Deformed-jellium model for the fission of multiply charged metal clusters

A deformed-jellium model is used to calculate the fission barrier height of positive doubly charged sodium clusters within an extended Thomas-Fermi approximation. The fissioning cluster is continuously deformed from the parent configuration until it splits into two fragments. Although the shape of the fission barrier obviously depends on the parametrization of the fission path, we have found that remarkably, the maximum of the barrier corresponds to a configuration in which the emerging fragments are already formed and rather well apart. The implication of this finding in the calculation of critical numbers for fission is illustrated in the case of multiply charged Na clusters.

Spin-phonon avalanches in Mn-12 acetate

We report experimental studies and suggest a quantitative model of spin relaxation in Mn12 acetate in a pulsed magnetic field in the temperature range 1.95.0 K. When the field applied along the anisotropy axis is swept at 140 T/s through a nonmagnetized Mn12 acetate sample, the samples magnetization switches, within a few milliseconds, from zero to saturation at a well-defined field whose value depends on temperature but is quantized in units of 0.46 T. A quantitative explanation of the effect is given in terms of a spin-phonon avalanche combined with thermally assisted resonant spin tunneling.

Variational Wigner-Kirkwood approach to relativistic mean field theory

The recently developed variational Wigner-Kirkwood approach is extended to the relativistic mean field theory for finite nuclei. A numerical application to the calculation of the surface energy coefficient in semi-infinite nuclear matter is presented. The new method is contrasted with the standard density functional theory and the fully quantal approach.

Nonmesonic weak decay of the hypertriton

The nonmesonic decay of the hypertriton is calculated based on a hypertriton wave function and 3N scattering states, which are rigorous solutions of three-body Faddeev equations using realistic NN and hyperon-nucleon interactions. The pion exchange together with heavier meson exchanges for the ¿N¿NN transition is considered. The total nonmesonic decay rate is found to be 0.5% of the free ¿ decay rate. Integrated as well as differential decay rates are given. The p- and n-induced decays are discussed thoroughly and it is shown that the corresponding total rates cannot be measured individually.