Levels and transitions in 227Ac

Levels and transitions in 227Ac were investigated by measuring perturbed and unperturbed γγ directional correlations and γ-ray distributions from oriented nuclei. The ensemble of oriented nuclei was prepared by diffusing 231Pa into a gadolinium host and cooling to 16 mK. The multipole mixing ratios of six transitions were evaluated and spin-parity assignments to a number of levels were confirmed. Singles and coincident spectra were measured and the relative intensities of transitions with Esub(γ) > equal to 120keV were obtained and the great majority of these were placed in the decay scheme. The data are consistent with previous interpretations of this nucleus in the context of the Nilsson model. (author)