Low-spin excitations in 146Sm

The low-spin excitations of the nucleus 146 Sm 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 143 Nd ( α, n ) and 144 Nd ( α , 2 n ) 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 γ-γ angular correlation analysis. The structure of the possible candidates for a 2 + ⊗ 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 146 Sm 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 + ⊗ 3 − quadrupole-octupole multiplet and also a series of collective properties such as the proposed double-octupole excitations.