SPECTROSCOPY OF GD-155 FOLLOWING COULOMB-EXCITATION - SIGNATURE-INDEPENDENT M1 PROPERTIES AND EVIDENCE FOR OCTUPOLE CORRELATIONS

The spectroscopy of Gd-155 has been studied following Coulomb excitati on. Gyromagnetic ratios were measured in the 3/2(-) [521] ground-state band by the transient field technique and the identification of state s up to spin 23/2(-) in the ground-state band was confirmed by gamma-g amma coincidence measurements. Level lifetimes were deduced from Doppl er broadened lineshapes; gamma-ray branching intensities and multipola rity mixing ratios were determined from particle-gamma-ray angular cor relations. The population of a positive parity band (mainly 3/2(+) [65 1]) by E3 Coulomb excitation from the ground-state band provides evide nce of octupole correlations. Particle-rotor model calculations were p erformed for the negative parity states. The spectroscopy is best desc ribed when the Coriolis interactions are attenuated by approximate to 50%. (C) 1998 Elsevier Science B.V.