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

Rotational bands in 108,110,112Ru have been investigated by means of γ–γ–γγ–γ–γ and γ–γ(θ)γ–γ(θ) coincidences of prompt γ rays emitted in the spontaneous fission of 252Cf. The positive parity bands are described by different versions of IBA, where 108Ru is best described as a γ-soft nucleus whereas 110,112Ru are more like rigid triaxial rotors. New ΔI=1ΔI=1 negative parity doublet bands are found. In case of 110,112Ru, 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.