Low-spin excitations in 146Sm

The low-spin excitations of the nucleus Sm-146 which is just two neutrons and two protons away from the N = 82 shell and Z = 64 subshell closures have been investigated by means of the Nd-143(alpha, n) and Nd-144(alpha, 2n) fusion-evaporation reactions. We established 47 hitherto unknown energy levels up to 4.7MeV and 75 new transitions. In addition, 7 spin assignments were possible from the gamma-gamma angular correlation analysis. The structure of the possible candidates for a 2(+) circle times 3(-) quadrupole-octupole multiplet are first discussed in terms of the harmonic vibrational model. A comparison of these states with the corresponding ones in the neighboring N = 84 isotones is also presented. Finally, the structure of the Sm-146 nucleus is interpreted in terms of the IBA-spdf model. It is shown that the model is able to reproduce the experimental relative transition strengths of the 2(+) circle times 3(-) quadrupole-octupole multiplet and also a series of collective properties such as the proposed double-octupole excitations.