Radiations fromHo164

The decay modes of 36.7-min ${\mathrm{Ho}}^{164}$ have been studied with a magnetic spectrometer, scintillation spectrometer, and proportional counter. Decay to the two even-even daughters, ${\mathrm{Dy}}^{164}$ by orbital electron capture, and ${\mathrm{Er}}^{164}$ by beta decay, is indicated. The beta spectrum appears to be complex, with maximum energy 0.99±0.03 Mev. Gamma rays of energy 90.5, 72.8, and 37.3 kev, together with x-rays at 45.7 kev, are found. There is also evidence for a gamma ray at approximately 46 kev. Photon-photon coincidences are found for 46-73 and 37-46 kev approximate energies. Photon-beta coincidences are found to involve photons of approximate energy 91 and 50 kev. The data are interpreted in terms of first excited levels at 72.8 kev in ${\mathrm{Dy}}^{164}$, 90.5 kev in ${\mathrm{Er}}^{164}$, with probably a second level in ${\mathrm{Dy}}^{164}$ at 110 kev. Delayed photon-beta and photon-photon coincidences were found with a half-life of 1.4×${10}^{-9\mathrm{}}$ sec. The former are associated with the 90.5-kev level of ${\mathrm{Er}}^{164}$; the assignment of the photon-photon coincidences is uncertain. A possible isomeric transition in ${\mathrm{Ho}}^{164}$ is also suggested. Spin and parity assignments, on the basis of conversion coefficients and $log\left(f_{0}t\right)$ value, are made for certain of the levels.