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The level structure of odd-proton '" Au was studied using the " Yb{' F,4n) reaction. Gammagamrna coincidence, angular distributions and y-y-time measurements were used to establish the energies, spins, parities, and lifetimes for the states in the decay scheme of '"Au. Both prolate and oblate structures have been established. The prolate bands are built on the~h9/2 (o, =+~) and thẽ i &3/2 (cx=~) particle states. An oblate, strongly coupled band built on a 90+10 ns isomeric state is reported for the first time. A second oblate structure built on the A»/~p roton-hole state was established to much higher spin than before. The backbend present in the~i »/2 band has been interpreted as the alignment of a pair of h9/p protons.

Multiple superdeformed rotational bands have been identified in a nucleus for the first time. Cascades of 14, 13, and 11 transitions have been assigned to three bands in 153 Dy. Despite the small intensities, it has been possible to follow the decay of these bands from an angular frequency of 0.7 down to 0.4 MeV/ft. In all three cases, the dynamic moment of inertia J (2) is nearly constant. Assignments to high-TV intruder orbitals are suggested through comparison of these values of J (2) with theoretical calculations based on the cranked shell model.

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Two excited superdeformed bands in ' Gd have been observed in y-ray spectroscopy. Based on the behavior of the dynamical moments of inertia we assign one band to a neutron excitation and the other to a proton excitation. The proton excited band y-ray energies are nearly identical to those already known in "Tb. In addition, two new members of the ' Gd yrast cascade have been observed extending the band to spin -", ' h. The results are discussed in terms of high-N intruder orbitals in the cranked shell model. The discovery of multiple superdeformed bands within one nucleus' has opened up the possibility of learning in greater detail the nuclear structure of these very interesting configurations. New impetus in this direction has also been generated by the observation of so-called "twinned" superdeformed bands in N=86 nuclei. 2 In the pairs (' 'Tb, ' Gd*) and (' Dy, ' 'Tb ), where one asterisk denotes the first excited superdeformed band, the same sequence of y-ray energies is found to within 1-2 keV over a span of fifteen or more transitions. This is a remarkable and unexpected phenomenon in nuclear structure physics.In the present work, we have been motivated to search for multiple bands in neighboring nuclei, and have reinvestigated the spectroscopy of ' Gd at a bombarding energy more favorable for populating the known, yrast superdeformed band and with improved statistics over our TABLE I. Transition energies and relative intensities of superdeformed bands observed in this experiment. Note that these values were derived from coincidence spectra gated by only clean gates. l49Gd E"(kev) 617.4(3) 664.4 (2) 7i i.7(3) 759.9 (2) 808.0(2) 857.0(2) 906.5(2) 957.3(

High-spin states in '"Pt have been studied with the ' Yb(' 0,4n }'"Pt reaction at 90 MeV using a multidetector array consisting of five Ge detectors and a multiplicity filter of six NaI counters. Rotational bands built on the Nilsson configurations -+[624], -[503], and -' [521] have been identified and interpreted within the framework of'the cranked shell model. Additional band structures built on levels at 3.131 and 3.294 MeV are observed which arise from more complex configurations. Experimental values of B(M1;I~I -1 }/B(E2;I~E -2} ratios have been extracted and compared to predictions of the semiclassical Donau and Frauendorf approach.

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