Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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32337 Publications
Enhancement of the photoluminescence of silicon nanocrystals under the influence of electric field
Vandyshev, E. N.; Zhuravlev, K. S.; Gilinsky, A. M.; Skorupa, W.;
The effect of electric field generated by the application of surface acoustic waves on photoluminescence (PL) of silicon nanocrystals embedded in SiO2 films is studied. It is shown that the application of electric field results in an increase in the intensity of nanocrystal PL, the increase amounting to 10% at a field amplitude of 6 kV cm(-1). The results are discussed within the frame of the self-trapped exciton model.
Keywords: photoluminescence, silicon dioxide, ion implantation, nanocrystals
  • Physica E 21(2004)2-4, 304-307

Publ.-Id: 9936 - Permalink


Ion Beam Processing for Silicon - Based Light Emission
Skorupa, W.; Dekorsy, T.; Gebel, T.; Helm, M.; Lysenko, V. S.; Nazarov, A. N.; Osiyuk, I. N.; Rebohle, L.; Schmidt, B.; Sun, J. M.;
In this talk an overview will be presented regarding the influence of ion irradiation effects and treatments on the formation of silicon-based light emission structures and devices. After a short overview to the complete field-as to my knowledge- we will concentrate on two activities performed at the FZR during the last years, (i) Blue-violet (400 nm) light emitters basing on Metal-Oxide-Silicon capacitors, and, (ii) Infrared (~1µm) light emitters basing on pn-junctions. Both approaches use ion beam processing as a key doping technique of advanced semiconductor technologies. For the first case we employed implantation of group IV ions (C, Si, Ge, Sn) into thermally silicon dioxide layers followed by an appropriate annealing step leading to electroluminescence effects with a power efficiency/external quantum efficiency of ~0.5/10 %. This preparation leads to the formation of semiconductor nanoclusters in the oxide matrix; the luminescence itself is related to defects. Comparing to other oxide production techniques like sputtering or evaporation it is shown that such high electroluminescence values are only possible on the base of ion beam processing, i.e. the combination of nanocluster synthesis and beam-induced energy deposition. For the second case we will demonstrate that appropriate boron implantation and annealing steps can lead to pn-junctions with two electroluminescence bands from bound excitons at 1.065 eV and around 0.95 eV. This effect needs local oversaturation of boron –which, of course, is only possible by ion implantation- leading to nanoclusters which produce the necessary doping and strain induced disturbances to the band structure.
Keywords: ion beam processing, silicon, light emission
  • Contribution to proceedings
    Materials Research Society Fall Meeting, 01.-05.12.2003, Boston, USA
    Materials Research Society Fall Meeting, vol. 792 (2004), R 11.1.1

Publ.-Id: 9935 - Permalink


Nanocluster-rich silicon dioxide layers: electroluminescence and charge trapping
Gebel, T.; Rebohle, L.; Yankov, R. A.; Nazarov, A. N.; Skorupa, W.; Keywords: Nanocluster, silicon dioxide layers, electroluminescence, charge trapping
  • Contribution to external collection
    Pistora, Jaromir (u.a.): Microwave and Optical Technology 2003, Proceedings of the SPIE, Volume 5445, Bellingham, WA, USA: SPIE Int. Soc. Opt. Eng., 2004, 284-289

Publ.-Id: 9934 - Permalink


Comparative evaluation of coolant mixing experiments at the ROCOM, Vattenfall, and Gidropress test facilities
Kliem, S.; Hemström, B.; Bezrukov, Y.; Höhne, T.; Rohde, U.;
Coolant mixing is an important mitigative mechanism against reactivity accidents caused by local boron dilution. Experiments on coolant mixing were carried out at three different test facilities representing three different reactor types. These are the ROCOM test facility modelling a German KONVOI-type reactor, the Vattenfall test facility being a model of a Westinghouse three-loop PWR and the Gidropress test facility modelling a VVER-1000 PWR. The scenario of the start-up of the first main coolant pump was investigated in all three facilities.
The experiments were accompanied by velocity measurements in the downcomer for the same scenario in the ROCOM and the Vattenfall test facilities. A similar flow structure was found in these measurements in both cases. A maximum of the velocity is measured at the opposite side in regard to the position of the loop with the starting-up pump whilst a recirculation area was found just below this inlet nozzle in both facilities.
The analysis of the slug mixing experiments showed also comparable flow behaviour. In accordance with the velocity measurements, the first part of the deboration is also found on the opposite side. In this region, the maximum deboration is measured in all three cases. These maximum values are in the same order of magnitude for nearly identical initial slug volumes.
  • Open Access LogoScience and Technology of Nuclear Installations 2007(2007), 25950
    DOI: doi:10.1155/2007/25950
  • Lecture (Conference)
    Annual Meeting of the AER Working Group D, 08.-09.05.2007, Paris, France

Publ.-Id: 9933 - Permalink


Deep level defects in He-implanted n-6H-SiC studied by deep level transient spectroscopy
Chen, X. D.; Ling, C. C.; Fung, S.; Beling, C. D.; Wu, H. S.; Brauer, G.; Anwand, W.; Skorupa, W.;
Deep level defects in He-implanted n-6H-SiC studied by deep level transient spectroscopy
Keywords: He-implantion, n-6H-SiC,deep level transient spectroscopy
  • Contribution to proceedings
    Materials Research Society Spring Meeting 2004, 12.-16.04.2004, San Francisco, USA
    Silicon carbide – materials, processing, and devices 815 (2004), J5.5, New York: Taylor & Francis

Publ.-Id: 9932 - Permalink


Slow positron implantation spectroscopy – a tool to characterize vacancy-type damage in ion-implanted 6H-SiC
Brauer, G.; Anwand, W.; Coleman, P. G.; Skorupa, W.;
A lecture is given about slow positron implantation spectroscopy as a tool to characterize vacancy-type damage in ion-implanted 6H-SiC
Keywords: positron beam, SiC, defects
  • Lecture (others)
    Lecture, Department of Physics, University of Texas at Austin, 19.10.2004, Austin/TX, USA
  • Lecture (others)
    Lecture, Physics Department, University of Texas at Arlington, 21.10.2004, Arlington/TX, USA
  • Lecture (others)
    Lecture, Department of Physics, Texas Christian University, 22.10.2004, Ft. Worth/TX, USA

Publ.-Id: 9931 - Permalink


Epitaxial 3C-SiC formation at the SiO2/Si interface by C+ Implantation into SiO2 and subsequent annealing
Voelskow, M.; Panknin, D.; Polychroniadis, E. K.; Ferro, G.; Monteil, Y.; Godignion, P.; Mestres, N.; Skorupa, W.; Stoemenos, J.;
The epitaxial 3C-SiC formation at the SiO2/Si interface by C+ Implantation into SiO2 and subsequent annealing is studied.
Keywords: SiC formation, carbon implantation, SiO2
  • Lecture (Conference)
    5th European Conference Silicon Carbide and Related Materials, 31.08.-04.09.2004, Bologna, Italy

Publ.-Id: 9930 - Permalink


Efficient silicon light emitting diodes by boron implantation: the mechanism
Sun, J. M.; Dekorsy, T.; Skorupa, W.; Schmidt, B.; Mücklich, A.; Helm, M.;
The mechanism of efficient light emission in boron implanted silicon diodes is discussed.
Keywords: silicon, light emission, boron implantation
  • Lecture (Conference)
    European Materials Research Society Spring Meeting, 24.-28.05.2004, Strasbourg, France

Publ.-Id: 9929 - Permalink


Temperature dependence of efficient silicon light-emitting diodes prepared by ion implantation
Sun, J. M.; Dekorsy, T.; Skorupa, W.; Schmidt, B.; Helm, M.;
The temperature dependence of efficient silicon light-emitting diodes prepared by ion implantation is investigated.
Keywords: silicon, light emitting diodes, ion implantation
  • Lecture (Conference)
    DPG Tagung, 08.-12.03.2004, Regensburg, Deutschland

Publ.-Id: 9928 - Permalink


Physik fernab vom Gleichgewicht: Nanostrukturierung mit Ionenstrahlen
Heinig, K.-H.; Keywords: Nanostruktur, Ionenstrahl
  • Lecture (others)
    Universität Jena, Physikalisches Kolloquium, 01.11.2004, Jena, Deutschland

Publ.-Id: 9927 - Permalink


CFD-modelling of mineral wool in the containment sump
Krepper, E.; Cartland-Glover, G.; Grahn, A.; Weiß, F.-P.; Alt, S.; Hampel, R.; Kästner, W.; Seeliger, A.;
The investigation of insulation debris generation, transport and sedimentation becomes more important with regard to reactor safety research for PWR and BWR, when considering the long-term behavior of emergency core coolant systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems.
Open questions of generic interest are for example the particle load on strainers and corresponding pressure drop, the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow. A joint research project on such questions is being performed in cooperation with Institute of Process Technology, Process Automation and Measuring Technology (IPM) Zittau. The project deals with the experimental investigation and the development of CFD models for the description of particle transport phenomena in coolant flow. While the experiments are performed at the IPM-Zittau, the theoretical work is concentrated at Forschungszentrum Dresden-Rossendorf.
In the paper the basic concepts for CFD modeling are described and feasibility studies including the conceptual design of the experiments are presented.
Keywords: CFD, two-fluid approach, fiber flows
  • Lecture (Conference)
    Annual Meeting on Nuclear Technology 2007, 22.-24.05.2007, Karlsruhe, Germany
  • Contribution to proceedings
    Annual Meeting on Nuclear Technology 2007, 22.-24.05.2007, Karlsruhe, Germany

Publ.-Id: 9926 - Permalink


Thermal model for flashlamp annealing of 3C-SiC/Si multilayer systems (i-FLASiC)
Smith, M.; Mcmahon, R. A.; Voelskow, M.; Skorupa, W.; Stoemenos, J.;
A thermal model for flash lamp annealing of 3C-SiC/Si multilayer systems is developed.
Keywords: thermal model, SiC, flash lamp annealing
  • Lecture (Conference)
    5th European Conference Silicon Carbide and Related Materials, 31.08.-04.09.2004, Bologna, Italy

Publ.-Id: 9925 - Permalink


Nanostructure formation with ion beams
Heinig, K.-H.;
An abstract is not available, please contact the author.
Keywords: ion beam, nanostructure
  • Lecture (others)
    Lecture at University of Aarhus, 07.10.2004, Aarhus, Danmark

Publ.-Id: 9924 - Permalink


Ultra-shallow junctions produced by plasma doping and flash lamp annealing
Skorupa, W.; Yankov, R. A.; Anwand, W.; Voelskow, M.; Gebel, T.; Downey, D. F.; Arevalo, E. A.;
The way how to fabricate ultra-shallow junctions by plasma doping and flash lamp annealing is demonstrated.
Keywords: ultra-shallow junctions, plasma doping, flash lamp annealing
  • Lecture (Conference)
    European Materials Research Society Spring Meeting, 24.-28.05.2004, Strasbourg, France

Publ.-Id: 9923 - Permalink


Advanced Thermal Processing of Semiconducting Materials Using Flash Lamp Annealing
Skorupa, W.; Panknin, D.; Voelskow, M.; Anwand, W.; Gebel, T.; Yankov, R. A.;
Advanced Thermal Processing of Semiconducting Materials using Flash Lamp Annealing is Discussed.
Keywords: thermal processing, flash lamp annealing, semiconductors
  • Lecture (Conference)
    Materials Research Society Spring Meeting, 13.-16.04.2004, San Francisco, USA

Publ.-Id: 9922 - Permalink


Manipulation of 2D arrays of Si nanocrystals by ultra-low-energy ion beam-synthesis for nonvolatile memories applications
Bonafos, C.; Cherkashin, N.; Carrada, M.; Coffin, H.; Ben Assayag, G.; Schamm, S.; Dimitrakis, P.; Normand, P.; Perego, M.; Fanciulli, M.; Mueller, T.; Heinig, K.-H.; Argawal, A.; Claverie, A.;
An abstract is not available, please contact the authors.
Keywords: Si, nanocrystals, nonvolatile memory
  • Lecture (Conference)
    2004 MRS Fall Meeting, 29.11.-03.12.2004, Boston, USA

Publ.-Id: 9921 - Permalink


Tailoring magnetic nanostructures by ion irradiation
Bernas, H.; Chappert, C.; Devolder, T.; Ravelosona, D.; Mathet, V.; Ferre, J.; Jamet, J. P.; Mougin, A.; Bauer, M.; Repain, V.; Samson, Y.; Marty, A.; Halley, D.; Attane, J.; Heinig, K.-H.; Stamps, R.; Chen, Y.; Suzuki, Y.; Kaitasov, O.; Ruault, M.-O.; Gautrot, S.;
An abstract is not available, please contact the authors.
Keywords: magnetic nanostructures, ion irradiation
  • Lecture (Conference)
    14th International Conference on Ion Beam Modification of Materials (IBMM 2004), 05.-10.09.2004, Monterey, USA

Publ.-Id: 9919 - Permalink


Optical and microstructural properties of doubly implanted SiO2 layers using combined Ge-Si implantation
Prucnal, S.; Cheng, X. Q.; Sun, J. M.; Kögler, R.; Zuk, J.; Skorupa, W.;
The optical and microstructural properties of doubly implanted SiO2 layers fabicated combined Ge-Si implantation are investigated.
Keywords: optical properties, defects, microstucture, SiO2, implantation
  • Lecture (Conference)
    5th Int. Conf. on Ion Implantation and other Applications of Ions and Electrons (ION2004), 14.-17.06.2004, Kazimierz Dolny, Poland

Publ.-Id: 9918 - Permalink


2D-arrays of Si nanocrystals embedded in thin SiO2 layers for new memory devices
Perego, M.; Ferrari, S.; Fanciulli, M.; Soncini, V.; Mathiot, D.; Heinig, K.-H.; Müller, T.; Schmidt, B.; Normand, P.; Dimitrakis, P.; Kapetanakis, E.; Ben Assayag, G.; Bonafos, C.; Carrada, M.; Claverie, A.;
An abstract is not available, please contact the authors.
Keywords: Si, nanostructures
  • Lecture (Conference)
    INFM-Workshop, 10.-15.06.2004, Genova, Italy

Publ.-Id: 9917 - Permalink


Nucleation control in FLASiC assisted short time liquid phase epitaxy by melt modification
Pezoldt, J.; Polychroniadis, E. K.; Stauden, T.; Ecke, G.; Chassagne, T.; Vennegues, P.; Leycuras, A.; Panknin, D.; Stoemenos, J.; Skorupa, W.;
The nucleation control in FLASiC assisted short time liquid phase epitaxy by melt modification is studied.
Keywords: nucleation, liquid phase epitaxy, flash lamp processing
  • Lecture (Conference)
    5th European Conference Silicon Carbide and Related Materials, 31.08.-04.09.2004, Bologna, Italy

Publ.-Id: 9916 - Permalink


Ion beam assisted Ge nanocrystallization in Ta2O5 films
Peeva, A.; Kalitzova, M.; Zollo, G.; Beshkov, G.; Vitali, G.; Skorupa, W.;
The ion beam assisted formation of Ge nanocrystals in Ta2O5 films is studied.
Keywords: ion beam assisted naocrystallization
  • Lecture (Conference)
    13th Int. School on Condensed Matter Physics, 30.08.-03.09.2004, Varna, Bulgaria

Publ.-Id: 9915 - Permalink


Detailed profiling of ion implantation induced excess vacancies in silicon
Peeva, A.;
Profiles of excess vacancies in silicon produced by ion implantation are studied by TEM.
Keywords: excess vacancies, Si, ion implantation
  • Lecture (others)
    Arbeitstreffen “Punktdefekte” TU Dresden, 01.-02.04.2004, Dresden, Deutschland

Publ.-Id: 9914 - Permalink


E1/E2 an Z1/Z2 deep level defects in n-type 6H silicon carbide induced by electron irradiation and He implantation
Ling, C. C.; Cheng, X. D.; Fung, S.; Beling, C. D.; Brauer, G.; Anwand, W.; Skorupa, W.;
E1/E2 an Z1/Z2 deep level defects in n-type 6H silicon carbide induced by electron irradiation and He implantation are studied.
Keywords: deep levels, SiC, electron irradiation, He implantation
  • Lecture (Conference)
    27th International Conference on the Physics of Semiconductors (ICPS-27), 26.-30.07.2004, Flagstaff, USA

Publ.-Id: 9913 - Permalink


EPOS – an intense positron beam project at the Research Center Rossendorf
Krause-Rehberg, R.; Brauer, G.; Sachert, S.; Bondarenko, V.; Rogov, A.; Noack, K.;
EPOS – an intense positron beam project at the Research Center Rossendorf is presented
Keywords: intense positron Beam
  • Lecture (Conference)
    International Symposium on Positron Beam and its Application, 29.-30.10.2004, Wuhan, China

Publ.-Id: 9912 - Permalink


Design of a mono-energetic positron source for positron lifetime measurements at the radiation source ELBE
Krause-Rehberg, R.; Sachert, S.; Brauer, G.; Rogov, A.; Noack, K.; Michel, P.;
The design of a mono-energetic positron source for positron lifetime measurements at the radiation source ELBE is presented.
Keywords: mono-energetic positron source
  • Lecture (Conference)
    18th International conference on the application of accelerators in research and industry (CAARI2004), 10.-15.10.2004, Ft. Worth/TX, USA

Publ.-Id: 9911 - Permalink


Investigation of gettering effects in CZ-type Silicon with SIMS
Krecar, D.; Fuchs, M.; Kögler, R.; Hutter, H.;
Gettering effects in CZ-type Silicon are investigated with SIMS
Keywords: gettering, SIMS, Si, defects
  • Lecture (Conference)
    13th Arbeitstagung Angewandte Oberflächenanalytik (AOFA), 14.-17.10.2004, Dresden, Deutschland

Publ.-Id: 9910 - Permalink


Effects of ion beam induced excess vacancies in silicon: analysis, modelling, application
Kögler, R.; Eichhorn, F.; Mücklich, A.; Skorupa, W.; Serre, C.; Perez-Rodriguez, A.;
Effects of ion beam induced excess vacancies in silicon are discussed.
Keywords: vacancies, silicon, defect engineering
  • Lecture (Conference)
    5th Int. Conf. on Ion Implantation and other Applications of Ions and Electrons (ION2004), 14.-17.06.2004, Kazimierz Dolny, Poland

Publ.-Id: 9909 - Permalink


Investigation of defects induced by ion implantation of noble gases in yttria-stabilized zirconia
Grynszpan, R. I.; Fradin, J.; Saude, S.; Thome, L.; Anwand, W.; Brauer, G.;
Investigation of defects induced by ion implantation of noble gases in yttria-stabilized zirconia
Keywords: defects, ion implantation, zirconia, PAS
  • Lecture (Conference)
    18th International conference on the application of accelerators in research and industry (CAARI2004), 10.-15.10.2004, Ft. Worth/TX, USA

Publ.-Id: 9908 - Permalink


Microarrays of miniaturized silicon-based light sources: fabrication and use
Gebel, T.; Rebohle, L.; Yankov, R. A.; Skorupa, W.; Gauglitz, G.; Frank, R.;
Microarrays of miniaturized silicon-based light sources: fabrication and use
Keywords: silicon, light emission, LED
  • Lecture (others)
    Statusseminar “Chiptechnologien, Mikroarrays, Hygiene und Gesundheit”, DECHEMA, Frankfurt/M., 26.-27.01.2004, Frankfurt/M., Deutschland

Publ.-Id: 9907 - Permalink


Microstructural characterization of 3C-SiC thin films epitaxially formed by the flash lamp process (FLASIC)
Ferro, G.; Panknin, P.; Polychroniadis, E. K.; Monteil, Y.; Skorupa, W.; Stoemenos, J.;
Microstructural characterization of 3C-SiC thin films epitaxially formed by the flash lamp process (FLASIC)
Keywords: flash lamp, annealing, SiC
  • Lecture (Conference)
    5th Europ. Conf. Silicon Carbide and Related Materials, 31.08.-04.09.2004, Bologna, Italy

Publ.-Id: 9906 - Permalink


Positron annihilation spectroscopy of ultra fine-grained metals prepared by severe plastic deformation
Cizek, J.; Prochazka, I.; Kuzel, R.; Matej, Z.; Cherkaska, V.; Cieslar, M.; Smola, B.; Stulikova, I.; Brauer, G.; Anwand, W.; Islamgaliev, R. K.; Kulyasova, O.;
In the present work, positron annihilation spectroscopy (PAS) is employed for microstructure investigations of various ultra fine grained (UFG) metals (Cu, Ni, Fe) prepared by severe plastic deformation (SPD), namely high-pressure torsion (HPT) and equal channel angular pressing (ECAP): Generally, UFG metals prepared using both the techniques exhibit two kinds of defects introduced by SPD: dislocations and small microvoids. The size of the microvoids is determined from the PAS data. Significantly larger microvoids are found in HPT deformed Fe and Ni compared to HPT deformed Cu. The microstructure of UFG Cu prepared by HPT and ECAP is compared and the spatial distribution of defects in UFG Cu samples is characterized. In addition, the mircrostructure of a pure UFG Cu prepared by HPT and HPT deformed Cu+Al2O3 nanocomposite (GlidCop) is compared.
Keywords: PAS
  • Lecture (Conference)
    35th Polish Seminar on Positron Annihilation, 20.-24.09.2004, Turawa, Poland

Publ.-Id: 9905 - Permalink


-Hydrogen-induced defects in niobium studied by positron annihilation spectroscopy
Cizek, J.; Prochazka, I.; Kuzel, R.; Becvar, F.; Cieslar, M.; Brauer, G.; Anwand, W.; Kirchheim, R.; Pundt, A.;
Our aim in the present work was to investigate changes of the defect structure of bulk niobium induced by hydrogen loading. The evolution of the microstructure with increasing hydrogen concentration was studied by x-ray diffraction and two complementary techniques of positron annihilation spectroscopies (PAS), namely positron lifetime spectroscopy and slow positron implantation spectroscopy with the measurement of the Doppler broadening, in defect-free Nb (99.9%) and Nb containing a remarkable number of dislocations. These samples were electrochemically loaded with hydrogen up to xH=0.06 [H/Nb], i.e. in the alpha-phase region, and it was found that the defect density increases with hydrogen concentration in both Nb samples. This means that hydrogen-induced defects are created in the Nb samples. A comparison of PAS results with theoretical calculations revealed that vacancy-hydrogen complexes are introduced into the samples due to hydrogen loading. Most probably these are vacancies surrounded by 4 hydrogen atoms.
Keywords: PAS
  • Lecture (Conference)
    The International Symposium on Metal-Hydrogen Systems, Fundamentals and Applications – MH2004, 05.-10.09.2004, Cracow, Poland

Publ.-Id: 9904 - Permalink


-Positron annihilation studies of microstructure of ultra fine grained metals prepared by severe plastic deformation
Cizek, J.; Prochazka, I.; Smola, B.; Stulikova, I.; Kuzel, R.; Cieslar, M.; Matej, Z.; Cherkaska, V.; Brauer, G.; Anwand, W.; Islamgaliev, R. K.; Kulyasova, O.;
In the present work, positron annihilation spectroscopy (PAS) is employed for microstructure investigations of various ultra fine grained (UFG) metals (Cu, Ni, Fe) prepared by severe plastic deformation (SPD), namely high-pressure torsion (HPT) and equal channel angular pressing (ECAP): Generally, UFG metals prepared using both the techniques exhibit two kinds of defects introduced by SPD: dislocations and small microvoids. The size of the microvoids is determined from the PAS data. Significantly larger microvoids are found in HPT deformed Fe and Ni compared to HPT deformed Cu. The microstructure of UFG Cu prepared by HPT and ECAP is compared and the spatial distribution of defects in UFG Cu samples is characterized. In addition, the mircrostructure of a pure UFG Cu prepared by HPT and HPT deformed Cu+Al2O3 nanocomposite (GlidCop) is compared.
Keywords: PAS
  • Lecture (Conference)
    Fourth International Conference on Materials Structure and Micromechanics of Fracture (MSMF-4), 23.-25.06.2004, Bro, CZ

Publ.-Id: 9903 - Permalink


Photoluminescence of Er doped SiO2 films embedded Si nanoclusters using dual implantation chamber and annealing
Cheng, X. Q.; Sun, J. M.; Kögler, R.; Skorupa, W.; Möller, W.; Prucnal, S.; Zuk, J.;
The photoluminescence of Er doped SiO2 films embedded Si nanoclusters is investigated. These clusters are fabricated by dual ion implantation and annealing.
Keywords: Er doped Si nanoclusters, photoluminescence, dual ion implantation
  • Lecture (Conference)
    5th Int. Conf. on Ion Implantation and other Applications of Ions and Electrons (ION2004), 14.-17.06.2004, Kazimierz Dolny, Poland

Publ.-Id: 9902 - Permalink


Potential energy retention of slow highly charged Ar-ions in chemical clean silicon surfaces
Kost, D.; Facsko, S.;
A UHV device with a base pressure of p<10^-9 mbar was connected to the ECR ion source of the Forschungszentrum Rossendorf for improved calorimetric measurements of the retention of the potential energy of highly charged ions. The chemical state of the target surface is controlled by AES using LEED optics. With a clean silicon and gold surface prepared by sputtering using Ar-ions, the retained energy of Ar^q+ (q = 1 up to 9) ions was determined at kinetic energies between q*60 eV and q*200 eV . By extrapolation to zero kinetic energy, the retained fraction of the potential energy is obtained, which is related to the full potential energy given by the ionization potentials. The potential energy retention coefficient results as (0.8 up to 0.9) +- 0.2 and decreases weakly with increasing charge state. This is about three times larger than earlier results with contaminated copper surfaces.
Keywords: highly charged ions, potential energy retention
  • Lecture (Conference)
    DPG-Frühjahrstagung, 08.-12.03.2004, Regensburg, Deutschland

Publ.-Id: 9901 - Permalink


Deep level defects in He-implanted n-6H-SiC studied by deep level transient spectroscopy
Chen, X. D.; Ling, C. C.; Fung, S.; Beling, C. D.; Wu, H. S.; Brauer, G.; Anwand, W.; Skorupa, W.;
Deep level defects in He-implanted n-6H-SiC are studied by deep level transient spectroscopy.
Keywords: deep levels, SiC, defects, DLTS, ion implantation
  • Lecture (Conference)
    Materials Research Society (MRS), 2004 Spring Meeting, 12.-16.04.2004, San Francisco/ CA, USA

Publ.-Id: 9900 - Permalink


Structures of actinide complexes: combining DFT calculations, EXAFS spectroscopy, and thermodynamic speciation
Tsushima, S.; Hennig, C.; Ikeda, A.; Rossberg, A.; Scheinost, A.;
Density functional theory (DFT) calculations in combination with the polarizable continuum model (PCM) are a very useful method for obtaining the structure of actinide complexes in aqueous solution. The accuracy in energy, however, is often not sufficient to find a definite answer on whether ligands are coordinated in monodentate or bidentate fashion [1], pinpointing the limitations of working solely with theoretical calculations. Extended X-ray absorption fine structure (EXAFS) spectroscopy is a powerful experimental method for the determination of structures of aqueous complexes; the limitation is, however, a relatively poor distal resolution and often no information on the spatial orientation, making the resolution of co-existing species difficult. Finally, thermodynamic calculations also do not always provide accurate information.
Therefore, we combined all three methods, DFT, EXAFS, and thermodynamic speciation, to study the speciation and structure of actinide complexes in aqueous solution. We will show examples of uranyl(VI) ligation towards water, carbonate, and sulfate. We will also address the formation of polymeric complexes.
  • Invited lecture (Conferences)
    American Chemical Society 234th National Meeting, Symposium: Computational Actinide and Transactinide Chemistry: Progress and Perspectives, 19.-23.08.2007, Boston, United States

Publ.-Id: 9899 - Permalink


Uranium redox chemistry and its importance in nuclear waste disposal
Tsushima, S.; Hennig, C.; Ikeda, A.; Scheinost, A.;
For the safety assessment of geological disposal of spent nuclear fuels, to predict and prevent migration of uranium in the geo-sphere is very important. Uranium can take oxidation states IV, V, and VI in aqueous solution. Its solubility differ several orders of magnitude depending on its oxidation state, but also depends strongly on pH and Eh of the solution and concentrations of co-existing organic/inorganic ligands. In this study, quantum chemical methods (MP2, CASPT2) were used to estimate the redox potential of the U(VI)/U(V) couple and the result was compared with experimental data. Similarly, An(VI)/An(V) redox potentials were also calculated for An = Np, Pu, and Am, and the importance of multi-configurational calculations and the role of spin-orbit effect were discussed.
Uranium may coordinate with various organic/inorganic ligands, and this is also a determining factor of the redox potential. We studied the complexation of uranium(VI) with several inorganic ligands (sulfate, carbonate, etc.) by DFT calculations and also by electrochemistry experiments. The structures of uranium complexes were characterized using EXAFS (extended X-ray absorption fine structure) spectroscopy at the Rossendorf Beamline, European Synchrotron Radiation Facility, in Grenoble, France. DFT and EXAFS were found to provide complementary structural information.
  • Invited lecture (Conferences)
    American Chemical Society 234th National Meeting, Symposium: Computational Electrochemistry for New Energy, 19.-23.08.2007, Boston, United States

Publ.-Id: 9898 - Permalink


RBS with high depth resolution using a small magnetic spectrometer
Grötzschel, R.; Klein, C.; Mäder, M.;
Rutherford Backscattering Spectrometry ( RBS) and Elastic Recoil Detection Analysis (ERDA) are well established techniques for quantitative thin film and surface analysis. The advantage of these methods consists in the simple physics they are basing on, namely the stopping of energetic ions in matter and the binary scattering of at the Coulomb potential of atomic nuclei.
In particular RBS with He ions is widely used at many small accelerators utilizing standard surface barrier or implanted silicon detectors with typical depth resolution values of 12 keV, which provides a depth resolution in the order of 10 nm.
The increasing importance of ultra-thin layers for novel technologies demands quantitative analysis techniques with a depth resolution of atomic monolayers, which can be obtained for RBS and ERDA by magnetic spectrometers only.
We operate at the 3 MV Tandetron accelerator a magnetic spectrometer consisting of an UHV scattering chamber and a simple magnet with circular field boundaries (Browne-Buechner spectrometer). Since in many cases of high resolution IBA the samples must be prepared in situ in UHV, the chamber with a base vacuum of 4x10-10 mbar is equipped with an Ar ion sputter gun and two OMICRON EFM3 low rate e-beam evaporators for in situ layer deposition.
A RHEED system is used to check the surface reconstruction and monitor the layer growth. Samples are transferred, together with a BN heater, to the precision 5-axes channelling goniometer . The magnet with a mean radius of 0.65 m is mounted vertically and can be positioned either at 35.5° or 144.5°. The backward position offers the advantage of a high mass resolution, but the Rutherford cross sections are a factor of about 100 lower than at the forward angle, which is the preferred position if kinematically possible.
Using a two-dimensional position sensitive focal plane detector the transversal position provides the possibility for kinematical corrections since the transversal focusing of the magnet is small. A multiple-pad PSD with a pitch of 4 mm is adequate.
This spectrometer is described, recent applications are discussed and as well as he influence of charge state transitions of ions on the obtainable depth resolution will be demonstrated.
  • Invited lecture (Conferences)
    14th Hellenic Symposium on Nuclear Physics, 21.-23.05.2004, Athens, Greece

Publ.-Id: 9897 - Permalink


Depth profiling of defects using a slow positron beam
Brauer, G.;
The fundamentals of and recent results on depth profiling of defects in materials by means of a slow positron beam are reported.
Keywords: depth profiling, defects, positron beam, PAS
  • Lecture (Conference)
    35th Polish Seminar on Positron Annihilation, 20.-24.09.2004, Turawa, Polska

Publ.-Id: 9896 - Permalink


AFM characterization of 6H-SiC surfaces after ion implantation and annealing
Brauer, G.; Brandstetter, S.; Teichert, C.; Anwand, W.; Skorupa, W.;
6H-SiC surfaces after ion implantation and annealing are characterized by AFM.
Keywords: AFM, SiC surface, ion implantation, annealing
  • Lecture (Conference)
    18th International conference on the application of accelerators in research and industry (CAARI2004), 10.-15.10.2004, Ft. Worth/TX, USA

Publ.-Id: 9895 - Permalink


The prototype of the new flash lamp apparatus: experiences, results, comparison old and new equipment
Anwand, W.;
The prototype of the new flash lamp apparatus is discussed and compared with the old equipment. First experiences and results are reported.
Keywords: flash lamp annealing, semiconductor processing
  • Lecture (others)
    EU-Projekttreffen FLASiC, 15.10.2004, Ilmenau, Deutschland

Publ.-Id: 9894 - Permalink


Chiral Condensate and Open Charm
Kämpfer, B.;
  • Invited lecture (Conferences)
    CBM-Meeting, 15.-16.12.2005, Darmstadt, Deutschland

Publ.-Id: 9893 - Permalink


Primordiale Nukleosynthese
Kämpfer, B.;
  • Lecture (Conference)
    IKTP, 10.11.2005, Dresden, Deutschland

Publ.-Id: 9892 - Permalink


QCD matter within quasi-particle model and the critical end point
Kämpfer, B.;
  • Lecture (Conference)
    Quark Matter 2005, 04.-09.08.2005, Budapest, Hungary

Publ.-Id: 9891 - Permalink


Konzeption und prototypische Realisierung einer Datenbankanwendung für die Verwaltung von Betriebsparametern von Ionenstrahlbeschleunigern
Kunze, P.;
Es wird beschrieben, wie eine Datenbank für Betriebswerte eines Teilchenbeschleunigers aufgebaut wurde. Der Schwerpunkt der Betrachtungen liegt dabei auf der Theorie zum Aufbau einer solchen Datenbank.
  • Other report
    Dresden: HTW Dresden, Diplomarbeit, 2005
    50 Seiten

Publ.-Id: 9890 - Permalink


Open charm and leptons at RHIC
Kämpfer, B.;
  • Lecture (Conference)
    ECT* - Electromagnetic probes of hot and dense matter, 03.-11.06.2005, Trento, Italy

Publ.-Id: 9889 - Permalink


Quasi-particle description of QCD matter
Kämpfer, B.;
  • Lecture (Conference)
    Probing QCD with High Energy Nuclear Collisions, 16.01.2005, Hirschegg, Deutschland

Publ.-Id: 9888 - Permalink


Digitalisierung der Signalverarbeitung eines Rotorvoltmeters
Arnold, S.;
Das Ziel der Diplomarbeit war, auf Basis eines 32-Bit Mikrocontrollers wesentliche Teile der Signalverarbeitung eines Rotorvoltmeters von analoger Schaltungstechnik in eine digitale Verarbeitung zu überführen. Mit diesem Schritt kann das am Institut für Ionenstrahlphysik und Materialforschung des FZR eingesetzte Rotorvoltmeter eines Van-de-Graaff-Ionenbeschleunigers in seiner Anwendung wesentlich verbessert werden. Erwartet werden neben der einfacheren Parametrierung und der erhöhten Flexibilität des Gerätes vor allem auch eine Erhöhung der Stabilität im Betrieb durch den Wegfall von Drifterscheinungen analoger Schaltungstechnik.
  • Other report
    Chemnitz: TU Chemnitz, Diplomarbeit, 2006
    50 Seiten

Publ.-Id: 9887 - Permalink


Digitalisierung der Funktion eines Meßgerätes zur Bestimmung der Beschleunigungsspannung von Van-de-Graaff-Ionenbeschleunigern
Voigtländer, G.;
Das Ziel der Diplomarbeit war, auf Basis eines 32-Bit Mikrocontrollers wesentliche Teile der Signalverarbeitung eines Rotorvoltmeters von analoger Schaltungstechnik in eine digitale Verarbeitung zu überführen. Mit diesem Schritt kann das am Institut für Ionenstrahlphysik und Materialforschung des FZR eingesetzte Rotorvoltmeter eines Van-de-Graaff-Ionenbeschleunigers in seiner Anwendung wesentlich verbessert werden. Erwartet werden neben der einfacheren Parametrierung und der erhöhten Flexibilität des Gerätes vor allem auch eine Erhöhung der Stabilität im Betrieb durch den Wegfall von Drifterscheinungen analoger Schaltungstechnik.
  • Other report
    Dresden: HTW Dresden, Diplomarbeit, 2004
    50 Seiten

Publ.-Id: 9886 - Permalink


Low-energy tail of the giant dipole resonance in 98Mo and 100Mo deduced from photon-scattering experiments
Rusev, G.; Schwengner, R.; Dönau, F.; Erhard, M.; Grosse, E.; Junghans, A. R.; Kosev, K.; Schilling, K. D.; Wagner, A.; Becvar, F.; Krticka, M.;
Dipole-strength distributions in the nuclides 98Mo and 100Mo up to the neutron-separation energies have been studied in photon-scattering experiments at the superconducting electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf. In order to determine the dipole-strength distribution up to the neutron emission threshold statistical methods were developed for the analysis of the measured spectra. The measured spectra of scattered photons were corrected for detector response and atomic background by simulations using the code GEANT3. Simulations of gamma-ray cascades were performed in order to correct the intensities of ground-state transitions for feeding from high-lying levels and to determine their branching ratios. The photoabsorption cross sections obtained for 98Mo and 100Mo from the present (gamma,gamma) experiments are combined with (gamma,n) data from literature resulting in a photoabsorption cross section covering the full range from 4 to about 15 MeV of interest for nuclear astrophysics network calculations. Novel information about the low-energy tail of the Giant Dipole Resonance and the energy spreading of its strength is derived. The photoabsorption cross sections deduced from the present photon-scattering experiments are compared with existing data from neutron capture and 3He induced reactions.
Keywords: Photon scattering, nuclear structure, giant dipole resonance, dipole strength, photoabsorption cross section

Publ.-Id: 9885 - Permalink


Defect profiling with positrons – recent results on ion implanted 6H-SiC
Anwand, W.; Brauer, G.; Skorupa, W.;
Positron annihilation spectroscopy is used to analyse implantation defects in 6H-SiC.
Keywords: Positron annihilation Spectroscopy, SiC, defects
  • Lecture (Conference)
    Frühjahrstagung des Arbeitskreises “Herstellung und Charakterisierung von massiven GaAs-, InP- und SiC-Kristallen” der Deutschen Gesellschaft für Kristallwachstum und Kristallzüchtung (DGKK),, 31.03.-01.04.2004, Halle (Saale), Deutschland

Publ.-Id: 9884 - Permalink


Ionenstrahlmodifikationen magnetischer Schichten
Fassbender, J.ORC
In dem Vortrag werden die neuen Ergebnisse auf dem Gebiet der Cr- bzw. Ni-Implantation in Permalloy vorgestellt. Darüber hinaus wird über erste Ergebnisse der Bestrahlung von FeAl-Legierungen berichtet.
Keywords: ion irradiation, ion implantation, magnetism, permalloy, FeAl
  • Lecture (Conference)
    Workshop zur "Ionenstrahlphysik und Nanotechnologie", 10.-11.05.2007, Bochum, Deutschland

Publ.-Id: 9883 - Permalink


Early stage of ripple formation on Ge(001) surfaces under near-normal ion beam sputtering
Carbone, D.; Alejandro, A.; Raul, G.; Facsko, S.; Plantevin, O.; Metzger, T. H.;
We present a study of the early stage of ripple formation on Ge(001) surfaces irradiated by a 1 keV Xe+ ion beam at room temperature and near-normal incidence. A combination of a grazing incidence x-ray scattering technique and atomic force microscopy allowed us to observe a variation of the symmetry of the surface nanopattern upon increase of the ion fluence. The isotropic dot pattern formed during the first minutes of sputtering evolves into an anisotropic ripple pattern for longer sputtering time. These results provide a new basis for further steps in the theoretical description of the morphology evolution during ion beam sputtering.
Keywords: ion beam sputtering, nanostructures

Publ.-Id: 9882 - Permalink


Polymorphism in Liquid Crystals from Star-shaped Mesogens
Gemming, S.; Popov, I.; Lehmann, M.;
Star-shaped molecules based on a phloroglucinol core with three oligobenzoate arms are powerful mesogens, that can be combined to columnar liquid crystalline materials and to soft organic crystals. The structural properties of such modern materials exhibit polymorphism at two different length scales. On the molecular level, the mesogens are highly flexible molecules with a large variety of almost isoenergetic conformers of different propensity towards a regular stacking in the bulk phase. On the supramolecular level, polymorphic structures occur, which comprise different liquid crystalline phases with anisotropic columnar order and soft crystals with a more isotropic three-dimensional ordering. For the smallest mesogen the present experimental structure data and computational results give evidence that the two forms of polymorphism are linked. Columnar liquid crystals form from a low-symmetry, folded conformer, which already accounts for the nano-segregation of the planar aromatic centre and the flexible aliphatic chain parts of the mesogen, whereas the soft, more isotropic crystals are grown from the C3-symmetric, star-shaped conformer. Molecular dynamics simulations confirm the stability of each structure at room temperature.
Keywords: liquid crystals, polymorphism, computer modelling, density-functonal methods

Publ.-Id: 9881 - Permalink


Comparison of different buncher cavity designs for the 4GLS ERLP
Wooldridge, E.; Beard, C. D.; Gerth, C.; Büchner, A.;
A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) presently being built at Daresbury Laboratory. A buncher is required for the ERLP downstream of the photocathode gun to decrease the relatively long bunches (20-30ps) from the GaAs cathode. Three different single-cell cavity designs were investigated: the Cornell buncher, the ELBE buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CSTs Microwave Studio and ASTRA. The fundamental frequency and field pattern of each buncher was investigated in Microwave Studio. The EU cavity was scaled from 500MHz to the required frequency for the buncher of 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.
Keywords: ELBE; RF; Buncher; Injector
  • Poster
    EPAC 2004, 05.-09.07.2004, Luzern, Schweiz
  • Contribution to proceedings
    EPAC 2004, 05.-09.07.2004, Luzern, Schweiz
    Proceedings of EPAC 2004: European Physical Society Accelerator Group, 92-9083-232-0, 467-469

Publ.-Id: 9880 - Permalink


FIB induced growth of antimony nanowires
Schoendorfer, C.; Lugstein, A.; Bischoff, L.; Hyun, Y. J.; Pongratz, P.; Bertagnolli, E.;
The impact of high energy Ga ion beams focused to diameters below 100 nm on antimony (Sb) substrates offers a new approach for the formation of pure Sb nanowires. In contrast to several well-known processes for bottom–up fabrication of one-dimensional nanostructures, for this process neither additional temperature treatment nor any additional material component is needed. Initially, the resulting nanostructures are completely amorphous and show very homogeneous diameters in the range of 20 nm. Lengths up to several microns can be achieved. Annealing at temperatures around 150 °C leads to re-crystallization of these nanowires.
Keywords: Nanowires; Nanofibers; Quantum wires; Antimony; Sb; Focused ion beam; FIB
  • Microelectronic Engineering 84(2007)5-8, 1440-1442

Publ.-Id: 9879 - Permalink


Nuclear astrophysics measurements with photo-neutrons and bremsstrahlung at ELBE
Junghans, A. R.;
  • Lecture (others)
    Physikalisch-Technische Bundesanstalt Dep. 6.4, 01.09.2005, Braunschweig, Deutschland

Publ.-Id: 9876 - Permalink


Search for pygmy strength in Molybdenum isotopes close to particle separation energies
Grosse, E.;
  • Lecture (Conference)
    Nuclear Physics in Astrophysics-II, 16.-20.05.2005, Debrecen, Hungary

Publ.-Id: 9875 - Permalink


Sterne und Kerne - Die Entstehung der chemischen Elemente durch nukleare Prozesse in Urknall, Sternen und Supernovae
Grosse, E.;
  • Lecture (others)
    Tag der offenen Tür, 30.04.2005, Dresden, Deutschland

Publ.-Id: 9874 - Permalink


Energie aus der Kernfusion und aus der Kernspaltung
Grosse, E.;
  • Lecture (others)
    Jugendzentrum Pi, 03.03.2005, Freiberg, Deutschland

Publ.-Id: 9873 - Permalink


Isovector Proton-Neutron Pairing
Frauendorf, S.;
  • Lecture (Conference)
    INT Program 05-3: Nuclear Structure Near the Limits of Stability, 14.11.2005, Seattle, USA

Publ.-Id: 9872 - Permalink


New Symmetries of rotating nuclei
Frauendorf, S.;
  • Lecture (Conference)
    Colloquium, Physics Division, 15.-16.12.2005, Argonne, USA

Publ.-Id: 9871 - Permalink


Infrarotspektroskopie an Proteinen: Fluoreszenz-IR-Kreuzkorrelation
Fahmy, K.;
  • Lecture (Conference)
    Anwendertreffen Bruker Ettlingen, 28.11.2005, Ettlingen, Deutschland

Publ.-Id: 9870 - Permalink


Structure and pH sensitivity of transmembrane helix 3 of rhodopsin
Fahmy, K.;
  • Lecture (Conference)
    European Conference on the Spectroscopy of Biological Molecules, 06.09.2005, Aschaffenburg, Deutschland

Publ.-Id: 9869 - Permalink


Coupling of helix 8 of rhodopsin to the retinal Schiff base studied by infrared and fluorescence cross-correlation spectroscopy
Fahmy, K.;
  • Lecture (Conference)
    Sektionstagung Deutsche Gesellschaft für Biophysik, 05.05.2005, Münster, Deutschland

Publ.-Id: 9868 - Permalink


Infrared and fluorescence spectroscopic studies on molecular switching by G protein.coupled receptors
Fahmy, K.;
  • Lecture (others)
    Deutsche Universität in Kairo, 22.03.2005, Kairo, Egypt

Publ.-Id: 9867 - Permalink


Molecular switching by GPCRs
Fahmy, K.;
  • Lecture (others)
    Université Strasbourg, 21.02.2005, Strasbourg, France
  • Lecture (others)
    Universität Osnabrück, 19.04.2005, Osnabrück, Deutschland

Publ.-Id: 9866 - Permalink


High resolution grazing incidence diffraction on lateral nanostructures created by focused ion beam implantation on semiconductor surfaces
Grenzer, J.; Bischoff, L.; Posselt, M.; Pietsch, U.;
  • Lecture (Conference)
    Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Grossgeräten (SNI-2006), 04.-06.10.2006, Hamburg, Germany

Publ.-Id: 9865 - Permalink


X-ray studies of semiconductor surfaces modified by focused ion beam implantation
Grenzer, J.; Bischoff, L.; Posselt, M.; Pietsch, U.;
  • Lecture (Conference)
    8th Biennial Conference on High Resolution X-ray Diffraction and Imaging, 19.-22.09.2006, Karlsruhe, Germany
  • Lecture (Conference)
    Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Grossgeräten (SNI-2006), 04.-06.10.2006, Hamburg, Germany

Publ.-Id: 9864 - Permalink


Influence of energetic ions on the L10 ordering of FePt films fabricated by magnetron sputtering
Cantelli, V.; von Borany, J.; Grenzer, J.; Fassbender, J.ORC
Due to the high uniaxial anisotropy L10-ordered FePt is currently the most favored candidate for future high density storage applications. With respect to a feasible fabrication technology, it is necessary (i) to produce such films on amorphous substrates, and (ii) to enable a low processing temperature (T<400°C). FePt films deposited at RT only exhibit the face-centered cubic A1-phase. Thus, either deposition or a post-deposition heat treatment at temperatures above typically 500°C is required, in order to achieve the L10-phase. We report on the L10 ordering of stoichiometric FePt thin films fabricated on SiO2/Si substrates by magnetron sputtering at various temperatures (RT - 400°C). Using a low deposition rate of about 0.6 Å/s and an Ar pressure of 0.3 Pa the ion/atom-ratio during deposition is » 1 where the ions exhibit energies of about 20 eV. In addition, FePt films have been irradiated subsequently with He ions of 50 keV and fluencies between 1x1015 and 3x1016 cm−2 for comparison. The kinetics of A1-L10 transition and ordering have been investigated with in-situ X-ray diffraction at the Synchrotron-beamline ROBL at ESRF. L10 ordered FePt films with an ordering parameter S=0.8 have been achieved already for an overall process temperature below 350°C. The results are discussed in terms of ion-assisted activation and segregation which supports the atomic relocation during L10 ordering.
Keywords: FePt, L10 transition, magnetron sputtering, ion irradiation
  • Lecture (Conference)
    15th Intn Conf. on Ion Beam Modification of Materials, 18.-22.09.2006, Taormina, Italy

Publ.-Id: 9863 - Permalink


Structural studies of ion beam synthesized nanocrystals: diamond in SiC and SiC in diamond
Eichhorn, F.; Heera, V.; Weishart, H.; Schell, N.;
  • Lecture (Conference)
    13th ESRF User Meeting, 12.02.2003, Grenoble, France

Publ.-Id: 9862 - Permalink


The Rossendorf CRG Beamline ROBL for radiochemistry and materials research
Schell, N.;
  • Lecture (others)
    Institute of Physics of the Academy of Sciences, 11.09.2003, Warsaw, Poland

Publ.-Id: 9861 - Permalink


Melt stirring during directional solidification using modulated magnetic fields
Willers, B.; Räbiger, D.; Dong, J.; Eckert, S.; Nikrityuk, P. A.; Eckert, K.;
The imposition of an RMF on a solidifying metal column causes problems like the occurrence of typical segregation pattern or a deflection of the upper free surface leading to surface defects or the entrainment of gas. The RMF application provides a permanent radial inward flow along the solidification front. Such flow is responsible for the transport of solute to the axis of the ingot resulting in typical freckle segregation pattern in form of vertical channels filled with alloy of eutectic composition. In this paper we present a new innovative method of electromagnetic stirring using a modulated RMF which offers a considerable potential for a well-aimed modification of casting properties Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb Sn alloys from a water cooled copper chill. A modulated rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure the temperature field during solidification. The velocity field in the liquid phase was determined by means of Ultrasound Doppler velocimetry (UDV). Our numerical model is based on the classical mixture formulation. The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results demonstrate the modulation magnetic field enables an effective control of the flow field and the structure of the solidified samples. Modifications of the grain structure and macrosegregation effects are discussed with respect to the details of the flow field.
Keywords: solidification, Pb-Sn alloys, convection, rotating magnetic field, Ultrasound Doppler Velocimetry
  • Lecture (Conference)
    EUROMAT2007 - European Congress on Advanced Materials and Processes, 10.-13.09.2007, Nürnberg, Germany

Publ.-Id: 9860 - Permalink


Materials research with synchrotron radiation at the Rossendorf Beamline ROBL at ESRF
Schell, N.;
  • Lecture (others)
    University of Sao Paulo, 20.03.2003, Sao Paulo, Brazil
  • Lecture (others)
    CENIMAT F.C.T./Universidade Nova de Lisboa, 04.04.2003, Lisbon, Portugal

Publ.-Id: 9859 - Permalink


PET-guided Radiotherapy - Fact or Fiction
Enghardt, W.;
  • Invited lecture (Conferences)
    Workshop of the Belgian Foundation against Cancer Emerging Hadron Therapy Projects in Europe, 13.11.2005, Brüssel, Belgium

Publ.-Id: 9858 - Permalink


Heavy Ion Tumour Therapy and In-Beam Position Emission Tomography
Enghardt, W.;
  • Lecture (others)
    TU Dresden, 06.06.2005, Dresden, Deutschland

Publ.-Id: 9857 - Permalink


Data Processing for In-Beam Position Emission Tomography
Enghardt, W.;
  • Invited lecture (Conferences)
    Real Time Conf. 2005, 08.06.2005, Stockholm, Sweden

Publ.-Id: 9856 - Permalink


Zentrum für Innovationskompetenz für Medizinische Strahlenforschung in der Onkologie Dresden
Enghardt, W.;
  • Lecture (others)
    Berufsakademie Riesa, 31.05.2005, Riesa, Deutschland

Publ.-Id: 9855 - Permalink


In-beam PET bei der Krebstherapie mit Ionenstrahlen
Enghardt, W.;
  • Invited lecture (Conferences)
    Atominst. der österreichischen Univ., 13.04.2005, Wien, Austria

Publ.-Id: 9854 - Permalink


PET-geführte Strahlentherapie - Vision oder Realität
Enghardt, W.;
  • Lecture (others)
    Medizinische Fakultät, 17.01.2005, Dresden, Deutschland
  • Lecture (Conference)
    GDC Jahrestagung 2005, Fachgruppe Nuklearchemie, 12.09.2005, Düsseldorf, Deutschland

Publ.-Id: 9853 - Permalink


RPC detectors at ELBE
Dohrmann, F.;
  • Lecture (Conference)
    CBM Collab. Meeting, 10.09.2005, Piaski, Poland

Publ.-Id: 9852 - Permalink


Testing RPC detectors at ELBE
Dohrmann, F.;
  • Lecture (Conference)
    HADES Collab. Meeting, 10.06.2005, Dubna, Russia

Publ.-Id: 9851 - Permalink


Tests of RPC detectors at ELBE: Status report
Dohrmann, F.;
  • Lecture (Conference)
    CBM Collab. Meeting, 10.03.2005, Darmstadt, Deutschland

Publ.-Id: 9850 - Permalink


Quasiparticle Model of QCD Matter and the QCD Critical End Point
Bluhm, M.;
  • Lecture (others)
    Universität Bielefeld, 20.09.2005, Bielefeld, Deutschland
  • Lecture (Conference)
    VI Workshop, 07.10.2005, Prerow, Deutschland

Publ.-Id: 9849 - Permalink


Strongly Interaction Matter within a Quasiparticle Perspective with Critical End Point Effects
Bluhm, M.;
  • Lecture (Conference)
    Extreme QCD, 04.08.2005, Swansea, England

Publ.-Id: 9848 - Permalink


Possible Critical End Point Effects on the QCD Equation of State
Bluhm, M.;
  • Invited lecture (Conferences)
    ITP, 27.05.2005, Dresden, Deutschland

Publ.-Id: 9847 - Permalink


Equation of state strongly interacting matter
Bluhm, M.;
  • Lecture (Conference)
    DPG Tagung Berlin, 08.03.2005, Berlin, Deutschland

Publ.-Id: 9846 - Permalink


Soft chiral vibrations in Mo-106
Zhu, S.; Hamilton, J.; Ramayya, A.; Gore, P.; Rasmussen, J.; Dimitrov, V.; Frauendorf, S.; Xu, R.; Hwang, J.; Fong, D.; Yang, L.; Li, K.; Chen, Y.; Zhang, X.; Jones, E.; Luo, Y.; Lee, I.; Ma, W.; Cole, J.; Drigert, M.; Stoyer, M.; Ter-Akopian, G.; Daniel, A.;
High-spin states in neutron-rich Mo-106 were investigated by detecting the prompt gamma-rays in the spontaneous fission of Cf-252 with Gammasphere. Several new bands are observed. Two sets of Delta I = 1 bands in Mo-106 are found to have all the characteristics of a new class of chiral vibrational doublets. Tilted axis cranking calculations support the chiral assignment and indicate that the chirality is generated by neutron h(11/2) particle and mixed d(5/2), g(7/2) hole coupled to the short and long axis, repectively.
  • European Physical Journal A 25(2005)Suppl.1, 459-462

Publ.-Id: 9845 - Permalink


Suppression of band crossing in the neutron-rich nuclei Yb-172,Yb-173 due to the absence of a static pair field
Venkova, T.; Cast, W.; Lieder, R.; Bazzacco, D.; de Angelis, G.; Lieder, E.; Pasternak, A.; Menegazzo, R.; Lunardi, S.; Alvarez, C.; Ur, C.; Martinez, T.; Axiotis, M.; Napoli, D.; Urban, W.; Rzaca-Urban, T.; Frauendorf, S.;
High-spin states in the neutron-rich nuclei Yb-172,Yb-173 have been populated in a Er-170(Li-7,(p,d,t)chi n) incomplete-fusion reaction and the emitted gamma-radiation was detected with the GASP array. The signature partners of the 7/2(+)[633] rotational band of the odd-N Yb-173 isotope have been newly established and were observed up to spin values of (45/2(+)) and (43/2(+)), respectively. The ground-state band of the even-even nucleus Yb-172 has been observed up to a spin value of (22(+)). No band crossings were found in these bands. To explain this observation; it is proposed that the static pair field is absent; considering that the neutron odd-even mass differences reach for these nuclei very small values and that the band crossing is absent in cranked shell modell calculations without pairing. The results indicate, however, that strong dynamic correlations are still present.
  • European Physical Journal A 26(2005), 19

Publ.-Id: 9844 - Permalink


Experimental investigations for head loss build up at clogged strainers after LOCA
Alt, S.; Hampel, R.; Kästner, W.; Grahn, A.; Krepper, E.;
During Loss-of-Coolant-Accidents (LOCA) in nuclear reactors insulation materials of pipes and pressure vessels can be released inside of drywells and containments under the impingment forces of steam and water jets. A portion of dislodged fragments of thermal insulation materials would transport to the screens and strainers arranged forwards of Emergency-Core-Cooling-System (ECCS) pumps. Within the „ German competence network East for nuclear engineering“ at the University of Applied Sciences Zittau/Görlitz (FH) and the Research Centre Rossendorf (FZR) generic investigations has been carried out for the development and improvement of CFD-models for the analytic simulation of insulation-water-two phase flow based on an experimental generated data basis. This paper presents the description of the test facility „Ring line-II“ and results of separate effect experiments regarding the behaviour of water-insulation fragments flow at a horizontal perforated plate used as strainer in BWR plants with the insulation material MD2-1999.
Keywords: Loss-of-Coolant-Accident, insulation material, Emergency-Core-Cooling-System (ECCS), two-phase flow, strainer clogging, sedimentation, resuspension
  • Contribution to proceedings
    Annual Meeting on Nuclear Technology 2006, 16.-18.05.2006, Aachen, Germany
    CD-ROM

Publ.-Id: 9843 - Permalink


The nanostructure evolution during and after magnetron deposition of Au films
Schell, N.; Jensen, T.; Petersen, J. H.; Andreasen, K. P.; Bottiger, J.; Chevallier, J.;
The evolution of the nanostructure of magnetron sputtered Au films has been experimentally studied. At a synchrotron-radiation beam line, during growth and subsequent annealing, in-situ X-ray diffraction has been carried out to follow the texture, the grain size, the microstrain and lattice-plane distances. With Bragg–Brentano geometry, only (111) grains, having a (111) plane parallel to the film surface, have been observed, while, with glancing incidence and exit X-ray diffraction, (111)* grains, having one of their (111) planes perpendicular to the film surface, have also been observed. Both during growth and subsequent annealing, the (111) texture changed, and some (111)* grains recrystallized and/or the orientation of the grains changed. The microstrain decreased drastically during the first few minutes of growth (300 A) while, simultaneously, the size of the coherently diffracting domains increased. Subsequently, the microstrain became constant, and the rate of increase of the size of coherently diffracting domains leveled off. Initially, during the first few minutes of annealing, a large decrease in the microstrain was observed simultaneously with a dramatic rise of the size of the coherently diffracting domains. After this initial annealing period, as during film growth, the microstrain became constant, and the rate of increase of the size of coherently diffracting domains leveled off.
The activation energy for the initial growth of the coherent diffracting domains was found to be Q=(0.25 +/- 0.03) eV, and the activation energy for normal grain growth was found to be Q=(0.99 +/- 0.04) eV.
Finally, the thin-film stress was followed during growth and subsequent annealing. A tensile contribution to the stress was observed during island coalescence.
Keywords: Nanocrystalline Au; Nanostructure; In-situ X-ray diffraction; Growth; Magnetron sputtering
  • Lecture (Conference)
    MRS Fall Meeting, 01.-05.12.2003, Boston, USA

Publ.-Id: 9842 - Permalink


Investigation of steel surfaces treated by a hybrid ion implantation technique
Reuther, H.; Richter, E.; Prokert, F.; Ueda, M.; Beloto, A. F.; Gomes, G. F.;
Kein Abstract vorhanden.
  • Lecture (Conference)
    Int. Conf. on the Applications of the Mössbauer Effect, 21.-25.09.2003, Muscat, Oman

Publ.-Id: 9841 - Permalink


In-situ GIXRD characterization of the crystallization of Ni-Ti sputtered thin films
Martins, R. M. S.; Silva, R. J. C.; Braz Fernandes, F. M.; Pereira, L.; Gordo, P. R.; Maneira, M. J. P.; Schell, N.;
Kein Abstract vorhanden.
  • Lecture (Conference)
    2nd Int. Materials Symposium, 14.-16.04.2003, Campus da Caparica, Portugal

Publ.-Id: 9840 - Permalink


Entstehung der chemischen Elemente im Universum
Grosse, E.;
  • Lecture (others)
    Naturwissenschaften Aktuell der Fakultät Mathematik und Naturwissenschaften, 20.10.2005, Dresden, Deutschland

Publ.-Id: 9839 - Permalink


Symmetries in Nuclear Physics
Frauendorf, S.;
  • Lecture (others)
    6th Nordic Summer School in Nuclear Physics, 08.-19.08.2005, Hillerod, Denmark

Publ.-Id: 9838 - Permalink


Investigation of Biological Mechanism by Spectroscopic Methods
Fahmy, K.;
  • Lecture (others)
    Biozentrum Basel, 01.01.2005, Basel, Switzerland

Publ.-Id: 9837 - Permalink


Formation of Uranium(IV) Colloids
Zänker, H.; Opel, K.; Weiß, S.; Hübener, S.; Bernhard, G.;
Tetravalent uranium is the typical form of uranium in reducing natural waters such as deep groundwaters or waters of the deeper zones of abandoned uranium mines. The colloidal behaviour of uranium(IV) was investigated. Coulometric titrations of strongly acidic U(IV) solutions in HClO4/NaClO4 medium (I = 0.2 M) were carried out in order to find the pH of first colloid formation. Laser-induced breakdown detection (LIBD) was applied for the detection of traces of uranium colloids as the pH was increased. The pH values at the onset of colloid formation were used for thermodynamic calculations aimed at determining the solubility products of crystalline and amorphous uranium dioxide (cf. [1]). Furthermore, the UO2·xH2O(am) colloids were investigated for their colloidal stability. Zeta potentials of ≥ 30 mV were found for pH values of less than 4. The point of zero charge was at pH ~ 6.9. Colloidal suspensions of 10-3 M UO2·xH2O(am) at a pH value of 2.5 proved to be stable over > 1.5 years. The interaction of the forming UO2·xH2O(am) colloids with other colloid-forming species was tested. Therefore, coulometric titrations of U(IV) solutions in the presence of (a) dissolved Al(III) and (b) dissolved silicate were carried out. The presence of Al(III) does not significantly influence the formation of the UO2·xH2O(am) colloids, and the presence of U(IV) does not significantly influence the behaviour of Al(III). There is more interaction of the U(IV) with silicate. Silicate, on the one hand, does not significantly influence the pH value of first UO2·xH2O(am) colloid formation, i.e. it does not significantly influence UO2·xH2O(am) solubility. However, the presence of U(IV) significantly influences the precipitation behaviour of the silicate (formation of U(IV)-Si “pseudocolloids” due to co-precipitation). The nature of the interaction between the silicate and the U(IV) is not yet known. Adsorption of the silicate onto the UO2·xH2O(am) colloids and/or formation of a coffinite (USiO4) precursor come into question. Measurements by extended X-ray absorption fine structure (EXAFS) spectroscopy with synchrotron radiation to elucidate the local structure around the U(IV) atoms in the pseudocolloids are underway. Reference: [1] Opel K., Weiß S., Hübener S., Zänker H., Bernhard G. Radiochim. Acta, 95 (2007) 143-149.
Keywords: colloids, reducing waters, tetravalent uranium
  • Lecture (Conference)
    43. Meeting of the German Colloid Society, 08.-10.10.2007, Mainz, Germany

Publ.-Id: 9836 - Permalink


An in-situ grazing incidence X-ray diffraction study of the crystallisation of the crystallisation of Ni-Ti thin films
Braz Fernandes, F. M.; Martins, R.; Silva, R. J. C.; Marques, A.; Martins, R. M. S.; Schell, N.;
Kein Abstract vorhanden.
  • Lecture (Conference)
    13th ESRF User Meeting, 12.02.2003, Grenoble, France

Publ.-Id: 9834 - Permalink


Universeller Gateway zum Datenaustausch zwischen dem Steuerungssystem der Strahlenquelle ELBE und den Datenaufnahmesystemen der Experimentatoren
Jainsch, R.;
Software zum Datenaustausch zwischen dem Steuerungssystem der Strahlenquelle ELBE und den Datenaufnahmesystemen der Experimentatoren
  • Lecture (others)
    Herbsttagung der Studiengruppe für Elektronische Instrumentierung im FZ Rossendorf, 27.-29.09.2004, Rossendorf, Deutschland

Publ.-Id: 9833 - Permalink


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