Intermediate structure and dipole bands in the transitional Ba134 nucleus

Abstract

The intermediate and high-spin states of the $^{134}\mathrm{Ba}$ nucleus have been investigated up to spin ${I}^{\ensuremath{\pi}}=({20}^{\ensuremath{-}})$ using the $^{124}\mathrm{Sn}(^{13}\mathrm{C}, 3n)^{134}\mathrm{Ba}$ reaction at a beam energy of 48 MeV. The ${R}_{\mathrm{DCO}}$ and polarization asymmetry measurements were carried out to assign the spin and parity of the levels. Three ($\mathrm{\ensuremath{\Delta}}I=2$) negative parity bands were studied above the 1985.9 keV level having spin ${I}^{\ensuremath{\pi}}={5}^{\ensuremath{-}}$. The two quasiparticle $\ensuremath{\nu}[{h}_{11/2}\ensuremath{\bigotimes}({s}_{1/2}/{d}_{3/2})]$ configuration has been assigned to these bands based on the systematics of the $\mathrm{Ba}$ (even-$N$) isotopes and similarity in the behavior of signature splitting and $B(M1)/B(E2)$ ratios. Further, two ($\mathrm{\ensuremath{\Delta}}I=1$) dipole bands have also been observed starting at the 5677.9 and 5284.5 keV levels with spin ${I}^{\ensuremath{\pi}}={14}^{\ensuremath{-}}$ and ${15}^{+}$, respectively. The configuration of these bands was suggested from the systematics of the similar structure in the neighboring nuclei. Tilted axis cranking (TAC) calculations were carried out using the four quasiparticle $\ensuremath{\pi}[{h}_{11/2}({g}_{7/2}/{d}_{5/2})]\ensuremath{\bigotimes}\ensuremath{\nu}{[{h}_{11/2}]}^{2}$ and $\ensuremath{\pi}[{h}_{11/2}({g}_{7/2}/{d}_{5/2})]\phantom{\rule{4pt}{0ex}}\ensuremath{\bigotimes}\phantom{\rule{4pt}{0ex}}\ensuremath{\nu}[{h}_{11/2}{d}_{3/2}]$ configurations for bands D1 and D2, respectively. The TAC calculations and systematic studies of similar structures in the neighboring $N=78$ isotones suggest that the dipole band (D1) observed at 5677.9 keV level may have the magnetic rotation character.