This paper reviews the most recent advances in the understanding of the physics of superdeformed nuclei from the point of view of the experimentalists. It covers among other subjects the following topics: (1) the discovery of a new region of superdeformed nuclei near A=190, (2) the surprising result of the occurrence of bands with identical transition energies in neighboring superdeformed nuclei near A=150 and A=190, (3) the importance of octupole degrees of freedom at large deformation and (4) the properties associated with the feeding and the decay of superdeformed bands. The text presented hereafter will appear as a contribution to the Annual Review of Nuclear and Particle Science, Volume 41. 88 refs., 11 figs

Janssens, R.V.F.

Khoo, Teng Lek.

The ever increasing accuracy with which nuclear structure studies can be performed experimentally and theoretically has yielded a wealth of fascinating new results. It is by now well known that throughout the periodic table nuclei can adopt a rich variety of shapes, particularly when rotated. The shape changes result from the interplay between macroscopic (liquid-drop) and microscopic (shell-correction) contributions to the total energy of the nucleus. The shell correction is a quantal effect arising from the occupation of nonuniformly distributed energy levels. Rotation affects the nuclear shape by modifying both the liquid-drop moment of inertia and the nucleonic occupation of specific shape-driving orbitals. Many interesting phenomena have been reported in rapidly rotating nuclei; exam ples are the alignment of particle spins along the rotation axis (back bending), the transition from prolate collective to oblate aligned-particle structures (band termination), the possible occurrence of triaxial shapes, and the onset of octupole instabilities. The most spectacular experimental re sult to date is the discovery of superdeformation, in which nuclei are trapped in a metastable potential minimum associated with very elongated ellipsoidal shapes co rresponding to an axis ratio of roughly 2: 1

Superdeformed nuclei

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