Theoretical Determination of Level Spins of Superdeformed Bands for Nuclei in the Mass Region A = 80 – 104

The bandhead spins of seventeen superdefomed bands in A = 80 – 104 region (38Sr, 39Y, 40Zr, 41Nb,42Mo, 43Tc, 46Pd) have assigned by an indirect method. The dynamical moment of inertia J(2) as a function of rotational frequency ђω are extracted from Harris expansion and fitted to the experimental values by using a computer simulated search program. The calculated dynamic moment of inertia with the best optimized parameters are integrated to give the spins. The intrinsic aligned angular momentum (the integration constant) is assumed to be zero. The values of the spins resulting from our approach are consistent with all spin assignments of other approaches, and have been used to determine the kinematic moment of inertia J(1). The systematic variation of J (2) and J (1) with rotational frequency ђω is investigated, which turns out to be helpful in the spin prediction. Most SD bands in this mass region exhibits decreasing in J(1) and J(2) with increasing ђω. The bandhead moment of inertia J0 which occur at J(2) = J (1) has been sensitive guideline parameter to spin proposition. The relationship between the Harris expansion three parameter model and the four parameter Bohr-Mottelson formula is derived.

COLLECTIVE BANDS IN SUPERDEFORMED NUCLEI

The collective properties of excited superdeformed bands have been investigated in the framework of self-consistent cranked Nilsson plus quasiparticle random-phase approximation. The expected octupole nature of some bands observed recently in some nuclei has been confirmed by a comparative analysis of their E1 decays to the yrast band and of the anomalous behavior of their dynamical moment of inertia. It is also shown that the onset of supederformation affects considerably the structure of the giant resonances and greatly enhances the collectivity of the low-lying scissors mode.