Correlations of decays above and below isomeric states in the normally deformed minimum of ${}^{192}\mathrm{P}\mathrm{b}$ have been used to identify discrete transitions in the decay of the superdeformed (SD) band. The data establish the absolute excitation energy of the lowest observed SD level as 4.425 MeV. Extrapolation to the bandhead indicates that the excitation energy of the superdeformed well in ${}^{192}\mathrm{P}\mathrm{b}$ is 0.5 MeV lower than in the heavier isotope ${}^{194}\mathrm{P}\mathrm{b}$. The results confirm the trend to decreasing excitation energy with decreasing neutron number predicted by both a macroscopic Strutinsky method approach and microscopic mean field calculations.

• Received 12 December 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.142501