Nuclear structure of Ac-231
  The low-energy structure of 231Ac has been investigated by means of gamma ray spectroscopy following the beta-decay of 231Ra. Multipolarities of 28 transitions have been established by measuring conversion electrons with a mini-orange electron spectrometer. The decay scheme of 231Ra --> 231Ac has been constructed for the first time. The Advanced Time Delayed beta-gamma-gamma(t) method has been used to measure the half-lives of five levels. The moderately fast B(E1) transition rates derived suggest that the octupole effects, albeit weak, are still present in this exotic nucleus. 
R. Boutami, M. J. G. Borge, H. Mach, W. Kurcewicz, L. M. Fraile, K.   Gulda, A. J. Aas, L. M. Garc\'ia-Raffi, G. L{\o}vh{\o}...