Band structures, lifetimes, and shape coexistence in La-130


Ionescu-Bujor M., Aydin S., Iordachescu A., Marginean N., Pascu S., Bucurescu D., ...Daha Fazla

PHYSICAL REVIEW C, cilt.102, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

The level structure of La-130 has been investigated using the (121)sb(C-12, 3n) reaction with the ROSPHERE array at IFIN-HH, Bucharest. The level scheme was significantly extended with the observation of 45 new states and 100 new transitions. Several band structures have been identified and a clear connection with the lower-lying states has been established. A lifetime of tau = 3.6(2) ns has been measured for the 346-keV 6(-) state by the in-beam fast timing technique. The lifetimes of 18 high-spin states have been determined by applying the Doppler-shift attenuation method. The deformations derived from the experimental B(E2) transition strengths indicate distinct coexisting shapes at high spins in La-130. The experimental properties of both low- and high-spin states were compared with theoretical calculations performed in the frame of the two-quasiparticles-plus-rotor model. Two new negative-parity decoupled bands, with a deduced quadrupole deformation beta(2) = 0.150(15), were interpreted by coupling the proton in the 1/2[550] and 3/2[541] orbitals with the odd neutron occupying mainly the low-Omega orbitals from the d(3/2) and 5(1/2) states. A quadrupole deformation beta(2) = 0.220(17) was derived for a newly identified positive-parity decoupled band. This enhanced deformation was attributed to the involvement in the band configuration of the Omega = 1/2 (f(7/2), h(9/2)) intruder neutron orbital. The multiparticle configuration pi g(7/2)(h(11/2))(2) circle times nu (h(11/2)) was assigned to a high-spin negative-parity dipole band, based on the comparison of the experimental B(M1) transition strengths with values calculated by applying the geometrical model of Donau and Frauendorf.