Neutron deficient isotopes of polonium and bismuth have been produced in the reactions ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ + ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Ce}$ and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ + ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$, separated from the primary beam by our gas-filled on-line mass separator. The half-lives have been determined by measuring the lifetimes of individual nuclei. The new isotope ${}_{}{}^{192}{}_{}{}^{}\mathrm{Po}$ ($T_{\frac{1}{2}}=34\mathrm{}\pm 3$ ms, $E_{\alpha }=7.17\mathrm{}$ MeV) and a short-lived isomeric state in ${}_{}{}^{191}{}_{}{}^{}\mathrm{Bi}$ ($T_{\frac{1}{2}}=150\mathrm{}\pm 15$ ms, $E_{\alpha }=6.86\mathrm{}$ MeV) have been identified.

RADIOACTIVITY ${}_{}{}^{192,193,194}{}_{}{}^{}\mathrm{Po}$, ${}_{}{}^{193}{}_{}{}^{}\mathrm{Po}_{}^m{}_{}{}^{}$, and ${}_{}{}^{191}{}_{}{}^{}\mathrm{Bi}_{}^m{}_{}{}^{}$; measured $T_{\frac{1}{2}}$, $E_{\alpha }$. Gas-filled on-line mass separator.

• Received 9 June 1981

DOI:https://doi.org/10.1103/PhysRevC.24.2370