th / 9 71 20 32 v 1 8 D ec 1 99 7 Excitation energy of superdeformed bands in Relativistic Mean Field Theory

Constrained Relativistic Mean Field (RMF) calculations have been carried out to estimate excitation energies relative to the ground state for superdeformed bands in the mass regions A ∼ 190 and A ∼ 150. It is shown that RMF theory is able to successfully reproduce the recently measured superdeformed minima in Hg and Pb nuclei. Superdeformation has become the recent years one of the most interesting topics of nuclear structure studies. After the well known area in the vicinity of the mass number A ∼ 150 a second region with A ∼ 190 has been discovered, where an impressive number of results has been obtained. However, despite the rather large amount of experimental information on superdeformed bands, there are still a number of very interesting properties , which have not yet been measured. A characteristic example is the excitation energy between ground and superdeformed bands. The excitation energy and the well depth of the superdeformed minimum are amongst the most important factors which affect the decay of the superdeformed bands to the ground state. Very recently discrete γ rays directly connecting states of a superdeformed band in 194 Hg to the yrast states have been discovered [1]. This has made it possible to determine accurately the excitation energy of the levels of the superdeformed band above the yrast line. Extrapolating to zero angular momentum the superdeformed minimum was found to be 6.017 MeV above the ground state. Similar measurements at about the same time have also been reported for the superdeformed band of 194 Pb nucleus [2]. The excitation energy between the SD band and the ground state was estimated to be 4.471(6) MeV.