Level density fluctuations and characterization of chaos in the realistic model spectra for odd-odd nuclei

Statistical properties of the realistic energy spectra of the odd-odd nuclei 106Ag, 198Au, 134Cs, 40K and 94Rb, calculated within the interacting boson fermion fermion model, are investigated by means of the Δ3 statistics and the nearest neighbor spacing distribution method. A new probability distribution function, which describes well the calculated results and enables the characterization of chaos with a physically meaningfull parameter, is proposed. The level spacing fluctuations of the examined nuclei exhibit the transitional behavior between Poisson and GOE limits, revealing different degrees of chaoticity in their dynamics. (orig.)