Abstract
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.
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