An oil vapor helium-jet transfer system was used to study the ${\beta }^{+}$ decay of ${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ produced in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$,2pn)${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ reaction at 110-130 MeV. Singles and coincidence measurements established the decay to four levels in ${}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ and allowed measurements of $T_{\frac{1}{2}}=0.9\mathrm{}\pm 0.2$ sec for the decay halflife and $Q_{\mathrm{EC}}=6986\mathrm{}\pm 227$ keV for the total decay energy. In-beam studies of the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}, 3\mathrm{p}\gamma ){}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ reaction were made at 117 MeV. Two distinct bands were observed in ${}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ and probable spin and parity assignments were made. These data favor $J^{\pi }={\frac{5}{2}}^{+}$ for the ${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ ground state. The ${}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$ bands are compared to neighboring odd-$A$ nuclei and to recent calculations.

RADIOACTIVITY ${}_{}{}^{77}{}_{}{}^{}\mathrm{Sr}$ [from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$,2pn)], $E=110-130\mathrm{}$ MeV. Measured $T_{\frac{1}{2}}$, $\sigma \mathrm{}\left(E\right)\mathrm{}$, $E_{\gamma }$, $E_{\beta }$, $I_{\beta }$, $\gamma -\gamma$, $x-\gamma$, and $\beta -\gamma$ coincidences, deduced levels, $Q_{\mathrm{EC}}$, $log\mathrm{ft}$. He jet, Ge(Li), Ge, and plastic detectors.

NUCLEAR REACTIONS ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}, 3\mathrm{p}\gamma ){}_{}{}^{77}{}_{}{}^{}\mathrm{Rb}$, $E=117\mathrm{}$ MeV. Measured $E_{\gamma }$, $I_{\gamma }$, $\sigma \left(\theta \right)$, $p-\gamma$, and $\gamma -\gamma$ coincidences. Deduced levels, branching ratios, $J^{\pi }$, $\delta$. Ge(Li) detectors. Enriched target. Comparison with systematic trends and calculations.

• Received 25 May 1983

DOI:https://doi.org/10.1103/PhysRevC.28.2127