Quasiparticles plus rotor model and the analysis of level statistics of odd-odd nucleus

The energy levels of odd-odd nucleus Y-84 at low spins were calculated by u sing the axially symmetric particles plus rotor model. In order to study th e statistical properties of the energy levels, the two standard tests of Ra ndom-Matrix Theory such as the nearest-neighbor level spacings and the spec tral rigidity were adopted. It is shown that the chaotic degree of the ener gy levels initially increases with increasing spin and reaches a maximum ar ound I=10, and then decreases for spins above I approximate to 10. On the o ther hand, the proton-neutron interaction makes the energy levels slightly regular/ordered. However, the Coriolis force which makes the energy levels chaotic plays a major role in the spectral structure of the odd-odd nucleus Y-84.