Universality of decay-out of superdeformed bands in the 190 mass region

Superdeformed nuclei in the 190 mass region exhibit a striking universality in their decay-out profiles. We show that this universality can be explained in the two-level model of superdeformed decay as related to the strong separation of energy scales: a higher scale related to the nuclear interactions, and a lower scale caused by electromagnetic decay. Decay-out can only occur when separate conditions in both energy regimes are satisfied, strongly limiting the collective degrees of freedom available to the decaying nucleus. Furthermore, we present the results of the two-level model for all decays for which sufficient data are known, including statistical extraction of the matrix element for tunneling through the potential barrier.