Decay schemes of excited states in Mg 24 and Si 28 and the collective model

Abstract

Gamma decay modes of the first six excited states of Mg 24 and the first four excited states of Si 28 have been determined with inelastic proton scattering. Mg 24 has been interpreted both on the axially symmetric rotational-vibrational, and the rotating triaxial ellipsoid colletive models. The decay modes require, on the former model, < 2% amplitude band mixing; they imply γ≈14° on the latter model, while the positions of the spin 2 levels suggest γ=22°. The higher Si 28 levels cannot be explained on either model. Thus Mg 24 is more susceptible to a deformed nucleus collective model interpretation than Si 28; this is correlated with the known greater nuclear deformation of Mg 24.