Collective vibrations in Si³⁰

Abstract

The possibility of collective vibrations in nuclei in the region A≈30 is discussed in terms of the systematics of the energy levels of even-even nuclei in the 2s-1d shell. As a test case, the energy levels and electromagnetic transition probabilities in Si³⁰ are calculated on the basis of the weak-coupling unified model. The inter-particle interactions between the last two neutrons as well as their interactions with the quantized harmonic vibrations of the Si²⁸ core (and s_½-d_3/2 configuration mixing) are taken into account. The results are found to be in fair agreement with the observed properties of Si³⁰, for a proper choice of the parameters.