On M3-transition rates in selected odd-mass nuclei

摘要

The reduced probabilities of M3 transitions are studied in five deformed and three spherical or near-spherical odd-mass nuclei. In deformed nuclei, the states linked by M3 transitions are predominantly of single-quasiparticle nature and the calculations are performed taking into account the single-quasiparticle as well as core-polarization terms in the M3-operator. Whereas in Ho-159, Yb-175, and Hf-179 the ratio between theoretical and experimental B(M3) values range from 0.5 to 1.4, the situation is much worse in neutron deficient nuclides W-179 and (183)pt where the theory used can not explain a very sharp drop of the B(M3) values. In the soft nuclei Cs-121 and (207)po the states connected by M3 transitions are treated as "quasiparticle circle times phonon" states. In Sn-113, the small "quasiparticle circle times phonon" components are not sufficient to compensate vanishing contribution of the dominant quasiparticle component, which shares Deltal forbidden transitions. Thus, on the whole theoretical description of B(M3) with the present simple models seems to be unsatisfactory. It constitutes a challenging problem both at the level of the nuclear structure and the transition operator. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 24]