Decay Properties ofU232

The alpha and gamma spectra of ${\mathrm{U}}^{232}$ have been studied with an alpha-particle spectrograph and gamma-ray scintillation, proportional, and coincidence counters. Alpha groups of 5.318 Mev (68 percent), 5.261 Mev (32 percent) and 5.134 Mev (0.32 percent) and gamma rays of 57.9 kev (0.21 percent), 131 kev (0.075 percent), 268 kev (0.004 percent), and 326 kev (0.004 percent) were observed. The half-life of the 58-kev first excited state of ${\mathrm{Th}}^{228}$ was found to be less than 10 microseconds. Spins and parities are assigned to the energy levels, and the results are evaluated with respect to the developing theory and systematics of complex alpha spectra and excited states of even-even nuclei.