Decay-out from low-lying superdeformed bands in Pb isotopes: Tunneling widths in a two-level mixing model

A recently developed two-level mixing model of superdeformed decay is applied to evaluate the tunneling width between the superdeformed and normally deformed potential wells in ¹⁹²Pb and ¹⁹⁴Pb. Estimates are made of level densities and γ decay widths for levels in the normally deformed well, which are required for evaluation of the model. Experimental quasicontinuum results are used to suggest a spin-dependent reduction of the energy gap in the level spectrum, resulting in approximately constant level densities and decay widths in the normal well over the decay-out region for each isotope. However, it transpires that the model's prediction of the tunneling width is nearly independent of the normally deformed state widths for both isotopes. This observation is used to extract potential barrier heights for the two nuclei that depend mainly on experimentally determined values.