No abstract available

[en] Abstract only

[en] Transition energies, incremental alignments of angular momentum, dynamic moments of inertia of triaxial superdeformed bands in rare-earth nuclei have been examined systematically. It is found that the incremental alignments are nearly constant and their dynamic moments of inertia are quite similar. Therefore these triaxial superdeformed bands in rear-earth nuclei are identical bands

[en] The ⁶⁴Ni(⁴He, ⁸He)⁶⁰Ni reaction was used at 58-MeV bombarding energy with the quadrupole-dipole-dipole-dipole magnet spectrograph, giving an improved value of the ⁸He mass excess of 31.611 +- 0.017 MeV

[en] The phenomenon of identical bands is studied by analyzing the distributions of fractional changes in the dynamical moments of inertia of pairs of bands in superdeformed (SD) nuclei. These distributions are found to exhibit a peak with a centroid at nearly zero. Their widths increase in going from the SD bands in the mass A ∼ 150, to the SD bands in the mass ∼190 and to the normally-deformed bands in the rare-earth region. These differences may be attributed to the weaker pairing correlations and the stabilizing role of intruder orbitals on the structures of SD bands. Precise level lifetimes have been measured for various pairs of identical SD bands in Gd and Dy isotopes. By comparing the derived quadrupole moments with calculations performed in the framework of the cranking Skyrme-Hartree-Fock model, it is shown that, independently of the intrinsic configuration and of the proton and neutron numbers, the charge moments calculated with respect to the doubly-magic SD core of ¹⁵²Dy can be expressed in terms of independent contributions from the individual hole and particle orbitals. (author)

[en] A reliable prediction of the in-pile and out-of-pile physics characteristics of nuclear fuel is one of the objectives of present-day reactor physics. The paper describes the main production paths of important actinides for light water and fast breeder reactors. The accuracy of recent nuclear data is examined by comparisons of theoretical predictions with the results from post-irradiation analysis of nuclear fuel from power reactors, and partly with results obtained in zero-power facilities. A world-wide comparison of nuclear data to be used in large fast power reactor burn-up and long term considerations is presented. The needs for further improvement of nuclear data are discussed. (orig.)

[en] The plant physiological and meteorological problems which must be considered by isotope dendroclimatologists are discussed. Stable isotope ratios in the cellulose and lignin across three growth rings of a Pinus radiata are presented. The C-H hydrogens of cellulose were found to be more than 20⁰/₀₀ depleted in the summer as compared with the winter and probably record the annual temperature cycle. Delta¹³C measurements on both cellulose and lignin showed an enrichment of 2⁰/₀₀ in summer as compared with winter wood, giving a temperature coefficient of at least +0.2⁰/₀₀/⁰C. This should be adequate for paleoclimatic studies provided one can assume that the delta¹³C of the atmosphere has remained constant or is known. Some possible future developments in the field of isotope dendroclimatology are discussed.(auth.)

[en] Although four decades ago it had been conclusively shown that the first excited 0₂⁺ state in ¹⁵⁶₆₆Dy⁹⁰ was a pairing isomer, the lessons of this identification has taken a long time to connect with the Nuclear Structure Community. The 0₂⁺ states that can be populated significantly with two particle neutron transfer, all have large enough cross-sections to demonstrate that simple monopole pairing in theoretical descriptions will be insufficient. The conclusion that these states cannot be associated with time-dependent β vibrations of the nuclear shape is also supported by their very weak excitation in inelastic scattering processes such as (d,d'). Blocking of the coupling of the single particle neutrons in odd nuclei to the 0₂⁺ states near N=90 have shown that a major part of their configurations is a pair of neutrons in the [505]11/2^- Nilsson orbit. This high-K orbit is extruded from the h_11/2 shell to the Fermi surface by the increasing deformation caused by adding neutrons outside the N=82 core. These data confirm the separation of prolate-prolate and oblate-oblate pairing. At iThemba LABS we have used conventional γ-ray spectroscopy to investigate structures in the pairing gaps of even-even nuclei in the ranges Z=62-70 and N=88-92, in particular to study the systematics of the excited Kπ = 0₂⁺2 and 2_γ⁺ positive parity bands. We find that the 02+ bands all have moments-of-inertia that are greater than those of the ground state 0₁⁺1 bands, in complete contradiction to the predictions of all Interacting Boson Models (IBM). The larger moments-of-inertia for 0₂⁺ bands are consistent with reduced pairing due to the low density of oblate (high-W) orbitals near the Fermi surface. The odd spin members of the γ bands all track the ground state bands while the even spin members can mix with the 0₁⁺ and 0₂⁺ bands. Indeed the γ bands and 0₂⁺ bands cross and interact strongly affecting the signature splittings S(I) observed in the γ bands. The systematic data will be discussed in terms of the Triaxial Projected Shell Model (TPSM) and the 5-Dimensional Collective Model (5-DCM). This document is composed of an abstract and the slides of the presentation. (author)

[en] Level densities and radiative strength functions in ¹⁷¹Yb and ¹⁷⁰Yb nuclei have been measured with the ¹⁷¹Yb(³He,³He(prime) γ)¹⁷¹Yb and ¹⁷¹Yb(³He, αγ)¹⁷⁰Yb reactions. A simultaneous determination of the nuclear level density and the radiative strength function was made. The present data adds to and is consistent with previous results for several other rare earth nuclei. The method will be briefly reviewed and the result from the analysis will be presented. The radiative strength function for ¹⁷¹Yb is compared to previously published work.

No abstract available