calixarene modified textile and cannot be mobilized. On the other hand, under acidic conditions an almost complete regeneration of the calixarene modified textile is feasible. The regenerated textile filter material can be utilized for further uranium separation cycles.

Keywords: Uranium; Calixarene; Complexation; Water Purification

  • Journal of Radioanalytical and Nuclear Chemistry 261(2004)1, 61-67

Publ.-Id: 5643

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