Single-proton-transfer studies of 153Eu levels

Levels in 153Eu have been studied with the (t,α) reaction at 15 MeV. Earlier (3He,d) and (α,t) results have also been supplemented by new measurements with improved resolution at selected angles. Spectroscopic strengths were extracted, using distorted wave Born analysis methodology, and interpreted in terms of the Nilsson model with Coriolis mixing. Several new level and band assignments are proposed. For the 5/2+ levels at 694 and 706 keV an interpretation consistent with all experimental data requires admixtures of the 1/2+[420] and 5/2+[402] orbitals, as well as other types of components. Specifically, in addition to the 5/2−[532]+Q30 components previously proposed to explain gamma-decay modes of these levels, (t,p) results indicate that complex configurations involving pairing excitations are important for the 706 keV and other 5/2+ levels. The 5/2+[402] strength is fragmented over several levels.A successful description of these complex structures will require consideration of several effects, including quasiparticle–phonon interactions, Coriolis mixing, and a detailed treatment of pairing correlations.