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We report on four recent results concerning the population and the decay of superdeformed states, namely the structure of excited superdeformed states in 194Hg, the search for fine structure of the last superdeformed transitions in 194Pb, the primary decay-out strength analysis in 194Hg and, as a consequence of this, the possibility of using the decay-out as a tool to study order-to-chaos properties of normally deformed states. [ABSTRACT FROM AUTHOR]

High-spin properties of the triaxial strongly deformed potential well in 163Lu at excitation energies above resolvable bands have been investigated. Gated Eγ- Eγ spectra display clear ridges with moments of inertia corresponding to those observed for the discrete strongly deformed bands. A fluctuation analysis of the ridges yields a number of two-step paths of ≈ 40 and ≈ 20, when gating on triaxial strongly or normally deformed bands, respectively. These results show that a potential well at large deformation coexists with the normally deformed well, and indicate a mixing between states in the two wells at higher excitation energy. [ABSTRACT FROM AUTHOR]

A systematic study of angular momentum dissipation in deep-inelastic heavy ion collisions is carried out by combining two experimental methods: the angular correlation of α particles and protons in coincidence with deeply inelastic light fragments; and the first two moments of the γ-ray multiplicity. The unified analysis of these data, using a quantum mechanical treatment of the particle anisotropies and statistical decay calculations, yields most probable fragment spins I=10.8±1.1ħ and 13.4±1.1ħ forNi andZn, respectively, close to the sticking limit. For the width of the vector spin distribution assumed in our analysis to be equal in all three directions we obtain σ=3.9±1.3 ħ and 2.9±1.8ħ forNi andZn, respectively. These values correspond to most probable alignment parameters 〈 P〉=0.66±0.19 and 0.82±0.17 forNi andZn, respectively. As only very few partial waves of this light system undergo deep-inelastic scattering, σ directly relates to spin fluctuations, and is compared to asymptotic values from transport theories. [ABSTRACT FROM AUTHOR]

Structural limitations in the Time-Dependent Hartree-Fock formalism when applied to heavy-ion collisions are discussed. These severely impair the ability of the method to correctly predict mass distributions and mass-to-charge ratios for the resulting fragments. [ABSTRACT FROM AUTHOR]

An analysis of the classical closed orbits in the infinitely deep elongated ellipsoidal well is given with respect to their relevance to the gross-shell structure of the single-particle spectra in deformed nuclei. It is shown that the deformed-shape gross-shells responsible for the ground state deformations, as well as those responsible for the fission intermediate states, find a reasonable explanation in terms of the semiclassical three-dimensional quantization involving the planar orbits in the axis-of-symmetry plane and the simplest three-dimensional orbits which appear at large distortions. The former are found important for the ground state shapes. The results are also compared with the harmonic oscillator model. [ABSTRACT FROM AUTHOR]

The analysis of the fluctuations of the counts of unresolved γ-γ energy spectra can extend our knowledge of the rotational motion at high angular momentum and excitation energy above the yrast band. Detailed studies of the rotational quasi-continuum built on specific intrinsic nuclear configurations are here discussed. First, the validity of the K-selection rules in the quasi-continuum region is investigated in the case of the normal deformed nucleus Er. The γ cascades feeding into low-K and high-K bands are analyzed studying variance and covariance of the spectrum fluctuations. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands, while the covariance between pairs of gated spectra shows that the cascades feeding into low-K bands are different from those feeding into high-K bands. These findings suggest a persistence of K-selection rules in the region of excitation energy and angular momentum probed by the rotational decay of Er. As a second case, the existence of a rotational quasi-continuum in the super deformed well of Eu is discussed. An intense bump of rotationally correlated transitions is observed to develop as function of fold in the high spin region of gated spectra. Fold distribution, angular anisotropies, moment of inertia and life time show that the bump consists of fully damped super deformed transitions. This gives experimental evidence of damped rotational motion up to several MeV excitation energy above the super deformed yrast line. [ABSTRACT FROM AUTHOR]

We present shell model calculations for warm rotating nuclei, combining the cranked Nilsson mean field and a residual surface-delta two-body interaction. The model is used to describe the transition from the region of well-defined rotational bands into the region dominated by rotational damping, and the results are in overall agreement with the experimental findings. [ABSTRACT FROM AUTHOR]

Rotational motion loses its coherence as a function of the nuclear internal excitation energy. The damping process does not proceed in a continuous fashion and scars of discrete rotational bands are found, inbedded in a background of damped rotational states, regardless whether the calculations are carried out using effective or 'random' forces. The complexity of the damping mechanism is revealed in the lineshape of the ridges in the γ-γ correlation spectrum. [ABSTRACT FROM AUTHOR]

The number of discrete rotational bands in the nucleus 168Yb is obtained by a fluctuation analysis of the rotational ridge structure in double and triple γ coincidence matrices. The data are compared with cranked shell model calculations including a surface delta interaction. It is found that the number of calculated bands strongly depends on the interaction strength V0, and agreement between data and calculations supports the standard value V0= 27.5/A MeV. [ABSTRACT FROM AUTHOR]

Exact and approximate quantum numbers of the cranked Nilsson-Strutinsky (CNS) formalism are exploited to calculate excited bands in fixed configurations with the energy of the individual bands minimized with respect to deformation for all spin values. The formalism is applied to 59Cu, where all bands which appear important in the decay out of the superdeformed band are calculated. [ABSTRACT FROM AUTHOR]