A sensitive neutron counter has been used for a study of delayed-neutron emission from mass-separated fission products. Five new delayed-neutron precursors, ${}_{}{}^{79}{}_{}{}^{}\mathrm{}(\mathrm{Z}\mathrm{n},\mathrm{G}\mathrm{a})\mathrm{}$, ${}_{}{}^{80}{}_{}{}^{}\mathrm{Ga}$, ${}_{}{}^{81}{}_{}{}^{}\mathrm{Ga}$, ${}_{}{}^{82}{}_{}{}^{}\mathrm{Ga}$, and ${}_{}{}^{83}{}_{}{}^{}\mathrm{Ga}$, have been found, and the half-life determination for seven other precursors has been improved.

RADIOACTIVITY ${}_{}{}^{79-83}{}_{}{}^{}\mathrm{Ga}$, ${}_{}{}^{85}{}_{}{}^{}\mathrm{As}$, ${}_{}{}^{87-92}{}_{}{}^{}\mathrm{Br}$, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Kr}$, ${}_{}{}^{92-98}{}_{}{}^{}\mathrm{Rb}$; measured delayed neutrons; deduced half-lives.

• Received 6 January 1975

DOI:https://doi.org/10.1103/PhysRevC.13.321