POSITIVE-PARITY ROTATIONAL BAND IN 158 Tb

Excited states of the odd-odd nucleus $^{158}\mathrm{Tb}$ have been studied via the $^{154}\mathrm{Sm}(^{7}\mathrm{Li},3n)^{158}\mathrm{Tb}$ reaction at a beam energy of 27 MeV. The new level scheme of $^{158}\mathrm{Tb}$ involving a positive parity rotational band is established up to excitation energy $\ensuremath{\sim}2.3\phantom{\rule{4.pt}{0ex}}\mathrm{MeV}$ and spin $\ensuremath{\sim}17\ensuremath{\hbar}$. By comparing with the rotational bands in the neighboring nuclei $^{157}\mathrm{Tb}$ and $^{157}\mathrm{Gd}$, the configuration was tentatively assigned as $\ensuremath{\pi}{d}_{5/2}\ensuremath{\bigotimes}\ensuremath{\nu}{i}_{13/2}$, and the phenomenon of signature inversion is discussed.