Statistical properties of quasiparticle spectra in deformed nuclei

The statistical properties of quasiparticle spectra in deformed heavy nuclei are studied. It has been found that at the ground state and at minima of the potential, Poisson-like spacing distributions are observed both in the quasiparticle spectra and in the single-particle ones. However, at the saddle point configuration in an even system, the original Wigner-like single-particle spacing distribution changes to a mixture of Wigner- and Poisson-like quasiparticle distributions, whereas for an odd system the pairing hardly changes the Wigner-like distribution. Therefore, from this study we have observed the tendency of the pairing effect to act to make the system more stable. [S0556-2813(99)05701-5].