The Radioactivities of Some High Mass Isotopes of Cobalt

By neutron bombardments of samples of Ni enriched in isotopes 61, 62, and 64, respectively, the following radioactivities have been identified: ${\mathrm{Co}}^{61}$, ${\beta }^{-}$ 1.3 Mev, no $\gamma$, half-life 1.75 hours, ${\mathrm{Co}}^{62}$, ${\beta }^{-}$ 2.3 Mev, $\gamma$ 1.3 Mev, half-life 13.9 min.

Evidence is also presented for a 1.6-minute $\beta$- and $\gamma$-activity associated with ${\mathrm{Co}}^{62}$, and for a 4- to 5-minute activity possibly of ${\mathrm{Co}}^{64}$.