Unified description of collective nuclei with the interacting boson model

It was recently demonstrated that the empirical linear correlation of E(41+) with E(21+) is reproduced by the interacting boson model 1 (IBA-1) if a constant value for the coefficient κ of the Q·Q term is used. This constancy motivates the present investigation of whether it is possible to find sets of IBA-1 parameters, with fixed κ, that reproduce the data for a more general set of observables and a wide range of nuclei. A consistent procedure, based on contour plots of key observables, was used to extract ε and χ values for 145 nuclei spanning the Z = 50 endash 82 shell, which give reasonable overall agreement with the data with smoothly varying parameters. The constant κ constraint sometimes leads to parameter values different than normal: finite ε values (∼ 0.1 MeV) even for rotational nuclei and large χ values for transitional and vibrational nuclei that even increase towards the vibrational region. Finally, a systematic correlation of ε values with E(21+) was found. copyright 1997 The American Physical Society