Comment on "Prolate-oblate band mixing and new bands in 182Hg"

Bindra et al. @1# have recently reported on in-beam g-ray spectroscopic studies of Hg and on the observation of different band structures in this nucleus. In particular, they discuss the position of the well-known prolate band relative to the oblate ground-state band. They identified the 2 member of the prolate band and developed on this basis a discussion of the minimum in the prolate-oblate energy difference as a function of neutron number. They point out that when the 0 and 2 members of the oblate and prolate band interact, the prolate band member energies will alter significantly from the values calculated by using the rotational formula and high-spin members of the band. They state that ‘‘Any conclusion about the prolate-oblate energy difference based on the high-spin members may be questioned.’’ Indeed, extrapolation of the prolate band using the rotational formula and the high-spin members results in the unperturbed excitation energy of the prolate 0 bandhead relative to the experimental 0 ground state and not to the unperturbed oblate 0 bandhead. The unperturbed excitation energy equals the energy difference between the unperturbed oblate and prolate bandhead (DEP-O) plus the energy shift ~D0! due to mixing Eunpert(02 )5DEP-O1D0 . A crucial test is then to compare the unperturbed energy with the experimental position on the 02 1 . Here the authors are not taking into account our measurement of the 02 1 bandhead position through the observation of fine structure in the a decay of Pb @2#. In Fig. 1 all the information is brought together on the oblate ground-state band ~up to spin 4! and the prolate band ~up to spin 8! for Hg. Also given is the position of the 0, 2 and 4 prolate band members extrapolated from the high-spin members ~6–12! with the rotational formula @E01AI(I11)1BI (I11)# . A nice agreement with the experimental values is obtained for the 0 and 4 states. Only the 22 1 states in Hg and Hg are significantly deviating. This means that the 0 bandhead of the prolate band is essentially not mixing with the oblate ground state when reaching its minimum at N5102. From a-decay studies of Pb it has been shown that the high hindrance of the a