No abstract available

[en] This talk consists of three parts: an introduction to the current situation regarding superdeformed bands; some recent highlights; and a quick look at the future. Due mainly to the large gamma-ray detectors coming into use, there is a lot going on in this area and the author does not try to include it all here. Rather, after a few general observations the author selects several highlights and tries to discuss those in some depth. Finally the author gives his thoughts as to the future of studying superdeformed nuclei. His definition of superdeformation is rather broad and generally includes nuclei where the long axis is 1.5-2 times longer than the short axis. Typically this is a second minimum in the potential energy surface; the first having smaller (perhaps open-quotes normalclose quotes) deformation. With this definition there are now five regions of superdeformation known in the heavier elements, having masses centered around 80, 130, 150, 190 and 240, the last of these being the fission isomers discovered more than 30 years ago. Altogether there are around 200 bands presently known in these five regions. The newest region is that around mass 80, where already some 20 bands are known in 10 nuclei. These bands show all the familiar properties seen in the heavier regions: assigned configurations, band crossings, identical bands, etc

[en] The variable moment of inertia (VMI) model has been used to study the properties of superdeformed (SD) bands in A < 100 mass region. The experimental γ-ray (E _γ) transitions energies are least square fitted to obtain the model parameters such as band head moment of inertia, (J ₀), and stiffness constant, (C). The observed E _γ transition energies obtained using the VMI formula are in excellent agreement with the experimental values. In the paper, we have studied the dynamic moment of inertia (J ⁽²⁾) and its variation with rotational frequency (ℏ ω). We also studied the ΔI = 2 staggering phenomena in SD bands of ⁶¹Zn(SD), ⁶²Zn(SD1), ⁸⁰Sr(SD1), ⁸¹Sr(SD1), ⁸²Sr(SD), ⁸³Sr(SD), ⁸⁴Zr(SD), ⁸⁶Zr(SD1), ⁸⁶Zr(SD4), ⁸⁷Nb(SD2), ⁸⁹Tc(SD) and ⁹¹Tc(SD) nuclei. The VMI model brings very comprehensive interpretation for spin assignment and to study the properties of SD bands in light mass region nuclei. (paper)

No abstract available

[en] A superdeformed band consisting of 14 transitions was discovered in ¹⁵⁴Er and has been reported earlier. The J⁽²⁾ of the band decreases rapidly with increasing frequency over the first 5 transitions. This behavior is similar to that of the isotone ¹⁵⁰Gd, where it has been attributed to a paired band crossing between the N=5 and the N=7 neutron orbitals. In addition, a staggering of ∼ 75 eV has been observed in ¹⁵⁴Er in the ΔE, above the crossing. Staggering of this sort has also been observed in this mass region in ¹⁴⁹Gd. The implication of these results for the deformation will be discussed in light of calculations using the Total Routhian Surface and Cranked Shell Models

[en] The triaxially superdeformed states in ¹⁶²Lu are investigated using the three-dimensional total routhian surface calculation, and the deformation parameters and the likely configuration are given. The shell and pairing correction energies are considered respectively, and the formation mechanism of triaxial superdeformation is investigated.

[en] We investigate the independent quasiparticle (QP) picture for superdeformed nuclei of the mass-190 region, which is expected to lead to additivity in certain physical quantities. Obvious deviations from additivity are found from both projected shell model calculations and experimental data. The cause of the deviation can be decomposed and identified through this model. Our study suggests that the independent QP picture may not be fully appropriate for this mass region. (author)

[en] Lifetimes of superdeformed (SD) states in ¹⁹³Hg were measured using the Doppler Shift Attenuation Method (DSAM). The data was collected with GAMMASPHERE early implementation, using the ¹⁵⁰Nd(⁴⁸Ca,5n) reaction at a beam energy of 213 MeV to populate these states. The target consisted of 1.1mg/cm² Au backing. Six SD bands had been previously observed in ¹⁹³Hg. Two of these bands show a correlated upbend and downbend in J⁽²⁾, which has been interpreted as being due to an interaction between quasi-particle orbitals. The results of the DSAM analysis currently in progress will be discussed

[en] Theoretical predictions of the existence of superdeformed (SD) shapes in the A = 80 region have recently been confirmed experimentally. Here the authors report the identification of a SD band in ⁸⁴Zr, which further supports the predicted N = 44 SD shell gap. States in ⁸⁴Zr were populated by the ⁵⁸Ni(²⁹Si,2pn) reaction with a beam energy of 128 MeV. The experimental setup consisted of the Gammasphere Early Implementation and the open-quotes Microballclose quotes array. Using proper particle and γ gating, the authors have identified a band of nine correlated γ rays in ⁸⁴Zr with energies ranging from 1526 to 2761 keV and energy differences about 150 keV. The moment of inertia of this band (∼ 27ℎ²/MeV) fits well with a superdeformed shape of β₂ ∼ 0.5. An investigation of the lifetimes of the transitions in the band by the Doppler attenuation method in a thin target gives a quadrupole moment of ∼ 5 eb and strongly supports the SD nature of this band

[en] We present recent results obtained with GAMMASPHERE for nuclei in the A∼80 mass region. These studies have concentrated on a systematic study of superdeformed bands and their transitional quadrupole moments. Normally-deformed rotational bands in a series of even-even T_z = 1 nuclei were also investigated to probe the possible influence of the np pairing on the structure of their yrast bands