The beta and gamma rays emitted in the decay of ${\mathrm{Zn}}^{69}$ and ${\mathrm{Zn}}^{71}$ have been studied with a ten-channel coincidence scintillation spectrometer. The previous assignments of a 435-kev isomeric transition to the 14-hr ${\mathrm{Zn}}^{69}$ activity and a 900-kev beta ray to the 1-hr ${\mathrm{Zn}}^{69}$ activity were confirmed. In addition to the 2.2-min activity of ${\mathrm{Zn}}^{71}$, a previously unreported 3-hr activity of ${\mathrm{Zn}}^{71}$ was detected. A beta ray with an end-point energy of 2.4±0.2 Mev and gamma rays with energies of 0.12, 0.51, 0.90, and 1.09 Mev were detected and assigned to the 2.2-min activity. A beta ray with an end-point energy of 1.5±0.1 Mev and gamma rays with energies of 0.38, 0.49, and 0.61 Mev were detected and assigned to the 3-hr ${\mathrm{Zn}}^{71}$ activity. It was established that each of the gamma rays in the 3-hr activity is in coincidence with the other two gamma rays as well as the 1.5-Mev beta ray. Decay schemes for the two ${\mathrm{Zn}}^{71}$ activities are proposed.

• Received 22 October 1954

DOI:https://doi.org/10.1103/PhysRev.97.750