The even isotopes of mercury have been systematically studied using the Interacting Boson Model (IBM). In order to treat shape coexistence in the light isotopes, two separate IBM calculations were performed with different configurations, which were subsequently mixed. The four Hamiltonian parameters, which were allowed to vary freely from isotope to isotope, were found to be consistent with the corresponding IBM parameters used for platinum and osmium. Overall, the calculated energy spectra and electromagnetic properties are in reasonable agreement with experiment.

No abstract

The acoustic scattering properties of spherical gas bubbles in a liquid differ from those of a pressure-release sphere by the well-known ’’giant’’ monopole resonance at very low frequencies, which is due to the compressibility of the gas contained in the bubble. We show here that, in addition to this monopole resonance, a large number of higher-frequency resonances exist which are either overtones of the monopole, or which correspond to both fundamental and overtones of bubble vibrations of higher multipolarity. Although much smaller in size than the giant monopole, these resonances may nevertheless constitute features of some importance in sound scattering from gas bubbles.

In this study we investigate the dynamics of surface motion of a penetrable spherical body subjected to an incident plane acoustic wave. The results should be valid for objects of rather general internal consistency, since they are based on quite basic physical considerations, but they are illustrated here by the example of a gas bubble in a fluid. It is shown that surface waves generated in the scattering process circumnavigate the target sphere and, by a process of in-phase "resonance reinforcement," excite its multipole resonances at those eigenfrequencies at which n + 1/2 wavelengths (n being an integer) span the circumference. Phase matching is achieved here due to the fact that the surface wave suffers a phase jump of •r/2 at each of the two "caustic points" on the sphere at which the surface waves converge. Surface motions and circumferential waves on the bubble are graphically demonstrated, both on and off resonance. It is shown that the resonance manifests itself by a large-amplitude angular oscillation of the gas contained in the bubble.