Additional Data on the Radioactive Decay of ${\mathrm{Ho}}^{166}$ (27 hr), ${\mathrm{Nd}}^{147}$, and ${\mathrm{Sm}}^{153}$

By using chemically pure ${\mathrm{Ho}}^{165}$ and enriched isotopes of ${\mathrm{Nd}}^{146}$ and ${\mathrm{Sm}}^{152}$, high-activity samples of ${\mathrm{Ho}}^{166}$, ${\mathrm{Nd}}^{147}$, and ${\mathrm{Sm}}^{153}$ were made by neutron caputre. Studies of the strong sources by both magnetic and scintillation spectrometers showed the existence of some gamma rays not previously reported, yielded more exact energy values for the low-energy gamma rays, and made possible better resolution of the components of the beta spectra. In ${\mathrm{Ho}}^{166}$, gamma rays occur at 80.25, 970, 1377, 1540, and 1620 kev, and the maximum beta energies are 1839, 1756, 869, 412, and 230 kev. ${\mathrm{Nd}}^{147}$ yields gamma rays at 91.3, 120.6, 198.2, 277, 321, 400, 441, 533, and 688 kev, with beta components at 812, 380, and 230 kev. In ${\mathrm{Sm}}^{153}$ gamma rays are found at 69.8, 103.5, 173.6, and 540 kev and beta components at 813, 710, and 640 kev. A level scheme in agreement with the observed data is presented for each nucleus.