Lifetimes of states in two DELTA-I = 1 bands in 198Pb have been measured using the Doppler-shift attenuation method. The in-band reduced transition probabilities are approximately 1-2 Weisskopf units, assuming magnetic dipole transitions. The measured lifetimes in conjunction with the partial level scheme support an oblate collective interpretation for these structures.

A weakly populated rotational band with energy spacings characteristic of superdeformation has been found in the reaction Sm-154(48Ca,xn) at E(48Ca) = 205 MeV. This band has seven transitions with an average gamma-ray energy spacing of approximately 42 keV. It is assigned to 198Pb on the basis of the excitation-function results. We also confirm the isotopic assignment of a previously reported superdeformed (SD) band in 196Pb via the cross bombardments 176Yb(Mg-26,xn) and 176Yb(Mg-24,xn). Three SD bands have now been identified in the Pb isotopes with neutron numbers 112, 114, and 116.

Levels of $^{96}\mathrm{Zr}$ populated following the ${\ensuremath{\beta}}^{\mathrm{\ensuremath{-}}}$ decay of the ${0}^{\mathrm{\ensuremath{-}}}$ ground state of $^{96}\mathrm{Y}$ have been investigated by \ensuremath{\gamma}-ray and conversion electron singles, \ensuremath{\gamma}-ray multispectral scaling, \ensuremath{\gamma}-\ensuremath{\gamma} and \ensuremath{\gamma}-${\mathrm{e}}^{\mathrm{\ensuremath{-}}}$ coincidence, and \ensuremath{\gamma}-\ensuremath{\gamma} angular correlation measurements. These data have been used to establish the population of eight excited levels of $^{96}\mathrm{Zr}$, to confirm the ${0}^{+}$ assignment of the 2695-keV level, and to determine a half-life of 5.4(1) s for $^{96}\mathrm{Y}$. The deduced beta transition strengths establish the decay to the ground state, with logft of 5.6, as one of the fastest first-forbidden decays known and support the notion of double subshell closure at Z=40 and N=56. The observed strong hindrance of transitions to excited ${0}^{+}$ states is indicative of shape coexistence. The observed level pattern of the band built on the ${0}_{2}^{+}$ state exhibits similarities to nearby vibrational-like nuclei having four valence protons and four valence neutrons. A four-particle, four-hole interpretation of the ${0}_{2}^{+}$ state is supported by the data, and we determine a deformation parameter, ${\ensuremath{\beta}}_{2}$\ensuremath{\sim}0.2, for this intruder bandhead.

Low-lying states of /sup 200/Pt have been studied by the /sup 198/Pt(t,p..gamma..) and (t,pe/sup -/) reactions with 16-MeV tritons. From detailed p-..gamma.., p-e/sup -/, and p-..gamma..-..gamma.. coincidence measurements, a level scheme that includes 16 excited states has been established. A 14.3-ns isomer is observed and is believed to correspond to the 7/sup -/ isomers prevalent in the lighter even-mass platinum nuclei. Limited comparisons are made with the U(5) and O(6) symmetries of the interacting boson model.