Half-lives of ${}_{}{}^{92-97}{}_{}{}^{}\mathrm{Rb}$ and ${}_{}{}^{142-145}{}_{}{}^{}\mathrm{Cs}$ have been measured by counting $\beta$ particles emitted from sources deposited on the first dynode of an electron multiplier at the collector end of an online mass spectrometer. Decay curve analysis included corrections for growth and decay of daughter and granddaughter activities as well as for growth and decay of delayed-neutron products. These results differ from some earlier measurements at masses 93, 94, and 145. They confirm with equal or smaller uncertainties the recent half-life measurements done by direct counting of neutrons from those nuclides which are delayed neutron precursors.

RADIOACTIVITY ${}_{}{}^{92,93,94,95,96,97}{}_{}{}^{}\mathrm{Rb}$, ${}_{}{}^{142,143,144,145}{}_{}{}^{}\mathrm{Cs}$; measured $T_{\frac{1}{2}}$, on-line mass spectrometer, $\beta$ counting.

• Received 1 May 1975

DOI:https://doi.org/10.1103/PhysRevC.12.718