Studies were made on the ${\mathrm{Pb}}^{212}$ (ThB) active deposit by means of gamma singles and beta-gamma, gamma-gamma, gamma-alpha, and gamma-gamma-alpha coincidence measurements. The singles and coincidence gamma-ray spectra were recorded on an RCL 256-channel analyzer, and an intermediate-image beta-ray spectrometer was used in the beta-gamma work. Beta intensities of 4.6±0.2, 23.9±0.8, 22.7±0.7, 48.8±2.7, and <0.5% were obtained for the 1.04-, 1.29-, 1.52-, 1.80-, and 2.38-Mev groups, respectively, of the ${\mathrm{Tl}}^{208}$→${\mathrm{Pb}}^{208}$ decay. Existence of the 1.800-Mev gamma ray in ${\mathrm{Po}}^{212}$ was established and 11.2±0.7% of the ${\mathrm{Bi}}^{212}$→${\mathrm{Po}}^{212}$ disintegrations were determined to go by way of the 0.727-Mev transition. Relative intensities of 11.1±0.7, 1.7±0.3, 0.66±0.07, 0.16±0.04, 0.99±0.08, 0.49±0.05, 2.8±0.2, and 0.17±0.03 were found for the 0.727-, 0.786-, 0.893-, 0.953-, 1.073-, 1.513-, 1.620-, and 1.800-Mev gamma rays, respectively, in ${\mathrm{Po}}^{212}$. The ratio of alpha to total disintegrations for the ${\mathrm{Bi}}^{212}$ decay was measured to be 0.3596±0.0006.

• Received 14 April 1960

DOI:https://doi.org/10.1103/PhysRev.120.189