Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31745 Publications
Coulomb dissociation of 8B at E(8B) = 254 MeV/nucleon
Baumann, T.; Blank, B.; Boue, F.; Czajkowski, S.; Förster, A.; Gai, M.; Geissel, H.; Grosse, E.; Hammache, F.; Hellström, M.; Iwasa, N.; Kohlmeyer, B.; Koczon, P.; Kulessa, R.; Laue, F.; Marchand, C.; Motobayashi, T.; Oeschler, H.; Pravikoff, M. S.; Schümann, F.; Schwab, E.; Senger, P.; Sümmerer, K.; Surowiec, A.; Surowka, G.; Wagner, A.; Walus, W.;
The precise knowledge of the solar thermonuclear fusion reaction of 7Be(p, γ)8B is crucial for estimating the 8B solar neutrino flux and the predicted neutrino rates in terrestrial neutrino detectors. The flux of 8B solar neutrinos is particularly important for the results of the Homestake, Super-Kamiokande, and SNO experiments, because they measure high-energy solar neutrinos mainly or solely from the 8B decay.

We have measured the Coulomb dissociation of 8B into 7Be and proton on a 208Pb target at 254 MeV/nucleon using the large acceptance focusing spectrometer KaoS at GSI. Since the dissociation process can be regarded as absorption of a virtual photon, the Coulomb dissociation cross section is converted to the photo-absorption 8B( γ,p)7Be cross section which is directly related to the 7Be(p, γ)8B cross section.

In a first experiment the astrophysical S factor for the 7Be(p,γ)8B reaction is extracted to be S17(0)=20.6 ±1.2(exp) ±1.0(theo) eV-b for 0.25-2.78 MeV (1). This result agrees with the presently adopted zero-energy S17 factor obtained in direct-reaction measurements and with the results of other Coulomb dissociation studies performed at 46.5 and 51.2 A MeV. A second run allowed to also obtain information on the E1/E2 ratio by analysing the angular correlation of 7Be and the proton.
Keywords: solar thermonuclear fusion reaction Be B neutrino flux detector Coulomb dissociation proton spectrometer KaoS GSI virtual photon photo-absorption astrophysical S factor
  • Poster
    Poster presentation at the INPC 2001, Univ. of California, Berkeley, USA, July 30 - Augst 3, 2001
  • Contribution to external collection
    Poster presentation at the INPC 2001, Univ. of California, Berkeley, USA, July 30 - Augst 3, 2001

Publ.-Id: 4076 - Permalink


Aspects of 6-[18F]fluoro-L-DOPA preparation: Precursor synthesis, preparative HPLC purification and determination of radiochemical purity
Füchtner, F.; Angelberger, P.; Kvaternik, H.; Hammerschmidt, F.; Peric Simovc, B.; Steinbach, J.;
A modified method for the synthesis of the intermediate product N-Boc-3,4-di(Boc-O)-6-iodo-L-phenylalanine ethyl ester of the [18F]FDOPA precursor preparation was developed. With the application of bis-(trifluoroacetoxy)-iodobenzene for the iodination step with elemental iodine the yield of the intermediate can be increased from 12% to 50-60%. By replacing silica-gel-based RP HPLC column by a polymer-based column for semi-preparative purification of [18F]FDOPA from the reaction mixture the radiochemical purity of the final product can be increased up to > 99 %. For the determination of the radiochemical impurity [18F]fluoride a HPLC method using a column with polymer-based RP material was introduced.
Keywords: 18F, FDOPA preparation, FDOPA quality control, PET
  • Nuclear Medicine and Biology, 29 (2002) 477-481

Publ.-Id: 4075 - Permalink


The EC-FOREVER-2 experiment: the pre-test analysis and comparisons with the experiment
Willschütz, H.-G.; Sehgal, B. R.;
Scaled coupled melt pool convection and vessel creep failure experiments are being performed in the FOREVER program at the Royal Institute of Technology, Stockholm. These experiments are simulating the lower head of a pressurized reactor vessel under the thermal load of a melt pool with internal heat sources. Due to the multi axial creep deformation of the three-dimensional vessel with a highly non-uniform temperature field these experiments offer an excellent opportunity to validate numerical creep models. A Finite Element model is developed and using the Computational Fluid Dynamic module, the melt pool convection is simulated and the temperature field within the vessel wall is evaluated. The transient structural mechanical calculations are then performed applying a new creep modelling procedure. Additionally, the material damage is evaluated considering the creep deformation as well as the prompt plasticity.
After post-test calculations for the FOREVER-C2 experiment, pre-test calculations for the forthcoming experiments are performed. Taking into account both - experimental and numerical results - gives a good opportunity to improve the simulation and understanding of real accident scenarios.
Keywords: Scaled core meltdown experiments, reactor pressure vesel, multi-axial creep, FE-Simulation
  • Lecture (Conference)
    OECD LOWER HEAD FAILURE, 4th Program Committee Meeting, March 5-7, 2001, Sandia National Laboratories, Albuquerque, New Mexico, USA, Proceedings, Paper No. 8.6
  • Contribution to proceedings
    OECD LOWER HEAD FAILURE, 4th Program Committee Meeting, March 5-7, 2001, Sandia National Laboratories, Albuquerque, New Mexico, USA, Proceedings, Paper No. 8.6

Publ.-Id: 4074 - Permalink


Coupled Melt Pool Convection and Vessel Creep Failure: The FOREVER Program
Sehgal, B. R.; Theerthan, S. A.; Willschütz, H.-G.; Nourgaliev, R. R.; Karbojian, A.;
The FOREVER (Failure Of REactor VEssel Retention) program is concerned with the phenomena of melt-vessel interactions during a postulated severe accident in a light water reactor. The objectives of the FOREVER program are to obtain data and develop validated models on (i) the melt coolability process inside the vessel, in the presence of water (in particular on the efficacy of the postulated gap cooling to preclude vessel failure) and (ii) the lower head failure due to the creep process in the absence of water inside or outside of the lower head.
Integral experiments were performed in a 1/10 scaled carbon steel vessels of 0.4 m diameter, 15 mm thickness and 60 mm height. Up to 20 litres of binary oxide melt (30wt% CaO -70wt% B2O3 ) was poured into the vessel and maintained at about 1300 °C by a specially designed electrical heater operating at about 40 kW. The melt pool undergoes natural con-vection as it would in the prototypic scenario and the vessel wall temperatures vary from ~ 600 to 1000 °C azimuthally. The pressure inside the vessel was maintained at about 2.6 MPa. The main diagnostics were several types of thermocouples and linear position transducers (LPT) which measure the displacement of the vessel due to its creep deformation.
The first three experiments, described here, are focussed on vessel creep and failure.The FOREVER/CI test was performed with the German steel (15Mo3) lower head, at about 25 bars of internal pressure and at the input power level of 22 kW. The maximum essel wall temperature was about 800 °C. A sizable database was obtained for the creep deformation rates over a period of 24 hours and the maximum creep strain obtained was about 5 %. The second test FOREVER/C2 employed a French reactor vessel steel (16MND5) lower head, and a power level of 40 kW. The maximum vessel wall temperature was measured to be about 1000 °C and the maximum creep strain obtained was about 10 %. The test ended without the failure of the lower head as the heater failed due to its unconvering from the melt as the melt level receded due to vessel expansion.
The third test, the EC-FOREVER-I, incorporated higher initial melt level to avoid heater failure. Although, the heater power level was maintained same, at about 40 kW, the internal pressure was increased to 28 bars in order to obtain the lower head failure. The lower head failure was achieved, albeit, at a lower than expected creep strain of only 6%. The failure site was located just above the welding joint between the hemispherical part and the cylindrical part. The cause for this mode of failure is being investigated.
A coupled thermal-structural analysis of these FOREVER tests was performed with the ANSYS Multiphysics code. An improvised creep model was incorporated into this code which avoids the use of a single creep law for the entire lower head. Instead, a three dimensional array was developed where the creep strain is evaluated according to the actual total strain, temperature and equivalent stress for each element. The material damage is evaluated considering the creep and the prompt plastic deformations. The calculated results for the creep strain and vessel failure time are in good agreement with those from the experiments.
Keywords: FOREVER-experiments, reactor pressure vessel, melt pool, creep failure
  • Lecture (Conference)
    CSNI/NEA RASPLAV Seminar 2000, 14-15 November 2000, Munich, Germany
  • Contribution to proceedings
    CSNI/NEA RASPLAV Seminar 2000, 14-15 November 2000, Munich, Germany

Publ.-Id: 4073 - Permalink


Pre-test Calculations for a Core Meltdown Experiment
Altstadt, E.; Willschütz, H.-G.;
Scaled coupled melt pool convection and vessel creep failure experiments are being performed in the FOREVER program at the Royal Institute of Technology, Stockholm. These experiments are simulating the lower head of a pressurized reactor vessel under the thermal load of a melt pool with internal heat sources. Due to the multi axial creep deformation of the three-dimensional vessel with a highly non-uniform temperature field these experiments offer an excellent opportunity to validate numerical creep models. A Finite Element model is developed and using the Computational Fluid Dynamic module, the melt pool convection is simulated and the temperature field within the vessel wall is evaluated. The transient structural mechanical calculations are then performed applying a new creep modelling procedure. Additionally, the material damage is evaluated considering the creep deformation as well as the prompt plasticity.
After post-test calculations for the FOREVER-C2 experiment, pre-test calculations for the forthcoming experiments are performed. Taking into account both - experimental and numerical results - gives a good opportunity to improve the simulation and understanding of real accident scenarios. After analysing the calculations, it seems to be advantageous to introduce a vessel support which can unburden the vessel from a part of the mechanical load and, therefore, avoid the vessel failure or at least prolong the time to failure. This can be a possible accident mitigation strategy. Additionally, it is possible to install an absolutely passive automatic control device to initiate the flooding of the reactor pit to ensure external vessel cooling in the event of a core melt down.

Keywords: Severe nuclear power plant accident, core melt down, multi-axial creep deformation, ANSYSâ User Programmable Feature
  • Lecture (Conference)
    19. CAD-FEM Users´ Meeting, 17.-19. Oktober 2001, Berlin, Potsdam, Germany, Proceedings Vol. 1, 1.6.9
  • Contribution to proceedings
    19. CAD-FEM Users´ Meeting, 17.-19. Oktober 2001, Berlin, Potsdam, Germany, Proceedings Vol. 1, 1.6.9

Publ.-Id: 4072 - Permalink


Stromerzeugung aus erneuerbaren Energien in Ostdeutschland
Rindelhardt, U.;
Im Beitrag wird die Nutzung erneuerbarer Energiequellen zur Stromerzeugung bis Ende 2000 im Einzelnen dargestellt sowie auf die möglichen Perspektiven eingegangen. Die Entwicklung in Ostdeutschland war einerseits durch einige - historisch bedingte - Besonderheiten geprägt, spiegelt aber andererseits auch generelle Tendenzen bei der Nutzung von erneuerbaren Energien zur Stromerzeugung in Deutschland wider.
Im Jahr 2000 wurde aus erneuerbaren Energien in Ostdeutschland eine Strommenge von 3,5 TWh erzeugt, was einem Anteil von 4,8 % am Nettostromverbrauch (abzüglich Netzverluste) entsprach. Mit Abstand dominierende erneuerbare Energie ist mit 70 % die Windenergie, gefolgt von Biomasse und Wasserkraft mit je 15 %. Die Photovoltaik spielt nur eine marginale Rolle. Der Anteil erneuerbarer Energien kann sich in diesem Jahrzehnt verdoppeln.

Keywords: Strom, erneuerbare Energien
  • Elektrizitätswirtschaft 100, Heft 25, S.30-39

Publ.-Id: 4071 - Permalink


Analyses of the OECD - MSLB Benchmark with the Codes DYN3D and DYN3D/ATHLET
Grundmann, U.; Kliem, S.;
The code DYN3D coupled with the thermal-hydraulic plant model ATHLET was used for the analysis of the OECD Main Steam Line Break (MSLB) Benchmark which is based on real plant design and operational data of the TMI-1 PWR. DYN3D is a three-dimensional core model for steady-state and transient analyses of thermal reactors with quadratic or hexagonal fuel as-semblies. The neutron kinetic model is based on the solution of the three-dimensional two-group neutron diffusion equation by nodal expansion. Models for the thermal hydraulics of the reactor core and the fuel pins are implemented in the DYN3D. The reactor core is modeled by parallel cooling channels which can describe one or more fuel elements. DYN3D can be used as a stand alone code with given thermal-hydraulic boundary conditions of the core. Besides the standard simulation given by the specification, modifications are introduced for sen-sitivity studies. The results presented here show the influence of a reduced number of thermal-hydraulic channels for the core for the exercise 2 and the influence of coolant mixing inside the reactor pressure vessel exercise 3. Based on the presented investigations, it can be concluded that the maximum values of local parameters as fuel temperatures are not conservative, if a few number of coolant channels is used for the simulation of the reactor core. If coolant mixing in the reactor vessel is modeled, the accident consequences are mitigated.



Keywords: nuclear reactors, transients, computer codes, simulation, benchmarks, best-estimate analysis, three-dimensional models, neutron kinetics, thermal hydraulics, nodal methods
  • Lecture (Conference)
    Transactions of the American Nuclear Society, June 2001, Volume 84, page 23 - 25
  • Contribution to external collection
    Transactions of the American Nuclear Society, June 2001, Volume 84, page 23 - 25

Publ.-Id: 4067 - Permalink


Relation between stress in cubic boron nitride films and the in plane TO phonon energy
Fitz, C.; Fukarek, W.; Möller, W.;
The high intrinsic stresses in as-deposited cBN films are relaxed employing thermal treatment and ion implantation. In-situ stress measurement and ex-situ polarized infrared reflection spectroscopy are utilized to study correlations between stress and cBN TO phonon energy. The in plane TO phonon energy of cBN films is found to be not unambiguously dependent upon the film stress in contrast to the dependence of the phonon energy of cBN crystallites upon hydrostatic pressure. Factors affecting the relation between stress and phonon position are discussed.
Keywords: cubic boron nitride, stress, infrared, phonon
  • Diamond and Related Materials 11 (8): 1532-1536 AUG 2002

Publ.-Id: 4066 - Permalink


Sorption of U(VI) on muscovite. Comparing SCM modeling with spectroscopic and microscopic results.
Arnold, T.; Krawczyk-Bärsch, E.; Walter, M.; Geipel, G.; Bernhard, G.;
The sorption of uranyl(VI) on muscovite was studied with the diffuse double layer model (DDLM). The required values for the surface site density, the surface acidity constants, the specific surface area, and the experimental sorption data were determined in [1].
The modeling favored the formation of two uranyl surface complexes. Both surfave complexes were simultaneously calculated with FITEQL [2]. The first one is a monodentate mononuclear surface complex:

XOH + UO22+ = (XO-UO22+)+ + H+

The second surface complex is a bidentate mononuclear surface complex:

X(OH)2 + UO22+ = (XO22-UO22+)+ + 2 H+

The results of the SCM (surface complexation model) modeling were compared with results obtained from extended x-ray absorption fine structure spectroscopy (EXAFS), high-resolution transmission electron microscopy (HRTEM), and time resolved laser induced fluorescence spectroscopy (TRLFS).
An EXAFS sample representing the sorption of U(VI) on muscovite at pH 5.8 with an initial U concentration of 1H10-4 M indicated that U(VI) is bound to the muscovite surface as an outer-sphere complex, as indicated by the missing Si/Al to U distance.
HRTEM investigations, representing the sorption of uranium on muscovite at pH 6.5 using an initial U concentration of 5H10-4 M, showed sorbed uranium particles on the muscovite surface. The particles were 5 to 10 nm in diameter. Diffraction patterns of these nano-sized particles gave indication for schoepite and metallic uranium.
TRLFS studies conducted with a muscovite suspension at pH 6.5 using an initial uranium concentration of 1×10-5 M revealed the presence of an uranium-muscovite surface species with a fluorescence lifetime of 120 ns ± 10 ns.

References

[1] Arnold, T. et al. (2001) Sorption Behavior of U(VI) on Phyllite: Experiment and Modeling. Journal of Contaminant Hydrology 47, 219-231.


[2] Herbelin, A. and Westall, J. (1996) FITEQL A Computer Program for Determination of Chemical Equilibrium Constants from Exp. Data, Version 3.2. Rep. 96-01, Dep. of Chem., Oregon St. Uni., Corvallis, Oregon.
  • European Journal of Mineralogy (2001)13, 17

Publ.-Id: 4065 - Permalink


Nuclear temperatures obtained from light-charged-particle yields in low-energy ternary fission
Andronenko, M.; Andronenko, L.; Neubert, W.; Seliverstov, D.;
Nuclear temperatures were determined from yields of isotopes with 1<Z<14 accompanying the spontaneous and neutron-induced fission of heavy elements. The mean temperature derived from the corresponding temperature distributions amounts to 1.10 +- 0.15 MeV.
Keywords: fission, isotopes, nuclear temperature, fragmentation
  • European Physical Journal A 12 (2001) 185

Publ.-Id: 4064 - Permalink


Construction of the Multipurpose Thermohydraulic Test Facility TOPFLOW using CAD Applications
Schaffrath, A.; Schmeisser, N.; Pietruske, H.; Schubert, S.;
The Forschungszentrum Rossendorf (FZR) e.V. is building the large-scale test facility TOPFLOW for thermal hydraulic single effect tests. The acronym TOPFLOW stands for Transient Two Phase Flow Test Facility. It will mainly be used for the investigation of generic and applied steady state and transient two phase flow phenomena in power- and process industries. Main research activities are the investigation of:
- transient flow regimes in horizontal, vertical and inclined tubes,
- the dynamic behaviour of interphase areas in gas-liquid flows,
- critical mass flows and oscillations during depressurization of chemical reactors,
- natural convection in large pools with local heating,
- natural convection in parallel channels and feed pipes and
- condensation phenomena.

CAE tools were consequently established for planning and construction of the facility. This includes e.g. in the basic/detail engineering phase pipe and process flow diagrams, three dimensional plot plans and isometric projections for construction. The 3D model of the facility was used for generation of cutaway sectional drawings, determination of connecting points of components, collision checking and generation of reports such as data sheets and part lists. At last the plant model will be used for the documentation of the built isometric projection. From this version a VRML-model will be created. It will be used for presentation in an immersive virtual-reality environment which was developed at FZR. Alternatively the model can be inspected by any web browser with a standard VRML viewer like CosmoPlayer.

Keywords: TOPFLOW, CAD, VRML
  • Contribution to external collection
    Proceedings CAD2002 Corporate Engineering Research, 4-5.03.2002, Dresden, Germany, ISBN 3-86005298-5, 289-298.

Publ.-Id: 4063 - Permalink


Radiochemisches Laborgebäude für die Actiniden Forschung -Technik. Strahlenschutz, Methoden-
Bernhard, G.; Friedrich, H.; Nitsche, H.;
In diesem Artikel werden die erforderliche Technik, die Strahlenschutz- und Genehmigungsbedingungen und die methodische Ausrichtung der Labors in diesem radiochemischen Laborgebäude für den Umgang mit Radionukliden, insbesondere Actiniden vor dem Hintergrund aktueller Forschungen beschrieben. Sowohl für Forschungen auf dem Gebiet der Radiopharmazie wie auch auf dem Gebiet der Grundlagen der Radiochemie und Radioökologie (z.B. für die Erforschung der Speziation und Migration von Radionukliden/Actiniden in Gebieten des ehemaligen Uranerzbergbaues, in radioaktiv kontaminierten Umgebungen resultierend aus Nuklearunfällen, im Nah- und Fernfeld potentieller nuklearer Endlager) sind radiochemische Laboratorien unabdingbar.
Im Forschungszentrum Rossendorf wurde ein radiochemisches Laborgebäude errichtet, in dem nach Paragr. 3 der Strahlenschutzverordnung mit einer Vielzahl radioaktiver Nuklide (170 Nuklide) in einer maximalen Aktivität für jedes Nuklid von 10E11Bq umgegangen werden kann. Das Laborgebäude hat 24 radiochemische Labors und 10 Service Raume. Die Labors sind mit einer Vielzahl von Abzügen, Laminarboxen und mit 22 Glove Boxen für den Umgang mit Gramm-Mengen von Actiniden ausgerüstet. Das gesamte Gebäude bildet einen Kontrollbereich und bietet Arbeitsplätze für 50 Mitarbeiter/innen. Moderne Analytische und spektroskopische Verfahren sind installiert, z.B. verschiedene Laserspektroskopische Verfahren, ICP-MS, FTIR, NMR, UV/Vis, chromatographische und elektrochemische Verfahren und a,ß,y - Spektrometrie.
  • Atw 46(2001), p. 653-658

Publ.-Id: 4062 - Permalink


Strong visible electroluminescence from Ge- and Sn-implanted silicon dioxide layers
Rebohle, L.; Gebel, T.; von Borany, J.; Fröb, H.; Borchert, D.; Skorupa, W.;
Silicon-based light emission is a key feature to make a real step into the world of integrated optical systems, laboratory-on-chip applications and high performance optical communication. One of the most promising approaches is ion implantation into thin SiO2 films. In this paper the electroluminescence (EL) properties of Sn-implanted SiO2 layers are investigated and compared with those of Ge-implanted SiO2 layers. Strong EL in the blue-violet spectral region with a power efficiency of 0.025 % is extracted from Sn-implanted oxide layers. Similar to the case of Ge, the main emission at 3.2 eV is attributed to a radiative T1®S0 transition of a Sn-related oxygen deficiency center, the EL intensity increases linearly over several orders of magnitude and the stability reaches comparable values. In contrast to the case of Ge, a low energy shoulder appears in the EL spectrum of Sn-implanted oxides. Finally, the suitability of Sn-implanted oxides for optoelectronic applications is discussed.
Keywords: Ge-implantation, Sn-implantation into SiO2, electroluminescence, Si based light emission
  • Material Science and Engineering C19 (2001) 373

Publ.-Id: 4059 - Permalink


Aufbau aromatischer Ringe mit Kohlenstoffisotopen
Mäding, P.; Zessin, J.; Steinbach, J.; Johannsen, B.;
Strukturbestimmende Bestandteile biologisch aktiver Verbindungen sind häufig meta-bolisch stabile aromatische Fragmente, die für die Positronen-Emissions-Tomographie (PET) von Interesse sein können. Dementsprechend wurden Markierungstechniken zur Einführung des kurzlebigen Radionuklids 11C (T1/2 = 20 min) in aromatische und hetero-aromatische Grundverbindungen entwickelt.

11C-kernmarkierte Benzolderivate

* Das Syntheseprinzip der synchronen Sechs-Elektronen-Cyclisierung von Hexatrien-Systemen [1] wird zur Darstellung von [11C]-Aromaten genutzt. In Anwesenheit einer Base lassen sich durch Umsetzung von Nitro-[11C]-methan mit Pentamethiniumsalzen 11C-kernmarkierte Nitrobenzole herstellen [2-4]. Diese Nitro-[1-11C]ben-zole können mit Na2S zu den entsprechenden [1-11C]Anilinen reduziert werden. Aus [1-11C]Anilin ist durch Diazotierung und Verkochen des gebildeten Diazoniumsalzes [1-11C]Phenol zu-gänglich [5]. Analoge Umsetzungen mit 13C wurden demonstriert.

* In Übertragung der bekannten Kondensation von Nitro-methan mit Pyryliumsalzen [6] konnten 4-Nitro-[4-11C]anisol sowie zwei 2,4,6-trisubstituierte Nitro-[1-11C]ben-zole syn-thetisiert werden[7]. Das Verfahren wurde methodisch auf Arbeiten mit 13C ausgeweitet.

11C-kernmarkierte N-Heteroaromaten

* Die Synthese von [11C]Pyridin und Cyano-[11C]pyridinen gelang durch Pyrolyse von N-[11C]Methylpyrrolen [8].
Das Indolgerüst wurde durch zwei verschiedene Synthesewege mit 11C markiert:

* [2-11C]Indol ist durch Kondensation von Nitro-[11C]-methan mit o-Nitrobenzaldehyd und nachfolgender Reduktion des gebildeten ß,2-Dinitro-[ß-11C]styrols zugänglich [9].

* Ein neuer11C-Baustein, das Triphenylarsonium-[11C]methylid, das in situ aus [11C]-Methyltriphenylarsoniumiodid unter Baseneinwirkung gebildet wird, lässt sich durch Reaktion mit o-Aminobenzoyl-Verbindungen direkt zu [2-11C]Indolen [10] kondensieren. Diese Umsetzung unterscheidet sich vom normalen Verlauf der Wittig-Reaktion [11].

[1] Ch. Jutz, Angew. Chem. 1972, 84, 299.
[2] J. Steinbach, J. Label. Compds. Radiopharm. 1995, 36, 33.
[3] P. Mäding, J. Label. Compds. Radiopharm. 1997, 39, 585.
[4] P. Mäding, J. Label. Compds. Radiopharm.1998, 41, 647.
[5] P. Mäding, J. Label. Compds. Radiopharm., 2000, 43, 557.
[6] K. Dimroth, Angew. Chem. 1960, 72, 331.
[7] P. Mäding, J. Label. Compds. Radiopharm., 2000, 43, 565.
[8] J. Steinbach, J. Label. Compds. Radiopharm. 1995, 37, 613.
[9] J. Zessin, J. Label. Compds. Radiopharm., 1998, 41, 669.
[10] J. Zessin, J. Label. Compds. Radiopharm., 1999, 42, 725.
[11] P. Bravo, Tetrahedron Lett. 1970, 52, 4535.
  • Lecture (Conference)
    Jahrestagung der Gesellschaft deutscher Chemiker, Würzburg, 23.-29.9.2001

Publ.-Id: 4058 - Permalink


Distribution of 16alpha-[18F]fluoro-estradiol-3,17beta-disulfamate (FESDS) in rats, tumour-bearing mice and piglets
Brust, P.; Rodig, H.; Römer, J.; Kasch, H.; Bergmann, R.; Füchtner, F.; Zips, D.; Baumann, M.; Steinbach, J.; Johannsen, B.;
Based on a high affinity to the enzyme estrone sulfatase (ES) 16alpha-[18F]fluoroestradiol-3,17beta-disulfamate ([18F]FESDS) has been suggested as a potential PET tracer for imaging steroid-dependent breast tumours. The distribution of [18F]FESDS was studied in rats, tumour-bearing nude mice and piglets. In all species evidence for tracer binding to a second target, the enzyme carbonic anhydrase (CA), was obtained. ES and CA inhibitors significantly reduced the radiotracer uptake in various organs but not in tumours. It is concluded that [18F]FESDS binds to ES and CA in vivo but this binding is not strong enough to allow tumour imaging with positron emission tomography (PET)..
Keywords: estradiol, disulfamate, estrone sulfatase, carbonic anhydrase, positron emission tomography, tumour
  • Applied Radiation and Isotopes 57 (2002) 687-695

Publ.-Id: 4057 - Permalink


Depth Distribution and Intrinsic Stress in a-Si-:H Films Prepared from Hydrogen-Diluted Silane
Danesh, P.; Pantchev, B.; Grambole, D.; Schmidt, B.;
The thickness dependencies and depth distributions of hydrogen and intrinsic mechanical stress are studied for a-Si:H films prepared with 10% silane in hydrogen. Nuclear reaction analysis has been used to establish the total concentration of the incorporated hydrogen. It has been shown that the hydrogen distribution in the films is uniform and does not depend on the film thickness. On contrary, the intrinsic stress depends on the film thickness and has a nonuniform depth distribution, as the stress increase linearly in the direction from the substrate/film interface to the film surface. The obtained results are discussed in view of the hydrogen-related processes and structural improvement of the silicon network during the film growth.
Keywords: a-Si:H layers, H depth profiling, intrinsic stress
  • Journal of Applied Physics 90 (2001) 3065-3068

Publ.-Id: 4052 - Permalink


Efficient blue light emission from silicon: The first integrated Si-based optocoupler
Rebohle, L.; von Borany, J.; Borchert, D.; Fröb, H.; Gebel, T.; Helm, M.; Möller, W.; Skorupa, W.;
We present the first all-silicon integrated optocoupler, whose fabrication, using ion implantation into SiO2, is completely compatible with standard Si technology. It is based on Ge-implanted SiO2 layers as light emitter exhibiting bright blue-violet electroluminescence light with a record wall-plug efficiency of 0.5%. The electroluminescence is explained with a model in which electrons enter the SiO2 layer via tunnel injection and excite the luminescence centers by impact excitation or field ionization. A radiative T1-S0 transition of these luminescence centers is then causing the observed electroluminescence. Finally we show, that these optocoupling devices hold great promise for integrated optoelectronic applications, especially in the field of sensor and biotechnology.
Keywords: Si based optocoupler, Ge implanted SiO2, electroluminescence
  • Electrochem. and Solid State Letters, 4( 7) G57-G60 (2001)

Publ.-Id: 4051 - Permalink


The beneficial role of flash lamp annealing on the epitaxial growth of the 3C-SiC on Si
Panknin, D.; Stoemenos, J.; Eickhoff, M.; Heera, V.; Voelskow, M.; Skorupa, W.;
For the realization of good quality 3C-SiC films epitaxially grown on Si the perfection of the film during the early stage of growth is substantial. In this paper the beneficial role of Flash Lamp Annealing (FLA) for the elimination of the defects in the SiC film and the strain reduction at the SiC/Si interface is discussed. FLA is a highly transient process, having a flash duration of a few milliseconds. When the energy density is sufficient high, it melts the silicon at the SiC/Si interface increasing the temperature there well above the melting point of the silicon. The melted Si dissolves the 3C-SiC near the interface. Additionally, the uppermost part of the 3C-SiC film is annealed due to the heat dissipation during the flash duration and the solidification of the molten region. During the solidification of the C-rich Si melt SiC grows by liquid phase epitaxy at the annealed uppermost 3C-SiC film which act as a seed. This process results in a substantial improvement of the SiC film, eliminating also the cavities and the stress at the interface.
Keywords: 3C-SiC interface, Flash lamp annealing, TEM
  • Applied Surface Science 184 (2001) 377-382

Publ.-Id: 4050 - Permalink


Institute of Nuclear and Hadron Physics; Annual Report 2000
Dönau, F.; Enghardt, W.; Grosse, E.; Kämpfer, B.; Schlett, M.; Schneidereit, C.; (Editors)
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-319 April 2001

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Publ.-Id: 4049 - Permalink


Charge State Distributions of Heavy Ions after Scattering at Surface atoms
Klein, C.; Grötzschel, R.; Mäder, M.; Möller, W.;
The charge-state distributions of Li, C, and F ions after a single collision with Au atoms deposited at a sub-monolayer coverage on Si were measured at energies below 500 keV/amu and compared to the equilibrium charge-state distributions. The influence of the surface on the charge state of the outgoing ions is demonstrated for Li ions at 3 MeV. It is found that the charge state distribution does not generally reach equilibrium after a single collision.
Keywords: Ion-atom collisions; Charge exchange; Charge State Distribution; High resolution RBS
  • Lecture (Conference)
    Proceedings of the 15th International Conference on Ion Beam Analysis, Cairns, Australia, 15-20 July 2001, published as a special volume of Nuclear Instruments and Methods in Physics Research B
  • Contribution to proceedings
    Proceedings of the 15th International Conference on Ion Beam Analysis, Cairns, Australia, 15-20 July 2001, published as a special volume of Nuclear Instruments and Methods in Physics Research B

Publ.-Id: 4048 - Permalink


TOPFLOW - eine neue Mehrzweckthermohydraulikversuchsanlage zur Untersuchung transienter Zweiphasenströmungen
Schaffrath, A.; Krüssenberg, A.-K.; Weiß, F.-P.; Hicken, E. F.;
In dem Vortrag wird der Stand der Arbeiten zur Errichtung der Versuchsanlage TOPFLOW (Transient Two Phase Flow Test Facility) präsentiert. Hierbei werden u.a. das Design der Anlage, die geplanten Experimente, die Dokumentation, das Internetprotal sowie der Zeitplan im Detail vorgestellt.
  • Lecture (others)
    Seminar des Lehrstuhls für Nukleare und Neue Energiesysteme, Ruhr-Universität Bochum, 03.07.2001

Publ.-Id: 4047 - Permalink


Untersuchung von Zweiphasenströmungen in vertikalen Rohren
Schaffrath, A.; Krüssenberg, A.-K.; Prasser, H.-M.; Lucas, D.;
Im Rahmen des Seminars des Lehrstuhls Nukleare und Neue Energiesysteme der Ruhr-Universität Bochum wurden ausgewählte experimentelle Untersuchungen von aufwaertsgerichteten Luft-Wasser Strömungen in vertikalen Rohren vorgestellt. Ein besonderes Kennzeichen dieser Untersuchungen ist der Einsatz von fortschrittlicher Zweiphasenmesstechnik, die am Institut für Sicherheitsforschung entwicklet wird.
  • Lecture (others)
    Seminar des Lehrstuhls Nukleare und Neue Energiesysteme, Ruhr-Universität Bochum 03.07.2001

Publ.-Id: 4046 - Permalink


OECD/CSNI ISP NR. 43 Rapid Boron Dilution Transient Tests For Code Verification Post Test Calculation With CFX-4
Gavrilas, M.; Höhne, T.;
The need of the experimental support for validation of the computational tools to be applied to analyze the mixing of diluted slugs has been recognized in various countries. The test series for the International Standard Problem ISP-43 provides a platform for experiences to be applied to the simulation of a well-defined test series. Test A and B of the UM2x4 loop test facility were calculated with the CFD Code CFX-4.3. Sensitivity studies were made to analyze the used turbulence model and numerical errors. The results show good agreement with the experimental data for both tests.
Keywords: Boron Dilution, PWR, Coolant Mixing
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-325 Juli 2001

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Publ.-Id: 4045 - Permalink


Application of CFX for modelling of natural convection and of subcooled boiling
Krepper, E.;
The paper comprises a short overview about the work in the Institute of Safety Research on CFD-modelling of natural convection and on subcooled boiling
  • CFX-Update No.22, Autumn 2002, p. 27

Publ.-Id: 4044 - Permalink


Tailored magnetic fields in industrial crystal growth, levitation, and melt extraction
Gerbeth, G.;
Industrial applications of magnetic field systems require tailored solutions
for the specific requirements of each technological process in order to keep
the effort, i.e. the magnetic field strength or the power consumption of the
control unit, as low as possible. In case of magnetic field control of
liquid metal processes this results often in combined systems of AC and DC
magnetic fields. The lecture presents examples for this approach.
  • Lecture (Conference)
    Lecture at: Int. Seminar on "Electromagnetic Control of Liquid Metal Processes" Coventry, UK, June 27-29, 2001

Publ.-Id: 4043 - Permalink


Radiopharmazeutische Sonden für die medizinische Diagnostik
Johannsen, B.;
Die verschiedenen heutzutage gebräuchlichen tomographischen Verfahren (CT, MRT, PET, SPECT) ergänzen sich vorzüglich in ihren Anwendungsmöglichkeiten. Informationen über die Struktur der Gewebe und Organe werden komplettiert durch Informationen zu deren Funktion und Biochemie. Letzteres ist die Domäne der Nuklearmedizin, die auf der Anwendung radioaktiver Substanzen beruht. Derartige radioaktive Substanzen fungieren in der Diagnostik als "molekulare Sonden" (Radiotracer), die in den Körper gebracht werden und in Form der nach außen dringenden Strahlung über ihre Verteilung, Reaktion mit Körperbestandteilen und Ausscheidung informieren. Radiotracermethoden machen so den Körper biochemisch transparent. Im Vortrag werden anhand von Beispielen radiopharmazeutische Arbeitsrichtungen vorgestellt. Kurzlebige Positronenstrahler, wie Kohlenstoff-11 und Fluor-18, ermöglichen die Entwicklung von molekularen Sonden für zahlreiche bio-chemische Prozesse. Neurologisch/psychiatrische und onkologische Fragestellungen sind derzeit dominierend in der klinischen Forschung mit Hilfe der Positronen-Emissions-Tomographie (PET). Der eine kostenintensive Infrastruktur erfordernden PET steht die Tomographie mit gammastrahlenden Isotopen (SPECT) gegenüber, insbesondere, wenn ein einfaches Generatorsystem die Erzeugung der kurzlebigen Radionuklide vor Ort in der Klinik ermöglicht und die anschließende Radiopharmakaherstellung problemlos erfolgen kann. Das Generatornuklid Technetium-99m ist das "Arbeitspferd" der nuklearmedizinischen Routinediagnostik. Als Übergangsmetall erfordert es eine koordinationschemische Arbeitsweise bei der Radiodiagnostikherstellung. Bei anspruchsvollen biochemischen Fragestellungen besteht die Herausforderung, den grundsätzlich unphysiologischen Verbindungen dieses Metalls eine solche Gestalt, Größe und Reaktivität zu verleihen, dass sie Biomoleküle ausreichend imitieren können.
  • Lecture (others)
    Wissenschaftliche Sitzung der Deutschen Pharmazeutischen Gesellschaft, Landesgruppe Bayern, Regensburg, 11.07.2001

Publ.-Id: 4042 - Permalink


Neptunium(IV) complexation by humic substances studied by X-ray absorption fine structure spectroscopy
Schmeide, K.; Reich, T.; Sachs, S.; Brendler, V.; Heise, K. H.; Bernhard, G.;
We studied the coordination environment of neptunium(IV) in complexes with various natural and synthetic humic and fulvic acids at pH 1 by X-ray absorption fine structure (XAFS) spectroscopy. The results were compared to those obtained for the interaction of neptunium(IV) with Bio-Rex70, a cation exchange resin having solely carboxylic groups as metal binding functional groups. In both neptunium humate complexes and neptunium Bio-Rex70 sorbates, Np4+ is surrounded by about 10 oxygen atoms at an average distance of 2.36 ± 0.02 Å. This verifies that the carboxylic groups are the main complexing sites of the humic substances responsible for binding neptunium(IV) in the acidic pH range. The data suggest a predominant monodentate coordination of the carboxylate groups to neptunium(IV) ions.
Keywords: Neptunium, Humic acid, Fulvic acid, Complexation, Structure, XANES, EXAFS
  • Radiochimica Acta 93(2005), 187-196

Publ.-Id: 4041 - Permalink


Anwendung eines Laserextensometers zur Ermittlung von Risswiderstandskurven
Böhmert, J.; Weiß, R.; Webersinke, W.;
Risswiderstandskurven haben sich zur zähbruchmechanischen Charakterisierung des duktilen Verformungsverhaltens metallischer Werkstoffe bewährt. Eine geeignete Methode zur Ermittlung von Risswiderstandskurven ist die Compliance-Methode, bei der Risswachstum aus der Veränderung der Probennachgiebigkeit bei Zwischenentlastungen ermittelt wird. Voraussetzung für die Methode ist eine hochgenaue Mes-sung der Rissöffnung. Üblicherweise werden dazu mechanische Wegaufnehmer (Clip-on-Gage) verwendet. Die Messung mit einem Laserextensometer eröffnet neue Anwendungsfelder.
Für eine erste Erprobung werden Risswiderstandskurven an Proben aus hochzähen ferritischen Stählen mit Charpy-Geometrie und unter 3-Punkt-Biegebelastung gleichzeitig mit einem Laserextensometer und einem mechanischen Wegaufnehmer er-mittelt. Die erreichte Endrisslänge am Ende des Versuches wird optisch ausgemessen und mit der aus der Probennachgiebigkeit ermittelten verglichen.
Es gelingt mit dem Laserextensometer die Rissöffnung so empfindlich auszumessen, dass Risswiderstandskurven ermittelt werden können. Die Streuungen zwischen den einzelnen Messschritten sind dabei leicht größer, aber vergleichbar mit den Streuungen gemäß dem Standardverfahren.
Für hochzähen Stahl unterscheiden sich jedoch die mit beiden Wegmessern ermittelten Risswiderstandskurven signifikant. Der Unterschied ist nicht im Wegaufnehmer, sondern versuchsmethodisch begründet.
Die mit dem Laserextensometer bestimmten Endrisslängen liegen innerhalb der vom Standard zugelassenen Abweichung und sind überwiegend besser als die mit dem mechanischen Wegaufnehmer ermittelten.
Messungen bei Prüftemperaturen unter- oder oberhalb Raumtemperatur unter Ver-wendung einer Temperierkammer stellen hohe Anforderungen an die Stabilität des optischen Übertragungsweges und führen zu stärkeren Streuungen der Messergebnisse. An der Lösung dieses Problems muss weiter gearbeitet werden.
  • Lecture (Conference)
    Vortrag auf 1. Anwendersymposium Laserextensometrie, Merseburg, Juni 2001, Tagungsband, S. 516-524
  • Contribution to proceedings
    Vortrag auf 1. Anwendersymposium Laserextensometrie, Merseburg, Juni 2001, Tagungsband, S. 516-524

Publ.-Id: 4038 - Permalink


Tailoring of dopant profiles in advanced nMOS transistors
Lebedev, A.; Posselt, M.; Feudel, T.; Variam, N.;
The properties of advanced CMOS transistors are strongly influenced by the dopant distribution in the transition region between the source (drain) and the channel. The tailoring of this distribution is achieved by appropriate halo and extension implants and subsequent annealing. Process and device simulations are performed to investigate the influence of the corresponding process parameters. The boundary condition used throughout the simulations is to keep the threshold voltage VTsat for the nominal nMOS transistor (sub-70 nm gate length) at 0.2 V. The following process conditions are studied:
(i) B+ halo implant: energy below 10 keV, tilt 45 degree, rotation 4x90 degree, dose varied to achieve VTsat = 0.2 V
(ii) As+ extension implant: 0.5, 1.0, 2.0 keV, tilt 0 degree, 1015 cm-2, and 2 keV, 1015 cm-2, tilt 20 degree, rotation 4x90 degree
(iii)RTA after both implants with special emphasis on soak and spike anneals (950...1100 degree C)
The model parameters employed in the simulation of the formation of the ultra-shallow extension profiles are calibrated using SIMS profiles of as-implanted and annealed samples, and sheet resistance data. The VTsat vs. LGate curve of the nMOS transistor is calculated. The dependence of the roll-off and roll-on behaviour on the process conditions considered is discussed.
Keywords: ion implantation, annealing, process and device simulation, TCAD, Si technology
  • Lecture (Conference)
    EMRS 2001 Spring Meeting, June 5-8, 2001, Strasbourg, France, Symposium B: Defect Engineering of Advanced Semiconductor Devices

Publ.-Id: 4031 - Permalink


TCAD calibration of USJ profiles for advanced deep sub-um CMOS processes
Zechner, C.; Matveev, D.; Erlebach, A.; Simeonov, S.; Menialenko, V.; Mickevicius, R.; Foad, M.; Al-Bayati, A.; Lebedev, A.; Posselt, M.;
For advanced technologies there is a lack of experimental data and calibrated physical models which enable accurate simulation of CMOS technologies down to channel lengths of 100 nm and below. This work aims to develop predictive modeling of USJ profiles for state-of-the-art and next generation CMOS devices.
Profiles were created by As (0.2-10 keV), B (0.2-10 KeV) and BF2(1-25 keV) ion implantation and annealed at various times and temperatures including typical drain extension spike anneals. B and BF2 profiles are investigated with and without pre-amorphization by implantation of Si or Ge.
The calibration is based on SIMS and SRP profiles as well as XTEM pictures. The BC code Crystal-TRIM was calibrated for ultra-low energy implantation. Annealing is simulated within the pairdiffusion framework of the process simulator DIOS, including first order reaction equations for interstitials and dopant clustering and a new model for dose loss, where impurities are stored in a thin surface layer on top of the silicon.
Keywords: ion implantation, annealing, modeling, TCAD, Si technology
  • Lecture (Conference)
    E-MRS Spring Meeting, June 5-8, 2001, Strasbourg, France, Symposium B: Defect Engineering of Advanced Semiconductor Devices
  • Nuclear Instruments and Methods in Physics Research B 186 (2002) 303-308

Publ.-Id: 4020 - Permalink


A small and compact AMS facility for tritium depth profiling
Friedrich, M.; Pilz, W.; Glugla, M.; Bekris, N.; Kiisk, M.; Liechtenstein, V.;
Depth profiling measurements of tritium at carbon samples have been performed during the past seven years at the AMS facility installed at the Rossendorf 3 MV tandetron. The samples have been cut from the inner wall of the fusion experiments ASDEX-upgrade/Garching and JET/Culham. The increasing amounts of tritium inside the samples from JET have been required a dedicated AMS facility to prevent any contamination of the versatile 3 MV tandetron. On base of an air-insulated 100 kV tandem accelerator equipped with a gas stripper a small dedicated AMS facility for tritium depth profiling was installed, tested and used for routinely measurements. After successful tests of diamond-like carbon (DLC) stripper foils at this accelerator a small and compact SF6-insulated 100 kV tandem accelerator with a DLC-stripper has been installed at the AMS facility. Results measured with the different tandem accelerators are presented.
Keywords: Tritium; Fusion; Mass Spectrometry; Tandem Accelerator
  • Lecture (Conference)
    PRAMANA-journal of physics 59 (2002) 1053-1059
  • Contribution to external collection
    PRAMANA-journal of physics 59 (2002) 1053-1059

Publ.-Id: 4019 - Permalink


Formation of a single interface-near, delta-like Ge nanocluster band in thin SiO2 films using ion-beam synthesis
Klimenkov, M.; von Borany, J.; Matz, W.; Grötzschel, R.; Herrmann, F.;
The possibility to create a delta-like, interface-near Ge nanocluster band in a 20 nm thin SiO2 layer by ion beam synthesis is demonstrated. The role of the post implantation annealing conditions for the formation of Ge nanoclusters in the centre of the layer, near the interface or in both regions is discussed. The presence of hydrogen in the annealing atmosphere accelerates the redistribution of Ge in SiO2. By applying a two-step annealing process, preannealing in hydrogen containing at low temperature followed by a rapid thermal annealing at high temperature, the controlled fabrication of a single delta-like, interface-near Ge nanocluster band was achieved. In some clusters <100> lattice planes of Ge were observed. From this and similar contrast situation for amorphous clusters it is concluded that the inerface near clusters consist of elementary germanium.
Keywords: nanocluster, transmission electron microscopy, Rutherford Backscattering, ion implantation, ion beam synthesis
  • Journal of Applied Physics Vol. 91 No. 12 (2002) 10062-10067

Publ.-Id: 4017 - Permalink


Bloch Oszillationen und ihre Kopplung an optische Phononen
Dekorsy, T.;
Die zeitaufgelöste optische Spektroskopie mit Femtosekunden Laserpulsen ermöglicht die Untersuchung der Dynamik von Elektronen und Phononen und deren Wechselwirkung in Halbleitern in Echtzeit. Ein besonderes Objekt des Interesses sind Bloch Oszillationen, die ein Faszinosum der Festkörperphysik darstellen. Bereits in frühen Arbeiten von Bloch und Zener wurde die Vorhersage gemacht, dass ein Elektron in einem periodischen Potential eines Festkörpers unter dem Einfluß eines statischen elektrischen Feldes oszilliert, wobei die Oszillationsfrequenz linear vom elektrischen Feld abhängt. In Abwesenheit von Streuprozessen hätte dies die Konsequenz, dass kein elektrischer Strom fließen würde. Anfang der 90er Jahre gelang es, künstliche Kristallgitter - sogenannte Halbleiter-Übergitter - mit hinreichender Qualität herzustellen, in denen Bloch Oszillationen in optischen Experimenten mit sub-Pikosekunden Zeitauflösung beobachtet werden konnten. Diese Halbleiter Übergitter sind ein Modellsystem für die Untersuchung kohärenter Wellenpakete und deren Dephasierung in Halbleiter Heterostrukturen. Von besonderem Interesse ist hierbei die Wechselwirkung der oszillierenden Elektronen mit optischen Phononen. Diese konnte kürzlich unter resonanten Bedingungen, d.h. bei Abstimmung der Bloch Frequenz auf die optische Phononfrequenz, untersucht werden, was Aufschluß über einen neuen Mechanismus zur Anregung kohärenter optischer Phononen gab.
Keywords: Bloch Oszillationen, Femtosekunden Spektroskopie, Übergitter, kohärente Phononen
  • Physikalische Blätter 57 (2001) Nr. 7/8, 67-73

Publ.-Id: 4014 - Permalink


Inorganic Colloids in Mine waters
Zänker, H.; Richter, W.; Brendler, V.; Moll, H.; Hüttig, G.;
Inorganic colloids in mine waters are mainly produced by the formation of oxyhydroxides and oxyhydroxy sulfates of iron(III) and aluminum due to the oxidation of Fe2+ and the hydrolysis of Fe3+ and Al3+. They are of relevance as they are able to influence heavy metal transport (emphasis is laid on the behavior of uranium here). Two extremely different types of mine waters can be observed:

(i) Type "acidic pore water"
These waters possess high salt concentrations and are very acidic (pH 1 to 3). Ultrafine particles of <5 nm are the main colloidal component. The colloid concentration reaches the range of >1 g/L. The particles consist mainly of H-jarosite and schwertmannite. As and Pb show a high tendency to adsorb onto these particles.

(ii) Type "bulk water"
This type of waters mainly refers to the flowing mine waters like adit waters which possess a near-neutral pH. Typical colloid contents of such waters are about 1 mg/L, typical particle sizes are 100 to 300 nm. The particles consist of Fe(III) and Al oxyhydroxides. Their electrostatic stabilization is weak, i. e. they show a larger tendency to coagulate. Contaminants such as As, Pb, Cu, Th, U(IV) and Po are bound onto these particles. Uranium(VI) adsorption is often suppressed due to the formation of uranyl carbonato complexes in mine waters.

An interesting colloid chemistry is observed during the transition of type (i) waters to type (ii) waters (flooding of abandoned ore mines). Huge amounts of iron(III) particles with a size of 100 to 300 nm are formed under such conditions. The adsorption rises drastically when the pH reaches the near-neutral region. Uranyl adsorption to the iron(III) particles is neither suppressed by high acidity nor by uranyl carbonate complexation in the pH region 4 to 6. Therefore, most of the uranium(VI) is colloid-borne in waters of the transition type.

Keywords: colloids, mine waters, flooding, uranium
  • Lecture (Conference)
    GSA Annual Meeting, Geological Society of America, Boston, Massachusetts, November 5-8, 2001

Publ.-Id: 4012 - Permalink


Microstructural Investigations on Russian Reactor Pressure Vessel Steels by Small Angle Neutron Scattering
Ulbricht, A.; Böhmert, J.; Strunz, P.; Dewhurst, C.; Mathon, M.-H.;
The effect of radiation embrittlement has high safety significance for Russian VVER reactor pressure vessel steels. Heats of base and weld metal of the as-received state, irradiated state and post-irradiation annealed state were investigated by SANS to get insights about the microstructural features caused by fast neutron irradiation. The SANS intensities increase in the momentum transfer range between 0.8 and 3 nm-1 for all material compositions in the irradiated state. The size distribution function of the irradiation-induced defect clusters has a pronounced maximum at 1 nm in radius. Their content varies between 0.1 and 0.7 vol.% dependent on material composition and increases with the neutron fluence. The comparison of nuclear and magnetic scattering indicates that the defects differ in their composition. Thermal annealing reduces volume fraction of irradiation defect cluster.
Keywords: PACS: 61.12.-q
  • Applied Physics A 74, Suppl. 1, 2002, pp. 1128-1130

Publ.-Id: 4008 - Permalink


Defect engineering and prevention of impurity gettering at Rp/2 in ion implanted silicon
Kögler, R.; Peeva, A.; Kaschny, J. R.; Eichhorn, F.; Hutter, H.;
Cu is especially suitable to decorate defects in silicon. The Cu decoration technique has been
applied for the detection of point defect clusters in the RP/2 region of Si+ ion implanted silicon. The results of
this technique are compared with the results obtained by other analysis techniques. Nanocavities at RP/2
could be observed only in cross section transmission electron microscopy specimen prepared by cleavage
technique. These nanocavities are probably the dominant gettering centres for Cu at RP/2. Small interstitial
clusters may exist there as well. The conditions for the formation and for the annealing of the gettering layer
at RP/2 have been determined. Impurity gettering at RP/2 can be prevented by a sequence of additional Si+
implantations to balance implantation-induced excess vacancies which are the origin of the nanocavities.
Keywords: Silicon, Defects, Gettering
  • Lecture (Conference)
    ECS Symposium DECON 2001, 13./14. 9. 2001 Nürnberg, Deutschland

Publ.-Id: 4007 - Permalink


The Radiochemistry Station for X-Ray absorption spectroscopy experiments at ROBL
Funke, H.; Reich, T.; Bernhard, G.; Matz, W.;
The radiochemistry experimental station at ROBL has been designed to perform environmentally relevant experiments on radionuclides, in particular actinides, using X-ray absorption fine structure spectroscopy. The technical concepts and the layout of this experimental station, where radioactive solids and liquids with activities of up to 185 MBq can be studied, are presented. The radiological safety of experimenters, equipment, and of the environment are ensured by the specially developed radiochemistry safety system.

  • Contribution to HZDR-Annual report
    II. Internationale DELSY-Workshop, JINR Dubna, 2.-6.4.2001

Publ.-Id: 4006 - Permalink


A splice program to connect two different EXAFS spectra of the same sample
Funke, H.; Böttger, H.; Reich, T.; Hennig, C.; Rossberg, A.;
A computer program is presented that is able to connect (to "splice") two EXAFS spectra of the same sample if they have an overlapping energy region. This tool will be useful in many situations when it is impossible to measure a spectrum over the desired energy range in a single scan.
Technical details of the SPLICE program are described to overcome the difficulties concerning the adjustment of different EXAFS spectra containing information about the same sample at different energies. The SPLICE program was tested at the U LIII edge using EXAFS spectra of an uranyl arsenate sample measured up to k of 22 Å -1 at a temperature of 15 K.

  • Contribution to HZDR-Annual report
    2nd Eurokonferenz Actinide-XAS-2000, Grenoble Sept. 2000

Publ.-Id: 4005 - Permalink


Formation of iron oxyhydroxide particles during the dissolution of chlorite: Effect on uranium sorption
Krawczyk-Bärsch, E.; Arnold, T.; Zänker, H.; Hüttig, G.; Brandt, F.; Bosbach, D.; Bernhard, G.;
The abandoned uranium mines in the Western Erzgebirge in Germany are mostly related to the rock phyllite. Currently, many of these mines are being flooded. The flood water, which contains concentration of uranium penetrates through cracks and fissures of the phyllite and leads to a dissolution of several minerals. One of the major components in the phyllite is an iron-rich chlorite [1], which dominates the sorption behaviour for heavy metals.
During the dissolution of the chlorite a reaction causes the loss of octahedral layer cations, primarily Fe. Ferrous iron is released in the aqueous solution, where it is oxidized rapidly to ferric iron. Hydrolysis of ferric iron leads to Fe-oxyhydroxide, which precipitates from the solution as due to the low solubility of iron in the pH region higher 4 [2]. By scanning electron microscopy, these precipitates of Fe-oxyhydroxide are detected as small spherical particles of ferrihydrite that are preferentially situated as immobile coatings on the most reactive edge surfaces of the chlorite crystals. During the dissolution of chlorite a mobile component of ferrihydrite is formed, too. These are colloids, which are found under similar geochemical conditions. The mobile colloids are aqueous species that do not adsorb to rock surfaces. The adsorption of contaminants, for example uranium onto the colloidal particles of ferrihydrite influences and enhances the rate of contaminant transport. In previous investigations the uptake of uranium on ferrihydrite reaches almost 95-100 % in a pH range from 5.0 to 7.5 [1]. Conclusively, the formation of secondarily formed ferrihydrite as mobile colloids and as immobile coatings during the dissolution of chlorite in the rock phyllite is an important process which has to be considered in risk management.
References:
[1] Arnold, T. et al. (1998): Chemical Geology 151,
129-141.
[2] Zänker, H. et al. (2000): Aquatic Geochemistry
(submitted).

  • Poster
    79. Jahrestagung der Deutschen Mineralogischen Gesellschaft, Potsdam, 9.9.-13.9.2001

Publ.-Id: 4004 - Permalink


Das Rigaer Dynamoexperiment: Wie man ein Magnetfeld aufrührt
Stefani, F.; Gerbeth, G.; Gailitis, A.; Lielausis, O.; Platacis, E.;
Das Erdmagnetfeld ensteht durch Strömungen im flüssigen äußeren Erdkern, welche durch Auftriebskräfte und die Rotation der Erde angetrieben werden. Trotz der Fortschritte, die insbesondere im letzten Jahrzehnt bei der numerischen Behandlung des gekoppelten Systems von Induktionsgleichung und Navier-Stokes-Gleichung gemacht worden sind, ist eine realistische Berechnung der Vorgänge im Erdinneren in absehbarer Zukunft nicht möglich. Flüssigmetallexperimente liefern einen komplementären Zugang zum Verständnis homogener Dynamos. Im Vortrag werden die Ergebnisse der jüngsten Rigaer Dynamoexperimente vorgestellt und mit den numerischen Prognosen verglichen.
  • Lecture (others)
    Vortrag im "Geophysikalischen Institutsseminar" der Uni Göttingen, 19. Juni 2001

Publ.-Id: 4003 - Permalink


Wie man ein Magnetfeld aufrührt: Zu den Ergebnissen des Rigaer Dynamoexperiments
Stefani, F.; Gerbeth, G.; Gailitis, A.; Lielausis, O.; Platacis, E.;
Als Quelle kosmischer Magnetfelder wird heute einhellig der homogene Dynamoeffekt in elektrisch leitfähigen Fluiden angesehen. Im Gegensatz zu der inzwischen weit entwickelten Theorie und Numerik dieses Effektes war die experimentelle Untersuchung bis vor kurzem nicht möglich gewesen. Am 11.11.1999 wurde an der Rigaer Natriumanlage erstmalig der homogene Dynamoeffekt in einem Flüssigmetall-Experiment nachgewiesen. Weitere Messungen im Juli 2000 haben die Vorhersagen der kinematischen Dynamotheorie gut bestätigt und eine umfangreiche Datenbasis für das Regime der nichtlinearen Rückwirkung geliefert.
  • Lecture (others)
    Vortrag im Seminar "Nichtlinearität und Unordnung in komplexen Systemen" der Uni Magdeburg, 18. Juni 2001

Publ.-Id: 4002 - Permalink


Quantum fluctuations in rotating nuclei
Almehed, D.;
This thesis is focused on quantum fluctuations in rotating nuclei and on the effect they have on observables such as relative energy and angular momentum. The study of the nucleus under extreme conditions has been one of the main sources of information about nuclear structure over the last decades. Nuclei at high angular momenta are studied by means of modern gamma-detector arrays. Among the phenomena studied in such experiments are the phase transition from superfluid to normal phase, orientation changes in rotating nuclei, shape changes in rotating nuclei, super deformation etc.

The most powerful method to calculate nuclear properties is the mean field approach known as Hartree-Fock or Hartree-Fock-Bogoliubov method. Within this method the two-body interaction is replaced by a selfconsistent one-body potential which is calculated in an iterative way.

The nuclear mean field breaks a series of symmetries present in any realistic two-body Hamiltonian. One motivation to include effects that go beyond the mean field is to restore these symmetries. Two methods of restoring symmetries are used in this thesis, namely, the projection method and the random phase approximation (RPA).

An advanced quantum mechanical description of a nuclei should take into account quantum fluctuations around the mean field minimum. The quantal fluctuations do not only lead to a series of collective excitations like vibrations and rotations but also add correlations to the mean field ground state. The correlation energy gained by these quantum fluctuations is, in general, state dependent and is important when describing observables like the moment of inertia, the ordering and relative energies between states.

Keywords: Nuclear strcture, Hartree-Fock-Bogoliubov, Random Phase Approximation, Projection, Tilted Axis Cranking
  • Other report
    Dissertation TU Dresden

Publ.-Id: 4001 - Permalink


Annual report 2000 Institute of Safety Research
Weiß, F.-P.; Rindelhardt, U.; (Editors)
The report gives an overview on the activities of the Institute of Safety Research in 2000.
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-316 April 2001

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Publ.-Id: 4000 - Permalink


High dose nitrogen and carbon shallow implantation in Si by plasma immersion ion implantation
Ueda, M.; Reuther, H.; Günzel, R.; Beloto, A. F.; Abramof, E.; Berni, L. A.;
PIII was used to dope Si (001) wafers with nitrogen and carbon at high doses, relying on two PIII systems: one at the FZR and the other at INPE.
  • Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 175-177 (2001) 715-720

Publ.-Id: 3999 - Permalink


Reciprocal space mapping of silicon implanted with nitrogen by plasma immersion ion implantation
Abramof, E.; Beloto, A. F.; Ueda, M.; Günzel, R.; Reuther, H.;
Nitrogen was implanted in (001) silicon wafers using 12 kV pulses in a glow-discharge PIII system and at 35 keV in an ECR PIII facility.
  • Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 175-177 (2001) 229-234

Publ.-Id: 3998 - Permalink


Porous silicon implanted with nitrogen by plasma immersion ion implantation
Beloto, A. F.; Ueda, M.; Abramof, E.; Senna, J. R.; Leite, N. F.; Da Silva, M. D.; Reuther, H.;
Porous silicon samples were prepared on (100) monocrystalline silicon wafers and implanted with nitrogen by PIII and analyzed by AES and reflectance measurements.
  • Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 175-177 (2001) 224-228

Publ.-Id: 3997 - Permalink


Effect of annealing on the interface structure of cross-beam pulsed laser deposited Co/Cu multilayers
Prokert, F.; Noetzel, J.; Schell, N.; Wieser, E.; Gorbunov, A.;
Co/Cu multilayers were prepared by cross-beam pulsed laser deposition and characterised by high-angle X-ray diffraction as well as specular and off-specular reflection before and after annealing (500 °C, 2h). Using synchrotron radiation at the K-edge energy of Co and Cu to enhance the scattering contrast, the study shows that annealing does not enlarge the interface roughness but strongly influences the interface morphology. In the fractal model of self-affine structures the latter is expressed by the drastic reduction of the extremely large lateral roughness correlation length parameter from about 4 µm in the as-deposited state to about 20 nm after annealing. High-angle X-ray diffraction indicates that the reduction of lateral roughness correlation length is caused by grain coarsening due to growth of crystallites and grain boundaries. Thermal treatment enhances the separation of Co and Cu at the interface, i.e. the initially very jagged (roughness exponent between 0.15 and 0.3) structure is smoothed (roughness exponent between 0.6 and 0.7).




Keywords: Interfaces; Multilayers; Laser ablation; X-ray diffraction
  • Thin Solid Films 416 (2002) 114-121

Publ.-Id: 3992 - Permalink


Elastic constants of tetrahedal amorphous carbon films: the effect of intrinsic stresses
Belov, A.; Jäger, H.-U.;
Atomic calculations, based on empirical potentials and the method of homogeneous deformation, are presented for the elastic properties of as-deposited amorphous carbon at 0 K. Several structural models of amorphous carbon generated by a realistic molecular-dynamics simulation of ion-beam deposition were studied. The models yield intrinsic compressive stresses of approximately 10 GPa. Here, we examine the dependence of the second-order elastic constants of amorphous carbon on the intrinsic stress, as well as on hydrostatic pressure. Different sets of elastic constants describing the behaviour of a solid under stress are considered. The nonlinear effects are shown to become appreciable at a pressure of 10 GPa, whereas the difference between the elastic constants in the equations of motion and the Lagrangian elastic constants is not large.
Keywords: Molecular dynamics, tetrahedral amorphous carbon, intrinsic stress, elastic constants
  • Surface and Coatings Technology 151-152 (2002) 128-132

Publ.-Id: 3991 - Permalink


Crystal growth melt flow control by means of magnetic fields
Galindo, V.; Gerbeth, G.; von Ammon, W.; Tomzig, E.; Virbulis, J.;
Contactless melt flow control is important in many crystal growth technologies. Typically, steady magnetic fields are used to damp convective flow. On the other hand active flow driving forces like in a rotating magnetic field can be of stabilizing character, too. We present numerical results for the combined action of steady and alternating magnetic fields for the silicon Czochralski crystal growth process. The melt flow is determined by various flow driving sources: besides the thermal convection and rotation of crystal and crucible, there are also the influence of driving and/or damping electromagnetic forces and the thermocapillary-driven flow at the free deformable melt surface.
Keywords: crystal growth, magnetic fields, flow control
  • Energy Conversion and Management 43 (2002) 309-316

Publ.-Id: 3990 - Permalink


Mapping of carbonic anhydrase and estrone sulfatase in rat brain using 16-Alpha-[18F]Fluoroestradiol-3,17-Beta-disulphamate ([18F]FESDS)
Rodig, H.; Brust, P.; Römer, J.; Kasch, H.; Bergmann, R.; Füchtner, F.; Steinbach, J.; Johannsen, B.;
16-Alpha-[18F]Fluoroestradiol-3,17-Beta-disulphamate ([18F]FESDS) has recently been discovered to display affinity to carbonic anhydrase (CA) and estrone sulfatase (ES), enzymes which are expressed in the CNS and suggested to play a regulatory role in various brain diseases. In this study the radioligand was used to provide quantitative data on the regional distribution of these enzymes in the rat brain. The expression of CA I, CA II and ES has been studied in rat brain regions with RT-PCR. CA II and ES but not CA I has been detected in all regions. About 80-90 % of the total binding of [18F]FESDS to brain slices represents binding to CA (displaceable with acetazolamide). Binding of [18F]FESDS to ES was studied with selective inhibition of CA using acetazolamide. Bmax values of between 0.3 pmol/mg (pons) and 11.5 pmol/mg (striatum) were obtained in various brain regions. The Kd and Bmax values of ES binding were used as constants to calculate Kd and Bmax of CA binding from inhibition studies with FESDS. Bmax values of between 6.2 pmol/mg protein (striatum) and 14.6 pmol/mg (cerebellum) were obtained. The Kd-values varied between 33 nM and 166 nM, which is similar to the Kd of [18F]FESDS binding to purified human CA-II (54 nM). The affinity of FESDS to ES is lower by about factor 5. Furthermore, the enzymatic activity of ES in six rat brain regions was determined and found to be correlated to the corresponding [18F]FESDS binding. It is concluded, that [18F]FESDS can be used for mapping of CA and ES in vitro. The in vivo use of the radioligand may be limited because of its bipolar binding profile.
  • Poster
    International Brain '01, Taipei/Taiwan, 9.6.-13.6. 2001
  • Abstract in refereed journal
    J. Cereb. Blood Flow Metab. 21(Suppl.1) (2001) S552

Publ.-Id: 3989 - Permalink


Synthesis , biological and autoradiographic evaluation of a novel Tc-99m radioligand derived from WAY 100635 with high-affinity for the 5-HT1A receptor and the alpha1-adrenergic receptor
Heimbold, I.; Drews, A.; Kretzschmar, M.; Varnäs, K.; Hall, H.; Halldin, C.; Syhre, R.; Kraus, W.; Pietzsch, H.-J.; Seifert, S.; Brust, P.; Johannsen, B.;
This paper reports synthesis, biological evaluation, in vitro and ex vivo autoradiography of the first Tc-99m ligand with subnanomolar affinity for the 5-HT1A receptor and a remarkably high affinity for the alpha1-adrenergicreceptor. The neutral "3+1" mixed-ligand complex combines 4-(6-mercaptohexyl)-1-(2-methoxyphenyl)piperazine as monodentate and 3-(N-methyl)azapentane-1,5-dithiol as tridentate unit with oxotechnetium(V). The analogous rhenium complex was synthesized for complete structural characterization and used in receptor binding assays. In competition experiments both complexes display subnanomolar affinity for the 5-HT1A receptor (IC50 0.24 nM for Re, 0.13 nM for Tc) but also very high affinities for the alpha1-adrenergic receptor (IC50 0.05 nM for Re, 0.03 nM for Tc). Biodistribution studies show a brain uptake in rat of 0.22 % ID five minutes post injection. In vitro autoradiographic studies in rat brain and postmortem human brain indicate the accumulation of the Tc-99m complex in brain areas which are rich in 5-HT1A receptors or in alpha1-adrenergic receptors. This in vitro enrichment can be blocked respectively by the 5-HT1A receptor agonist 8-OH-DPAT or by prazosin hydrochloride, an alpha1-adrenergic receptor antagonist. Ex vivo autoradiographic studies in rats show a slight accumulation of the Tc-99m complex in 5-HT1A receptor-rich areas of the brain which could not be blocked, as well as in regions rich in alpha1-adrenergic receptors, which could be blocked by prazosin hydrochloride.
Keywords: Serotonin 5-HT1A receptor; Tc-99m receptor ligand; WAY 100635 analogue; Ligand synthesis; In vitro and ex vivo autoradiography; Receptor binding assay
  • Nuclear Medicine and Biology 29 (2002) 375-387

Publ.-Id: 3987 - Permalink


Calculation of intrinsic stresses in amorphous carbon films grown by molecular dynamics simulation: from atomic to macroscopic scale
Belov, A.; Jäger, H.-U.;
We present a method to calculate macroscopic bulk stresses in tetrahedral amorphous carbon (ta-C) films grown by a realistic atomic scale simulation of ion-beam deposition. Similar to real as-deposited films, the simulated films have a high content of sp3 bonded atoms and large intrinsic compressive stresses. Deriving atomic stresses from an interatomic potential and averaging them over slices inside the film, we show that average stresses in the inner film region converge to realistic values (~10 GPa) as the thickness of the slices exceeds 1 nm. The analysis of stress variation with depth reveals that in amorphous films deposited with low energy (20-30 eV) ions the highest compressive stress is attained in the region of steady-state growth, while in films grown with 80 eV ions it reaches a maximum in an intermediate layer adjacent to the crystalline substrate. The transition from graphitic carbon to ta-C is found to occur at a threshold stress of about 13 GPa
Keywords: Molecular dynamics, tetrahedral amorphous carbon, intrinsic stress
  • Computational Materials Science 24 (2002) 154-158

Publ.-Id: 3986 - Permalink


Evolution of ion implantation caused vacancy-type defects in 6H-SiC probed by Slow Positron Implantation Spectroscopy
Anwand, W.; Brauer, G.; Skorupa, W.;
6H-SiC n-type wafers were implanted with Al+ and N+ ions in two steps: first Al+ double implantation (100 keV, 5x1016 cm-2 and 160 keV, 1.3x1017 cm-2 ) followed by N+ double implantation (65 keV, 5x1016 cm-2 , 120 keV, 1.3x1017 cm-2 ). The implantation was carried out at a substrate temperature of 800 0C in order to avoid amorphisation. In this way a buried SiC1-x(AlN)x layer could be created. Variable-energy positron Doppler broadening measurements were performed at room temperature using a computer-controlled magnetic transport beam system in order to characterize the vacancy-type defects created by ion implantation. Depth profiles could be evaluated from the measured Doppler broadening profiles. The defect distribution and the defect size after the complete co-implantation are discussed and the contribution of the different implantation steps to the evolution of this defect structure is shown.

This research is supported by the Deutsche Forschungsgemeinschaft (DFG) under
Grant No. Br 1250/13-1 and Br 1250/13-2.
Keywords: 6H-SiC, N and Al co-implantation, vacancy-type defects, slow positron spectroscopy
  • Applied Surface Science 184 (2001) 247
  • Poster
    European Materials Research Society Spring Meeting, Strasbourg, France, June 5-8, 2001

Publ.-Id: 3972 - Permalink


Complex formation of uranium(IV) with phosphate and arsenate studied by spectroscopic methods
Geipel, G.; Bernhard, G.; Brendler, V.; Fanghänel, T.;
Uranium is one of the main potential contaminants in East Germany's former mining areas. Under reducing conditions uranium(IV) is stable and can be complexed by phosphate and arsenate at low pH. Due to their low water solubility no thermodynamic complex formation constants are available for the uranium(IV)-phosphate and arsenate complexes.. For example, the solubility product /1/ of U(HPO4)2·4H2O limits the uranium(IV) concentration in 1 M perchloric acid to less than 1.2 x 10-4 M. Moreover there is a general lack of information on the aqueous chemistry and thermodynamics of tetravalent actinides.
We studied the formation of these complexes at uranium concentrations between 2 x 10-6 M and 1 x 10-4 M by Laser-Induced Photoacoustic Spectroscopy and UV-vis spectroscopy in acid media. To determine the complex formation constant we measured and analyzed the spectra from 600 nm to 690 nm. The spectra were corrected for the absorption of the solvent water. The solvated uranium(IV) shows a very intensive absorption band with a maximum at 650 nm and a smaller maximum at 672 nm. We found a shoulder at 630 nm deconvoluting the absorption spectrum.
The spectrum changes with increasing phosphate and arsenate concentration. Two isosbestic points were determined at 661 nm and 670 nm in the phosphate system. In the arsenate system three isosbestic point were found to be at 628 nm, 660 nm and 667 nm.
From measurements with variable ionic strength, ligand and proton concentration the complexation reaction according to
U4+ + H3LO4 <=> UH2LO43+ + H+ (L = P, As)
was quantified
The stoichiometry of the formed phosphate and arsenate complexes was confirmed by slope analysis. The formation constant at infinite dilution in the phosphate system was found to be log b0 = 3.52 ± 0.18 using the SIT extrapolation. For the arsenate system we found the complex formation constant to be log b0 = 2.13 ± 0.32.
  • Lecture (Conference)
    Actinides, 4.-8. November 2001, Hayama, Japan

Publ.-Id: 3969 - Permalink


Combination of EXAFS and powder diffraction for solving heavy-atom structures
Hennig, C.; Reich, T.; Schell, N.; Reck, G.; Kraus, W.;
Poster -
Combination of EXAFS and powder diffraction for solving heavy-atom structures
  • Poster
    Aussois Science Days Seminar, 9.-11.05.2001, Aussois, France

Publ.-Id: 3968 - Permalink


Ion beam processing for Si/C-rich thermally grown SiO2 layers: photoluminescence and microstructure
Rebohle, L.; Gebel, T.; Fröb, H.; Reuther, H.; Skorupa, W.;
In this paper the luminescence properties of thin thermally grown SiO2 layers implanted with silicon and carbon ions are explored. The doses and energies were chosen in such a way that the resulting peak concentration of excess Si and C amounts to 5...10 % in a depth region of 60 to 180 nm below the surface. The microstructure was investigated by Auger electron spectroscopy and transmission electron microscopy. Amorphous nanostructures with a size between 2 and 3.5 nm were found in depth region between 80 and 150 nm below the oxide surface. Strong photoluminescence around 2.1 and 2.7 eV has been observed after excitation at 4.77 eV. SiyC1-yOx complexes with x<2 are assumed to cause the observed PL in the blue spectral region.
Keywords: silicon carbide, ion implantation, photoluminescence, Auger electron spectroscopy
  • Applied Surface Science 184 (2001) 156

Publ.-Id: 3967 - Permalink


Project-Group ESRF-Beamline (ROBL-CRG), Bi-Annual Report 1999/2000
Matz, W.;
The second report from the Project-Group ESRF-Beamline of the Forschungszentrum Rossendorf covers the period from July 1999 until December 2000. The ROssendorf BeamLine (ROBL) at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France performed quite well during this time. In the beamtime used by the FZR and collaborating institutes 44 scheduled experiments were performed, while in the ESRF scheduled beamtime 12 experiments. Additionally, a distinct amount of beamtime was devoted to in-house research of the FZR and methodical experiments.
Since February 2000 ROBL is part of the European Commission’s programme ”Access to Research Infrastructure” which supports user groups from member and associated states of the EU during experiments at ROBL. In the year 2000 ROBL hosted 6 groups for experiments.

The report is organised in three main parts. The first part contains extended contributions on results obtained at ROBL. The second part gives an overview about the scheduled experiments, publications, guests having visited ROBL with support of the EC, and some other information. Finally, the third part collects the experimental reports of the user groups received.
Keywords: ROBL, synchrotron radiation, EU large scale facility, annual report
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-322 Juni 2001

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Publ.-Id: 3966 - Permalink


Transport of reacting solutes through the unsaturated zone
Kuechler, R.; Noack, K.;
Unsaturated flows within subsurface regions control many large-scale hydrological
and environmental processes. This contribution presents and discusses the results of numerical calculations dealing with the flow of water, the chemical reaction at the water-mineral interface and the transport of chemical species caused by such flows. The reason for the water flow through the soil is solely the rainfall.
The water motion is calculated for two different soil classes and for a typical annual precipitation. The transport of chemical species is described by a set of partial differential equations, and the homogeneous chemical processes, under the assumption of equilibrium, are described by a set of nonlinear algebraic equations. The source terms of these partial differential equations are given by rate laws of chemical weathering. Rainfall and chemical weathering are therefore the reason of the transport of reactive multispecies in this model.
  • Transport in Porous Media 49 (2002) 361-375

Publ.-Id: 3965 - Permalink


Prevention of impurity gettering in the RP/2 region of ion implanted silicon by defect engineering
Kögler, R.; Peeva, A.; Kaschny, J.; Skorupa, W.; Hutter, H.;

Si+ ion implantation into Si under inclined incidence angle was applied to demonstrate that Cu gettering in the region around half of the projected ion range, RP/2, of ion-implanted Si is controlled by the same mechanism working for excess vacancy generation. The obtained results directly relate the appearance of the RP/2 gettering effect to radiation-induced excess vacancies. Excess vacancies were found to be origin for the dominating gettering sites of Cu at RP/2. Moreover, it was shown that the undesired impurity trapping at RP/2 can be prevented by means of additional Si+ implantation into the vacancy-rich region of ion-implanted Si to balance the excess of vacancies. The parameters were determined for the additional Si+ implantation to remove Cu gettering at RP/2. If the threshold fluence necessary to remove the Cu gettering at RP/2 is exceeded, the excess vacancies are overcompensated and new interstitial-type dislocation loops form.

Keywords: Ion implantation, defects, gettering, Si, Cu
  • Nuclear Instruments and Methods in Physics Research B 186 (2002) 298-302
  • Lecture (Conference)
    E-MRS Spring Meeting, Strasbourg, June 5-8, 2001

Publ.-Id: 3964 - Permalink


Entwicklung einer Niederenergie-Implantationskammer mit einem neuartigen Bremslinsensystem
Teichert, J.; von Borany, J.;
In diesem Report wird eine Niederenergie-Implantationskammer (NEI-Kammer) beschrieben, die im Forschungszentrum Rossendorf entwickelt und aufgebaut wurde. Die Kammer ermöglicht es, die Implantation von Ionen bei niedrigen Energien (< 30 keV) mit einer Implantationsanlage für mittlere Energien durchzuführen. In der Kammer werden der Ionenstrahl, den der Implanter liefert, auf die erwünschte niedrige Energie abgebremst. Dazu wird ein elektrostatisches Bremslinsensystem eingesetzt, das auf einem neuartigen Prinzip basiert. Das System besteht aus einer Sammellinse und einer Zerstreuungslinse, wobei die Öffnungsfehler beider Linsen entgegengesetzte Vorzeichen besitzen und sich gegenseitig kompensieren. Dadurch ist es möglich, Wafer gebräuchlicher Größe bei geringer Energie mit hoher Dosishomogenität zu implantieren. Die NEI-Kammer ist insbesondere für Forschungseinrichtungen eine vorteilhafte Lösung, da sie eine wesentlich kostengünstigere und flexiblere Alternative zur Anschaffung einer Niederenergie-Implantationsanlage darstellt.
Keywords: ion implantation, low-energy implantation, implanter, decel lens system, electrostatic lens, deceleration, dose uniformity
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-323 Mai 2001

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Publ.-Id: 3963 - Permalink


P-type doping of SiC by high dose Al implantation - problems and progress
Heera, V.; Panknin, D.; Skorupa, W.;
The development of optimized processes for p-type doping of SiC by ion implantation and subsequent annealing is a remaining challenge to SiC-device technology. Al is a promising acceptor in SiC. Compared to B it has a shallower acceptor level and a stronger tendency to occupy atomic sites in the Si sublattice which makes it more suitable for the production of heavily doped, low resistivity layers. However, also in the case of Al very high acceptor concentrations (>1019 cm-3) are necessary to obtain SiC layers with low resistivities (<1 cm). The physical consequences of such high impurity concentrations in SiC for the annealing of implantation damage and the electrical activation will be discussed. A survey of the results of several implantation and annealing schemes is presented.


Keywords: SiC, P-type doping, Al implantation, resistivity, annealing
  • Applied Surface Science 184 (2001) 307-316

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Publ.-Id: 3962 - Permalink


Spreading resistance measurements on nanocrystalline SiC produced by ion beam induced crystallization
Madhusoodanan, K. N.; Heera, V.; Panknin, D.; Skorupa, W.;
Ion beam induced crystallization (IBIC) of preamorphized surface layers on 6H-SiC has been stimulated by high dose Al implantation (0.3 - 3 E17 cm-2) at elevated temperatures (300 -500°C). Randomly oriented 3C-SiC nanocrystals withn diameters between 2 and 25 nm are formed depending on the implantation parameters as proved by XRD and XTEM. Spreading resistance measurements have been performed at bevelled as-implanted and annealed (1500°C, 10 min) samples in order to study the electrical behaviour of the Al acceptors in the nanocrystalline layer. Reference experiments have been carried out on single crystalline 6H- SiC crystals implanted at the similar conditions. It has been found that in the as-implanted state Al doped fine granular SiC has much lower spreading resistance than the corresponding single crystalline SiC. Only minor differences have been observed between the nano- and single crystalline samples after annealing.
Keywords: 6H-SiC, Ion implantation, amorphisation, recrystallisation, spreading resistance
  • Lecture (Conference)
    E-MRS 2001 SPRING MEETING, Strasbourg (France), June 5-8, 2001
  • Applied Surface Science 184 (2001) 209-213

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Publ.-Id: 3960 - Permalink


Writing Cobalt FIB implantation into 6H:SiC
Bischoff, L.; Teichert, J.;
Focused ion beam implantation of cobalt at 35 keV into 6H:SiC is used to investigate a possible ion beam synthesis of CoSi2 micro-structures. The pattern were studied using SEM and EDX measurements. The resistivity of the implanted test-structures was determined as a function of dose, implantation and annealing temperature. For room temperature irradiated samples after a 1150°C annealing resistivities of about 100 µScm could be achieved and a diode like behaviour influenced by parasitic resistors between structure and bulk was found.
Keywords: Focused ion beam, cobalt implantation, SiC, annealing, resistivity, diode
  • Lecture (Conference)
    E-MRS Spring Meeting, 5-8 June 2001, Strasbourg, France,
  • Applied Surface Science 184 (2001) 336 - 339

Publ.-Id: 3959 - Permalink


Focused Ion Beam Sputtering Investigations on SiC
Bischoff, L.; Teichert, J.; Heera, V.;
The focused ion beam is a very useful tool to sputter holes with well defined dimensions which can be easily analysed by surface profiling measurements. Applying this the sputte-ring yields of 6H:SiC were -measured for 35 and 70 keV Si, Co, Ge, Nd and Au ions from a mass separated focused ion beam. Additionally, the sputtering yield was determin-ed as a function of the angle of incidence and the target temperature for gold ions. The swelling due to ion implantation will be discussed.
Keywords: Focused ion beam, sputtering, SiC, swelling, millling rate
  • Lecture (Conference)
    E-MRS Spring Meeting, 5-8 June 2001, Strasbourg, France,
  • Applied Surface Science 184 (2001) 372 - 376

Publ.-Id: 3958 - Permalink


Quantitative analysis of deuterium in a-C:D layers, a Round Robin experiment
Behrisch, R.; Mayer, M.; Jacob, W.; Assmann, W.; Dollinger, G.; Bergmayer, A.; Kreissig, U.; Friedrich, M.; Sun, G.-Y.; Hildebrandt, D.; Akbi, M.; Schneider, W.; Schleußner, D.; Knapp, W.; Edelmann, C.;
The absolute amount of deuterium in amorphous deuterated carbon (a-C:D) layers has been measured by six laboratories with different techniques, such as MeV ion beam analysis, secondary ion mass spectrometry (SIMS), and thermal desorption spectrometry (TSD). The a-C:D layers have been deposited from a CD4 glow discharge plasma onto carbon and silicon substrates. The results for the absolute numbers obtained with the different analysing techniques show a scatter of up to about 35% around the average value. The deviations are larger than the errors stated by the experimentalists and indicate possible systematic uncertainties in some of the experiments.
Keywords: Mass spectrometry; Deuterium
  • Journal of Nuclear Materials 281 (2000) 42-56

Publ.-Id: 3957 - Permalink


Accelerator mass spectrometry at the Rossendorf tandem accelerators
Friedrich, M.; Bürger, W.; Grötzschel, R.; Henke, D.; Sun, G.-Y.; Turuc, S.; Hebert, D.; Rothe, T.; Stolz, W.;
A short description of the Rossendorf AMS system is given and first experimental results are presented. The planned applications are listed.
Keywords: Mass spectrometry; Radiodating; Electrostatic accelerators
  • Nuclear Instruments and Methods in Physics Research B 92 (1994) 58-60

Publ.-Id: 3956 - Permalink


Status and research report at the Tritium Laboratory Karlsruhe
Penzhorn, R.-D.; Bekris, N.; Coad, P.; Dörr, L.; Friedrich, M.; Glugla, M.; Haigh, A.; Lässer, R.; Peacock, A.;
The Tritium Laboratory Karlsruhe (TLK) has mainly designed for the conduction of technological experiments relevant to fusion under simulation of the conditions actually expected in the various tritium processing systems. Presently ongoing experimental and design work is almost exclusively oriented towards the needs of JET and ITER-H-FEAT. Basic research, while increasing in importance, plays predominatly a complementary role. This paper presents the most recent progress and developments related to the technological and applied experiments at the TLK.
Keywords: Tritium Laboratory Karlsruhe (TLK); Infrastructure systems; Calorimeters
  • Fusion Engineering and Design 49-50 (2000) 753-767

Publ.-Id: 3950 - Permalink


Unterstützung der ukrainischen Aufsichtsbehörde beim Aufbau einer modernen KKW-Überwachung
Beyer, M.; Carl, H.;
Das Mitte der 90er Jahre im KKW Saporoshje als Pilotprojekt für den 5. Block eingerichtete Fernüberwachungssystem wurde auf alle Blöcke der KKW Saporoshje und Rovno (Ukraine) erweitert und mittels moderner Kommunikationstechnik an das Informations- und Krisenzentrum der ukrainischen Aufsichtsbehörde in Kiew angeschlossen. Nach entsprechender Weiterentwicklung der Software für die Informationsverarbeitung, -übertragung und -bewertung können von diesen KKW-Blöcken sicherheitsrelevante betriebliche und radiologische Messwerte kontinuierlich erfasst, vor Ort in Form von Tabellen, Grafiken und Schemata online dargestellt sowie nach Kiew übertragen und dort visualisiert und bewertet werden.
Keywords: Kernkraftwerk, Ukraine, Fernüberwachung
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2001, Dresden, 15.-17. Mai 2001, Tagungsbericht, S. 463-466
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2001, Dresden, 15.-17. Mai 2001, Tagungsbericht, S. 463-466

Publ.-Id: 3949 - Permalink


Aufbau und Funktionsweise eines Fernüberwachungssystems für technologische Parameter ukrainischer Kernkraftwerke (in Russisch)
in Russian
Beyer, M.; Carl, H.; Schumann, P.; Chernousov, V.;
Es wird ein System zur Überwachung technologischer Parameter für Blöcke ukrainischer Kernkraftwerke beschrieben. Die Autoren erläutern die theoretischen Grundlagen der Fernüberwachung sowie Aufbau und Wirkungsweise des Systems. Nachfolgend wird seine Einordnung in die ukrainischen kerntechnischen Aufsichtsbehörden dargelegt. Die Bestandteile der speziell für diese Anwendung entwickelten Software werden anhand von Beispielen erklärt und die Implementierung auf die Hardware beschrieben. Erste Erprobungsergebnisse und Vorschläge zur Erweiterung des Systems beenden den Artikel.
Keywords: Kernkraftwerk, Fernueberwachung, Ukraine, Aufsichtsbehoerde
  • Kybernetische Systeme und Anlagen, Informationstechnologie

Publ.-Id: 3948 - Permalink


Velocity measurements in liquid sodium by means of Ultrasound Doppler Velocimetry
Eckert, S.; Gerbeth, G.;
A successful application of the Ultrasound Doppler Velocimetry (UDV) in liquid sodium flows is described.
To get sufficient Doppler signals different problems had to be solved: the transmission of the ultrasonic
beam through the channel wall made of stainless steel, the acousting coupling between transducer and
channel wall and the wetting of the inner surface of the wall by the liquid metal, respectively.
A sodium flow in a square duct exposed to a transverse magnetic field is investigated. According to the
existing knowledge about MHD channel flows we found the velocity profiles modified to a M-shape due to
the effect of an inhomogeneous magnetic field.
Keywords: flow measurement technique, ultrasound Doppler technique, fluid velocity, opaque fluids, liquid metal, MHD channel flow
  • Experiments in Fluids 32(2002)5, 542-546

Publ.-Id: 3946 - Permalink


Self-Organization of Nanostructures With Ion Beams
Heinig, K.-H.; Schmidt, B.; von Borany, J.; Müller, T.; Bernas, H.;
Self-organized nanostructures produced by far-from-equilibrium processing of semiconductor materials with ion beams can be applied in microelectronics (e.g. nanocluster memories), optoelectronics (luminescence from Si nanocrystals) and photonics (plasmonic devices using Au nanoclusters). Our recent experimental, theoretical and computer simulation work, which aimed at optimization and improved fundamental understanding of these processes, will be reviewed.
Two different regimes of self-organization will be distinguished: (i) Relaxation regime: Ion implantation of impurity atoms may produce extremely supersaturated solid solutions. During subsequent annealing this far-from-equilibrium state relaxes towards equilibrium by phase separation (nucleation, growth) and minimization of interface energy (Ostwald ripening, coalescence). Self-organization phenomena (e.g. pattern formation during spinodal decomposition, Rayleigh or pearling instability during interface minimization) are observed. (ii) Driven system: Interfaces or compounds like SiO2 can be driven into a steady state far from equilibrium by ion irradiation. The steady state is established by a competition between collisional mixing, diffusion and re-formation of the compound. The application of resulting effects like nanocluster d-layer formation and ''inverse'' Ostwald ripening for devices will be discussed.
Keywords: Ion beam synthesis, Ostwald ripening, nanocluster, far-from-equilibrium, inverse Ostwald ripening, Rayleigh instability
  • Lecture (Conference)
    E-MRS Spring Meeting, 5-8 June 2001, Strasbourg, France

Publ.-Id: 3944 - Permalink


Institute of Bioinorganic and Radiopharmaceutical Chemistry; Annual Report 2000
Johannsen, B.; Seifert, S.;
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-312 Januar 2001

Downloads:

Publ.-Id: 3933 - Permalink


Investigating interatomic solid state potentials using Crystal-GRID: a study of applicability; Dissertation
Hauschild, T.;
Dissertation
Keywords: Crystal-GRID, interatomic solid state potentials, gamma spectroscopy, molecular dynamics, maximum likelihood estimation
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-321 Mai 2001

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Publ.-Id: 3932 - Permalink


Das Sorptionsverhalten von U(VI) am Granit von Eibenstock (Erzgebirge) und seinen mineralogischen Komponenten
Krawczyk-Bärsch, E.; Arnold, T.; Bernhard, G.;
Die Migration von Uranspezies durch geologische Formationen wird durch die mineralogische Zusam-mensetzung der Gesteine sowie durch die che-mischen Eigenschaften der wässrigen Lösung bestimmt. In Abhängigkeit von den chemisch-physikalischen Bedingungen wird Uran an den Mineralen sorbiert. Um diese Bedingungen näher einzugrenzen, wurden Batchexperimente im Labor durchgeführt, die die natürlichen Bedingungen simulieren. Als Gesteinsprobe wurde der Granit von Eibenstock ausgewählt, der als geologische Formation einen großen Bereich der ehemaligen Uranbergbauregion im westlichen Erzgebirge bestimmt. Die mineralogischen Bestandteile des Eibenstocker Granits sind Quarz (45 %), Orthoklas (35 %), Albit (7,5 %), Biotit (7,5 %) sowie Muskowit (4 %). Für die Batchexperimente wurden 0,5 g der Granitprobe (63-200 µm Körnung) sowie 0,5 g der einzelnen Mineralkomponenten des Granits mit jeweils 40 ml 0,1 M NaClO4-Lösung der Verwitterung über mehrere Wochen ausgesetzt. Im Anschluß an die Stabilisierung der eingestellten pH-Werte erfolgte die Zugabe einer 1.10-6 M UO2(ClO4)-Lösung. Nach einer Sorptionsdauer von 2,5 Tagen wurde der Urangehalt in den Lösungen massenspektrometrisch bestimmt.
Die Ergebnisse zeigen eine hohe Sorption von U(VI) am Granit in einem pH-Bereich von 5 bis 7 mit einer maximalen Sorption von 94,62 % bei einem pH von 6.57. Bei einem pH < 5 sowie > 7 nimmt die Sorption stark ab. Unterhalb pH 4, bzw. oberhalb pH 8.5 ist die Sorption < 1 %. Im Vergleich zu anderen Gesteinen des Erzgebirges ist die U(VI)-Sorption am Granit deutlich auf einen kleinen pH-Bereich beschränkt [1]. Die Sorption an den Mineralkomponenten des Granits zeigt eine ähnliche Tendenz, wobei die Schichtsilikate Muskowit und Biotit durch ihre im Vergleich zu den Feldspäten höhere Sorption dominieren [2].

Literatur:
[1] Krawczyk-Bärsch, E. (2000): Final Report DFG (Ni 210/5-1).
[2] Arnold, T. et al. (1998): Chemical Geology 151, 129-141.






  • Lecture (Conference)
    Vortrag / 79. Jahrestagung der Deutschen Mineralogischen Gesellschaft, Potsdam, 9.9.-13.9.2001

Publ.-Id: 3931 - Permalink


Implantation induced defects in silicon detected by Cu decoration technique
Kögler, R.; Peeva, A.; Eichhorn, F.; Kaschny, J.; Voelskow, M.; Skorupa, W.; Hutter, H.;
Cu is especially suitable to decorate defects in silicon. The Cu decoration technique has been applied for the detection of point defect clusters in the RP/2 region of Si+ ion implanted silicon. The results of this technique are compared with the results obtained by other analysis techniques. Nanocavities at RP/2 could be observed only in cross section transmission electron microscopy specimen prepared by cleavage technique. These nanocavities are probably the dominant gettering centres for Cu at RP/2. Small interstitial clusters may exist there as well. The conditions for the formation and for the annealing of the gettering layer at RP/2 have been determined. Impurity gettering at RP/2 can be prevented by a sequence of additional Si+ implantations to balance implantation-induced excess vacancies which are the origin of the nanocavities.
Keywords: Ion implantation, defects, silicon, Cu, impurity gettering, Rp/2 defects, TEM specimen preparation
  • Journal of the Electrochemical Society 29 (2001) 133
  • Lecture (Conference)
    Symp. on Crystalline Defects and Contamination DECON 2001, Nürnberg Sept. 13-14, 2001

Publ.-Id: 3927 - Permalink


Energy resolution and energy-light response of CsI (Tl) scintillators for charged particle detection
Wagner, A.; Tan, W. P.; Chalut, K.; Charity, R. J.; Davin, B.; Larochelle, Y.; Lennek, M. D.; Lui, T. X.; Liu, X. D.; Lynch, W. G.; Ramos, A. M.; Shomin, R.; Sobotka, L. G.; de Souza, R. T.; Tsang, M. B.; Verde, G.; Xu, H. S.;
This article describes the crystal selection and quality control utilized to develop and calibrate a high resolution array of CsI(TI) scintillator crystals for the detection of energetic charged particles. Alpha sources are used to test the light output variation due to thallium doping gradients. Selection of crystals with better than 1% non-uniformity in light output is accomplished using this method. Tests with 240 MeV alpha beam reveal that local light output variations within each of the tested CsI(TI) crystals limit the resolution to about 0.5%. Charge and mass dependences in the energy - light output relationship are determined by calibrating with energetic projectile fragmentation beams.
Keywords: crystal selection quality control CsI(TI) scintillator light output variation thallium doping gradient projectile fragmentation beam
  • Nucl.Instrum.Meth. A 456 (2001) 290-299

Publ.-Id: 3924 - Permalink


The merits of particle induced X-ray emission in revealing painting techniques
Neelmeijer, C.; Mäder, M.;
Particle Induced X-ray Emission (PIXE) at the external proton beam has proved ideal to study the individual techniques used for creating art objects. In particular, PIXE is tailored for examining paintings because of the low level of background produced by organic components like binders and paper backings. Thus, even traces of pigments as deposited by pens on cardboard can be identified by this method. The combination of PIXE with external Rutherford Backscattering Spectrometry (RBS) allows non-destructive gain of knowledge on near-surface and thin film arrangements of paint materials. Thicker but less complex layers of oil paintings can be identified by special procedures of depth resolved PIXE investigation. In this case, RBS provides additional information on organic coverings like madder lake or varnishes.
  • Nuclear Instruments and Methods in Physics Research B 189 (2002) 293

Publ.-Id: 3923 - Permalink


Windenergie - heute und morgen
Rindelhardt, U.;
Die Nutzung der seit Jahrhunderten bekannten Windkraft zur Erzeugung von
Strom hat im letzten Jahrzehnt eine dynamische Entwicklung erfahren. Basierend
vor allem auf den erreichten Fortschritten in der Technologie der Windenergie-
anlagen (WEA) und den damit verbundenen erheblichen Kostensenkungen steht
die Windenergienutzung heute an der Schwelle zur Wirtschaftlichkeit. Diese ent-
scheidende Voraussetzung hat besonders in Deutschland zur zunehmenden, in
einigen Gebieten sogar massenhaften Nutzung der Windenergie geführt. Die
wichtigsten technischen Entwicklungen der WEA im letzten Jahrzehnt werden
im Beitrag vorgestellt.
Gefördert wurde diese Entwicklung durch verschiedene größere Vorhaben des
Bundes und einzelner Länder. Hervorzuheben sind hier das 250-MW-Programm
sowie das Stromeinspeisegesetz. In den 90er Jahren bestanden somit stabile
Rahmenbedingungen für die Entwicklung der Windenergie. Die installierte WEA-
Leistung in Deutschland stieg von weniger als 30 MW im Jahr 1989 auf etwa
6000 MW zum Jahresende 2000. Im Jahr 2001 wird in Deutschland eine
Strommenge durch WEA erzeugt werden, die etwa 50% der aus Wasserkraft-
werken erzeugten Strommenge oder der Stromerzeugung des größten deutschen
Kernkraftwerkes entspricht.
Nach anfänglicher Zurückhaltung der meisten Energieversorgungsunternehmen
(EVU) erwägen derzeit auch diese ein Engagement in der Windkraftnutzung.
Dennoch werden sich die in den letzten Jahren erreichten Zuwachsraten mittel-
fristig nicht aufrechterhalten lassen. Ein absehbarer Leistungszuwachs bei den
Einzelanlagen auf bis zu 3 MW führt zwar zu einer Entlastung bei den benötigten
Standorten, die aus objektiven und subjektiven Gründen folgende Begrenzung
der nutzbaren Standorte limitiert jedoch insgesamt die Ausschöpfung der vor-
handenen Potenziale. Ein wesentliches begrenzendes Element ist bereits heute
der vermeintliche Widerspruch zwischen dem durch den Einsatz von WEA beför-
derten Umweltschutz (CO2-Problem) und dem Naturschutz in vielen Gebieten
(Landschaftsschutz), der auf der zuständigen kommunale Ebene kaum aufgelöst
werden kann.
Dennoch rechnet der Autor mit einer Verdoppelung der durch WEA erzeugten
Strommenge bis zum Jahr 2010 durch Neuinstallation bzw. Ersatz alter WEA auf
der Landfläche Deutschlands. Dies würde – bei unverändertem Stromverbrauch
– einem Anteil der Windkraft am Stromverbrauch von etwa 5 % entsprechen.
Etwa die gleiche Strommenge könnte um das Jahr 2015 durch offshore-WEA in
der Nord- und Ostsee erzeugt werden, so dass künftig mit einem „Windstroman-
teil“ von 10% in Deutschland gerechnet werden kann.


Keywords: Windenergie, WEA, Stromerzeugung
  • Lecture (Conference)
    6. Symposium "Energie und Energieversorgungssysteme der Zukunft", Lauta, 18. Mai 2001, Tagungsband Beitrag 12
  • Contribution to proceedings
    6. Symposium "Energie und Energieversorgungssysteme der Zukunft", Lauta, 18. Mai 2001, Tagungsband Beitrag 12

Publ.-Id: 3922 - Permalink


Effect of a superimposed DC magnetic field on the melt flow in an induction furnace experimental model
Bojarevics, A.; Gelfgat, Y.; Gerbeth, G.; Cramer, A.;
The unsteady flow field has been studied experimentally in a cold metal
model of an existing 10 kHz induction furnace for the inter-metallic fibre
extraction process in presence of a DC magnetic field. It has been shown
that a vertical DC magnetic field normal to the free liquid metal surface
efficiently decreases turbulence in the melt volume and suppresses surface
deformations. Whereas the turbulence and free surface deformations were not
suppressed by a DC field parallel to the free surface.
  • Lecture (Conference)
    Lecture at: International Scientific Colloquium "Modelling for Saving Resources" Riga, May 17-18, 2001

Publ.-Id: 3921 - Permalink


In-beam PET measurements of beta+ radioactivity induced by proton beams
Parodi, K.; Enghardt, W.; Haberer, T.;
Our first in-beam PET measurements of the beta+activation induced by proton irradiation are presented.
Monoenergetic proton beams in the energy and intensity range suited for the treatment of deep-seated tumours were delivered by the synchrotron of the Gesellschaft fuer Schwerionenforschung (GSI) at Darmstadt. They were stopped in PMMA blocks placed in the centre of the field of view of the positron camera that is installed in the heavy ion tumour treatment facility at GSI.
The beta+ activity signal was found to be three times larger than that produced by carbon ions at the same range and applied physical dose. The reconstructed spatial beta+ activity distributions were analysed and compared with the production of positron emitters predicted by a calculation based on experimental cross-sections and on the proton flux given by the FLUKA Monte Carlo code. The shape of the depth-activity-profiles was well reproduced by the model and the correlation with the proton
range and the depth-dose-distributions was carefully investigated. Despite the nontrivial range determination from the beta+ activity distribution in the proton case, our experimental investigation supports the feasibility of an in-situ proton therapy monitoring by means of in-beam PET, as already clinically implemented for the monitoring of carbon ion therapy at GSI Darmstadt.
  • Physics in Medicine and Biology 47 (2002) 21

Publ.-Id: 3920 - Permalink


Investigations of Natural Circulation Instabilities in VVER-type Reactors at LOCA Conditions
Schäfer, F.;
An important component of nuclear safety research is the analysis of abnormal transients and accident scenarios in nuclear power plants. In the presented work the ATHLET code was used for thermohydraulic calculations of small and intermediate break loss of coolant accident experiments, which were performed at the Hungarian test facility PMK-2. In the experiments different kinds of natural circulation instabilities could be observed. Such instabilities play an important role in the behaviour of the primary circuit, because the instabilities can disturb the heat removal from the reactor core. The aim of the presented calculations is to investigate whether the code is capable of modelling natural circulation phenomena in VVER-440-type reactors. It could be shown, that ATHLET can calculate the accident behaviour in good agreement with the experimental data. All significant phenomena, such as hot and cold leg loop seal clearing, stagnation of the natural circulation and especially the natural circulation instabilities are calculated very well. Calculations for a VVER-reactor show that the instabilities can also appear in a real plant.
Keywords: thermal-hydraulics, flow instabilities, code validation
  • Lecture (Conference)
    4th International Symposium on Safety and Reliability Systems of PWRs/VVER, 2001 May 14-17, Brno, Czech Republic, p. 94-100
  • Contribution to proceedings
    4th International Symposium on Safety and Reliability Systems of PWRs/VVER, 2001 May 14-17, Brno, Czech Republic, p. 94-100

Publ.-Id: 3917 - Permalink


Kühlmittelvermischung in Druckwasserreaktoren
Höhne, T.;
Die systematische Weiterentwicklung der gekoppelten neutronenkinetischen und thermohydraulischen Codes (DYN3D-ATHLET) erfordert den Einsatz von dreidimensionalen Vermischungsmodellen.

CFX-4-Nachrechnungen experimenteller Daten der Vermischungsanlage ROCOM ergeben im hochturblenten Bereich eine gute Übereinstimmung mit den Messdaten.

- Vierschleifenbetrieb:
- Sektorformation am Kerneintritt
- zeitliche Schwankungen der Konzentrationsprofile an den Sektorgrenzen

- Anlaufen der Kühlmittelzirkulation:
- Unterschiedliche Vermischungsbilder je nach Durchsatz und Anfahrvorgang
- Eintritt des Pfropfens in den Kern in den Randzonen der gegenüberliegenden Seite
Keywords: DWR, Borverdünnung, CFD
  • Poster
    Jahrestagung Kerntechnik 15.-17. Mai 2001, Dresden

Publ.-Id: 3916 - Permalink


Modellierung des Kernkraftwerks Stade Vorarbeiten für Rechnung mit dem Programm RALOC Mod4.0AG Teil2: Rekombinatoren, Eingabedatensatz, Rechnungen
Krüssenberg, A.-K.; Schaffrath, A.;
In dem vorliegenden Bericht wird die Erstellung eines Containmenteingabedatensatzes für das Kernkraftwerk Stade (KKW Stade) für das von der Gesellschaft Anlagen- und Reaktorsicherheit (GRS) entwickelte Programmsystem RALOC (Radiolyse und lokalen Konzentrationen (der Gase, z.B. Wasserstoff) im Containment beschrieben und der Aufbau des Eingabedatensatzes, erste Rechnungen zum Nachweis der Lauffähigkeit, der Einbau der Rekombinatoren in den Datensatz sowie erste Testläufe dokumentiert. In einem ersten Bericht sind im Detail die verwendete Nodalisierung, d.h. die Unterteilung des Contaniments in Zonen, Verbindungen und Strukturen beschrieben
  • Other report
    FWS 01-2, Februar 2001

Publ.-Id: 3915 - Permalink


Erprobung passiver Komponenten für den SWR 1000 - Ergebnisse von Experimenten an den Versuchsanlagen PANDA und NOKO
Hicken, E. F.; Dreier, J.; Meseth, J.; Schaffrath, A.;
Zur Validierung der thermohydraulischen Wirksamkeit der im SWR 1000 verwendeten passiven Sicherheitssysteme zur Nachwärmeabfuhr aus dem Reaktordruck-sowie dem Sicherheitsbehälter bei Störfällen wurden in den Versuchsanlagen PANDA (PSI / Schweiz) und NOKO (Forschungszentrum Jülich / Deutschland) umfangreiche Versuchsserien durchgeführt. Das Experimentalprogramm beinhaltete im Detail Versuche zum Notkondensator (zwei verschiedene Bündel), zum Passiven Flutsystem sowie dem Gebäudekondensator, der sowohl in NOKO (als Einzeleffektversuch) als auch in PANDA (als Systemversuch) getestet wurde. Zusätzlich wurden in NOKO noch mehrere Bauformen Passiver Impulsgeber erprobt. Allen Versuchen war gemein, dass die zu untersuchenden Systeme in Originalabmessungen sowie -materialien nachgebildet und unter adäquaten thermohydraulischen Randbedingungen getestet wurden. Die Versuchsergebnisse bestätigen ausnahmslos die Funktionalität und Effektivität der passiven Sicherheitssysteme.
Die Wärmeabfuhr in den Not- und Gebäudekondensatoren wurde mit den weltweit zur Sicherheitsanalyse von Reaktoren etablierten 1D-Thermohydraulikprogrammsystemen nachgerechnet. Die Ergebnisse der mit den unterschiedlichen Codes berechneten, integral durch Notkondensatoren abgeführten Energie stimmen sowohl untereinander als auch mit den Experimenten gut überein.
Bei den Gebäudekondensatoren konnten ebenfalls die globalen Werte mit den gebräuchlichen 1D-Containmentprogrammsystemen berechnet werden. Aufgrund der lokalen Anordnung der Gebäudekondensatoren stellen sich im Sicherheitsbehälter jedoch mit diesen 1D-Codes nicht beschreib- und somit modellierbare dreidimensionale Strömungs- und Temperaturfeldern (speziell Stratifizierungen) ein. Diese konnten zwar durch moderne Computational Fluid Dynamic (CFD) Codes punktuell wiedergegeben werden, zur Nachrechnung vollständiger Störfallsequenzen sind jedoch weitere Codeverbesserungen sowie schnellere Computer notwendig.

Keywords: NOKO, PANDA, SWR1000, Passive Komponenten
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2001, 15.-17. Mai 2001, Dresden, Berichtsheft der Fachsitzung "Grossversuche zur verbesserten Sicherheitsbewertung von LWR", S. 137-167
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2001, 15.-17. Mai 2001, Dresden, Berichtsheft der Fachsitzung "Grossversuche zur verbesserten Sicherheitsbewertung von LWR", S. 137-167

Publ.-Id: 3914 - Permalink


Comparison of the Irradiation Effects on Microstructure and Mechanical Properties of VVER-Type RPV Steels
Viehrig, H.-W.; Böhmert, J.; Ulbricht, A.;
A German/Russian irradiation experiment has been performed at the pressurised water reactor VVER-70 of the Rheinsberg NPP (Germany). The programme aims at the evaluation of neutron embrittlement and annealing behaviour in dependence on the content of alloying elements and impurities. Charpy V-notch, SENB, tensile, and CT-type specimens have been irradiated.
Specimens have been subjected to instrumented Charpy V impact and fracture mechanical toughness testing according to the ASTM E 1921-97 standard for reference temperature, T0, de-termination. The results of Charpy-V testing were presented on the IAEA Specialist’s Meeting in Madrid 1999. This paper continues the presentation with reference temperature testing and results of microstructural investigations. The microstructure is analysed using SANS technique.
The Charpy-V transition temperature shifts due to neutron irradiation could be confirmed by the reference temperatures T0 shifts. Furthermore, the SANS experiments provide a clear evidence of irradiation-induced microstructural features. Between a microstructural and an embrittlement based radiation coefficient, there is a obvious correlation. The main parameters of influence are the neutron fluence and the nickel content.

Keywords: VVER-type reactor pressure vessel steel, irradiation, irradiation coefficients, Charpy-V parameter, fracture toughness, mechanisms, microstructure, small angle neutron scattering, defects, volume fraction
  • Lecture (Conference)
    Proceedings of the IAEA Specialists Meeting on Irradiation Embrittlement and Mitigation, Gloucester, England, 14-17 May 2001, p. 121-130
  • Contribution to proceedings
    Proceedings of the IAEA Specialists Meeting on Irradiation Embrittlement and Mitigation, Gloucester, England, 14-17 May 2001, p. 121-130

Publ.-Id: 3913 - Permalink


Magnetofluiddynamik - Beeinflussung metallischer Schmelzen mittels elektromagnetischer Felder
Gerbeth, G.;
Es wird eine Übersicht über die Arbeiten zur Magnetofluiddynamik gegeben.
Die wesentlichen Effekte bestehen in der strömungsantreibenden Wirkung von
magnetischen Wechselfeldern und der dämpfenden Wirkung von Gleichfeldern.
Die Kombination beider Felder erlaubt meist die Entwicklung einer
Feldkonfiguration, die eine maßgeschneiderte Wirkung auf Strömung sowie
Wärme- und Stofftransport des jeweiligen Prozesses gestattet. Dafür werden
Beispiele aus Kristallzüchtung und Metallurgie angegeben.
  • Lecture (others)
    Einladungsvortrag im Kolloquium "Physik amorpher und flüssiger Legierungen", TU Chemnitz, 24.04.2001

Publ.-Id: 3912 - Permalink


The inverse approach to Magnetofluiddynamics
Gerbeth, G.;
Today there are two developments for an inverse approach to liquid metal
magnetohydrodynamics. At first, the reconstruction of a three-dimensional
velocity field out of external magnetic field measurements. At second, the
design of tailored magnetic field actions specific for the heat- and mass
transfer needs of the corresponding process. Results for both methods are
presented. The application to the steel flow in the mould are discussed.
  • Lecture (others)
    Lecture at ABB Process Industries, Västeras, Sweden, 27.03.2001

Publ.-Id: 3911 - Permalink


Parametrische Bildgebung von [18F]OMFD Hirn-PET-Studien
Hinz, R.; Bredow, J.;

Ziel:
Das Aminosäurederivat 3-O-methyl-6-[18F]fluoro-L-DOPA ([18F]OMFD) zeigt eine hohe Aufnahme in Hirntumoren im Gegensatz zum normalen Hirngewebe. Ziel dieser Arbeit war die Generierung parametrischer Datensätze des Tracer-Verteilungsraumes in der Positronen-Emissions-Tomographie (PET).
Methodik:
Nach vorangegangener Transmissionsmessung für die Schwächungs- und Streukorrektur wurden dynamische PET-Aufnahmen mit 34 Frames innerhalb von 90 Minuten auf einem hochauflösenden Scanner ECAT EXACT HR+ nach der intravenösen Gabe von 330 MBq [18F]OMFD akquiriert. Zur Reduktion des Rauschens wurden die Bilder nach der iterativen Rekonstruktion mit einem Savitzky-Golay-Filter geglättet. Die Angebotsfunktion wurde entweder extern aus gemessenen venösen Blutproben oder nichtinvasiv aus der A. carotis interna bestimmt. Eine Korrektur auf Metabolite ist bei
[18F]OMFD nicht erforderlich. Für die Erzeugung parametrischer Bilder wird das Eingewebs-Kompartimentmodell zur Beschreibung des kinetischen Verhaltens reversibler Tracer benutzt. Pixelweise werden die Einstromkonstante K1, die Eliminationskonstante k2 und das anteilige Blutvolumen fbv geschätzt. Das Verteilungsraumvolumen Vd des Tracers wird als Quotient von k1 und k2 bestimmt.
Ergebnisse:
In den parametrischen Bildern des Verteilungsraumvolumens ist eine klarere Abgrenzung maligner Areale als in den Aktivitätsverteilungen möglich. Der Wert von Vd ist ein Indikator für die Aminosäuretransporteraktivität in den Zellen, von der angenommen wird, dass sie in Tumorzellen gegenüber Normalgewebe erhöht ist. Das Verhältnis der Vd-Werte von Tumor zu Nichttumor lag bei dem untersuchten Patientenkollektiv zwischen 2,2 : 1 und 3,2 : 1.
Schlussfolgerungen:
Die Berechnung der Verteilungsraumkoeffizienten Vd führt zu einer Quantifizierung onkologischer PET-Studien mit [18F]OMFD, mit der zahlenmäßige Aussagen bei Verlaufskontrollen und interindividuelle Vergleiche möglich werden.

Keywords: Positronen-Emissions-Tomographie Modellierung
  • Lecture (Conference)
    39. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin Hamburg 25.04. - 28.04.2001

Publ.-Id: 3910 - Permalink


Post Test CFD Calculations of Experiments at the ROCOM Mixing Test Facility related to Boron Dilution and Cold Water Transients
Höhne, T.; Rohde, U.; Prasser, H.-M.;
The temperature and boron concentration fields established by the coolant mixing during nominal and transient flow conditions in the reactor pressure vessel of the PWR Konvoi were analyzed by numerical and experimental studies. The validation of the CFD results (CFD-code CFX-4) was carried out at the Rossendorf mixing test facility ROCOM. ROCOM is a 1:5 scaled Plexiglas model of the PWR Konvoi allowing velocity measurements by the LDA technique. Plugs of coolant with low boron acid concentration and/or different temperature are simulated by salt water injection. The CFD calculations were based on the assumption of incompressible turbulent flow. The turbulence was considered by an k--model. The perforated drum, as well as the reactor core with core internals, were represented by the model of a porous body. Calculations were performed for constant flow in the loops as well as for the scenario of an onset of the circulation. For transient CFD-calculation sensitivity studies were performed to check the numerical diffusion and the choice of different turbulence models.
Keywords: Boron Dilution, Coolant Mixing, CFD, PWR
  • Lecture (Conference)
    CFX Users Conference 2001,28-30 May 2001, Berchtesgaden
  • Contribution to proceedings
    CFX Users Conference 2001,28-30 May 2001, Berchtesgaden

Publ.-Id: 3909 - Permalink


Modellierung des Kernkraftwerks Stade Vorarbeiten für Rechnungen mit dem Programm RALOC Mod 4.0AG Teil 1: Zonen, Verbindungen, Strukturen
Krüssenberg, A.-K.; Schaffrath, A.;
Grundlage für die Erstellung des Eingabedatensatzes ist die Nodalisierung, eine Unterteilung des Containments in Bilanzräume (sog. Zonen), die über definierte Strömungswege (sog. Junctions) miteinander verbunden sind. Für die Zonen werden während einer Rechnung Massen- und Energiebilanzen, für die Verbindungen hingegen Impulsbilanzen aufgestellt und gelöst. Zusätzlich können mit Hilfe von sog. wärmeleitenden Strukturen Wärmequellen und -senken definiert werden. Diese erlauben die Modellierung der Zufuhr von Wärme in bzw. die Abfuhr von Wärme aus einzelnen Zonen sowie die Berechnung von Temperaturprofilen in festen Materialien (z.B. Wänden, Einbauten, Armaturen, Leitungen, Komponenten) sowie des Wärmeübergangs an deren Oberflächen.
  • Other report
    FWS 01-1, April 2000

Publ.-Id: 3908 - Permalink


16Alpha-[18F]fluor-17Beta-Estradiol (FES) und [18F]FDG-PET zur präoperativen Diagnostik bei Mamma-Carcinom
Bredow, J.; Richter, B.; Beuthien-Baumann, B.; Römer, J.; Füchtner, F.; Distler, W.; Franke, W.-G.;
ZIEL:
Patientinnen (Pat.) mit hochgradigem V.a. Mamma-CA wurden präoperativ mit FES oder FDG untersucht. Ziel war die Beurteilung von Multizentrizität, axillärem Lymphknotenbefall und Estrogenrezeptorstatus (ER) bzw. metabolischen Aktivität mittels PET sowie der Vergleich mit den histologischen Befunden incl. Estrogenrezeptorstatus.

METHODIK:
Die Pat. wurden radomisiert mit FDG oder FES im klinischen Stadium =pT2 an einem dedizierten PET-System (ECAT EXACT HR+, SIEMENS/CTI) untersucht. FES: Injektion von ca. 220 MBq i.v., 2 bed positions ab Axiallae bis Oberbauch in Bauchlage (Lagerungshilfe) ab 90 min p.i., anschließend ab prox. Oberschenkel bis Schädelbasis in Rückenlage, jeweils mit gemessener Transmissionskorrektur im 2D-Modus. FDG: Injektion von 290-370 MBq i.v., ab 60 min p.i. gleiche Aufnahmeparameter wie bei FES.

ERGEBNISSE:
Es wurden bisher 5 Pat. mit FES und 4 Pat. mit FDG untersucht (Tabelle). Erste Daten zeigen für FES und FDG eine positive Carcinomdarstellung auch bei Multizentrizität. Bei einer Pat. fand sich mittels FES ein falsch-positiver bzw. ein falsch negativer Befund bezüglich der axillären LK und des Estrogenrezeptorstatus.

Lfd...Diagnose postoperativ....Präparat......PET:... .ER.. ..Vergleich PET - Histologie
Nr.........................................................T/LKall...[%]
....................................................................................T.......MZ.......LKax......ER......SUV

1......pT4NxM1G3L1 (MZ)......FDG.............+/-........0.......RP......RP.......(FN).................2,0
2......pT4bN1M1G2...............FES..............-/-........0.......RN......RN........RN.......RN.......0,2
3......pT2N0M0G2L0V0.........FDG..............+/-.......0.......RP......RN........RN...................6,8
4......pT2N1M0G3L1 (MZ)......FES..............+/+...>80......RP......RP........RP.......RP.......4,3
5......pT2M0M0G2L0V0.........FES..............+/-....>80......RP......RN........RN.......RP.......1,5
6......pT4N1M1G3L1.............FDG..............+/+.....20......RP......RP........RP..................4,5
7......pT2N0M0 Dcis (MZ)......FDG..............+/-.......0.......RP......RN........RN..................1,8
8......pT2N1M0L1V1 (MZ)......FES..............+/-.......0.......RP......RP........FN.......FP.......1,6
9......pT4NxM1 (MZ).............FES..............+/+....>90......RP......RP.......(RP)......RP.......7,3

SCHLUSSFOLGERUNGEN:
Erste mittels FES in Deutschland durchgeführte Untersuchungen weisen auf die Eignung zur präoperativen Diagnostik des Mamma-CA hin. Eine abschließende Beurteilung ist bei kleiner Fallzahl noch nicht möglich.
  • Poster
    39. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, Hamburg, 25.-28.4.2001
  • Abstract in refereed journal
    Nuklearmedizin 40 (2001) A82

Publ.-Id: 3907 - Permalink


4. Workshop "Measurement techniques for stationary and transient multiphase flows", Rossendorf, November 16 - 17, 2000
Prasser, H.-M.; (Editor)
In November 2000, the 4th Workshop on Measurement Techniques for Stationary and Transient Multiphase Flows took place in Rossendorf. Three previous workshops of this series were national meetings; this time participants from different countries took part. The programme comprised 14 oral presentations, 9 of which are included in these proceedings in full length. A special highlight of the meeting was the main lecture "Ultrasonic doppler method for bubbly flow measurement" of Professor Masanori Aritomi, Dr. Hiroshige Kikura and Dr. Yumiko Suzuki, which was read by Dr. Hiroshige Kikura. The workshop again dealt with high-resolution phase distribution and phase velocity measurement techniques based on electrical conductivity, ultrasound, laser light and high-speed cinematography. A number of presentations were dedicated to the application of wire-mesh sensors developed by FZR for different applications used by the Technical Universities of Delft and Munich and the Tokyo Institute of Technology. The presentations were in particular:

M. Aritomi, H. Kikura, Y. Suzuki (Tokyo Institute of Technology): Ultrasonic doppler method for bubbly flow measurement

V. V. Kontelev, V. I. Melnikov (TU Nishny Novgorod): An ultrasonic mesh sensor for two-phase flow visualisation

A. V. Duncev (TU Nishny Novgorod): Waveguide ultrasonic liquid level transducers for power generating equipment

H.-M. Prasser, E. Krepper, D. Lucas, J. Zschau (FZR), D. Peters, G. Pietzsch, W. Taubert, M. Trepte (Teletronic Ingenieurbüro GmbH), Fast wire-mesh sensors for gas-liquid flows and decomposition of gas fraction profiles according to bubble size classes

D. Scholz, C. Zippe (FZR): Validation of bubble size measurements with wire-mesh sensors by high-speed video observation

A. Manera, H. Hartmann, W.J.M. de Kruijf, T.H.J.J. van der Hagen, R.F. Mudde, (TU Delft, IRI): Low-pressure dynamics of a natural-circulation two-phase flow loop

H. Schmidt, O. Herbst, W. Kastner, W. Köhler (Siemens AG KWU): Measuring methods for the investigation of the flow phenomena during external pressure vessel cooling of the boiling water reactor SWR1000

A. Traichel, W. Kästner, S. Schefter, V. Schneider, S. Fleischer, T. Gocht, R. Hampel (HTWS Zittau/Görlitz - IPM): Verification of simulation results of mixture level transients and evaporation processes in level measurement systems using needle-shaped probes

S. Richter, M. Aritomi (Tokyo Institute of Technology): Methods for studies on bubbly flow characteristics applying a new electrode-mesh tomograph

Keywords: multiphase flow, measurement instrumentation, workshop, transient flow
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-320 Mai 2001

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Publ.-Id: 3906 - Permalink


Non-volatile memories based on Si+ - implanted Gate oxides
Gebel, T.; von Borany, J.; Thees, H.-J.; Wittmaack, M.; Stegemann, K.-H.; Skorupa, W.;
Electrical properties of 20 ... 30 nm gate oxides implanted with Si+ ions are investigated using MOS capacitors and transistor structures. The observed programmming window can reach several volts and the structures exhibit good retention behavior. A first 256k - nvSRAM is demonstrated showing a programming window >1V for write pulses of 12V / 8 ms.
Keywords: nanocrystal, ion implantation, non-volatile memory
  • Microelectronic Engineering 59 (2001) 247-252
  • Lecture (Conference)
    INFOS Conference 2001, 20.-23.06.2001, Udine (Italy)

Publ.-Id: 3904 - Permalink


Die Sorption des Uran(VI) und anderer radiotoxischer Schwermetalle an Kolloidpartikeln im Flutungswasser des Uranbergwerks Königstein
Zänker, H.; Richter, W.;
Das untersuchte Flutungswasser (pH 5,5) enthält Fe(II), welches bei Sauerstoffzutritt Fe(III)-Oxyhydroxidpartikel bildet. Diese Partikel adsorbieren Radionuklide wie Po-210 und Pb-210. Im pH-Bereich von 4 bis 6 wird auch der größte Teil des Urans, welches in sechswertiger Form vorliegt, sorbiert. Radium dagegen ist kaum kolloidgetragen.

Keywords: colloids, particles, uranium, radium, polonium, iron oxyhydroxides, sorption
  • Lecture (others)
    Vortrag Universität Jena, Fachbereich Geologie der Universität Jena, 19. April 2001

Publ.-Id: 3903 - Permalink


TRIDYN_FZR User Manual
Möller, W.; Posselt, M.;
The present report contains the User Manual of the FZR version of the dynamic binary-collision computer simulation code TRIDYN. The present version of the code is based on TRIDYN Vs. 4.0 by W.Möller and W.Eckstein, Department of Surface Physics, Max-Planck Institute of Plasma Physics, Boltzmannstraße 2, 85748 Garching, Germany (1989). Modifications, in particular for PC implementation, quasi-dynamic display and the input dialog have been performed at the Institute of Ion Beam Physics and Materials Research by V.Kharlamov, T.Schwieger, M.Posselt, and W.Möller (1995-2001).
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-317 April 2001

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Publ.-Id: 3902 - Permalink


Pulsed Electron-Beam Melting of High-Speed Steel: Structural Phase Transformations and Wear Resistance
Ivanov, Y.; Matz, W.; Rotshtein, V.; Günzel, R.; Shevchenko, N.;
The structural and phase transformations occurring in the near-surface layers of pre-quenched high-speed steel subjected to pulsed electron beam melting have been investigated. Melting was induced by a low-energy (20–30 keV), high-current electron beam with a pulse duration of 2.5 µs and an energy densities ranging from 3 to 18 J/cm2. Using electron microscopy and x-ray diffraction it has been revealed that with increasing beam energy density gradual liquid-phase dissolution of initial globular M6C carbide particles occurs in the near-surface layer of thickness up to ~1 µm. This process is accompanied by formation of martensite crystals (gamma-phase) and an increase of residual austenite (alpha-phase) content. When the carbide particles are completely dissolved, martensitic transformation is suppressed. In this case, a nonmisoriented structure is formed consisting predominantly of submicron cells of -phase separated by nanosized carbide interlayers. Irradiation of cutting tools (drills) in a mode corresponding to an abrupt decrease in the content of M6C particles due to their liquid-phase dissolution enhances the wear resistance of the drills by a factor of 1.7. This is associated with the fixation of undissolved particles in the matrix, the formation of residual compressive stresses and of dispersed M3C carbide particles as well as the high (~50 %) content of the metastable -phase in the surface layer.
Keywords: steel, electron beam melting, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, wear resistance
  • Surface & Coatings Technology 150 (2002) 188-198

Publ.-Id: 3901 - Permalink


Infrarotspektroskopie von Halbleiter-Quantenstrukturen: vom Modellsystem zum Infrarot- und THz-Bauelement
Helm, M.;
please contact the author
Keywords: Infrarotspektroskopie, Halbleiter
  • Lecture (others)
    Kolloquiumsvortrag am Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin (9.4.2001)

Publ.-Id: 3900 - Permalink


Energy dependence of quantum dot formation by ion sputtering
Facsko, S.; Kurz, H.; Dekorsy, T.;
Ordered quantum dot patterns are generated on GaSb and InSb surfaces due to a
surface instability induced by Ar+ ion sputtering under normal incidence.
The characteristic length of the generated patterns scales with the square
root of the ion energy over the energy range of 75 - 1800 eV. This energy
dependence is compared to the solutions of the isotropic Kuramoto-Sivashinsky
equation and allows the determination of the lateral width of the energy
distribution deposited by the incident ions in the very low energy range. We
show that the observed energy dependence is in agreement with the linear
continuum theory under the assumption that the dominant smoothing process is
due to effective ion induced diffusion without mass transport on the surface.
Keywords: self-organization ion sputtering quantum dots surface roughening
  • Physical Review B 63 (2001) 165329 -1-5

Publ.-Id: 3898 - Permalink


Institute of Ion Beam Physics and Materials Research; Annual Report 2000
von Borany, J.; Jäger, H.-U.; Helm, M.; Möller, W.; Wieser, E.;
Summary of the Scientific Activities of the Institute in 2000
Keywords: Highlight Reports, Short Contributions, Statistics
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-314 März 2001

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Publ.-Id: 3897 - Permalink


Synthesis of [1,2-14C]Trichloroacetic acid
Bubner, M.; Fuksora, K.; Matucha, M.; Heise, K.-H.; Bernhard, G.;
Modern trends in investigating the phytotoxic effects of trichloroacetic acid (TCA) have initiated an actual interest in [1,2-14C]TCA with specific activities > 3.7 GBq/mmol. One-pot synthesis starting from potassium [1,2-14C]acetate yielding 80% of [1,2-14C]TCA is described. The specific activity of the product corresponds to that of the potassium or sodium [1,2-14C]acetate and the radiochemical purity is higher than 98%. The synthesis method is usable for the synthesis scale < 1 mmol.
Keywords: Key Words: [1,2-14C]trichloroacetic acid, one-pot synthesis
  • Labelled Comp. Radiopharm

Publ.-Id: 3896 - Permalink


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