SYSTEMATICS OF ALPHA-CLUSTER STATES ABOVE DOUBLE SHELL CLOSURES

Alpha particle cluster models have been very successful in reproducing energy spectra, static and dynamic electromagnetic properties, α-emission widths and α-nucleus elastic scattering data in light nuclei around the double shell closures at O16 and Ca40. We extend the application of one such model to the heavier mass regions above Zr90 and Pb208. In all cases we employ a potential of given geometric form with all parameters fixed except for the radius that is tailored to each nucleus in turn. We find that the potentials needed for Ne20 and Ti44 are very similar to the real parts of the optical potentials used in an accurate description of α-16O and α-40Ca elastic scattering up to high energies. By suitable choice of the quantum numbers that describe the relative motion of the α particle and the core nucleus we are able to give a good account of the spectra, the reduced E2 transition strengths, and the α-particle emission widths (or lifetimes) of the members of the ground state bands in the four nuclei Ne20, Ti44, Mo94, and Po212. The potential chosen also allows a consistent description of the half-lives for favored α decay throughout the Periodic Table. © 1995 The American Physical Society.