The structure of low-lying rotational bands in the nucleus 170Tm

Abstract

The data of the 1 − (ground state) and 0 − (first excited) rotational bands in 170Tm are analysed within the framework of a simple model where these Bands are mixed by the Coriolis coupling. Due to the symmetry properties of the internal wave functions, the even- I and odd- I members of the 0 − band essentially act as two independent bands. The main intrinsic configuration is assumed to be 1 2 + [411] p 1 2 − [521] n . The band-head energies, the Coriolis matrix elements, and the moments of inertia are overdetermined by a fit to the experimental energy levels. The transition data also give information about the band mixing, and in addition determine some of the intrinsic M1 and E2 matrix elements. For the intrinsic structure and the mixing of the bands, the result of the analysis shows satisfactory agreement with model calculations and with evidence from adjacent nucleides. The two relevant energy splittings are calculated with a residual neutron-proton interaction, taken to be given by a central, spin and exchange dependent potential with Gaussian shape. We find that with such an assumption one can reproduce the observed energy splittings, although the available parameters are not uniquely determined from the data.