Breaking of axial symmetry in excited heavy nuclei as identified in Giant Dipole Resonance data

A recent theoretical prediction of a breaking of axial symmetry in quasi all heavy nuclei is confronted to a new critical analysis of photon strength functions of nuclei in the valley of stability. For the photon strength in the isovector giant dipole resonance (IVGDR) regime a parameterization of GDR shapes by the sum of three Lorentzians (TLO) is extrapolated to energies below and above the IVGDR. The impact of non-GDR modes adding to the low energy slope of photon strength is discussed including recent data on photon scattering and other radiative processes. These are shown to be concentrated in energy regions where various model calculations predict intermediate collective strength; thus they are obviously separate from the IVGDR tail. The triple Lorentzian (TLO) ansatz for giant dipole resonances is normalized in accordance to the dipole sum rule. The nuclear droplet model with surface dissipation accounts well for positions and widths without local, nuclide specific, parameters. Very few and only global parameters are needed when a breaking of axial symmetry already in the valley of stability is admitted and hence a reliable prediction for electric dipole strength functions also outside of it is expected.Comment: 21 pages, 21 figures, PACS: 26.50.+x, 25.20.Dc,27.60.+j Accepted by Europ. Phys. Journal

Impact of Triaxiality on the Emission and Absorption of Neutrons and Gamma Rays in Heavy Nuclei

For many spin-0 target nuclei neutron capture measurements yield information on level densities at the neutron separation energy. Also the average photon width has been determined from capture data as well as Maxwellian average cross sections for the energy range of unresolved resonances. Thus it is challenging to use this data set for a test of phenomenological prescriptions for the prediction of radiative processes. An important ingredient for respective calculations is the photon strength function for which a parameterization was proposed using a fit to giant dipole resonance shapes on the basis of theoretically determined ground state deformations including triaxiality. Deviations from spherical and axial symmetry also influence level densities and it is suggested to use a combined parameterization for both, level density and photon strength. The formulae presented give a good description of the data for low spin capture into 124 nuclei with 72<A<244 and only very few global parameters have to be adjusted when the predetermined information on ground state shapes of the nuclei involved is accounted for.Comment: Contribution to the Proceedings of Scientific Workshop on Nuclear Fission Theory-2, November 2012 at Biarritz, Franc

Importance of nuclear triaxiality for electromagnetic strength, level density and neutron capture cross sections in heavy nuclei

Cross sections for neutron capture in the range of unresolved resonances are predicted simultaneously to level distances at the neutron threshold for more than 100 spin-0 target nuclei with A >70. Assuming triaxiality in nearly all these nuclei a combined parameterization for both, level density and photon strength is presented. The strength functions used are based on a global fit to IVGDR shapes by the sum of three Lorentzians adding up to the TRK sum rule and theory-based predictions for the A-dependence of pole energies and spreading widths. For the small spins reached by capture level densities are well described by only one free global parameter; a significant collective enhancement due to the deviation from axial symmetry is observed. Reliable predictions for compound nuclear reactions also outside the valley of stability as expected from the derived global parameterization are important for nuclear astrophysics and for the transmutation of nuclear waste.Comment: Contribution to the proceedings of the ERINDA workshop held at CERN in October 2013 with modification

Daten in verteilten Systemen. Seminar SS 1995 & WS 1995/96

Verteilte Systeme gewinnen zunehmend an Bedeutung f"ur moderne Anwendungen. Um sie geeignet unterst"utzen zu k"onnen, bedarf es innovativer Mechanismen zur Fehlertoleranz, zur Integration von Datenbanken und zur Verteilung von Daten, bei gleichzeitiger Bereitstellung von geeigneten Synchronisationsverfahren. Diese Mechanismen waren Gegenstand des Seminars ``Daten in verteilten Systemen\u27\u27, das im Sommersemester 1995 sowie im Wintersemester 1995/96 am Institut f"ur Telematik der Universit"at Karlsruhe abgehalten wurde

Description of dipole strength in heavy nuclei in conformity with their quadrupole degrees of freedom

In conformity to new findings about the widespread occurrence of triaxiality arguments are given in favor of a description of the giant dipole resonance in heavy nuclei by the sum of three Lorentzians. This TLO parameterization allows a strict use of resonance widths {\Gamma} in accordance to the theoretically founded power law relation to the resonance energy. No additional variation of {\Gamma} with the photon energy and no violation of the sum rule are necessary to obtain a good agreement to nuclear photo-effect, photon scattering and radiative capture data. Photon strength other than E1 has a small effect, but the influence of the level density on photon emission probabilities needs further investigation.Comment: Presented at the 3rd International Workshop on Compound Nuclear Reactions and Related Topics at Prague, 2011, to be published via the EPJ Web of Conference

Architektur vernetzter Systeme. Seminar SS 1996 & WS 1996/97

Der vorliegende Interne Bericht enthält die Beiträge von Studenten zum Seminar "Architektur vernetzter Systeme", das im Sommersemester 1996 und im Wintersemester 1996/97 am Institut für Telematik der Universität Karlsruhe stattgefunden hat. Themen waren dabei Replikationsverfahren im Mobilumfeld sowie Dienste und Konzepte in verteilten Systemen als auch alternative Ansätze wie Memory-Consictency-Modelle

Architektur vernetzter Systeme - Seminar SS 1997 und WS 1997/98

Der vorliegende interne Bericht enthält die Beiträge von Studenten zum Seminar "Architektur vernetzter Systeme", das im Sommersemester 1997 und im Wintersemester 1997/98 am Institut für Telematik der Universität Karlsruhe stattgefunden hat. Themen waren dabei die Performanzuntersuchung bei Vermittlungsinstanzen, alternative Kommunikationsparadigmen wie mobile Agenten und Push-Techniken als auch die Betrachtung verteilter Anwendungen im WWW oder die Optimierung des WWW durch den Harvest-Ansatz