Systematic behavior ofB(E2) values in the yrast bands of doubly even nuclei

Abstract

The experimental information on B(E2) transition rates in the yrast bands of doubly even nuclei (126<A<184) is systematized. The strength function x E(I~I-2) is found to reveal characteristic behavior significant for structure studies of yrast bands. The energy-weighted B(E2, I~I-2) values (Sexp) and 2J/h 2 (jr: moment of inertia) are plotted versus the rotational frequency squared h2co 2 for each nucleus. In strongly deformed nuclei (N >90), the Sex p curves smoothly increase for low rotational frequencies suggesting that up to spin values I ~ 8 the ratio Qz/j is nearly constant (Q0: quadrupole moment). This is not the case in nuclei with a soft core (N<88). In the relevant discussion, the hydrodynamical model as well as the CAP effect are considered. The results in the backbending region are qualitatively discussed in terms of the twoband crossing model. Evidence is found supporting the prediction of an oscillating behavior of the yrast-yrare interaction.