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The existing experimental value of the ratio B4/2=B(E2;41+→21+)/B(E2;1+→01+) in 134Ce is less than unity, which is outside the range allowed by current collective models and is highly anomalous. In the present work, new lifetime measurements of excited states in 134Ce have been performed in order to clarify this discrepancy. Excited states of 134Ce were populated by the fusion-evaporation reaction 122Sn(16O,4n)134Ce. The recoil distance doppler shift method was employed, and reliable lifetimes for the 21+, 41+, 102+, and 122+ states were derived from the differential decay curve method. The resulting B4/2 value is larger than unity, resolving the disagreement with traditional collective models. The new experimental data is in very good agreement with the calculation in the framework of the interacting boson model. The systematic evolution in collectivity of the Ce isotopes is discussed. [ABSTRACT FROM AUTHOR]

Lifetime measurements of yrast levels in 167W were measured using the recoil-distance Doppler-shift method. The differential decay-curve method was applied for a lifetime determination. Excited states of the nucleus 167W were populated by the reaction 142Nd (28Si28, 3n) at a beam energy of 144 MeV. The energy spectra and measured transition quadrupole moments inferred from the lifetimes of 167W are compared with the predictions of the cranked Nilsson-Strutinsky-Bogoliubov calculations. The changes of deformations and shapes with increasing spin due to the γ-polarization effect of aligned particles are discussed. The signature inversion visible in the negative parity yrast band is explained to be related to the triaxial shapes. [ABSTRACT FROM AUTHOR]