ON THE SHELL STRUCTURE OF NUCLEAR BUBBLES

We investigate the shell structure of spherical nuclear bubbles in sim ple phenomenological shell model potentials. The bunching is produced by the energy gaps between single-particle states with a different num ber of radial nodes. The shell correction energies for doubly magic bu bbles may be as large as -40 MeV and probably imply a very long lifeti me against spontaneous fission. beta-stability occurs for ratios of th e neutron number N to the proton number Z which differ markably from t he beta-stability valley of ordinary compact nuclei. The alpha-decay p robability is shown to be very small for proton rich bubbles with a mo derately large outer radius, Metastable islands of nuclear bubbles are shown to exist for nucleon numbers in the range A = 450-3000. (C) 199 7 Elsevier Science B.V.