Short-lived isomers inPo192andPo194

Abstract

Isomeric states in $^{194}\mathrm{Po}$ and $^{192}\mathrm{Po}$ were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions $^{141}\mathrm{Pr}$($^{56}\mathrm{Fe}, \mathrm{p}2\mathrm{n})^{194}\mathrm{Po}$ and $^{144}\mathrm{Sm}$($^{51}\mathrm{V}, \mathrm{p}2\mathrm{n})^{192}\mathrm{Po}$. Several new $\ensuremath{\gamma}$-ray transitions were attributed to the isomers and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in $^{194}\mathrm{Po}$, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (${11}^{\ensuremath{-}}$) to (${10}^{\ensuremath{-}}$). The de-excitation of the (${11}^{\ensuremath{-}}$) isomeric level in $^{192}\mathrm{Po}$ by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV ($E3$) transition to (${8}^{+}$) level of the ground-state band was suggested. Moreover, side feeding to the (${4}^{+}$) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting ${11}^{\ensuremath{-}}$ isomers in neighboring Po and Pb isotopes.