Decay ofSr77and level structure ofRb77

Abstract

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.