Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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43570 Publications
Coprecipitation of Arsenate with Metal Oxides. 3. Nature, Mineralogy, and Reactivity of Iron(III)-Aluminum Precipitates.
Violante, A.; Pigna, M.; Del Gaudio, S.; Cozzolino, V.; Banerjee, D.
Abstract
Coprecipitation involving arsenic with aluminum or iron has been studied because this technique is considered particularly efficient for removal of this toxic element from polluted waters. Coprecipitation of arsenic with mixed iron-aluminum solutions has received scant attention. In this work we studied
(i) the mineralogy, surface properties, and chemical composition of mixed iron-aluminum oxides formed at initial Fe/Al molar ratio of 1.0 in the absence or presence of arsenate [As/Fe+Al molar ratio (R) of 0, 0.01, or 0.1] and at pH 4.0, 7.0, and 10.0 and aged for 30 and 210 days at 50 °C and
(ii) the removal of arsenate from the coprecipitates after addition of phosphate. The amounts of short-range ordered precipitates (ferrihydrite, aluminous ferrihydrite and/or poorly crystalline boehmite) were greater than those found in iron and aluminum systems (studied in previous works), due to the capacity of both aluminum and arsenate to retard or inhibit the transformation of the initially formed precipitates into well-crystallized oxides (gibbsite, bayerite, and hematite). As a consequence, the surface areas of the iron-aluminum oxides formed in the absence or presence of arsenate were usually much larger than those of aluminum or iron oxides formed under the same conditions. Arsenate was found to be associated mainly into short-rangeorderedmaterials. Chemicalcompositionofallsamples was affected by pH, initial R, and aging. Phosphate sorption was facilitated by the presence of short-range ordered materials, mainly those richer in aluminum, but was inhibited by arsenate present in the samples. The quantities of arsenate replaced by phosphate, expressed as percentages of its total amount present in the samples, were particularly low, ranging from 10% to 26%. A comparison of the desorption of arsenate by phosphate from aluminum-arsenate and iron-arsenate (studied in previous works) and iron-aluminum-arsenate coprecipitates evidenced that phosphate has a greater capacity to desorb arsenate from aluminum than iron sites.
Keywords: Arsenic; XPS; Coprecipitate
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Environmental Science & Technology 43(2009)5, 1515-1521
DOI: 10.1021/es802229r
Cited 43 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12329
Was tut ein Medizinphysikexperte? Der Masterstudiengang Medical Radiation Sciences an der medizinischen Fakultät
Enghardt, W.
Abstract
Was tut ein Medizinphysikexperte? Der Masterstudiengang Medical Radiation Sciences an der medizinischen Fakultät
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Invited lecture (Conferences)
Uni-Tag der TU Dresden, 31.05.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12328
Neue Anwendungen ionisierender Strahlen in der Medizin
Enghardt, W.
Abstract
1. Motivation für neue Therapiestrahlen
2. Physikalische Eigenschaften von Ionenstrahlen
3. Biologische Eigenschaften von Ionenstrahlen
4. Technologische Umsetzung
5. Klinische Ergebnisse
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Invited lecture (Conferences)
1. Strahlenschutzseminar für Führungskräfte in Sachsen, 13.10.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12327
Erste dosimetrische und strahlenbiologische Experimente an Laser beschleunigten Elektronenstrahlen
Enghardt, W.
Abstract
1. Laser Beschleuniger für die Strahlentherapie
2. Das Verbundprojekt onCOOPtics (Jena Dresden)
3. Dosimetrie Laser beschleunigten Elektronenstrahlen
4. Strahlenbiologische Experimente
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Invited lecture (Conferences)
Radioonkologisches Kolloquium, 02.04.2008, München, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12326
Der Masterstudiengang Medical Radiation Sciencesund die Ausbildung von MPE an der medizinischen Fakultät der TU Dresden
Enghardt, W.
Abstract
Der Masterstudiengang Medical Radiation Sciencesund die Ausbildung von MPE an der medizinischen Fakultät der TU Dresden
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Invited lecture (Conferences)
39. Wissenschaftliche Jahrestagung der DGMP 2008 Medizinische Physik, 13.09.2008, Oldenburg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12324
Monitoring of Hadron Therapy by means of PET Techniques
Enghardt, W.
Abstract
1. PET and hadron therapy (PT-PET)
2. Clinical implementation
3. Results and conclusions
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Invited lecture (Conferences)
ESTRO 27, 16.09.2008, Göteborg, Schweden
Permalink: https://www.hzdr.de/publications/Publ-12323
Erfahrungen zum und künftige Anforderungen an das Verhältnis zwischen großen Forschungseinrichtungen und dem Rechnungshof
Joehnk, P.
Abstract
Neues Steuerungsmodell in der Wissenschaft und die Rolle der Rechnungshöfe
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Invited lecture (Conferences)
Veranstaltung des ZWM Wissenschaftsmanagement Speyer, 29.-30.01.2009, Berlin, Germany
Permalink: https://www.hzdr.de/publications/Publ-12322
The detector system for measurement of multiple cosmic muons in the central detector of KASCADE
Bozdog, H.; Elzer, M.; Gils, H.; Haungs, A.; Herm, F.; Koepernik, H.; Kohler, K.; Kretschmer, M.; Leibrock, H.; Mathes, H.; Petcu, M.; Proehl, D.; Rebel, H.; Wentz, J.; Wolf, A.; Zagromski, S.
Abstract
A detector system for directional and time correlation measurements of multiple cosmic muons has been set up within the extensive air shower experiment KASCADE. The system consists of two layers (129 m(2) area each) of position-sensitive multiwire proportional chambers (MWPC) triggered by a layer of segmented plastic scintillation counters placed upon an iron/concrete shielding above the MWPCs. Operation conditions and performance of the MWPCs have been studied by means of a prototype arrangement consisting of a stack of four detectors and two trigger layers. Results of the detailed prototype studies are presented and discussed. In particular, it has been found that for the present purposes an operation with a commonly used argon-methane gas mixture instead of previously used argon-isobutane leads to an excellent performance. The chambers are integrated into the KASCADE experiment as described and are in continuous operation since 1996. Some typical measurements with the full detector assembly are used to illustrate which features of extensive air showers can be studied. (C) 2001 Elsevier Science B.V. All rights reserved.
Keywords: multiwire proportional chambers; data processing; extensive air showers; cosmic muons; extensive air showers
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Nuclear Instruments and Methods in Physics Research A 465(2001)2-3, 455-471
ISSN: 0168-9002
Permalink: https://www.hzdr.de/publications/Publ-12321
In-beam PET for moving targets in particle therapy
Laube, K.; Bert, C.; Chaudhri, N.; Fiedler, F.; Parodi, K.; Rietzel, E.; Saito, N.; Enghardt, W.
Keywords: in-beam PET; moving targets; ion therapy
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Poster
OncoRay, Retreat, 14.-15.01.2009, Bautzen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12320
PET-CT Co-Registrierung for In-Beam PET
Fiedler, F.; Sobiella, M.; Enghardt, W.
Keywords: in-beam PET
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Poster
Oncoray, Retreat, 14.-15.01.2009, Bautzen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12319
In-beam PET for ion therapy monitoring
Fiedler, F.
Keywords: in-beam PET
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Lecture (others)
Oncoray-Meeting, 03.06.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12318
Local setting of magnetic anisotropy in amorphous films by Co ion implantation
McCord, J.; Mönch, I.; Fassbender, J.; Gerber, A.; Quandt, E.
Abstract
The local setting of magnetic anisotropy by low fluence Co ion implantation in amorphous magnetic thin films is demonstrated. For a wide range of ion fluences no structural changes occur and the adjustment of anisotropy is reversible. A quantitative relationship between the anisotropy change and the atomic displacements is found. Magnetic domain investigations of the purely magnetically patterned stripes reveal an effective quasi-cubic anisotropy below a critical width for orthogonal magnetic anisotropy alignment. The method of ion-annealing allows for a local setting of anisotropy without irreversible structural and magnetic alterations.
Keywords: magnetism; ion implantation; amorphous films; patterning; anisotropy
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Journal of Physics D: Applied Physics 42(2009), 055006
DOI: 10.1088/0022-3727/42/5/055006
Cited 26 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12317
Local stress engineering of magnetic anisotropy in soft magnetic thin films
Martin, N.; McCord, J.; Gerber, A.; Strache, T.; Gemming, T.; Mönch, I.; Farag, N.; Schäfer, R.; Fassbender, J.; Quandt, E.; Schultz, L.
Abstract
The magnetic anisotropy of amorphous thin films was modified laterally by masked ion irradiation without alteration of the intrinsic magnetic properties. The changes were introduced by local ion implantation in a protection layer, causing additional stress-induced magnetic anisotropy in the magnetostrictive layer. The underlying local variation of magnetic anisotropy was modelled and confirmed experimentally. The described method, relying purely on magneto-elastics, introduces a new path to the alteration of magnetic properties subsequent to magnetic film preparation. With the use of the resulting artificial magnetization patterns it is possible to tailor the ferromagnetic thin film structure used in magneto-electronic applications.
Keywords: magnetism; ion irradiation; amorphous films; magneto-elastic; patterning
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Applied Physics Letters 94(2009), 062506
DOI: 10.1063/1.3079664
Cited 18 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12316
Künstliche magnetische Materialien durch Nanostrukturierung
Abstract
Nanostrukturierte magnetische Materialien wurden in den letzten 15 Jahren intensiv untersucht. In den allermeisten Fällen handelte es sich dabei um magnetische Inseln die mittels Lithographietechniken auf einem unmagnetischen Substrat hergestellt wurden. Eine völlig neuartige Klasse von Materialien entsteht, wenn anstelle einer topographischen eine rein magnetische Strukturierung verwendet wird. Dies geschieht durch lokale Modifikation der Oberflächenrauhigkeit oder Grenzflächenschärfe bei Vielfachschichtsystemen. Derartige Modifikationen können leicht mittels Ionenbestrahlung [1], Ionenimplantation [2,3] oder Ionenstrahlerosion [4] erzielt werden. Alternativ können auch strukturelle Phasenübergänge, die mit magnetischen Phasenübergängen einhergehen realisiert werden [5], die die Erzeugung magnetischer Nanostrukturen im sub-100 nm Bereich zulassen [6]. Der Vortrag gibt einen Überblick über die auftretenden physikalischen Phänomene unter Einbezug einiger Anwendungsbeispiele.
[1] J. Fassbender, D. Ravelosona, Y. Samson, J. Phys. D: Applied Physics 37, R179 (2004).
[2] J. Fassbender, J. McCord, J. Magn. Magn. Mater. 320, 579 (2008).
[3] J. McCord, L. Schultz, J. Fassbender, Advanced Materials 20, 2090 (2008).
[4] M. O. Liedke, B. Liedke, A. Keller, B. Hillebrands, A. Mücklich, S. Facsko, J. Fassbender, Phys. Rev. B 75, 220407(R) (2007).
[5] J. Fassbender, M. O. Liedke, T. Strache, W. Möller, E. Menendez, J. Sort, K. V. Rao, S. C. Deevi, J. Nogues, Phys. Rev. B 77, 174430 (2008).
[6] E. Menendez, J. Sort, M. O. Liedke, J. Fassbender, T. Gemming, A. Weber, L. J. Heydermann, S. Surinach, K. V. Rao, S. C. Deevi, M. D. Baro, J. Nogues, Small 5, 229 (2009).
Keywords: magnetism; ion irradiation; implantation; patterning; nano; ion erosion
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Invited lecture (Conferences)
Kolloquiumsvortrag, Universität Mainz, 16.02.2009, Mainz, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12315
Superconductivity in heavily Ga-doped Ge
Heera, V.; Herrmannsdörfer, T.; Heinig, K.-H.; Ignatchik, O.; Mücklich, A.; Posselt, M.; Schmidt, B.; Skrotzki, R.; Skorupa, W.; Uhlarz, M.; Voelskow, M.; Wündisch, C.; Helm, M.; Wosnitza, J.
Abstract
Recently, superconductivity was detected in heavily boron doped group IV semiconductors like diamond (cB=2.8 at%, TC=4 K) [1] and silicon (cB=1.2 at%, TC=0.34 K) [2]. These unexpected results initiated a new debate about the possibility and the mechanism of superconductivity in doped semiconductors. Theoretical calculations, based on the classical electron-phonon coupling mechanism, demonstrated that critical temperatures in diamond can clearly exceed 1 K for acceptor concentrations higher than 5 at% [3]. However, unrealistic high doping concentrations are predicted for observable superconductivity in Si or even Ge. It was an open question whether superconductivity can be achieved in doped Ge.
In order to fabricate group IV semiconductors with acceptor concentrations much higher than their equilibrium solid solubility exotic doping methods like high-pressure-high-temperature synthesis [1] or gas immersion laser doping [2] were applied. We used a more conventional doping process consisting of high dose implantation and 3 ms flash lamp or 60 s rapid thermal annealing in order to form Ge layers with Ga concentrations up to 6 at%. According to Hall effect measurements the hole concentrations are in the range between 0.3x1021 and 1.4x1021 cm-3. Superconductivity was found in the Ga-doped Ge samples below critical temperatures between 0.1 and 0.5 K in dependence on the annealing conditions.
References
[1] E. A. Ekimov et al., Nature 428 (2004) 542
[2] E. Bustarret et al., Nature 444 (2006) 465
[3] L. Boeri, J. Kortus, O. K. Anderson, J. Phys. Chem. Solids 67 (2006) 552
Keywords: Ga doped Ge; Ga implantation; flash lamp annealing; Hall effect measurements; superconductivity
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Lecture (Conference)
Workshop Ionenstrahlphysik, 06.-08.04.2009, Jena, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12314
Synthesis, Modification and Applications of Ge Nanoclusters Embedded in SiO2 Films
von Borany, J.; Beyer, V.; Heinig, K.-H.; Mücklich, A.; Schmidt, B.; Skorupa, W.
Abstract
Due to their quantum confinement properties and the large surface-to-volume-ratio, semiconductor and metal nanoparticles embedded in a matrix play a significant role for new functional materials. Among them, Si, Ge, or SiC nanoclusters (-or crystals) are of particular interest for future (opto)electronic devices due to the full compatibility with semiconductor technology.
The contribution focus on recent studies on Ge nanoparticles embedded in dielectric films (mainly SiO2). Based on phase separation of supersaturated solid solutions, Ge nanocluster have been fabricated using ion beam synthesis or magnetron sputtering techniques. The size, density, density and position of the Ge nanocrystals can be varied in a technological relevant way by the degree of supersaturation and the spatial distribution of the Ge. Moreover, subsequent thermal or ion-beam processing enables to tailor nanocluster properties like shape, size or composition. Taking into account the ion beam interaction at interfaces, the generation of delta-like nanocluster bands has been successfully demonstrated. For Ge nanocrystals formation, relatively low process temperatures (< 950°C) are characteristic, but careful processing remains necessary to avoid Ge loss in thin films due to the formation of volatile GeO components. Some conceivable (opto)electronic applications of Ge nanoclusters will be discussed more in detail. Thin gate oxides containing ion beam synthesized Ge nanoclusters have been applied to study non-volatile me¬mory with low-field programming (< 5 MV/cm) capability. The violet luminescence in Ge doped SiO2 films was investigated with respect to their possible use to fabricate luminescence or opto-coupling devices. Finally, nanocluster films offer a new interesting approach for light absorption in bandgap engineered absorber materials designed for next generation solar cells.
Keywords: Ion beam synthesis; Ge nanoclusters; Nanocrystal memory; Bandgap engineering; Photovoltaics
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Invited lecture (Conferences)
The IUMRS International Conference in Asia 2008 (IUMRS-ICA2008), Session M "Innovative Material Technologies Utilizing Ion Beams", 08.-13.12.2008, Nagoya, Japan
Permalink: https://www.hzdr.de/publications/Publ-12313
Evidence of a thermally stimulated charge transfer mechanism and interface defect formation in metal-oxide-semiconductor structures with germanium nanocrystals
Beyer, R.; von Borany, J.
Abstract
The trapping of charge carriers and the mechanism of the charge transfer were examined in metal-oxide-semiconductor structures with germanium nanocrystals embedded in a 20 nm silicondioxide layer. The nanoclusters were generated by ion beam synthesis. Capacitance-voltage (C-V) measurements exhibit a hysteresis loop due to the charge trapping and detrapping. Effective oxide trap densities were derived and could be related to the nanoclusters. A strong temperature dependence of the C-V loop indicates, that a thermally stimulated process is involved in the charge transfer between the clusters and the interface, thus ruling out direct tunneling. The application of deep level transient spectroscopy revealed a large amount of interface states in the Ge implanted samples, including a distinct trap state at 0.32 eV above the valence band edge with a concentration up to 2e13 /(cm²eV), which is much likely involved in the emission of carriers from cluster related states in a two stage process.
Keywords: Ion beam synthesis; Ge nanocrystals; CV characteristics
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Journal of Applied Physics 105(2009), 064513
DOI: 10.1063/1.3087131
Cited 12 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12312
X rays from relaxation of slow highly charged ions hitting thin metallic foils: emission depth and time
PeIć, Z. D.; Vikor, G.; Schuch, R.
Abstract
Nanotechnological devices are reaching the size of few molecules and there is a quest for new nanoscale materials. It has been prompted already in the eighties that the high potential energy carried by highly charged ions (HCIs) might be exploited for surface modifications . For example, the use of potential sputtering for nanostructuring would avoid unwanted damage caused by fast ions. Therefore, the knowledge of the exact time and depth scale for the energy deposition is essential.
Apart from the work reported in, there are very few direct experimental determinations of the relaxation time in the bulk. Recently, we introduced a method to determine the relaxation time of the innermost vacancies for highly ionized heavy ions moving through the bulk . The method compares the intensities of photons emitted through the front and back-side of a thin metal foil. Using foils with known thickness and x-ray absorption cross-sections, we obtained directly the mean x-ray emission depth, and thereafter the mean relaxation time.
The experiment was performed at the Manne Siegbahn Laboratory in Stockholm. Two Si(Li) detectors were used to measure X-rays emitted following the impact of 8.5xq keV and 23.5xq keV Pbq+ ions (q=53-58) on thin Ta foils oriented 45o relative to the ion-beam direction. This geometry allowed simultaneous detection of photons that escape through the back and the front surface of the foil.
The difference of the intensities of front- and back-side x-ray spectra is caused by different path lengths through the absorbing material (Ta foil) as well as by different detection efficiencies of the two Si(Li) detectors. The fitting procedure is illustrated in Fig.1, clearly showing that it is necessary to correct both spectra for the proper absorption by the Ta foil.
The experimental results of the emission depth are combined with a trajectory simulation to obtain the slowing down of the ion in the solid, to get the range and to convert the length scale to a time scale. We found that the relaxation time ranges from 30-60 fs.
The extracted mean relaxation time is compared with the prediction of the rate-equations model that incorporates radiative and non-radiative transitions, combined with a molecular orbital (MO) calculation for the Pb-Ta collision system which gives the projectile levels that are filled in close collisions with target atoms. The calculated mean relaxation time is found to be in fair agreement with the experimental results.
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Invited lecture (Conferences)
IISC-17, 17th International Workshop on Inelastic Ion-Surface Collisions, 21.-26.09.2008, Porquerolles, France
Permalink: https://www.hzdr.de/publications/Publ-12311
Fragmentation of Water Molecule by Slow Multiply Charged Ions
PeIć, Z. D.; Hellhammer, R.; Sulik, B.; Stolterfoht, N.
Abstract
Fragmentation of molecules subsequent to the interaction with ions has been studied intensively in the last decade, with the focus on relatively fast projectiles (the interaction time is 1-2 orders of magnitude smaller than the dissociation time). If the projectile is slow that the interaction time is comparable with the dissociation time, it strongly alters the angular and energy distribution of ionic fragment.
The energy and angular distribution of ionic fragments from water molecules formed upon impact of highly charged 1-220 keV Xeq+ ions (q=10, 15 and 22) was studied. These results are compared with our previous studies of water fragmentation induced by He1,2+, Ne(3-9)+ and Ar13+ ions [1-3]. A strong difference of the intensities and kinetic energy of ions scattered in forward and backward directions is observed as a function of the ion velocity. The data are interpreted by means of a classical trajectory simulation within the framework of a Coulomb Explosion.
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Invited lecture (Conferences)
RADAM 2008 - Radiation Damage in Biomolecular Systems, 13.-15.06.2008, Debrecen, Hungary -
Contribution to proceedings
RADAM 2008 - Radiation Damage in Biomolecular Systems, 13.-15.06.2008, Debrecen, Hungary
Proceedings of the 5th International Conference (RADAM 2008), Melville, New York: American Institute of Physics, 978-0-7354-0611-7, 88-97
Permalink: https://www.hzdr.de/publications/Publ-12310
Strong Forward-Backward Asymmetry of Water Ionic Fragments by Slow Highly Charged Ions Impact
Peić, Z. D.; Hellhammer, R.; Sulik, B.; Stolterfoht, N.
Abstract
Fragmentation of molecules subsequent to the interaction with ions has been studied intensively in the last decade. If the projectile is fast that the interaction time is orders of magnitude smaller than the dissociation time, the collision can be considered as a two-step process . On the other hand, for slow (v < 1 a. u.), highly charged projectiles the energy and angular distribution of fragments is determined by the energy and momentum transferred from the projectile, in addition to the energy gained by the repulsive dissociation of the molecule.
We present the results of the fragment ion spectroscopy studies of water molecules subsequent to impact of highly charged 1-220 keV Xeq+ ions (q=10, 15 and 22). We observed a strong forwardbackward asymmetry in the emission of the ionic fragments. For example, the ion yield in the forward direction is almost completely suppressed for the impact of below 10 keV Xe22+ ions.
These results are compared with our previous studies of water fragmentation induced by He1,2+ and Ne(3-9)+ ions . For projectiles with low charge state, the final kinetic energy is apparently determined by the related Franck-Condon transition. In order to guide the interpretation of the experimental data, we performed a classical trajectory simulation within the framework of a Coulomb Explosion model wherein a satisfactory agreement is achieved. Finally, the integrated cross sections over all fragmentation channels are compared with results of the semiempirical scaling law deduced from a multi-electron capture model.
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Lecture (Conference)
HCI 2008, 14th International Conference on the Physics of Highly Charged Ions., 01.-05.09.2008, Tokyo, Japan
Permalink: https://www.hzdr.de/publications/Publ-12309
Measurements of electron bunch lengths
Debus, A.
Abstract
Particle-in-Cell (PIC) simulations suggest that laser accelerated electron bunches have pulse lengths down to below 10fs. Classic approaches known from the accelerator community are known to be limited to longer electron bunches. An all-optical, single-shot approach is presented that shows how the spectral analysis of the coherent transition radiation from a thin foil in the mid-infrared can be used to extract the electron bunch length on a scale from 8fs to 50fs.
Keywords: electron bunch lengths; transition radiation; laser wakefield accelerated electrons; ultrashort electrons
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Lecture (others)
3rd PhD Seminar of FZD, 27.-29.8.2008, Feriendorf Hoher Hain, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12308
Synchrotron radiation from laser-accelerated monoenergetic electrons
Schlenvoigt, H.-P.; Haupt, K.; Debus, A.; Budde, F.; Jaeckel, O.; Pfotenhauer, S.; Gallacher, J. G.; Brunetti, E.; Shanks, R. P.; Wiggins, S. M.; Jaroszynski, D. A.; Rohwer, E.; Schwoerer, H.
Abstract
In this paper, we report on the generation of incoherent synchrotron radiation in the visible spectral range which is produced by laser-accelerated electrons with 55-75-MeV energy as they propagate through an undulator. Simultaneous detection of electron and photon spectra allows for precise comparison between experimental results and undulator theory. First- and second-order undulator radiation was detected. The agreement between experiment and theory and the exclusion of other effects proves that the observed radiation is generated in the undulator. Beyond that, this experiment introduces laser-accelerated electrons into the radio-frequency accelerator domain of synchrotron light sources. This marks a noticeable step toward a new, compact, and brilliant short-wavelength light source.
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IEEE Transactions on Plasma Science 36(2008)4, 1773-1781
ISSN: 0093-3813
Permalink: https://www.hzdr.de/publications/Publ-12307
4D in-beam PET of moving targets for different irradiation scenarios
Laube, K.; Bert, C.; Chaudhri, N.; Fiedler, F.; Parodi, K.; Rietzel, E.; Saito, N.; Enghardt, W.
Keywords: in-beam PET; moving targets; ion therapy
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Contribution to external collection
in: GSI Scientific Report 2008, Darmstadt: GSI, 2009
Permalink: https://www.hzdr.de/publications/Publ-12306
Characterization of neutron-irradiated ferritic model alloys and a RPV steel from combined APT, SANS, TEM and PAS analyses
Meslin, E.; Lambrecht, M.; Hernández-Mayoral, M.; Bergner, F.; Malerba, L.; Pareige, P.; Radiguet, B.; Barbu, A.; Gomez-Briceno, D.; Ulbricht, A.; Almazouzi, A.
Abstract
Understanding the behaviour of reactor pressure vessel (RPV) steels under irradiation is a mandatory task that has to be elucidated in order to be able to operate safely a nuclear power plant or to extend its lifetime. To build up predictive tools, a substantial experimental data base is needed at the nanometre scale to validate the theoretical models and to extract quantitative information on neutron irradiated materials. To reach this experimental goal, ferritic model alloys and French RPV steel were neutron irradiated in a test reactor at an irradiation flux of 9 x 1017 n.m-2.s, doses from 0.18 to 1.3 x 1024 n.m-2 and 300°C. The main goal of this paper is to report the characterisation of the radiation induced microstructural change in the materials by using the state of the art of characterisation techniques available in Europe at the nanometre scale. Possibilities, limitations and complementarities of the techniques to each other are highlighted.
- Journal of Nuclear Materials 406(2010), 73-83
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Lecture (Conference)
15th Workshop of the International Group on Radiation Damage Mechanisms in Pressure Vessel Steels (IGRDM-15), 11.-16.10.2009, Budapest, Ungarn
Permalink: https://www.hzdr.de/publications/Publ-12305
On the correlation between irradiation-induced microstructural features and the hardening of reactor pressure vessel steels
Lambrecht, M.; Meslin, E.; Malerba, L.; Hernández-Mayoral, M.; Bergner, F.; Pareige, A. P.; Radiguet, B.; Almazouzi, A.
Abstract
A correlation is attempted between microstructural observations by various complementary techniques, which have been implemented within the PERFECT project and the hardening measured by tensile tests of reactor pressure vessel steel and model alloys after irradiation to a dose of ~71019 n cm-2. This is done, using the simple hardening model embodied by the Orowan equation and applying the most suitable superposition law, as suggested by a parametric study using the DUPAIR line-tension code. It is found that loops are very strong obstacles to dislocation motion, but due to their low concentration, they only play a minor role in the hardening itself. For the precipitates, the contrary is found, although they are quite soft (due to their very small sizes and their coherent nature), they still play the dominant role in the hardening. Vacancy clusters are important for the formation of both loops and precipitates, but they will play almost no role in the hardening by themselves.
- Journal of Nuclear Materials 406(2010), 84-89
Permalink: https://www.hzdr.de/publications/Publ-12304
Cyclotron resonance absorption of 2D holes in strained InGaAs/GaAs quantum wells under high magnetic fields
Drachenko, O.; Kozlov, D.; Gavrilenko, V.; Maremyanin, K.; Ikonnikov, A.; Zvonkov, B.; Goiran, M.; Leotin, L.; Fasching, G.; Winnerl, S.; Schneider, H.; Wosnitza, J.; Helm, M.
Abstract
We report a systematic study of the cyclotron resonance (CR) absorption of two dimensional (2D) holes in strained InGaAs/GaAs quantum wells (QWs) in the quantum limit. The energies of CR transitions are traced as a function of magnetic field up to 55 T. A remarkable CR line splitting was evidenced when the resonant field exceeds 20 T. We analyze our date with a 4x4 Luttinger Hamiltonian including strain and QW potentials and find excellent agreement in the positions of the resonances. On the other hand, the spectral weight distribution of the split components suggests an inverted position of the two first Landau levels compared to the theoretical model.
Keywords: cyclotron resonance; strain; 2D holes; quantum wells
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Poster
Workshop of GDR-E "Semiconductor sources and detectors of THz frequencies", 26.-27.09.2008, Paris, France
Permalink: https://www.hzdr.de/publications/Publ-12302
On the accuracy of range determination from in-beam PET data
Fiedler, F.; Shakirin, G.; Skowron, J.; Braess, H.; Crespo, P.; Kunath, D.; Pawelke, J.; Pönisch, F.; Enghardt, W.
Keywords: in-beam PET
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Contribution to external collection
in: GSI Scientific Report 2008, Darmstadt: GSI, 2009
Permalink: https://www.hzdr.de/publications/Publ-12301
Advanced laser driven accelerator concepts at the FZD
Schramm, U.
Abstract
Summary of laser acceleration projects to be performed at FZD
Keywords: laser particle acceleration; ELBE
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Lecture (others)
Laser Physics Seminar Univ. Twente, NL, 28.01.2009, Enschede, Niederlande
Permalink: https://www.hzdr.de/publications/Publ-12299
Laser-accelerated ion beams for future medical applications
Kraft, S.
Abstract
Recent success in laser-driven particle acceleration has increased interest in laser-generated accelerator-quality beams, for example, protons and ions have been produced with up to several tens of MeV per nucleon, and with extremely low emittance (<0.01 mm mrad, normalized). Compact, high-gradient laser-accelerators are therefore now being discussed as a potentially viable technology for a host of particle-beam applications, including future compact medical accelerators for medical diagnostics and therapy. After commissioning of a 150 TW laser system at the FZD, a joint research center for radiation therapy with laser-accelerator ions is being established together with the OncoRay Center for Radiation Research in Oncology, and the University Clinic of the Technical University of Dresden. The present status and future plans of the center, and the results from first proton acceleration experiments at FZD will be presented.
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Lecture (Conference)
Second Internatioanl Symposium on Laser-Driven Relativistic Plasma Applied to Science, Industry and Medicine, 19.-23.01.2009, Kyoto, Japan
Permalink: https://www.hzdr.de/publications/Publ-12298
Physikalisch- technische Vorbereitung von Zellbestrahlungen am intensiven Channeling-Röntgenstrahl der Strahlungsquelle ELBE
Zeil, K.
Abstract
Derzeit erfolgt im Forschungszentrum Dresden-Rossendorf (FZD) die schrittweise Inbetriebnahme und Erprobung der Strahlungsquelle ELBE, welche unter anderem intensive quasimonochromatische und in der Energie durchstimmbare Röntgenstrahlung durch Channeling relativistischer Elektronen in Diamantkristallen erzeugt. Im Rahmen strahlenbiologischer invitro Experimente soll diese zur Bestimmung der relativen biologischen Wirksamkeit (RBW) von Photonenstrahlung in Abhängigkeit von der Photonenenergie eingesetzt werden. Die hierzu notwendige Durchführung strahlenbiologischer Experimente und die Bestimmung von Dosis-Effekt-Kurven unter Berücksichtigung der Diversität lebender Zellen erfordern die Bestrahlung einer größeren Anzahl von Zellproben mit verschiedenen vorgegebenen Dosiswerten (ca. 0, 5 − 10 Gy) und für praktikable Bestrahlungsdauern eine Dosisleistung von 1 Gy/min. Gleichzeitig muss die auf die Zellproben übertragene Dosis exakt bestimmt und ihre räumliche sowie spektrale Verteilung charakterisiert werden. ...
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Diploma thesis
HU Berlin, 2007
100 Seiten
Permalink: https://www.hzdr.de/publications/Publ-12297
Oncoray Retreat 2008: Laserteilchenbeschleunigung
Zeil, K.
Abstract
Presentation der Aktivitäten der Gruppe Laserteilchenbeschleunigung am FZD.
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Invited lecture (Conferences)
Oncoray Retreat 2009, 15.1.2009, Bautzen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12296
Detector response to ps electron bunches with high bunch charge
Zeil, K.
Abstract
Presentation of the scientific program of the Laser Particle Acceleration Group at the FZD as well as the status of the Laser lab. Then the major topic of the talk are measurements of detector response calibration to ps - pulses from the ELBE electron source with different electron bunch charges.
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Invited lecture (Conferences)
Radiation Protection Workshop, 16.12.2008, Chamonix, France
Permalink: https://www.hzdr.de/publications/Publ-12295
In-Medium QCD Sum Rules for omega Meson, Nucleon and D Meson
Thomas, R.
Abstract
The modifications of hadronic properties caused by an ambient nuclear medium are investigated within the scope of QCD sum rules. This is exemplified for the cases of the ω meson, the nucleon and the D meson. By virtue of the sum rules, integrated spectral densities of these hadrons are linked to properties of the QCD ground state, quantified in condensates. For the cases of the ω meson and the nucleon it is discussed how the sum rules allow a restriction of the parameter range of poorly known four-quark condensates by a comparison of experimental and theoretical knowledge. The catalog of independent four-quark condensates is covered and relations among these condensates are revealed. The behavior of four-quark condensates under the chiral symmetry group and the relation to order parameters of spontaneous chiral symmetry breaking are outlined. In this respect, also the QCD condensates appearing in differences of sum rules of chiral partners are investigated. Finally, the effects of an ambient nuclear medium on the D meson are discussed and relevant condensates are identified.
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Other report
Dresden: Technische Universität Dresden, 2008
105 Seiten
Permalink: https://www.hzdr.de/publications/Publ-12294
QCD equation of state of hot deconfined matter at finite baryon density - A quasiparticle perspective
Bluhm, M.
Abstract
The quasiparticle model, based on quark and gluon degrees of freedom, has been developed for the description of the thermodynamics of a hot plasma of strongly interacting matter which is of enormous relevance in astrophysics, cosmology and for relativistic heavy-ion collisions as well. In the present work, this phenomenological model is extended into the realm of imaginary chemical potential and towards including, in general, different and independent quark flavour chemical potentials. In this way, nonzero net baryon-density effects in the equation of state are selfconsistently attainable. Furthermore, a chain of proximations based on formal mathematical manipulations is presented which outlines the connection of the quasiparticle model with the underlying gauge field theory of strong interactions, QCD, putting the model on firmer ground.
A comparison of quasiparticle model results with available lattice QCD data for, e. g., basic bulk thermodynamic quantities and various susceptibilities such as
diagonal and off-diagonal susceptibilities, which provide a rich and sensitive testing ground, is found to be successful. Furthermore, different thermodynamic quantities and the phase diagram for imaginary chemical potential are faithfully described. Thus, the applicability of the model to extrapolate the equation of state known from lattice QCD at zero baryon density to nonzero baryon densities is shown. In addition, the ability of the model to extrapolate results to the chiral limit and to asymptotically large temperatures is illustrated by confrontation with available first-principle lattice QCD results. These extrapolations demonstrate the predictive power of the model.
Basing on these successful comparisons supporting the idea that the hot deconfined phase can be described in a consistent picture by dressed quark and gluon degrees of freedom, a reliable QCD equation of state is constructed and baryon-density effects are examined, also along isentropic evolutionary paths. Scaling properties of the equation of state with fundamental QCD parameters such as the number of active quark flavour degrees of freedom, the entering quark mass parameters or the numerical value of the deconfinement transition temperature are discussed, and the robustness of the equation of state in the regions of small and large energy densities is shown. Uncertainties arising in the transition region are taken into account by constructing a family of equations of state whose members differ from each other in the specific interpolation prescription between large energy density region and a realistic hadron resonance gas equation of state at low energy densities.
The obtained family of equations of state is applied in hydrodynamic simulations, and the implications of variations in the transition region are discussed by considering transverse momentum spectra and differential elliptic flow of directly emitted hadrons, in particular of strange baryons, for both, RHIC top energy and LHC conditions. Finally, with regard to FAIR physics, implications of the possible presence of a QCD critical point on the equation of state are outlined both, in an exemplary toy model and for an extended quasiparticle model.
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Other report
Dissertation: Technische Universität Dresden, 2008
155 Seiten
Permalink: https://www.hzdr.de/publications/Publ-12293
Uran(VI)-Sorption an Ton in An- und Abwesenheit von Huminsäure
Joseph, C.; Schmeide, K.; Sachs, S.; Bernhard, G.
Abstract
Die Endlagerung radioaktiver Abfälle steht im Mittelpunkt vieler politischer Debatten. Neben Salzstöcken (Gorleben, Asse) kommen in Deutschland auch Ton und Granit als Wirtsgestein für ein Endlager in Frage. Ton und Salz werden favorisiert und für eine bessere Entscheidungsfindung werden die Untersuchungen am Ton derzeit intensiviert. Schwerpunkt unserer Untersuchungen ist die Wechselwirkung von Uran(VI) mit Ton (Referenzton: Kaolinit; natürlicher Ton: Opalinuston, Mont Terri, Schweiz). Natürliche Tone können organische Substanzen, wie z. B. Humin- und Fulvinsäuren, enthalten. Aufgrund dessen wird in unseren Versuchen der Einfluss von Huminsäure auf die Uran(VI)-Ton-Wechselwirkung untersucht.
Zunächst wurde der Einfluss des Elektrolyten auf die Uran(VI)-Sorption an Kaolinit erforscht. Neben dem bisher in unseren Experimenten verwendeten NaClO4 [1], wurde synthetisches Opalinustonporenwasser (I = 0.42 M, pH 7.6) [2] untersucht. Es zeigte sich, dass bei Verwendung von Opalinustonporenwasser weniger Uran(VI) an Kaolinit sorbiert. Dieses Verhalten kann mit der Uran(VI)-Speziation erklärt werden. Der im Opalinustonporenwasser bei pH 7.6 vorliegende neutrale Ca2UO2(CO3)3-Komplex sorbiert schlechter als die in 0.42 M NaClO4-Lösung gebildeten geladenen Uranspezies UO2(CO3)34-, (UO2)2CO3(OH)3- und UO2(CO3)22-. Bei Anwesenheit von Huminsäure wird weniger Uran(VI) im NaClO4-System sorbiert, da es durch die Bildung von Uran(VI)-Humat-Komplexen mobilisiert wird und die Huminsäure mit dem Uran(VI) um Bindungsplätze auf dem Ton konkurriert. Durch Huminsäuresorption auf dem Ton stehen wiederum zusätzliche Uran(VI)-Bindungsstellen zur Verfügung und die Menge an sorbiertem Uran(VI) steigt mit steigender Huminsäurekonzentration. Im Opalinustonporenwassersystem ist jedoch kein signifikanter Einfluss von Huminsäure auf die Menge an sorbiertem Uran(VI) zu beobachten, da die Huminsäure keinen Einfluss auf die Uranspeziation in Opalinustonporenwasser bei pH 7.6 nimmt. Weiterhin wurden Kaolinit und Opalinuston hinsichtlich ihres Uran(VI)-Sorptionsvermögens in Opalinustonporenwasser verglichen. Es zeigt sich, dass mehr Uran(VI) an Kaolinit (2.8 ± 0.2 µg/m2) sorbiert als an Opalinuston (0.049 ± 0.002 µg/m2). Dieses Ergebnis ist unerwartet, da Opalinuston einerseits eine größere spezifische Oberfläche als Kaolinit besitzt, andererseits mehr Eisenminerale enthält, die sehr gut Uran(VI) sorbieren [3] können (Opalinuston: BET = 42 m2/g, 5 Gew.-% Fe; Kaolinit: BET = 11.7 m2/g, 0.27 Gew.-% Fe [1]). Der Grund für diesen Unterschied scheint somit im Anteil an Uran(VI) schlecht sorbierenden Mineralen im Opalinuston zu liegen, möglicherweise an Quarz [3].
[1] A. Křepelová et al., Radiochim. Acta 2007, 94, 825. [2] F.J. Pearson, PSI Internal Report TM-44-98-07 1998, Paul Scherrer Institut, Villigen, Schweiz. [3] K. Schmeide et al., Radiochim. Acta 2000, 88, 723.
Keywords: uranium(VI); clay; kaolinite; opalinus clay; sorption; speciation; opalinus clay pore water; humic acid
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Lecture (Conference)
Fachgruppentagung der GDCh-Fachgruppe Nuklearchemie, 30.08.-02.09.2009, Frankfurt/Main, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12290
Komplexierung von Curium(III) und Europium(III) mit organischen Liganden unter physiologischen Bedingungen erste Hinweise auf ihre Speziation in Biofluiden
Heller, A.; Barkleit, A.; Bernhard, G.
Abstract
Curium und Europium sind zwei f-Elemente, deren Metabolismus im Biosystem bis heute nicht vollständig geklärt ist. Um diese Wissenslücke zu schließen, wurde das Komplexbildungsverhalten beider Metalle mit relevanten organischen Substanzen unter physiologischen Bedingungen bestimmt. Außerdem wurde die Speziation beider Ele-mente im menschlichen Urin untersucht.
Da Curium innerhalb des Kernbrennstoffzyklus gebildet wird und nur radioaktive Isotope aufweist, stellt es im Falle einer Kontamination oder unfallbedingter Freisetzung in die Umwelt eine ernste Gefahr für die Gesundheit dar. Um mögliche Dekontaminationsmittel zu erforschen, müssen daher sein Metabolismus und die Bindungsform in Biofluiden bekannt sein. Im Gegensatz dazu ist Europium nicht radioaktiv und gewinnt in der Medizin immer mehr an Bedeutung als Bestandteil von Kontrastmitteln in der bildgebenden Diagnostik. Trotz seiner wachsenden Applikation ist auch der Metabolismus dieses Metalls bisher unbekannt.
Beide Elemente weisen ähnliche Eigenschaften auf, da sie in Form ihrer dreiwertigen Ionen vergleichbare Elektronenkonfigurationen besitzen. Aufgrund seiner besseren Handhabbarkeit wird Europium daher oft als Analogon für Curium verwendet. Darüber hinaus weisen beide Elemente einzigartige Fluoreszenzeigenschaften auf. Dies erlaubt Untersuchungen mittels zeitaufgelöster laserinduzierter Fluoreszenzspektroskopie im Spurenkonzentrationsbereich.
Urin ist das Hauptausscheidungsmedium im menschlichen Körper und besteht zu über 90 % aus Harnstoff. Mögliche Reaktionen mit dieser Matrixkomponente wurden daher zuerst untersucht. Beide Metalle bilden Komplexe vom Typ ML 3+ und MLOH 2+, was zu signifikanten Änderungen in den Lumineszenzspektren führt, allerdings nur bei sehr hohem Harnstoffüberschuss Dies spricht ebenso für schwache Komplexe wie die sehr niedrigen Komplexbildungskonstanten.
Ein weiterer biologisch relevanter, organischer Ligand ist Citronensäure. Auch hier führte die Bildung verschiedener Komplexe vom Typ MLH2 2+, MLH +, ML2H 2- und ML bei beiden Elementen zu deutlichen Veränderungen im Lumineszenzspektrum, im Gegensatz zu Harnstoff aber schon bei der kleinsten Ligandkonzentration. Berücksichtigt man, dass Citronensäure in der Biosphäre weitverbreitet ist, spricht dies zusammen mit den hohen Komplexbildungskonstanten dafür, dass Citronensäure eine Hauptrolle bei der Curium- und Europiumspeziation in Biofluiden spielt.
Erste Aufnahmen von Lumineszenzspektren natürlicher, menschlicher Urinproben, die in vitro mit einem der beiden Elemente versetzt wurden, zeigen, dass bei niedrigeren pH-Werten Komplexe mit Citronensäure die Speziation dominieren. Im Gegensatz dazu scheinen bei höheren pH-Werten Komplexe mit anorganischen Liganden, die noch näher untersucht werden müssen, vorzuherrschen. Allgemein weisen Curium und Europium ähnliche Komplexbildung und Speziation auf, wobei das Lanthanid aber etwas stärkere Komplexe bildet als das Actinid.
Keywords: curium(III); europium(III); TRLFS; complexation; human biofluids; heavy metal speciation
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Lecture (Conference)
GDCh-Wissenschaftsforum Chemie 2009, 30.08.-02.09.2009, Frankfurt am Main, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12289
Total neutron cross section measurements at nELBE
Junghans, A. R.; Altstadt, E.; Bemmerer, D.; Beyer, R.; Galindo, V.; Grosse, E.; Hannaske, R.; Marta, M.; Matic, A.; Nair, C.; Naumann, B.; Schilling, K. D.; Schneider, S.; Schlenk, R.; Schwengner, R.; Wagner, A.; Weiss, F.-P.; Mosconi, M.; Nolte, R.; Röttger, S.
Abstract
Total neutron cross section measurements at nELBE
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Lecture (Conference)
EFNUDAT progress and general assembly meeting, 01.-03.10.2008, Uppsala, Schweden
Permalink: https://www.hzdr.de/publications/Publ-12288
The fate of uraniumin phosphate-rich soils
Read, D.; Black, S.; Beddow, H.; Trueman, E.; Arnold, T.; Baumann, N.
Abstract
A number of industrial processes concentrate natural radionuclides to levels that cannot be disregarded on health or environmental grounds. These activites include mining of metalliferous and non-metalliferous ores; ore processing; oil and gas extraction; metal smelting and power production from coal (IAEA 2003; Ceccarello et al. 2004; Read et al. 2004). The phosphate industry, which encompasses fertilizer production, is another. Concern has been raised that the radiological consequences of such processes have been underestimated. While this is undoubtedly true in many cases, there is considerable debate as to whether the widespread application of fertilizer has any significant effect on human exposure or the broader environment. This paper adds to the debate by addressing the likely fate of uranium in phosphate-rich soil media.
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Contribution to external collection
L. J. De Kok, E. Schnug: Loads and Fate of Fertilizer-derived Uranium, AH Leiden: Backhuys Publishers BV, 2009, 978-90-5782-193-6, 65-71
Permalink: https://www.hzdr.de/publications/Publ-12287
P0703 - Verfahren zur Messung von lokalen Strömungsgeschwindigkeiten in flüssigen Schmelzen
Eckert, S.; Gerbeth, G.; Gundrum, T.
Abstract
Die Erfindung betrifft ein Verfahren zur Messung der Strömungsgeschwindigkeit in flüssigen Schmelzen in einem Temperaturbereich oberhalb von 200°C mit einem Ultraschallgenerator sowie zugehörigem Ultraschall-Wellenleiter nach dem Ultraschall-Doppler-Verfahren.
Mit der Erfindung soll eine gute Signalein- und -auskopplung gewährleistet werden. Erreicht wird das durch Herstellen der Benetzbarkeit der Stirnfläche des Ultraschallwellenleiters vor dem Messvorgang, anschließendes direktes Einkoppeln von Ultraschall-Messsignalen in die Schmelze unter einem Winkel verschieden von 90°, indem zumindest die Stirnfläche des Ultraschallwellenleiters in die Schmelze eingetaucht wird, und Auskoppeln der in der Schmelze reflektierten Ultraschallsignale über die Stirnfläche des Ultraschallwellenleiters und Weiterleitung derselben an eine Auswerteschaltung. Die Herstellung der Benetzbarkeit erfolgt durch mechanisches und chemisches Reinigen der Stirnfläche und nachfolgendes Beschichten derselben mit einem geeigneten Material.
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Patent
DE 10 2007 027 392 B3 - 2009.01.15 -
Patent
WO 00 2008 152 025 A2 - 2008.12.18 -
Patent
US 7950293 B2 - 31.05.2011 -
Patent
KR101196407B1 - 25.10.2012
Permalink: https://www.hzdr.de/publications/Publ-12286
Inverse Compton backscattering source driven by the multi-10 TW laser installed at Daresbury
Priebe, G.; Laundy, D.; Macdonald, M.; Diakun, G.; Jamison, S.; Jones, L.; Holder, D.; Smith, S.; Phillips, P.; Fell, B.; Sheehy, B.; Naumova, N.; Sokolov, I.; Ter-Avetisyan, S.; Spohr, K.; Krafft, G.; Rosenzweig, J.; Schramm, U.; Gruner, F.; Hirst, G.; Collier, J.; Chattopadhyay, S.; Seddon, E.
Abstract
Inverse Compton scattering is a promising method to implement a high brightness, ultra-short, energy tunable X-ray source at accelerator facilities. We have developed an inverse Compton backscattering X-ray source driven by the multi-10 TW laser installed at Daresbury. Hard X-rays, with spectral peaks ranging from 15 to 30 keV, depending on the scattering geometry, will be generated through the interaction of laser pulses with electron bunches delivered by the energy recovery linac machine, initially known as energy recovery linac prototype and subsequently renamed accelerators and lasers in combined experiments. X-ray pulses containing 9 × 107 photons per pulse will be created from head-on collisions, with a pulse duration comparable to the incoming electron bunch length. For transverse collisions 8 × 106 photons per pulse will be generated, where the laser pulse transit time defines the X-ray pulse duration. The peak spectral brightness is predicted to be ~1021 photons/(s mm2 mrad2 0.1% Δλ/λ).
Keywords: ALICE; Compton scattering; Compton synchrotron radiation; Energy recovery linac; ERLP; Laser Compton scattering; Laser synchrotron radiation; Thomson scattering; Ultra-short X-ray pulses; X-ray source
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Laser and Particle Beams 26(2008)4, 649-660
DOI: 10.1017/S0263034608000700
Cited 44 times in Scopus
Downloads
Permalink: https://www.hzdr.de/publications/Publ-12285
S-Layer basierte Forschungsarbeiten zur Eliminierung von Organika in Wasser
Raff, J.; Pollmann, K.
Abstract
Vorstellung der S-Layer basierten Forschungsarbeiten am Institut für Radiochemie zur Eliminierung von Organika in Wasser über fotokatalytische Verfahren
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Lecture (others)
Vortrag im Rahmen des Besuchs der IBL Umwelt- und Biotechnik GmbH, 21.01.2009, Heidelberg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12284
Anisotropic ion-enhanced diffusion during ion nitriding of single-crystalline austenitic stainless steel
Martinavicius, A.; Abrasonis, G.; Möller, W.; Templier, C.; Riviere, J. P.; Declemy, A.; Chumlyakov, Y.
Abstract
Nitrogen diffusion is investigated in single crystalline austenitic stainless steel AISI 316L (ASS) during ion beam nitriding and subsequent annealing at different crystalline orientations. After nitriding at 400ºC and ion energy of 1 keV, the N penetration depth depends significantly on the crystalline orientation, with the highest penetration depth for (001) orientation. The experimental observations are quantitatively reproduced by fitting using the model of diffusion under the influence of traps. During subsequent isothermal annealing, the N diffusion becomes significantly slower than during nitriding and independent of the orientation. Possible mechanisms of the anisotropic ion enhanced N diffusion are discussed.
Keywords: Stainless steel; Ion nitriding; AISI316L single crystal
- Journal of Applied Physics 105(2009)9, 093502
Permalink: https://www.hzdr.de/publications/Publ-12283
Native Sn-Pb droplets in a zeolitic amygdale (Isle of Mull, Inner Hebrides)
Dekov, V. M.; Hålenius, U.; Billström, K.; Kamenov, G. D.; Munnik, F.; Eriksson, L.; Dyer, A.; Schmidt, M.; Botz, R.
Abstract
Despite the particular scientific interest in the elements with high affinity to S and O2, but found in zero-valence state in nature, the origin of these native minerals has been little explored and remains obscure. Here we describe unique Sn-Pb droplets found in a closed analcime-calcite amygdale collected from a basaltic unit cropping out at Carsaig Bay (Isle of Mull, Inner Hebrides). The droplets consist of intimate intergrowths of nearly pure Sn0 and Pb0 domains in proportion 88:12 and are enveloped in a thin, brownish, amber-like film of organic composition, which gives the impression of metallic embryos in organic placenta. The occurrence of the Sn-Pb droplets in a closed amygdale, their relationship with the host analcime+calcite and their Pb isotope composition (which does not match any known anthropogenic Pb source) rule out the possibility of anthropogenic contamination and support the natural origin of the Sn-Pb alloy.
The variable isotope (Pb, Sr, Nd) compositions in different members of the host basaltic sequence suggest that a parent basaltic magma was modified by crustal assimilation and post-emplacement alteration processes. Considering all possible scenarios, it appears that the most likely source of Pb for the Sn-Pb alloy is a discrete basaltic unit with an isotopic composition comparable to the Antrim basalts (Northern Ireland). The amygdale phases, on the other hand, show isotopic evidence for incorporation of elements from both local basaltic and sedimentary units. The apparent isotopic disequilibrium between Sn-Pb droplets and amygdale phases indicates a complex, multi-stage fluid evolution. The occurrence of Sn-Pb droplets in organic capsules suggests that the droplets and the enveloping organic substances are co-precipitates. This implies that the transportation and deposition of Sn and Pb might have occurred through organometallic compounds. We assume interaction of seawater fluids carrying metals leached from basaltic rocks with hydrocarbons from sedimentary units as a prerequisite for the formation of the organometallic complexes. The zeolites lining the basaltic vesicles might have destabilized the migrating organo- Sn and Pb compounds causing their breakdown and precipitation of Sn-Pb alloy.
Keywords: Sn-Pb alloy; organometallic compounds; Isle of Mull; Inner Hebrides
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Geochimica et Cosmochimica Acta 73(2009), 2907-2919
DOI: 10.1016/j.gca.2009.02.017
Permalink: https://www.hzdr.de/publications/Publ-12282
Tracked megawatt PV plants: Operation results 2008 in Germany and Spain
Rindelhardt, U.; Dietrich, A.; Rösner, C.
Abstract
An increasing number of 2-axis tracked Megawatt PV plants have been put into operation during the last years. The higher final yield of such plants (compared to plants with fixed generator orientation) must be paid with higher plant costs and larger area consumption. The absolute yield is determined by the insolation conditions at the sites. The paper compares design and operation results of four 2-axis tracked plants operating in Germany and Spain in 2008, which are representative PV sites in Europe.
The plant locations are distributed between 37 and 50 degrees northern latitude (Fig.1), in South Spain and Central Germany. Some technical features of the investigated plants are given in the table below.
plant total power /MW tracker Plant area/m² module supplier
Borna 3.44 Solon 210000 Solon
Penig 0,2 Deger 22000 Sanyo,Sharp,SunLink
Alqueria 1.02 Solon 125000 Solon
Ventanas 1.01 Solon 102000 Solon
The used tracker systems differ in their construction and in the applied tracking principle. Whereas the Solon mover (Fig. 2) follows every 10 minutes the astronomic sun path, the Deger tracker (Fig. 3) tries to find the optimal generator position also at cloudy conditions. The tracker distance varies between the both used tracker types and the sites. The most plants started their operation in 2007. The operation of the plants was monitored by the owners or by professional service providers.
The operation results of the year 2008 are exemplarily presented. The solar irradiance in 2008 in Germany was higher than the long year average, similar to the years before. The final yield of the both plants is about 1300 kWh/kW (Fig. 4), with an advantage of 8 % for the plant using Deger trackers. The annual performance ratio was fond to be 82 %.
The yields of the Spain plants exceed the yield of the German plants with 2250 kWh/kW by more than 70 %. Only in one month (May) the yield of the German reaches the yield of the Spain plants due to the extraordinary insolation in Germany (high) and Spain (low), respectively. The performance ratios of the Spain plants were also about 82 %.
A number of operation details will be given.
Finally a long term estimation of the yield for the different plants will be given.
Keywords: PV plants; tracked systems; performance
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Lecture (Conference)
24th European Photovoltaic Solar Energy Conference and Exhibition, 21.-25.09.2009, Hamburg, Deutschland -
Contribution to proceedings
24th European Photovoltaic Solar Energy Conference and Exhibition, 21.-25.09.2009, Hamburg, Deutschland
Proceedings CD-ROM, contribution 5AO.8.5, 3-936338-25-6
Permalink: https://www.hzdr.de/publications/Publ-12281
Beltline welding seam and base metal investigations of a WWER-440/230 reactor pressure vessel from the former Greifswald NPP
Rindelhardt, U.; Schuhknecht, J.; Viehrig, H.-W.
Abstract
Nuclear plants operators must demonstrate that the structural integrity of the nuclear reactor pressure vessel (RPV) is assured during routine operations or under postulated accident conditions. Russian type WWER reactors are operated in Russia and many other European countries like Ukraine, Finland, Czech Republic and Hungary. Surveillance specimens programmes for inspection of aging of the RPV materials were implemented for the second generation (213) of WWER-440 reactors.
The paper presents results of the circumferential core weld SN0.1.4 and the base metal ring 0.3.1 of the RPV from the unit 1 of the Greifswald WWER-440/230. The investigated trepans represent the irradiated-annealed-re-irradiated (IAI) condition. The working program is focussed on the characterisation of the RPV steels through the RPV wall. The key part of the testing is aimed at the determination of the reference temperature T0 following the ASTM Test Standard E1921-05 to determine the fracture toughness in different thickness locations. It is shown that the Master Curve approach as adopted in ASTM E1921 is applicable to the investigated original WWER-440 weld and base metal.
The evaluated T0 varies through the thickness of the welding seam. The lowest T0 value was measured in the root region of the welding seam representing a uniform fine grain ferritic structure. The highest T0 of the weld seam was not measured at the inner wall surface. This is important for the assessment of ductile-to-brittle temperatures measured on sub size Charpy specimens made of weld metal compact samples removed from the inner RPV wall. Our findings imply that these samples may not represent the most conservative condition. The Charpy transition temperature TT41J estimated with results of sub size specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens. The evaluated transition temperature of 51°C is close to the estimated critical embitterment temperature for the initial condition TK0 of the welding seam SN0.1.4.
The T0 from the trepan 1-4 of base metal ring 0.3.1 varies through the thickness of the welding seam. T0 decreases from -124°C at the inner surface to -90°C at a distance of 33 mm from it and again to -113°C at the outer RPV wall. The KJc values generally follow the course of the MC, although the scatter is large. The re-embrittlement during 2 campaigns operation can be assumed to be low. Hence, the variation of T0 measured through the thickness of the base metal ring 0.3.1 results basically from differences in the structure. With metallographic characterization the scatter of the MC will be investigated.
The Charpy transition temperature TT41J estimated with results of sub size specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens.
Keywords: Russian WWER-type reactor; WWER; reactor pressure vessel steel; weld metal; trepans; fracture toughness; Master Curve
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Lecture (Conference)
6th International Scientific and Technical Conference Safety Assurance of NPP with WWER, 26.-29.05.2009, Podolsk, Russian Federation -
Contribution to proceedings
6th International Scientific and Technical Conference Safety Assurance of NPP with WWER, 26.-29.05.2009, Podolsk, Russian Federation
Conference CD, Podolsk
Permalink: https://www.hzdr.de/publications/Publ-12280
Neutron fluence calculations for embrittlement surveillance specimens in VVER-1000
Konheiser, J.; Mittag, S.; Zaritsky, S.
Abstract
Neutron fluence spectrum calculations have been performed for the reactor pressure vessel of a VVER-1000, applying the Monte Carlo code TRAMO. Activities measured earlier in Balakovo-1 by fluence monitors, placed in special Charpy surveillance containers, are compared to TRAMO results. The average deviation from the measurements is about 5 %. A good agreement of the fluence spectra near the RPV inner side, at the height of the core beltline, to the spectra at the Charpy probe positions on top of the radial reflector has been demonstrated.
Keywords: Neutron Fluence Calculation; Surveillance specimens; VVER-1000; Monte-Carlo; TRAMO
- Annals of Nuclear Energy 36(2009)8, 1235-1241
Permalink: https://www.hzdr.de/publications/Publ-12279
High pressure materials for energy storage. The case of V2O5
Arroyo-De Dompablo, M. E.; Amador, U.; GallardoAmores, J. M.; Baehtz, C.; Biskup, N.; Morán, E.
Abstract
The high pressure polymorph of V2O5 is investigated as example of a high-pressure material (HP-V2O5) with potential applications in electrochemical devices, such as lithium batteries. HP-V2O5 reversibly intercalates up to 2 lithium ions down to 1 Volt vs Li+/Li. The typical voltage-composition profile of HP-V2O5 shows distinct features than that of the ambient pressure polymorph, AP-V2O5. Remarkably, the specific capacity retention with cycling of HP-V2O5 // Li cells (250 Ah/Kg at a C/3.5 rate) is comparable to that of the ambient pressure polymorph. Furthermore, the measured resistivities at room temperature (10000 Ωcm in AP and 400 Ωcm in HP) reveal that HP-V2O5 is a better electronic conductor than AP-V2O5. The enhanced electronic conductivity of HP-V2O5 is an advantage for electrochemical applications.
Keywords: in-situ diffraction; lithium ion battery; synchrothron
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Journal of Physics: Conference Series 121(2008), 032001
DOI: 10.1088/1742-6596/121/3/032001
Cited 3 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12278
Thermal order-disorder behaviour in (Na1-xKx)4B8O14 solid solutions investigated by X-ray powder diffraction
Georgievskaya, M.; Albert, B.; Bubnova, R.; Cordier, G.; Baehtz, C.; Filatov, S.
Abstract
In the potassium-rich part of the binary system Na4B8O14-K4B8O14 solid solutions have been found that can be described with the formula (Na1-xKx)4B8O14 with 0.45 ≤ x < 1.0. The crystal structures of (Na0.25K0.75)4B8O14 and (Na0.45K0.55)4B8O14 were refined at room temperature by the Rietveld method. The solid solutions crystallize like K4B8O14 in the triclinic crystal system, space group P-1, with K partially substituted for Na.
An ordered distribution of the alkali atoms over the four cation sites at room temperature has been discovered. The structure of (Na0.25K0.75)4B8O14 was also refined for data collected at 300 and 500°C. The refinements show that sodium and potassium atoms are less ordered at higher temperatures.
Keywords: borates; solid solutions; Rietveld refinement; structure refinement; high temperatures
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Crystal Research and Technology 43(2008)10, 1150-1160
DOI: 10.1002/crat.200800338
Cited 2 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12277
TOPFLOW hot leg model experiments: Overview, examples, status of data analysis and future work
Vallee, C.; Seidel, T.; Lucas, D.
Abstract
The presentation gives an overview about the experiments performed in the hot leg model built in in the pressure vessel of the TOPFLOW facility.
These experiments were conducted in a flat test-section representing a model of the hot leg of a pressurised water reactor. The region of the elbow and of the steam generator inlet chamber is equipped with glass side walls in order to allow high-speed video observations of the two-phase flow in this region. The used fluids were air and water at ambient temperature and pressures up to 0.5 MPa as well as steam and saturated water at pressures up to 5.0 MPa and temperatures up to 264°C. Four types of experiments were performed: experiments without water circulation, co-current flow experiments, steady counter-current flow experiments and counter-current flow limitation (CCFL) experiments. The test procedures, detailed test matrices and selected examples of the measurements are shown.
The current status of data analysis is presented. Data sheets were arranged in order to give an overview of the 191 runs. The water level measured during co-current flow experiments was analysed over probability distributions. Furthermore, the flooding characteristics of the hot leg model was determined and a new parameter is proposed to correlate the data. Finally, a first approach for the interface detection in high-speed camera images was presented.
In the next future, the acquired data will be compared with CFD calculations for validation purposes.
Keywords: hot leg; pressurised water reactor; PWR; two-phase flow; counter-current flow; counter-current flow limitation; CCFL
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Lecture (others)
15th Meeting of the German CFD Network, 21.-22.01.2009, Garching, Germany
Permalink: https://www.hzdr.de/publications/Publ-12276
High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS
Trots, D. M.; Senyshyn, A.; Mikhailova, D. A.; Knapp, M.; Baehtz, C.; Hoelzel, M.; Fuess, H.
Abstract
Results of simultaneous thermal analysis, synchrotron and neutron powder diffraction in the range from room temperature up to the melting point at 936 K on non-superionic orthorhombic β-AgCuS as well as on superionic hexagonal α- and cubic δ-AgCuS are reported. On heating the sample is only stable in argon. The following phase transitions occur in AgCuS at elevated temperatures: β 361 K −→ α 399 K −→ α + δ 439 K −→ δ. The volume changes at the superionic β −→ α and α −→ δ phase transitions are about 2.3 and 0.6%. The volume thermal expansion coefficients are 26 × 10−6, 130 × 10−6 and 85 × 10−6 K−1 for the pure β-, α-and δ-phases, respectively. Models forthe average structures of α-and δ-AgCuS are proposed and discussed. Ionic conductivity in δ-AgCuS may originate from cation jumps in skewed (100) directions between nearest-neighbour tetrahedral sites via the peripheries of the octahedral cavities. A correlation between the temperature dependence of the cation redistribution in δ-AgCuS and the temperature dependence of the ionic conductivity is assumed. A two-dimensional nature of the ionic conductivity due to cation jumps in slabs perpendicular to the c-direction is supposed for α-AgCuS. There is no evidence for ionic diffusion through the (1/2, 1/2, 1/2) site in (111) directions in either superionic α-or δ-phases.
Keywords: XRD phase transition AgCuS
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Journal of Physics: Condensed Matter 19(2007), 136204-136217
DOI: 10.1088/0953-8984/19/13/136204
Cited 26 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12275
Annual Report 2007 - Institute of Radiation Physics
Kämpfer, B.
Abstract
activities etc. in line of previous reports. In 2007, the various research directions were organized and performed in four departments: radiation physics, biophysics (both belonging to the program Life Science), nuclear physics and hadron physics (both belonging to Structure of Matter). A substantial part of the institutes tasks is the performance and further development of the radiation source ELBE, for which a fifth department is responsible. Besides providing secondary beams for radiation physics and biology, nuclear and hadron physics, ELBE is used by groups from other institutes of the Forschungszentrum Dresden-Rossendorf, too in parts in common projects and by external users. Beamtime is used extensively by outside users while all beam time requests have been rated by an international advisory committee.
Some highlights in 2007 related to ELBE have been: first electron beam from superconducting HF gun, first pulsed fast neutron beams from nELBE, and first experiments with single electron pulses of high bunch charge (cell irradiation for radiobiological studies). These achievements are not yet documented in this report.
-
Article, self-published (no contribution to HZDR-Annual report)
Forschungszentrum Rossendorf 2008
72 Seiten
ISSN: 1437-322X
Downloads
Permalink: https://www.hzdr.de/publications/Publ-12274
Labeling of peptides and proteins with 18F via click chemistry using a novel prosthetic group 4-[18F]fluoro-N-methyl-N-(prop-2-ynyl)benzenesulfonamide
Ramenda, T.; Knieß, T.; Steinbach, J.; Wüst, F.
Abstract
Ziel/Aim:
The radiolabeling of peptides or proteins with the short-lived positron emitter 18F requires rapid and mild reaction conditions compatible with the structural and functional integrity of these biopolymers. Over the last two years several approaches have been published focusing on the application of copper(I)-mediated 1,3-dipolar [3+2]cycloaddition of azides and alkynes for labeling peptides with 18F. The peptides were functionalized with an azide- or alkyne group to be reacted with an appropriately 18F-labeled azide or alkyne, respectively. We report on the radiosynthesis of a novel alkine containing 18F-labeled prosthetic group having the advantage of a stable aromatic 18F-label and low lipophilicity caused from the sulfonamide backbone. First applications for click chemistry by labeling azide-functionalized phosphopeptides and human serum albumin (HSA) are demonstrated.
Methodik/Methods:
Two labeling precursors containing different leaving groups (nitro- and trimethylammoniumtriflate) and the reference substance were prepared by the reaction of N methylpropargylamine with the corresponding sulfonic acid chlorides. Radiofluorination was performed in a single step on an automated synthesizer. After purification on semi-preparative HPLC click reaction was performed with a phosphopeptide and the HSA protein. Peptide and protein have been modified with an azide linker. Click reaction occurs in the presence of copper(I) salts and in combination with different copper-chelating ligand systems.
Ergebnisse/Results:
The radiolabeled sulfonamide can be obtained in radiochemical yields of 19 % (d. c.) in high radiochemical purity of > 99 % after HPLC purification within 84 min. First promising results in labeling an azide modified phosphopeptide and protein via click chemistry gave labeling yields about 42 % for posphopeptides after semi-preparative HPLC and about 31 % for HSA after size exclusion chromatography.
Schlussfolgerungen/Conclusions:
The novel prosthetic group 4-[18F]fluoro-N-methyl-N-(prop-2-ynyl)benzenesulfonamide for peptide and protein labeling with 18F via click chemistry can be prepared in reasonable radiochemical yields and high radiochemical purity. Moreover, by this method for the first time click chemistry was successfully applied to the 18F-labeling of a phosphopeptide and a protein. The radiopharmacological investigation of the 18F-labeled phoshopeptides and HSA including metabolic stability, biodistribution and cell uptake studies is in progress.
-
Lecture (Conference)
47. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 22.-25.04.2009, Leipzig, Deutschland -
Abstract in refereed journal
Nuklearmedizin 48(2009)2, A38
ISSN: 0029-5566
Permalink: https://www.hzdr.de/publications/Publ-12273
Die Relevanz der Borflüchtigkeit bei Langzeittransienten in einem mit Bor vergifteten Siedewasserreaktor
Laczko, G.; Böhlke, S.; Ohlmeyer, H.; Schuster, C.; Hurtado, A.
Abstract
Die Analyse der Reaktivitätswirksamkeit der Boreinspeisung am SWR erfolgt im Rahmen einer sich im Abschluss befindlichen Dissertation an der Technischen Universität Dresden. Die Finanzierung dieses Vorhabens nahm Vattenfall Europe Nuclear Energy (VENE) GmbH über den Kompetenzverbund Kerntechnik wahr. Innerhalb dieses Projektes wurde die Flüchtigkeit des Bors aus Boratlösungen in Abhängigkeit der Einflussgrößen Borkonzentration, Temperatur, pH-Wert und Volumendampfgehalt aus Zweiphasenströmungen experimentell bestimmt. Aus den Messwerten erfolgte die Ableitung empirischer Funktionen, welche für Simulationsrechnungen mit System-Codes und einfache Abschätzungen nutzbar sind [BoB08].
Keywords: Boreinspeisung am SWR; Zweiphasenströmung; Simulationsrechnung
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Lecture (Conference)
Jahrestagung Kerntechnik 2009, 12.-14.05.2009, Dresden, Deutschland -
Contribution to proceedings
Jahrestagung Kerntechnik 2009, 12.-14.05.2009, Dresden, Deutschland
Tagungsband der Jahrestagung Kerntechnik 2009, paper 311, Berlin: INFORUM GmbH
Permalink: https://www.hzdr.de/publications/Publ-12272
Im Kern - Energie
Weiß, F.-P.; Hurtado, A.
Abstract
Weltweit sind derzeit 439 Kernkraftwerke in Betrieb, in Deutschland waren es noch 17 Anlagen. Diese 17 Anlagen haben im Jahre 2007 22,1% des gesamten in Deutschland erzeugten Stromes geliefert. An der Grundlast macht der Strom aus Kernenergie sogar 45% aus.
Die Bundesregierung hat den Ausstieg aus der Nutzung der Kernenergie zum Zwecke der Stromerzeugung beschlossen, weltweit zeichnet sich jedoch ein erheblicher Ausbau der Kernenergie ab. Im Oktober 2008 waren 36 Anlagen im Bau und 99 weitere in Planung.
Vor diesem Hintergrund geht der Vortrag auf die physikalischen und technischen Grundlagen der friedlichen Nutzung der Kernenergie, der Sicherheitsprinzipien sowie auf die mit dem Betrieb von Kernkraftwerken verbundenen Risiken im Vergleich zu anderen Formen der Stromerzeugung ein. Dabei wird auch der Beitrag der Kernenergie zu CO2-Vermeidung dargestellt. Darüber hinaus werden Aspekte der Brennstoffversorgung, insbesondere der Reichweiter des Urans, und der Abfallentsorgung beleuchtet.
Keywords: Strom aus Kernenergie; Brennstoffversorgung; CO2-Vermeidung; Abfallentsorgung
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Invited lecture (Conferences)
Im Kern - Energie Veranstaltungsreihe der Katholischen Akademie, 11.11.2008, Katholische Akademie Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12271
Impossibility to describe repulsion with contact interaction
Morawetz, K.; Maennel, M.
Abstract
Contact interactions always lead to attractive behaviour. Arguments are presented to show why a repulsive interacting system, e.g. Bose gases, cannot be described by contact interactions and corresponding treatments are possibly obscured by the appearance of bound states.
- Physics Letters A 374(2010), 644-646
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Contribution to WWW
arXiv:0901.3650v1: http://xxx.lanl.gov/PS_cache/arxiv/pdf/0901/0901.3650v1.pdf
Permalink: https://www.hzdr.de/publications/Publ-12270
Application of a step-wise verification and validation procedure to the 3D neutron kinetics code DYN3D within the European NURESIM project
Rohde, U.; Mittag, S.; Grundmann, U.; Petkov, P.; Hadek, J.
Abstract
The generic strategy of core physics codes benchmarking which has been elaborated within the European NURESIM code platform development was applied to benchmarking of the 3D neutron kinetics code DYN3D for applications to VVER-type reactors. Numerical and experimental benchmark problems were considered for code verification and validation.
Mathematical problems with given cross sections are used for the verification of the mathematical methods applied e.g. in nodal codes against finite difference solutions.
After minimisation of numerical errors, modelling errors have to be considered. Diffusion approximation and homogenisation error are due to simplified physical approaches and can be estimated by comparing diffusion solutions with more accurate Monte Carlo or deterministic transport solutions.
A series of 2D whole core benchmarks for different core loadings and operational conditions for VVER-1000 reactors was defined for this purpose. Reference transport solutions were calculated by the MARIKO and APOLLO codes based on Method of Characteristics. Homogenised two-group and few-group diffusion parameters were derived from the reference solutions and used as cross section data for the nodal diffusion code DYN3D. The DYN3D solutions were compared to the reference solution. It was shown that the homogenisation error can be significantly reduced, if Assembly Discontinuity Factors (ADF) and Reference Discontinuity Factors (RDF) which are obtained from the transport solution by applying equivalence theory are used.
A study using the multi-group version of DYN3D has shown that increasing the number of groups in the considered cases has only a small effect in comparison with homogenisation error.
Experimental problems are used for code validation. Experimental data for VVER reactors, which were used for the benchmarking of the DYN3D code within NURESIM, are power distribution measurements at the full-size (VVER-1000) experimental facility V-1000, which have been well documented within the EC project VALCO, and kinetic experiments at the LR-0 zero power reactor in NRI Ře.
The code DYN3D has proved to be an effective tool for steady-state and kinetics core calculations. The high accuracy of the code is based on the advanced nodal method HEXNEM2, multi-group approach, applying discontinuity factors, and intra-nodal flux reconstruction.
Keywords: reactor physics; neutron kinetics; verification; validation; benchmarking; diffusion theory; homogenisation
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Lecture (Conference)
17th International Conference on Nuclear Engineering ICONE17, 12.-17.07.2009, Brussels, Belgium -
Contribution to proceedings
17th International Conference on Nuclear Engineering ICONE-17, 12.-16.07.2009, Brussels, Belgium
CD-ROM paper 75446
Permalink: https://www.hzdr.de/publications/Publ-12269
Switching Ti Valence in SrTiO3 by a dc Electric Field
Leisegang, T.; Stöcker, H.; Levin, A. A.; Weißbach, T.; Zschornak, M.; Gutmann, E.; Rickers, K.; Gemming, S.; Meyer, D. C.
Abstract
A (001) SrTiO3 wafer has been investigated in situ at room temperature under application of a static electric field of varying polarity by the fluorescence X-ray Absorption Near Edge Structure (XANES) analysis at the Sr-K and Ti-K absorption edges. The XANES spectra show a clear shift of the Ti-K absorption edge energy. The shift is attributed to a change of the Ti valence state in a volume invoked by diffusion of the oxygen ions and vacancies. No shift was observed for the Sr-K absorption edge energy. Theoretical calculations support these findings.
Keywords: functional oxide; density-functional; XANES; electric field; strontium titanate
-
Physical Review Letters 102(2009), 087601
DOI: 10.1103/PhysRevLett.102.087601
Cited 43 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12268
On the effect of spatial discretization in integral transport calculations with HELIOS 1.9
Merk, B.; Weiß, F. P.
Abstract
In this study the consequences of the discretization effect is investigated for the full calculation chain starting with the steady state calculation continuing with the burnup calculations and finishing with the evaluation of the safety coefficients. The investigation is based on Mixed Oxide (MOX) Fuel with reactor grade Plutonium. Detailed evaluation of the convergence behavior, the influence of the discretization on the neutron spectrum and the isotopic composition during burnup is given. Finally the influence on the few group cross section preparation and an estimation of the influence of discretization on the safety coefficients is shown.
Keywords: Cell- and Lattice calculation; cross section preparation; HELIOS; Discretization; Burnup calculation; Depletion; Safety coefficients
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Contribution to proceedings
XXI International Conference on Transport Theory, 12.-17.07.2009, Torino, Italy
Permalink: https://www.hzdr.de/publications/Publ-12267
A three scale expansion solution for the Telegraphers equation with external source: development and first application
Merk, B.; Glivici, V.; Weiß, F. P.
Abstract
This work presents a improved onset for the analysis of experiments by the development of an analytical approximation solution for a space-time dependent P1 neutron transport problem in a one dimensional system consisting of homogenized medium with a central external source with Green's functions. The delayed neutron production is implemented in two additional time scales with the multiple scale expansion method. The approximation solutions are developed for the switch off of the source. First applications are shown for the analysis of the YALINA Booster experiment.
Keywords: Time dependet neutron transport; Accelerator driven system; Experimental analysis; Green's funtion expansion; YALINA experiment
-
Contribution to proceedings
XXI International Conference on Transport Theory, 12.-17.07.2009, Torino, Italy -
Lecture (Conference)
XXI International Conference on Transport Theory, 12.-17.07.2009, Torino, Italy
Permalink: https://www.hzdr.de/publications/Publ-12266
ATWS analysis for PWR using the coupled code system DYN3D/ATHLET
Kliem, S.; Mittag, S.; Rohde, U.; Weiß, F.-P.
Abstract
The ATWS transient Loss of main feed water supply in a generic four-loop PWR at the nominal power of 3750 MW was analyzed using the coupled code system DYN3D/ATHLET. A variation of the MOX-fuel-assembly portion in the core has an effect on the reactivity coefficients of the fuel temperature and the moderator density. These two parameters mainly influence the behaviour of the coolant pressure, which is safety-relevant. It has been demonstrated that the pressure maximum decreases with an increasing portion of MOX. For all core loadings considered, both primary-circuit mechanical integrity and sufficient core cooling are guaranteed.
Keywords: reactor safety; MOX, reactivity; temperature-feedback; thermal-hydraulics; transient
-
Annals of Nuclear Energy 36(2009), 1230-1234
DOI: 10.1016/j.anucene.2009.04.001
Cited 13 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12265
Evaluation leistungsbezogener Budgetierungsmodelle
Gilge, B.; Joehnk, P.
Abstract
Wird die an öffentlich finanzierten außeruniversitären Forschungseinrichtungen zunehmend wichtiger werdende Programmbudgetierung durch eine leistungsbezogene Budgetierung ergänzt, kann die durch das Neue Steuerungsmodell geforderte Wirkungsorientierung der Ressourcenallokation forciert werden. Darüber hinaus ermöglicht die Übernahme von Kriterien der externen Evaluierung in die budgetierungsrelevanten Leistungsindikatoren eine Verknüpfung zwischen externen Anforderungen der Träger der Einrichtungen und internen Leistungsanreizen. Mit dem vorliegenden Beitrag wird eine Evaluationskonzeption vorgestellt, mit welcher das leistungsbezogene Budgetierungsmodell einer öffentlich finanzierten außeruniversitären Forschungseinrichtung bewertet sowie verbessert werden kann.
- Wissenschaftsmanagement 4(2008), 12-19
Permalink: https://www.hzdr.de/publications/Publ-12264
Preparatory Grants for Collaboratory European Research Projects
Joehnk, P.
-
Lecture (Conference)
Bioingteh - The exploratory Workshop on Advanced Materials & Technologies in Biology and Medicine, 18.-20.09.2008, Poiana Brasov, Romania
Permalink: https://www.hzdr.de/publications/Publ-12263
High-resolution hydrogen profiling in AlGaN/GaN heterostructures grown by different epitaxial methods
González-Posada Flores, F.; Redondo-Cubero, A.; Gago, R.; Bengoechea, A.; Jiménez, A.; Grambole, D.; Braña, A. F.; Muñoz, E.
Abstract
Hydrogen (H) incorporation into AlGaN/GaN heterostructures used in high electron mobility transistors, grown by different methods, is studied by high-resolution depth profiling. Samples grown on sapphire and Si(1 1 1) substrates by molecular-beam epitaxy and metalorganic vapour phase epitaxy; involving H-free and H-containing precursors, were analysed to evaluate the eventual incorporation of H into the wafer. The amount of H was measured by means of nuclear reaction analysis (NRA) using the 1H(15N,αγ )12C reaction up to a depth of ∼110 nm into the heterostructures. Interestingly, the H profiles are similar in all the samples analysed, with an increasing H content towards the surface and a negligible H incorporation into the GaN layer (0.24 ± 0.08 at%) or at the AlGaN/GaN interface. Therefore, NRA shows that H uptake is not related to the growth process or technique employed and that H contamination may be due to external sources after growth. The eventual correlation between topographical defects on the AlGaN surface and the H concentration are also discussed. (Some figures in this article are in colour only in the electronic version)
Keywords: PACS: GaN; AlGaN; Hydrogen; NRA; HEMT; AFM; MOCVD; MBE
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Journal of Physics D: Applied Physics 42(2009), 055406
DOI: 10.1088/0022-3727/42/5/055406
Permalink: https://www.hzdr.de/publications/Publ-12262
Experimental studies and CFD calculations for buoyancy driven mixing phenomena
Da Silva, M. J.; Thiele, S.; Höhne, T.; Vaibar, R.; Hampel, U.
Abstract
In nuclear reactor safety the mixing of borated and deborated water is a critical issue that needs investigation, assessment and prediction. Such mixing is buoyancy driven and numerical codes must correctly model momentum transfer between components of different density. To assess and develop CFD models for buoyancy driven mixing we set up a simple vertical mixing test facility (VeMix) and equipped it with a newly developed planar electrical imaging sensor. This imaging sensor acquires conductivity images of the liquid at the rear channel wall with a speed of 2,500 frames per second. By adding NaCl tracer to the denser component we were able to visualize the mixing process in high spatial and temporal detail. Furthermore, an image processing algorithm based on the optical flow concept was implemented and tested which allows the measurement of flow pattern velocities. Selected experiments at different Richardson numbers were run with two components of different density (pure water and glucose-water mixture) simulating borated and deborated water in a light water reactor scenario. These experiments were compared to CFD calculations using standard turbulence models. Good agreement between experimental data and first CFD simulations was found.
Keywords: buoyancy driven flow; mixing; deborated water; flow visualization; CFD; simulation; planar array sensor
- Nuclear Engineering and Design 240(2010)9, 2185-2193
Permalink: https://www.hzdr.de/publications/Publ-12261
Collisional Energy Loss: A Welcoming Component for Jet Quenching Phenomenology in Heavy-Ion Collisions
Mustafa, M.
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Lecture (others)
Universität Gießen, 10.09.2008, Gießen, Deutschland -
Lecture (others)
Seminar am Max-Planck-Institut fuer extraterrestrische Physik, 11.09.2008, Garching, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12260
Strongly Coupled QGP - Equation of State
Bluhm, M.
-
Lecture (Conference)
Workshop of the European Network SIM, 08.-12.09.2008, Villasimius, Italien
Permalink: https://www.hzdr.de/publications/Publ-12259
Nuclear data needs for transmutation of nuclear waste
Ignatyuk, A.
-
Lecture (others)
Seminar FWK, 10.04.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12258
Quantal Rotation: Molecular view on nuclei
Frauendorf, S.
-
Lecture (others)
Seminar FWK, 30.04.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12257
Exotic modes of rotation
Frauendorf, S.
-
Lecture (others)
Seminar FWK, 04.06.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12256
Raman Spectrometer for monitoring Isotope Exchange Reactions and Energy Transfer in Low Temperature Plasmas
Borysow, J.
Abstract
One of the major elements in tritium processing systems is hydrogen isotopes identification and separation. Work with multiple hydrogen isotopes at the is often accompanied by isotopic mixing. Maintaining isotopic purity of tritium is one of the major tasks in new generation Texas Neutrino Mass Experiment (NEXTEX). We developed unique Raman Spectrometer capable of detecting hydrogen isotopes T2, HT, H2, D2, TD and H2 at pressures near 10 Pa with signal-to-noise ratio better than 2 during minutes long observations. This spectrometer is capable of distinguishing traces of numerous isotopomers at partial concentration as low as 1:4000 and can be also used as a medical diagnostic tool. Additionally I will discuss some aspect of our Coherent Raman Spectrometer and its ability to measure molecular kinetics in low temperatures plasmas.
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Lecture (others)
Seminar Institut für Strahlenphysik, 01.07.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12255
Ultra-sensitive in-beam g-ray spectroscopy deep underground
Caciolli, A.
Abstract
Ultra-sensitive in-beam γ-ray spectroscopy studies for nuclear astrophysics are performed at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400 kV accelerator, deep underground in Italy's Gran Sasso laboratory. By virtue of a specially constructed passive shield, the laboratory γ-ray background for Eγ < 3 MeV at LUNA has been reduced to levels comparable to those experienced in dedicated offline underground γ-counting setups. The γ-ray background induced by
an incident α-beam has been studied. The data are used to evaluate the feasibility of sensitive inbeam experiments at LUNA and, by extension, at similar proposed facilities.
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Lecture (others)
Seminar Institut für Strahlenphysik, 05.08.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12254
Influence of system and neutron-kinetic parameter variations on an anticipated transient without SCRAM in a PWR
Kliem, S.; Mittag, S.; Rohde, U.; Weiß, F.-P.
Abstract
The complete failure of the reactor scram system upon request during an operational transient is called anticipated transient without scram (ATWS). According to the German regulatory guidelines, postulated ATWS events have to be analyzed with regard to their consequences on the safety of nuclear power plants.
Since the course of ATWS transients is determined by a strong interaction of the neutron kinetics with the thermal hydraulics of the system, coupled 3D neutron kinetic/thermal hydraulic code systems are adequate tools for the analysis of such transients. The coupled code system DYN3D/ATHLET developed at FZD is applied to the analysis of an ATWS transient. The objective of the present work is to perform a best-estimate analysis with consequent use of a 3D neutron kinetic code (DYN3D) in combination with an advanced thermal hydraulic system code (ATHLET) together with a quantification of differences in the course and the results of transients, which arise from the uncertainties of thermal hydraulic and neutron-physical conditions.
Typically, the complete failure of the main feed water supply is assumed to be the bounding ATWS event with regard to the maximum primary coolant pressure, which can be reached during the transient. The limitation of the coolant pressure is a pre-condition for the integrity of the primary circuit. The situation is aggravated if the main coolant pumps remain in operation.
For this particular transient, the influence of different thermal hydraulic and neutron-physical conditions on the course of the transient was analyzed.
In a number of code runs all systems which have an influence on the course of the transient were varied. These are the auxiliary boration system and the auxiliary feed water supply. Further, the influence of the modeling of the pressurizer safety and relief valves as well as the steam bypass system on the secondary side was assessed. The variation of the pressurizer relief and safety valve behavior has the biggest influence on the primary circuit coolant pressure.
In the second part, two different core loading patterns were generated for the analyses by varying the number of MOX (mixed oxide) fuel assemblies (FA) in the core. The basic core loading contains 64 MOX FA. All these MOX FA were replaced by standard uranium oxide FA. The presence of MOX in the core has a remarkable influence on the reactivity coefficients of the fuel temperature and the moderator density. These two parameters mainly influence the behavior of the coolant pressure in the first part of the transient. It has been demonstrated that the pressure maximum decreases with growing MOX portion in the core.
The maximum pressure determined in the calculations with variation of system and neutron-physical boundary conditions does not reach the allowed limit for the primary circuit.
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Contribution to proceedings
17th International Conference on Nuclear Engineering, 12.-16.07.2009, Brussels, Belgium
Proceedings of the 17th International Conference on Nuclear Engineering, CDROM, paper 75569: ASME -
Lecture (Conference)
17th International Conference on Nuclear Engineering, 12.-16.07.2009, Brussels, Belgium
Permalink: https://www.hzdr.de/publications/Publ-12253
Instantaneous Shape Sampling for Calculation of the Electromagnetic Dipole Strength
Zhang, S.
Abstract
Electromagnetic dipole absorption cross-sections of transitional nuclei with large-amplitude shape fluctuations are calculated in a microscopic way by introducing the concept of Instantaneous Shape Sampling, which is based on the slow shape dynamics as compared to the dipole vibrations. The dipole strength is calculated by means of RPA for the instantaneous shapes, the probability of which is obtained by means of IBA-1. Very good agreement with the experimental absorption cross sections near the nucleon emission threshold is obtained. The dipole strength in this energy region is controlled by the Landau fragmentation.
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Lecture (others)
Seminar Institut für Strahlenphysik, 11.08.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12252
Radiation of electromagnetically and strongly interacting plasmas
Mustafa, M.
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Lecture (others)
Seminar Institut für Strahlenphysik, 05.09.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12251
Photoneutron measurement of Se-80, La-139: implications for the nucleosynthesis
Makinaga, A.
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Lecture (others)
Seminar Institut für Strahlenphysik, 08.09.2008, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12249
phi production in hadronic processes and phi mesons in nuclear matter
Kämpfer, B.
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Invited lecture (Conferences)
Donnersberg Workshop 2008 - A1 Collaboration, 31.03.-03.04.2008, Donnersberg, Germany
Permalink: https://www.hzdr.de/publications/Publ-12248
Bremsstrahlung
Kämpfer, B.
Abstract
Hadron masses; If we would have a theory; Modelling, parametrizing, guessing
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Lecture (Conference)
HADES Collaboration Meeting XIX, 05.07.2008, Darmstadt, Deutschland -
Lecture (others)
Seminar an der TU München, 28.01.208, München, Deutschland -
Lecture (Conference)
Workshop on Virtual Bremsstrahlung and HADES, 12.08.2009, Frankfurt am Main, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12247
eta, eta' meson production in NN collisions
Kämpfer, B.
Abstract
eta, eta' meson production in NN collisions
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Lecture (Conference)
Symposium on Meson Physics, 01.-04.10.2008, Krakow, Poland
Permalink: https://www.hzdr.de/publications/Publ-12246
Equation of state above T_c
Kämpfer, B.
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Invited lecture (Conferences)
Erice School on Nuclear Physics, 20.-25.09.2008, Erice, Italy
Permalink: https://www.hzdr.de/publications/Publ-12245
Hot 1-2 Loop QCD
Kämpfer, B.
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Invited lecture (Conferences)
Workshop of the European SIM Network, 08.-12.09.2008, Villasimius, Italy
Permalink: https://www.hzdr.de/publications/Publ-12244
Chiral Symmetry and Medium-Modifications of Hadrons
Kämpfer, B.
Abstract
Chiral Symmetry and Medium-Modifications of Hadrons
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Lecture (Conference)
Hot and Dense Matter: the next few years, 17.11.2008, Rehovot, Israel
Permalink: https://www.hzdr.de/publications/Publ-12243
Medium-Modifications of Hadrons
Kämpfer, B.
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Invited lecture (Conferences)
International Symposium on Heavy Ion Physics 2008 (ISHIP2008), 17.-20.11.2008, Darmstadt, Germany
Permalink: https://www.hzdr.de/publications/Publ-12242
Naturwissenschaftliches Arbeiten am Forschungszentrum Dresden-Rossendorf.
Bussmann, M.
Abstract
Der Vortrag soll Schülern einen Einblick in die Arbeit eines Naturwissenschaftlers geben und Ihnen helfen, sich für Ihr anstehendes Studium zu orientieren.
Keywords: physics; natural science; work; student; pupil; school
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Lecture (others)
Podiumsdiskussion des Gymnasiums Radeberg, 24.11.2008, Radeberg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12241
Lasers and Particle Beams - From the Ultracold to the Ultrafast
Bussmann, M.
Abstract
The Creation and Manipulation of Particle Beams using Lasers opens new Paths towards compact, ultrabright Radiation Sources. With the advent of high-intensity, ultrashort Laser Sources it has become possible to accelerate Electrons and Ions with table top Laser Systems in the Laboratory. Moreover, Lasers can be used to cool Ion Beams to millikelvin Temperatures. In my talk I will focus on the Study of Laser-Matter Interaction by realistic large-scale Particle Simulations which can give insight into the complex Plasma Phenomena leading to the Creation of ultrabrilliant Particle Beams. I will introduce the numerical Methods used in these Computer Experiments and draw the Connection towards recent and future Experiments planned at FZD and GSI.
Keywords: laser acceleration; electron beam; ion beam; laser cooling; molecular dynamics; simulation; strong coupling; plasma; highly charged ions; particle-in-cell; md; pic
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Invited lecture (Conferences)
Seminar "Materialwissenschaft/Materials Science", 16.09.2008, Dresden Rossendorf, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12240
Kompakte Laserbeschleuniger und ihre Anwendungen
Bussmann, M.
Abstract
In diesem Vortrag werden die Prinzipien der Laserteilchenbeschleunigung sowie wichtige Anwendungen der dabei erzeugten Teilchenstrahlen vorgestellt.
Keywords: laser; particle; acceleration
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Lecture (others)
FZD-Vortrag für Besucher des Abendgymnasiums Bautzen, 08.07.2008, Dresden Rossendorf, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12239
Thermal and Chemical Freeze-out in Spectator Fragmentation
Trautmann, W.; Bassini, R.; Begemann-Blaich, M.; Ferrero, A.; Fritz, S.; Gaff-Ejakov, S. J.; Groß, C.; Imme, G.; Iori, I.; Kleinevoß, U.; Kunde, G. J.; Kunze, W. D.; Le Fevre, A.; Lindenstruth, V.; Lukasik, J.; Lynen, U.; Maddalena, V.; Mahi, M.; Möhlenkamp, T.; Moroni, A.; Müller, W. F. J.; Nociforo, C.; Ocker, B.; Odeh, T.; Orth, H.; Petruzzelli, F.; Pochodzalla, J.; Raciti, G.; Riccobene, G.; Romano, F. P.; Rubehn, T.; Saija, A.; Sann, H.; Schnittker, M.; Schüttauf, A.; Schwarz, C.; Seidel, W.; Serfling, V.; Sfienti, C.; Trzcinski, A.; Tucholski, A.; Verde, G.; Wörner, A.; Hongfei, X.; Zwieglinski, B.
Abstract
Isotope temperatures from double ratios of hydrogen, helium, lithium, beryllium, and carbon isotopic yields, and excited-state temperatures from yield ratios of particle-unstable resonances in 4He, 5Li, and 8Be, were determined for spectator fragmentation, following collisions of 197Au with targets ranging from C to Au at incident energies of 600 and 1000 MeV per nucleon. A deviation of the isotopic from the excited-state temperatures is observed which coincides with the transition from residue formation to multi-fragment production, suggesting a chemical freeze-out prior to thermal freeze-out in bulk disintegrations.
- Physical Review C 76(2007), 064606
Permalink: https://www.hzdr.de/publications/Publ-12238
Nuclear Astrophysics with real photons at ELBE
Nair, C.; Junghans, A. R.; Erhard, M.; Bemmerer, D.; Beyer, R.; Grosse, E.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.
Abstract
The neutron deficient p-nuclei thought to be produced in explosive stellar environments through chains of photodisintegration reactions on heavy seed nuclei. The modelling of the nucleosynthesis for the p-nuclei is mainly based on statistical model calculations and the knowledge of the experimental cross sections for the prediction of the p-nuclei abundances is of crucial importance. To forward in this direction we have started and experimental program at the bremsstrahlung facility of the superconducting electron accelerator ELBE of FZ Dresden-Rossendorf . Photodisintegration measurements on the astrophysically relevant p-nuclei 92Mo and 144Sm have been performed via photoactivation technique with bremsstrahlung end-point energies from 10.0 to 16.5 MeV. In particular the (gamma,alpha) reactions of the mentioned nuclei were studied for the first time at different endpoint energies above and close to the threshold. The activation yields from all measurements are compared with calculations using cross sections from recent Hauser-Feshbach models .
Keywords: p-nuclei; photoactivation; bremsstrahlung
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Invited lecture (Conferences)
Seminar at the National Superconducting Cyclotron Laboratory, Michigan State University as a JINA (Joint Institute of Nuclear Astrophysics) visitor, 04.08.2008, Michigan, United States of America
Permalink: https://www.hzdr.de/publications/Publ-12237
Photoactivation studies on astrophysically relevant nuclei: measuring techniques for activated samples
Nair, C.; Junghans, A. R.; Erhard, M.; Bemmerer, D.; Degering, D.; Beyer, R.; Grosse, E.; Koehler, M.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Wagner, A.; Schwengner, R.
Abstract
For studying the neutron deficient p-nuclei experimentally, we have started and experimental program at the bremsstrahlung facility of the superconducting electron accelerator ELBE of FZ Dresden-Rossendorf . Photodisintegration measurements on the astrophysically relevant p-nuclei 92Mo and 144Sm have been performed via photoactivation technique with bremsstrahlung end-point energies from 10.0 to 16.5 MeV. In particular the (gamma,alpha) reactions of the mentioned nuclei were studied for the first time at different endpoint energies above and close to the threshold. The activation yields from all measurements are compared with calculations using cross sections from recent Hauser-Feshbach models. The radioactive decay of irradiated targets with very low counting statistics was studied at the low-background underground laboratory "Felsenkeller" in Dresden.
Keywords: photoactivation; p-nuclei; underground laboratory 'felsenkeller'
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Poster
IEEE Nuclear Science Symposium, 20.-24.10.2008, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-12236
Experimental and numerical investigations of natural circulation phenomena in passive safety systems for decay heat removal in large pools
Krepper, E.; Beyer, M.
Abstract
Modern concepts of nuclear power reactor systems are equipped with passive systems for decay heat removal. Examples are the pool of the emergency condenser (BWR-1000) or the pool of the ESBWR. These systems operate without active influence from outside. The questions arise: How reliable are the based physical mechanisms? Are they understood completely? Are actual models able to describe the phenomena?
In different passive systems the energy is transferred by natural circulation into large pools which are considered as infinite heat sink. The paper deals with experiments and with CFD simulations to investigate the capability of actual CFD codes to describe these phenomena. In the FZ Dresden-Rossendorf at the facility TOPFLOW heating up tests of an emergency condenser were performed. During these tests also the temperature courses on the secondary side of the pool were recorded. The data recording comprises periods starting from single phase liquid until steam on the secondary pool side was found. During these experiments temperature stratification phenomena were observed, which were found in earlier small scale tests. In the paper also these small scale experiments are described. A detailed CFD analysis of these experiments was performed. An explanation of the observed phenomena on the basis of the small scale tests and the CFD simulations is presented.
Keywords: Passive safety systems; Experiments; CFD; natural circulation
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Contribution to proceedings
17th International Conference on Nuclear Engineering, ICONE-17, 12.-16.07.2009, Brussels, Belgium -
Lecture (Conference)
17th International Conference on Nuclear Engineering, ICONE-17, 12.-16.07.2009, Brussels, Belgium -
Nuclear Engineering and Design 240(2010), 3170-3177
DOI: 10.1016/j.nucengdes.2010.05.050
ISSN: 0029-5493
Cited 45 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12235
Surfing the plasma wake - particle acceleration with laser light
Schramm, U.
Abstract
Modern short-pulse high-power lasers can, for a few optical cycles, generate electrical field strengths strong enough to accelerate electrons to relativistic energies. Rectifying these fields by means of a laser plasma can lead to acceleration gradients that exceed conventional rf-based technology by many orders of magnitude. Recent results in this field will be discussed as well as potential applications of laser accelerated particle pulses.
Keywords: laser plasma acceleration
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Invited lecture (Conferences)
Tata Institute of Fundamental Research, Institute Seminar, 12.1.2009, Mumbai, India -
Invited lecture (Conferences)
Institute of plasma research, Seminar, 13.1.2009, Ahmenabad, India
Permalink: https://www.hzdr.de/publications/Publ-12234
Prospects of high intensity laser driven radiation sources
Schramm, U.
Abstract
Recent development in table-top high-power lasers of the 100 Terawatt class combined with an improved understanding of relativistic laser matter interaction now allows for the discussion of applications of laser accelerated particle beams and secondary radiation sources. In this presentation, an introduction covering the underlying mechanisms will be given followed by a presentation of the novel combined laser-accelerator facility at FZD and its goals as, e.g., laser driven proton oncology.
Keywords: laser particle acceleration; secondary sources
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Invited lecture (Conferences)
Eighth DAE-BRNS National Laser Symposium (NLS-08), 07.-10.1.2009, Delhi, India -
Invited lecture (Conferences)
Lecture Laser and Neutron Physics Section of BARC, 14.1.2009, Mumbai, India
Permalink: https://www.hzdr.de/publications/Publ-12233
Structural investigations of ZnO thin films grown by reactive pulsed magnetron sputtering at different substrate temperatures
Redondo-Cubero, A.; Vinnichenko, M.; Krause, M.; Gago, R.
Abstract
Zinc oxide (ZnO) is a promising material for electronic and optical applications [1]. As in the case of other wide bandgap compounds (i.e. GaN) grown in heteroepitaxy conditions, the final electrical properties of the film are affected by its crystal quality. Rutherford backscattering spectrometry (RBS) in channeling mode (RBS/C) is a well proved method to obtain this physical information in such structures, with the additional advantage of in-depth information [2]. In this work, we report RBS/C and Raman characterization of ZnO thin films grown onto (0001) oriented sapphire [3] by reactive pulsed magnetron sputtering at substrate temperatures (Ts) spanning from 22ºC to 550ºC .
Random and RBS/C measurements were performed along the and axes of the wurtzite lattice (P63mc) of ZnO [1] with a 3.035 MeV He+ beam. The sample position was controlled by a 3-axis goniometer. The micro-Raman spectra were collected at an excitation wavelength of 532 nm. The influence of substrate temperature onto low- and high-frequency E2 modes of the resulting film was monitored. The low-frequency E2 mode is associated with the vibration of the heavy Zn sublattice, while the high-frequency E2 mode involves only the oxygen atoms.
Stoichiometry of the oxide layer was determined from the random RBS spectra, which showed a constant composition except for an O-rich interface (associated with Zn in-diffusion). RBS/C angular scans along the axis revealed a progressive enhancement of crystal quality of wurtzite ZnO with substrate temperature, with a <0001> textured growth even for low substrate temperatures (100ºC). The film crystallinity is greatly increased for substrate temperatures above 400ºC, a behaviour also confirmed by Raman measurements. The latter shows significant decrease of the line width which in the case of low-frequency E2 mode at Ts>400 °C approaches and even becomes smaller than the values of reference single crystal sample. Also, the Raman peak positions do not change for the films grown at temperatures above 400°C. Further RBS/C analysis along the oblique axis was carried out to determine the possible influence of strain. The angular scan showed no-shift among different ZnO depths, revealing a non-strained film under the technique limits. From these measurements, it can be concluded that epitaxial ZnO films can be grown by pulsed reactive magnetron sputtering without appreciable strain on sapphire substrates at Ts ~550ºC.
References:
1. Ü. Özgür, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Dogan, V. Avrutin, S.-J. Cho, and H. Morkoc, J. Appl. Phys. 98, 041301 (2005).
2. L.C. Feldman, J.W. Mayer and S.T. Picraux, Material analysis by ion channeling, NY, Academic Press (1982).
3. M. Vinnichenko, N. Shevchenko, A. Rogozin, R. Grötzschel, A. Mücklich, A. Kolitsch and W. Möller, J. Appl. Phys. 102, 113505 (2007)
Keywords: ZnO; epitaxial growth; reactive pulsed magnetron sputtering
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Poster
Charged and neutral particles channeling phenomena (Channeling 2008), 25.10.-01.11.2008, Erice, Italy
Permalink: https://www.hzdr.de/publications/Publ-12232
Experiments on nuclear rotation
Schwengner, R.
Keywords: Nuclear structure; gamma-ray spectroscopy; collective rotation; magnetic rotation; cranking model; shell model
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Lecture (others)
Institutsseminar des Instituts für Strahlenphysik, 20.08.2008, Dresden-Rossendorf, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-12231
Flavonoids organic compounds with strong interactions towards uranium
Geipel, G.; Viehweger, K.; Bernhard, G.
Abstract
Flavonoids belong to a class of secondary plant metabolites. They are most commonly known for their antioxidant activity. Next to chlorophyll flavonoids are the most important group of visible plant pigments.
We studied by use of spectrophotometric techniques the interaction of several flavonoids with uranium. The change in the spectral properties of the flavonoids was used to determine the stability constants. Spectra were evaluated with the factor analysis program Specfit. All spectra of flavonoids show strong change with increasing uranium concentration at constant pH. Stability constants were derived for quercetin, hesperetin, hesperidin, the aglycon of hesperetin. Hesperetin was obtained by hydrolytic splitting of the glycoside hesperidin.
The overall structure Isosbestic points in the absorption spectra indicate a clear interaction between the flavonoids and uranium(VI).
The most strong interaction was found for quercetin. The derived stability constant was assigned to be log β131 = 41.4 ± 0.4 at an ionic strength of 0.1 M for the reaction
UO22+ + C15H5O75- + 3 H+ → UO2C15H8O7 (1)
Hesperidin and hesperetin show much lower stability constants. For example the stability constant for the hesperetin complex at 0.1 M ionic strength was determined to be log β121 = 31.0 ± 0.6.
We assume that the complex formation occur by a ring formation, whereas quercitin forms a 6-membered ring between a phenolic group and the ketone oxygen in the benzopyran-4-one ring whereas hesperidin and hesperetin form 5-membered rings.
Keywords: Uranium; Flavonoids
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Lecture (Conference)
Actinides 2009, 12.-17.07.2009, San Francisco, USA
Permalink: https://www.hzdr.de/publications/Publ-12230
An U accumulating plant a suitable tool for remediation?
Viehweger, K.; Geipel, G.; Bernhard, G.
Abstract
Abstract. Large areas were disturbed in the southern Erzgebirge, Germany, due to former uranium mining activities. Great efforts were done for the remediation and restoration during the last decade. Nevertheless there are some small areas, which are not yet rehabilitated and therefore possess exalted uranium soil contents.
The first step was the evaluation of different former U mining sites. Reconstructed areas contain considerable less amounts of U compared with a leaved stock pile near Johanngeorgenstadt. To get more reliable data on the bioavailability of U in this distinct soil, a sequential chemical soil fractionation procedure was accomplished. The bioavailable U were recovered from the first 3 extraction steps (~ 30 mg*Kg-1).
Fortunately we could identify the well known heavy metal hyperaccumulator Arabidopsis halleri (also known as Cardaminopsis halleri) in this U contaminated area. A basic tool for the characterisation of metal mobility within the soil-plant system is the soil-to-plant transfer factor or accumulation factor. Arabidopsis plants growing on the mining dump achieved accumulation factors around 2.6 for roots and 1.1 for shoots, respectively.
To get more insight in mechanisms underlying plant U uptake and accumulation, a hydroponic grow system under laboratory conditions was developed. The accumulation factors in this system were around 1670 for roots and 625 for shoots. It is obvious that U is clear more bioavailable for plants in hydroponic solution than in the soil from the former mining side.
Despite this enormous U accumulation it is mandatory to evaluate the U tolerance and toxicity under hydroponic conditions. The classical root-elongation test was used for estimation of the tolerance index (TI). Plants growing permanent with U could increase their TI within 7 weeks. Nevertheless U had a negative impact on the plant fitness indicated by a significant decrease of chlorophyll a/b ratio during the growth period. Additionally, spectroscopic measurements of leaves and chlorophyll extracts revealed some disturbances of chlorophyll biosynthesis and proper function of photosystem I, respectively.
We could identify a U accumulating plant, which is able to take up enormous amounts of U in hydroponic solution. To make this plant suitable for remediation processes it is crucial getting a deeper insight in uptake, sequestration and U tolerance pathways. The described hydroponic system could be useful tool for this purpose.
Keywords: Plants; uranium
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Lecture (Conference)
Actinides 2009, 12.-17.07.2009, San Francisco, USA
Permalink: https://www.hzdr.de/publications/Publ-12229
Dipole strength in 89Y and 90Zr up to the neutron-separation energy
Schwengner, R.
Keywords: Nuclear structure; nuclear spectroscopy; photon scattering; gamma-ray strength functions; photoabsorption cross section; random-phase approximation
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Lecture (Conference)
DPG Frühjahrstagung, 10.-14.03.2008, Darmstadt, Germany
Permalink: https://www.hzdr.de/publications/Publ-12228
Strength-function measurements
Schwengner, R.
Keywords: Nuclear structure; gamma-ray spectroscopy; photon scattering; strength functions; absorption cross sections; random-phase approximation
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Lecture (Conference)
Workshop on Modern Methods Using Fast Neutrons for Research Related to the Transmutation of Nuclear Waste, 13.-15.02.2008, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-12227
NeuLAND MRPC Prototype construction and testing at Electron Linear Accelerator (ELBE)
Bemmerer, D.; Yakorev, D.; Stach, D.; Wagner, A.
Abstract
Different prototypes of Multigap resistive plate chamber detector (MRPC) for the future NeuLAND detector were built and tested at the ELBE electron beam in FZD. Results and future plans are discussed.
Keywords: MRPC; RPC; Multigap resistive plate chamber; Resistive plate chamber; NeuLAND; FAIR; gas chamber; ELBE
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Lecture (Conference)
NeuLAND Working Group Meeting, 24.-26.09.2008, Sinaia, Romania
Permalink: https://www.hzdr.de/publications/Publ-12226
Room-temperature ferromagneticlike behavior in Mn-implanted and postannealed InAs layers deposited by Molecular Beam Epitaxy
González-Arrabal, R.; González, Y.; González, L.; García-Hernández, M.; Munnik, F.; Martín-González, M. S.
Abstract
We report on the magnetic and structural properties of Ar- and Mn-implanted InAs epitaxial films grown on GaAs (100) by Molecular Beam Epitaxy (MBE) and the effect of Rapid Thermal Annealing (RTA) for 30 s at 750 °C. Channelling Particle Induced X- ray Emission (PIXE) experiments reveal that after Mn implantation almost all Mn atoms are subsbtitutional in the In site of the InAs lattice, like in a diluted magnetic semiconductor (DMS). All of these samples show diamagnetic behavior. However, after RTA treatment the MnInAs films exhibit room-temperature magnetism. According to PIXE measurements the Mn atoms are no longer substitutional. When the same set of experiments was performed with Ar as implantation ion, all of the layers present diamagnetism without exception. This indicates that the appearance of room-temperature ferromagneticlike behavior in the MnInAs-RTA layer is not related to lattice disorder produced during implantation but to a Mn reaction produced after a short thermal treatment. X-ray diffraction patterns and Rutherford backscattering measurements evidence the segregation of an oxygen-deficient MnO2 phase (nominally MnO1.94) in the MnInAs-RTA epitaxial layers which might be the origin of the room-temperature ferromagneticlike response observed.
Keywords: DMS; InMnAs; room temperature magnetism; PIXE; implantation; III-V semiconductors
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Journal of Applied Physics 105(2009), 073911-1-073911-6
DOI: 10.1063/1.3087477
Cited 2 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-12225
Fast Digitizing and Digital Signal Processing of Detector Signals
Hannaske, R.
Abstract
A fast-digitizer data acquisition system recently installed at the neutron time-of-flight experiment nELBE, which is located at the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf, is tested with two different detector types. Preamplifier signals from a high-purity germanium detector are digitized, stored and finally processed. For a precise determination of the energy of the detected radiation, the moving-window deconvolution algorithm is used to compensate the ballistic deficit and different shaping algorithms are applied. The energy resolution is determined in an experiment with γ-rays from a 22Na source and is compared to the energy resolution achieved with analogously processed signals. On the other hand, signals from the photomultipliers of barium fluoride and plastic scintillation detectors are digitized. These signals have risetimes of a few nanoseconds only. The moment of interaction of the radiation with the detector is determined by methods of digital signal processing. Therefore, different timing algorithms are implemented and tested with data from an experiment at nELBE. The time resolutions achieved with these algorithms are compared to each other as well as to reference values coming from analog signal processing. In addition to these experiments, some properties of the digitizing hardware are measured and a program for the analysis of stored, digitized data is developed. The analysis of the signals shows that the energy resolution achieved with the 10-bit digitizer system used here is not competitive to a 14-bit peak-sensing ADC, although the ballistic deficit can be fully corrected. However, digital methods give better result in sub-ns timing than analog signal processing.
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Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; FZD-510 2009
ISSN: 1437-322X -
Poster
Graduate Students Seminars, 27.-29.08.2008, Limbach-Oberfrohna, Deutschland -
Lecture (others)
IKTP Institutsseminar, 20.11.2008, Dresden, Deutschland
Downloads
Permalink: https://www.hzdr.de/publications/Publ-12224
Years: 2024 2023 2022 2021 2020 2019 2018 2017 2016
Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.] [351.] [352.] [353.] [354.] [355.] [356.] [357.] [358.] [359.] [360.] [361.] [362.] [363.] [364.] [365.] [366.] [367.] [368.]