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Understanding the fundamental excitations of many-fermion systems is of significant current interest. In atomic nuclei with even numbers of neutrons and protons, the low-lying excitation spectrum is generally formed by nucleon pair breaking and nuclear vibrations or rotations. However, for certain numbers of protons and neutrons, a subtle rearrangement of only a few nucleons among the orbitals at the Fermi surface can result in a different elementary mode: a macroscopic shape change. The first experimental evidence for this phenomenon came from the observation of shape coexistence in 16O (ref. 4). Other unexpected examples came with the discovery of fission isomers and super-deformed nuclei. Here we find experimentally that the lowest three states in the energy spectrum of the neutron deficient nucleus 186Pb are spherical, oblate and prolate. The states are populated by the alpha-decay of a parent nucleus; to identify them, we combine knowledge of the particular features of this decay with sensitive measurement techniques (a highly efficient velocity filters with strong background reduction, and an extremely selective recoil-alpha-electron coincidence tagging methods). The existence of this apparently unique shape triplet is permitted only by the specific conditions that are met around this particular nucleus.

The new element 111 was produced and unambiguously identified in an experiment at SHIP, GSI Darmstadt. Three nudlei of the isotope 272111 were observed in irradiations of 2~ targets with a4Ni projectiles of 318 MeV and 320 MeV energy. The cross-sections are (1.72~ pb and (3.5_ +4-6) pb, respectively. The nuclei decay by cc emission into the new and so far the heaviest isotopes of the elements 109 and 107 with mass numbers A = 268 and A=264. The ~-decay chains were followed down to the known nuclei 260105 and 256Lr.

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to the superspace. Such localized configurations could then help our understanding of quark con-finement^° and hadronic matter (bags). These solutions could also shed light on the bubble formation in early universe.It is a pleasure to thank R. Jackiw for suggestions and discussions, and A. Kupiainen and A. Luther for discussions. Part of this work was completed at Helsinki University of Technology and I thank E. Byckling and K. Kajantie for their hospitality. This work was supported in part by the U. S. Department of Energy under Contract No. DE-ACO2-76ERO3069.Note added,-^After completion of this manuscript I learned that J. Cardy (University of Washington, Seattle) has also found finite-energy solitons and arrived at similar conclusions. <^^present address. ^a Grinstein, Phys. Rev. Lett. ^, 944 (1976);