The previously unreported decay of ${}_{}{}^{152}{}_{}{}^{}\mathrm{Pr}$ to levels in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Nd}$ has been studied from mass-separated activity produced in the thermal neutron fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. The ${}_{}{}^{152}{}_{}{}^{}\mathrm{Pr}$ half-life was measured to be 3.24±0.19 s, and its decay scheme was constructed based on $\gamma$ singles and coincidence measurements. Excited states in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Nd}$ at 72.6 ($2^{+}$) and 236.6 ($4^{+}$) were established and the $\frac{E\left(4^{+}\right)}{E\left(2^{+}\right)}$ ratio of 3.26 is close to the rigid rotor value of 3.33. The implications of the above ratio for the systematics of deformation in this region are discussed. A $\gamma$ transition observed at 285.0 keV probably results from the ${\beta }^{-}$ decay of ${}_{}{}^{152}{}_{}{}^{}\mathrm{Ce}$ with a half-life of 3.1±0.3 s, but that conclusion is tentative. The most likely $J$ for the ${}_{}{}^{152}{}_{}{}^{}\mathrm{Pr}$ ground state is 3.

RADIOACTIVITY ${}_{}{}^{152}{}_{}{}^{}\mathrm{Pr}$ and ${}_{}{}^{152}{}_{}{}^{}\mathrm{Ce}$ [from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(n, f)$]; measured $T_{\frac{1}{2}}$, $E_{\gamma }$, $I_{\gamma }$, $\gamma \gamma$, and $\gamma X$ coin, Ge(Li) detectors; ${}_{}{}^{152}{}_{}{}^{}\mathrm{Nd}$ and ${}_{}{}^{152}{}_{}{}^{}\mathrm{Pr}$ deduced levels, $J$, $\pi$, $log\mathrm{ft}$. Mass separated ${}_{}{}^{152}{}_{}{}^{}\mathrm{Pr}$ and ${}_{}{}^{152}{}_{}{}^{}\mathrm{Ce}$ activity.

• Received 11 January 1983

DOI:https://doi.org/10.1103/PhysRevC.27.2857