We propose a model for the geometry of a dynamical spherical shell in which the metric is asymptotically Schwarzschild, but deviates from Ricci-flatness in a finite neighbourhood of the shell. Hence, the geometry corresponds to a ‘hairy’ black hole, with the hair originating on the shell. The metric is regular for an infalling shell, but it bifurcates, leading to two disconnected Schwarzschild-...

Pauli-projected random gaussians are used as a representation to solve the shell model equations. The elements of the representation are chosen by a variational procedure. This scheme is particularly suited to describe cluster formation and cluster decay in nuclei. It overcomes the basis-size problem of the ordinary shell model and the technical difficulties of the cluster-configuration shell m...

We adopt a personal approach here reviewing several calculations over the years in which we have experienced confrontations between cluster models and the shell model. In previous cluster conferences we have noted that cluster models go hand in hand with Skyrme Hartee-Fock calculations in describing states which cannot easily, if at all, be handled by the shell model. These are the highly defor...

Shell-model calculations are presented for electric quadrupole moments of A =17—39 nuclei. The shell-model wave functions, which span the complete Ods/2-1sl/2 Dd3/2 model space in all instances, are obtained by diagonalizing an sd-shell Hamiltonian which consists of a fixed singleparticle energy spectrum and a single set of two-body matrix elements scaled as a function of the mass number A. Res...

Because of the complexity of tracing rays through a gradient refractive index medium, the human eye's lens is sometimes approximated by a shell structure with constant refractive index within shells. In the shell model, power arises from a combination of an axial variation in index and the curvatures of the shell surfaces. We develop an equation which gives the power due to the gradient index o...

We develop a shell-model Monte Carlo (SMMC) method to calculate densities of states with varying exciton (particle-hole) number. We then apply this method to the doubly closed-shell nucleus 40 Ca in a full 0s-1d-0f-1p shell-model space and compare our results to those found using approximate analytic expressions for the partial densities. We find that the effective one-body level density is red...