SUPERDEFORMED SHAPES AND CONFIGURATIONS IN THALLIUM NUCLEI

Superdeformation studies in Tl-189,Tl-191,Tl-192 Gammasphere are discu ssed. New results on Tl-191 are the observation of interband transitio ns between the signature partner E2 bands and the measurement of an av erage quadrupole moment (Q(0) = 18 +/- eb) for these superdeformed str uctures. These data enable us to derive absolute M1 strengths and conf irm that the 81(st) proton occupies the [642]5/2 orbital. Tentative da ta for one superdeformed sequence in Tl-189 are consistent with the pr ediction of a decrease in quadrupole deformation for the lightest nucl ei at the limit of this island of superdeformation.