Filters
Results 1 - 10 of 710
Results 1 - 10 of 710.
Search took: 0.022 seconds
| Sort by: date | relevance |
[en] Published in summary form only
Journal
[en] Emission of spallation products with mass numbers A=147-173 from tantalum targets irradiated by 660 MeV protons has been investigated. Cascade-evaporation model calculations are compared to experimental results and data for smaller energies and various targets. Calculations are in agreement with experiments. Relations allowing to estimate the 'practical range' of neutron deficient nuclides in thick targets have been obtained. (orig.)
[de]
Untersucht wurde die Emission von Spallationsprodukten mit den Massenzahlen A=147-173 aus Tantaltargets bei der Bestrahlung mit 660 MeV Protonen. Berechnungen nach einem Kaskaden-Verdampfungsmodell wurden verglichen mit experimentellen Ergebnissen und Literaturwerten fuer andere Protonenenergien und Targets und ergeben eine gute Uebereinstimmung. Gefunden wurden einfache Beziehungen zur Abschaetzung kinetischer Energien und 'praktischer Reichweiten' fuer neutronendefizite Nuklide aus dicken Targets. (orig.)Journal
[en] The phytotoxicity as well as the fate of dinobuton and dinobutonmethyl in bean and cucumber plants and in apple fruits was investigated. Dinobutonmethyl is more phytotoxic than dinobuton. Generally, dinobuton and dinobutonmethyl behave similarly after application on the apple surface and also after treatment of the leaves of bean and cucumber plants. After 3 to 5 days only about 50% of the applied radioactivity were found on the surface of the systems. Probably dinobuton and dinobutonmethyl as well as dinoseb as hydrolysis product are able to leave the plant systems unchanged. (orig.)
[de]
Die Phytotoxizitaet sowie auch das Schicksal von Dinobuton und Dinobutonmethyl wird in Bohnen- und Gurkenpflanzen und in Apfelfruechten untersucht. Dinobutonmethyl ist phytotoxischer als Dinobuton. Allgemein verhalten sich Dinobuton und Dinobutonmethyl aehnlich nach Anwendung auf die Apfeloberflaeche und auf die Blaetter von Bohnen- und Gurkenpflanzen. Nach 3-5 Tagen werden nur etwa 50% der angewendeten Radioaktivitaet auf der Oberflaeche der Systeme gefunden. Wahrscheinlich vermag Dinobuton und Dinobutonmethyl wie auch Dinoseb als Hydrolyseprodukt die Pflanzensysteme unveraendert zu verlassen. (orig.)Journal
[en] The discovery and the chemistry of neptunium is described. Improvements in redox reactions, analytical determinations and environmental research work are discussed. (orig.)
[de]
Es wird die Entdeckung des Neptuniums und seine Chemie in Loesungen beschrieben. Dabei werden Entwicklungstendenzen bei Redoxreaktionen, in der analytischen Bestimmung und dem Umweltverhalten diskutiert. (orig.)Journal
[en] The paper reports on the results of 210Pb measurement in sediment cores from the Baltic Sea. The models used for the interpretation are derived and discussed. In general, the sedimentation parameters calculated with different models are consistent. However, parameters of cores independently taken on same partly show clearly differing values. The reasons of this observation have to be analysed by further studies. An essential problem considered in this paper is the dating of disturbed sediments. The use of such cores for the reconstruction of the input history of chemical indicators requires a deconvolution of data. The response function necessary for this procedure can be derived from 210Pb measurements. The results of such a reconstruction considerably differ from those obtained by conventional dating models. The analysis of the measuring uncertainty of the indicator (e.g. lead) in the deconvolution procedure unveals the limits of the method and prevents it from overinterpretation. (orig.)
[de]
In der Arbeit werden Ergebnisse von 210Pb-Untersuchungen an Sedimentkernen aus der Ostsee mitgeteilt und interpretiert. Die fuer die Interpretation benutzten Modelle werden abgeleitet und diskutiert. Eine Anwendung dieser Modelle auf gemessene 210Pb-Verteilungen ergibt in der Regel konsistente Sedimentationsparameter. Bei einem Vergleich der Ergebnisse von unabhaengig entnommenen Kernen gleicher Stationen zeigen sich z.T. stark unterschiedliche Werte, die durch weiterfuehrende Untersuchungen geklaert werden muessen. Speziell untersucht wird die Datierung von Sedimentkernen mit durchmischten oberflaechennahen Schichten. Eine Nutzung derartiger Kerne fuer die zeitliche Rekonstruktion von Indikatorprofilen erfordert eine Entfaltung der Daten mit einer Uebertragungsfunktion, die aus den 210Pb-Messungen bestimmt werden kann. Die Ergebnisse einer solchen Rekonstruktion unterscheiden sich betraechtlich von den Datierungen mit Standardmodellen. Eine Bewertung der Messunsicherheit des genutzten Indikators (z.B. Blei) bei der Entfaltungsprozedur zeigt die Grenzen des Verfahrens und verhindert eine Ueberinterpretation. (orig.)Journal
[en] The distribution of elements during the process of coal combustion was partly studied under laboratory conditions and the concentrations of elements were determined in coal, bottom ash and fly ash from power plants. It was found that the fly ash, retained by filter, was enriched with Cu, Zn, As, I, Pb, and Pl. The bottom ash, collected at 90 0C, contained Sb, Ni, Cr, and Mo. In the fly ash were also determined the elements Mo, Sb, I, and Pb whose concentrations in the initial coal were lower than the detection limits. The concentrations of elements were measured by instrumental photon activation analysis. (author)
Journal
[en] For the further processing of silicon nitride powders it is necessary to know the content of oxygen. The 14 MeV neutron generator has been used for the nondestructive and rapid determination of oxygen by the nuclear reaction 16O(n,p)16N. The important interfering reactions and errors in the determination of oxygen has been discussed. (author)
Journal
[en] With pulse radiolysis and detection by optical absorption spectroscopy in transparent, molten and highly viscous PE doped with aromatic olefins as styrene, 1-methylstyrene, 1,1'-diphenylethylene and tetraphenylethylene radical and ionic transients of these scavengers were observed. From the rapid formation behaviour of the benzyl type radicals a mechanism is concluded consisting in a fast motion of excitation energy along the polymer chain with a subsequent trapping by foreign molecules under direct dissociation into radicals. Because of the PE parent cation fragmentation ionic species derived from the aromatic olefins were generated only at scavenger concentrations of ≥ 10-2 mol dm-3. (author)
Journal
[en] A prerequisite to the application of MOS sensors for measurement in neutron fields is the investigation of detection of heavy ions and fission fragments using these sensors. The detection efficiency of MOS sensors for heavy ions and fission fragments depends on the angle of incidence and the energy of incident particles. Therefore, investigations were carried out for measurement of the pulse rate-voltage characteristics for different angles of incidence of heavy ions and fission fragments and for different energies of fission fragments slowed down in air. From these characteristics the angular dependence of detection efficiency and the registration threshold to the specific ionization losses of fission fragments as a function of operation voltage were determined. The experiments described in the paper were performed with 129Xe ions and 252Cf fission fragments. (author)
Journal
[en] Activation analysis is an important method for elemental analysis, mainly because of its sensitivity. The accuracy and precision achievable with charged particle activation analysis (CPAA) have been significantly improved. Standardization problems were studied thoroughly and the accuracy was demonstrated during various interlaboratory comparisons. Most of the applications of CPAA deals with the determination of light elements, such as hydrogen, carbon, nitrogen and oxygen, in metals and semiconductors. Because the surface layer containing the activity formed at the surface can be removed by chemical etching after irradiation, CPAA has shown that for some metals the concentrations are orders of magnitude lower than expected on the basis of chemical analytical methods. CPAA was very often applied as a reference method for certification analyses. (author)
Journal
| 1 | 2 | 3 | Next |