No abstract

Levels in ' '' ' Sm were populated by the beta decay of Eu, following (HI, pxn) reactions and on-line mass separation. The beta decay of " Eu with a half-life of 3.9(+0.5j s was observed for the first time. Members of the y band were observed in all three daughter nuclei. Spectroscopic calculations were made using the triaxial rotor model, with all parameters derived microscopically from a Woods-Saxon deformed shell model. Other spectroscopic models were also considered.Comparison with the data supports the characterization of these nuclei in terms of a triaxial intrinsic shape,

The/~-decays of l~ and l~ have been studied at the fission product separators JOSEF and LOHENGRIN. Half-lives of (1.5_0.2)s and (2.95+0.06)s, respectively, have been determined for these decays. From 7 singles and 7-7 coincidence measurements extended level schemes for ~~ and 1~ have been established for the first time. The lowest energy levels of these nuclei are consistent with the interpretation as members of rotational bands built on a 3/2 + [411] Nilsson state. Evidence is presented for the location of the 9/2 + [404] configuration.

Radioactive l~was produced as a fission product and separated by use of the gasfilled magnetic separator JOSEF. Isomeric l~ half lives of 0.99 and 4.8s were determined. It was established that the shorter half life is due to the decay of a highspin isomer. Singles and ~-~ coincidence spectra were used to identify 45y-rays of t~The previous assignment of the principal y-rays to ~~ was confirmed. An energy level scheme of ~~ with levels up to 2,888keV of excitation has been constructed. Calculations in the frame of the interacting boson approximation (IBA) have been performed. The data are consistent with a description of ~~ as a nucleus at the limit between the transitional and the deformed region.