Decay-out probabilities of superdeformed bands in statistical and two-level mixing models

A recent measurement has established the excitation energy above yrast of a superdeformed band in ¹⁹²Pb as only 2 MeV at the point of decay. This value is significantly lower than is generally assumed in models of the decay-out process (but is consistent with several theoretical predictions). Estimates of level densities and 7 decay widths for levels in the superdeformed band, and for levels at the same energies in the normally-deformed well, are made for this nucleus and the neighbour ¹⁹⁴Pb. Two recent models of the decay are then used to explore the data, and the results of these analyses are compared. Finally, questions are raised about the interpretation of the resulting spreading widths/interaction matrix elements and the implications for the decay-out process.