INTERACTING BOSON MODEL FOR SUPERDEFORMATION

The superdeformation is discussed from the point of view of the interacting boson model (IBM). By studying the structure of the superdeformed band in terms of the Nilsson model, it is suggested that superdeformed states have a spherical inert core which is much smaller than that for normal states. Based on the dominant role of the J-pi = 0+ and 2+ nucleon pairs in the Nilsson wave function, the super interacting boson model is proposed. Due to the small inert core, the number of bosons in the super IBM is increased by a factor of 2-3 from the normal IBM. The SU(3) symmetry is shown to be suitable, indicating a possibility of super beta and gamma-bands around 2.4 MeV for 194Hg. The boson charge and the interaction strength of the super IBM turn out to be comparable to those in the normal IBM. The decay out of the superdeformed band is reproduced in agreement with experiment for 194Hg.