Superdeformed bands at high spin in Z=60, 66 and 68 isotopes

The nucleus 152Dy, with sharp ridges in the γ-γ -energy correlation matrix, stands out as a single case among three neighboring nuclei, which exhibit less pronounced structures. The ridges include the observed discrete superdeformed (SD) band, but must be composed mainly of unresolved superdeformed bands, which decay predominantly to less deformed states. A simple decay model is proposed, based on the possible lowering in energy of one SD band due to shell (and/or pairing) effects. SD bands with β≅0.4-0.5 and with spins up to ∼40, were found in 134,135,136Nd. The band in 135Nd is the most strongly populated of all SD bands observed so far and the only one with established connections to known low-lying yrast states. 13 refs., 6 figs. (author)