The new spectroscopy of superdeformed states: Systematics in the light rare earths and unexpected feeding patterns

A systematic study in the light rare earth (N<82), concentrating on N=74 and Z=60, has revealed five superdeformed bands, in contrast to the situation for N>82, indicating that there is not a 'magic' superdeformed nucleus in the region. Striking population intensity differences are observed which are not explained by standard potential energy calculations. Open problems, particularly in connection with feeding into and out of the superdeformed bands, are discussed.