Quasiparticle features and level statistics of odd-odd nucleus

The energy levels of the odd-odd nucleus Y-84 are calculated by using the a xially symmetric rotor plus quasiparticles model. The two standard statisti cal tests of Random-Matrix Theory such as the distribution function p(s) of the nearest-neighbor level spacings (NNS) and the spectral rigidity Delta (3) are used to explore the statistical properties of the energy levels. By analyzing the properties of p(s) and Delta (3) under various conditions, w e find that the quasiparticle features mainly affect the statistical proper ties of the odd-odd nucleus 84Y through the recoil term and the Coriolis fo rce in this theoretical mode, and that the chaotic degree of the energy lev els decreases with the decrease of the Fermi energy and the energy-gap para meters. The effect of the recoil term is small while the Coriolis force pla ys a major role in the spectral structure of Y-84.