Decay ofZn61

The 88.5-sec activity observed among the products of the bombardment of nickel with 16-Mev alpha particles is assigned to ${\mathrm{Zn}}^{61}$. The decay properties of this isotope have been investigated by beta and gamma scintillation techniques and by coincidence measurements. Approximately 80% of the ${\mathrm{Zn}}^{61}$ beta decays are to the ground state of ${\mathrm{Cu}}^{61}$. The positron end point is 4.38 Mev which corresponds to a log ft of 5.2 and to an allowed transition. Gamma rays of 0.48, 0.98, and 1.64 Mev have been observed with intensities of 11.2, 2.9, and 6.2% of the positrons. There is some indication of gamma rays at 0.69 Mev and possibly other energies in lower intensities. A decay scheme is proposed which incorporates the above data into an existing level scheme of ${\mathrm{Cu}}^{61}$ derived from ($p, \gamma$) experiments.