Level structure of 227Th investigated in the α decay of 231U

The level structure of Th-227 has been studied using the alpha decay of U-231. The use of mass-separated U-231 sources and high-resolution alpha-particle and gamma-ray spectroscopy enabled the identification of 16 excited levels of (227)Tn. The angular distribution of alpha particles in the decay of low-temperature oriented Th-227 is consistent with a (227)Tn ground-state spin of 1/2. The low-lying levels of Th-227,an be interpreted in terms of a K = 1/2(+/-) parity doublet and a K = 3/2(+) band coupled with the 1/2(+) member of the parity doublet by the Coriolis interaction.