Delayed neutron emission probabilities, $P_{\mathrm{n}}$, have been measured for ${}_{}{}^{98,99}{}_{}{}^{}\mathrm{Sr}$, ${}_{}{}^{97}{}_{}{}^{}\mathrm{Y}_{}^{g,m}{}_{}{}^{}$, ${}_{}{}^{96}{}_{}{}^{}\mathrm{Y}_{}^g{}_{}{}^{}$, ${}_{}{}^{99}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{147}{}_{}{}^{}\mathrm{Ba}$, and ${}_{}{}^{147,148}{}_{}{}^{}\mathrm{La}$. This is the first reported measurement for ${}_{}{}^{97}{}_{}{}^{}\mathrm{Y}_{}^m{}_{}{}^{}$. Upper limits to the $P_{\mathrm{n}}$ for ${}_{}{}^{97}{}_{}{}^{}\mathrm{Sr}$, ${}_{}{}^{146,148}{}_{}{}^{}\mathrm{Ba}$, and ${}_{}{}^{146}{}_{}{}^{}\mathrm{La}$ were established. The $P_{\mathrm{n}}$ values measured here are much smaller than a set of published measurements. Calculations of total delayed neutron yields from fission are consistent with experimental measurements of total delayed neutron yields except for fast neutron fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. Improved half-lives are reported for 13 of the Rb, Sr. Y, Cs, Ba, and La nuclides at masses 97-99 and 146-148.

RADIOACTIVITY ${}_{}{}^{97-99}{}_{}{}^{}\mathrm{Rb}$, ${}_{}{}^{97-99}{}_{}{}^{}\mathrm{Sr}$, ${}_{}{}^{97-99}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{146,147}{}_{}{}^{}\mathrm{Cs}$, ${}_{}{}^{147,148}{}_{}{}^{}\mathrm{Ba}$, ${}_{}{}^{147,148}{}_{}{}^{}\mathrm{La}$ [from ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}(\mathrm{n}, f)$]; measured $t_{\frac{1}{2}}$, $P_{\mathrm{n}}$; on-line mass separation, n, $\beta$ multiscaling.

• Received 24 January 1983

DOI:https://doi.org/10.1103/PhysRevC.28.1740