Evolution of chirality from γ soft ~(108)Ru to triaxial ~(110,112)Ru

摘要

Rotational bands in ~(108,110,112)Ru have been investigated by means of γ-γ-γ and γ-γ(θ) coincidences of prompt γ rays emitted in the spontaneous fission of ~(252)Cf. The positive parity bands are described by different versions of IBA, where ~(108)Ru is best described as a γ-soft nucleus whereas ~(110,112)Ru are more like rigid triaxial rotors. New △I = 1 negative parity doublet bands are found. In case of ~(110,112)Ru, these are interpreted as soft chiral vibrations. Many of the experimental findings can be explained by microscopic calculations that combine the TAC mean-field with random phase approximation but a simple geometrical explanation is not apparent.