E2 transition probabilities in the decoupled band of the 129La nucleus.

Lifetimes of the yrast levels with spins I ^π = 23/2⁻ to 39/2⁻ in ¹²⁹La produced via the ¹²⁰Sn(¹⁴N, 5 n) reaction at a beam energy of 77MeV have been measured by the Doppler shift attenuation method. The properties of the studied levels belonging to the πh_11/2 band were compared with the theoretical predictions obtained in the framework of the core quasi-particle coupling model. It is suggested that the rigid-rotor model used to describe the cores is too simplified as the even-even nuclei from the A ∼ 130 region are susceptible to shape deformation. Reasonable agreement was obtained with the phenomenological cores based on the experimental data of ¹²⁸Ba. [ABSTRACT FROM AUTHOR]