Evidence for Two-Nucleon Polarization in the π(h9/2i13/2)11- ν(j-2)0+ Level in 208Po

From in-beam gamma-ray spectroscopy measurements on the 208Pb(α, 4n)208Po reaction using the Stockholm 225-cm cyclotron, we have concluded that there is an 11-, 8 ns isomeric state in 208Po, which lies 1 175 keV above the π(h 9/2 2)8+ state and that this isomeric state should have the configuration π(h 9/2 i 13/2)11- ν(j -2)0+. Calculations based on the use of empirical two-particle interactions give a position of the 11- level which deviates by about + 100 keV from the experimentally found position. It is suggested that this deviation is mainly due to the difference in the polarization of the 206Pb-and 208Pb-cores by the two aligned h 9/2 and i 13/2 protons.