ANGULAR-MOMENTUM STRUCTURE OF THE YRAST BANDS OF DEFORMED-NUCLEI

We have quantitatively analyzed the wave functions of the low-lying yr ast states of deformed, heavy nuclei (specifically U-238 and Er-168) g iven by different models to determine the relative contribution of the valence nucleons to the total angular momentum of the nucleus. In all models, an yrast state is generated, as expected, by collective contr ibutions from both proton and neutron angular momenta. We have also ex amined the relative contribution of valence nucleons in the normal-par ity states and in the abnormal-parity, high-j, intruder states to the yrast angular momentum. If the stares with definite angular momenta pr ojected from the Nilsson intrinsic state of the nucleus are assumed to provide a good approximation to the structure of the yrast band, the contribution of nucleons in the abnormal-parity states to the yrast an gular momentum is shown to be about the same as that of nucleons in th e normal-parity states. This result is in marked contrast to the assum ption made in two prominent models (pseudo-SU3 model and its symplecti c extension and fermion dynamic symmetric model) that the nucleons in abnormal-parity states, do not, in the first approximation. contribute any angular momentum to the yrast band. We also find that the distrib ution of angular momenta contained in the intrinsic state of the abnor mal-parity nucleons in the j(n) configuration, which does not have any SU3 symmetry, is surprisingly similar to the distribution of angular momenta contained in an SU3 intrinsic state with the same average valu e of angular momentum.