Band structures, lifetimes, and shape coexistence in La130
Makaleler > Tam Makale · 2020
Yazarlar: M. Ionescu-Bujor, S. Aydin, A. Iordăchescu, N. Mărginean, S. Pascu, D. Bucurescu, C. Costache, N. Florea, T. Glodariu, A. Ionescu, R. Mărginean, C. Mihai, R. E. Mihai, A. Mitu, A. Negret, C. R. Niţă, A. Olăcel, B. Sayğı, L. Stroe, R. Suvăilă, S. Toma, A. Turturică
Physical Review C, Uluslararası, Wos, 2020, cilt 102
DOI: 10.1103/physrevc.102.044311
Özet
The level structure of $^{130}\mathrm{La}$ has been investigated using the $^{121}\mathrm{Sb}(^{12}\mathrm{C}$, 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 $\ensuremath{\tau}=3.6(2)$ ns has been measured for the 346-keV ${6}^{\ensuremath{-}}$ 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 $^{130}\mathrm{La}$. 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 ${\ensuremath{\beta}}_{2}=0.150(15)$, were interpreted by coupling the proton in the 1/2[550] and 3/2[541] orbitals with the odd neutron occupying mainly the low-$\mathrm{\ensuremath{\Omega}}$ orbitals from the ${d}_{3/2}$ and ${s}_{1/2}$ states. A quadrupole deformation ${\ensuremath{\beta}}_{2}=0.220(17)$ was derived for a newly identified positive-parity decoupled band. This enhanced deformation was attributed to the involvement in the band configuration of the $\mathrm{\ensuremath{\Omega}}=1/2$ $({f}_{7/2},{h}_{9/2})$ intruder neutron orbital. The multiparticle configuration $\ensuremath{\pi}{g}_{7/2}{({h}_{11/2})}^{2}\ensuremath{\bigotimes}\ensuremath{\nu}({h}_{11/2})$ 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 D\"onau and Frauendorf.