Superdeformation inPb198,196

Abstract

A weakly populated rotational band with energy spacings characteristic of superdeformation has been found in the reaction ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$ ${(}^{48}$Ca,xn) at E${(}^{48}$Ca)=205 MeV. This band has seven transitions with an average γ-ray energy spacing of approximately 42 keV. It is assigned to ${}_{}{}^{198}{}_{}{}^{}\mathrm{Pb}$ on the basis of the excitation-function results. We also confirm the isotopic assignment of a previously reported superdeformed (SD) band in ${}_{}{}^{196}{}_{}{}^{}\mathrm{Pb}$ via the cross bombardments ${}_{}{}^{176}{}_{}{}^{}\mathrm{Yb}$ ${(}^{26}$Mg,xn) and ${}_{}{}^{176}{}_{}{}^{}\mathrm{Yb}$ ${(}^{24}$Mg,xn). Three SD bands have now been identified in the Pb isotopes with neutron numbers 112, 114, and 116.