Ground-stateβbranching of gaseous fission products and their daughters forA=88−91

The ground-state $\beta$ branchings for several mass-separated Kr fission products and their daughters have been measured at the TRISTAN on-line separator facility at the Ames Laboratory Research Reactor. Absolute $\beta$ counting was done with a $4\pi$-geometry plastic scintillation detector and $\gamma$ spectra were taken simultaneously with a Ge(Li) detector. The deduced values of the ground-state $\beta$ branching ${\beta }_{\mathrm{gs}}$, expressed as a percentage of decays, are: ${}_{}{}^{88}{}_{}{}^{}\mathrm{Kr}$, 14±4; ${}_{}{}^{88}{}_{}{}^{}\mathrm{R}\mathrm{b},$ 78.0±1.2; ${}_{}{}^{89}{}_{}{}^{}\mathrm{K}\mathrm{r},$ 23±4; ${}_{}{}^{89}{}_{}{}^{}\mathrm{R}\mathrm{b},$ 25±5; ${}_{}{}^{90}{}_{}{}^{}\mathrm{K}\mathrm{r},$ 29±4; ${}_{}{}^{90}{}_{}{}^{}\mathrm{Rb}_{}^{\mathrm{g}}{}_{}{}^{}$, 37±5; ${}_{}{}^{91}{}_{}{}^{}\mathrm{K}\mathrm{r},$ 10±4; ${}_{}{}^{91}{}_{}{}^{}\mathrm{R}\mathrm{b},$ 5±5.