Observation of identical superdeformed bands inN=86 nuclei

Excited superdeformed bands have been observed in the {ital N}=86 isotones {sup 150}Gd and {sup 151}Tb. The properties of these bands were found to closely resemble those of the yrast superdeformed bands in their {ital Z}+1 {ital N}=86 isotones ({sup 151}Tb and {sup 52}Dy) such that, on average, the transition energies are identical to an accuracy of 1:1000. It is proposed that these excited superdeformed bands are based on single-proton excitations from the (301)1/2 orbital into the (651)3/2 intruder orbital and thus they are the first obsrevation of proton excitations in superdeformed nuclei.