Yrast superdeformed band in Pb-194: J(pi) and E-x

The yrast superdeformed band in Pb-194 has been populated using the Yb-174(Mg-25,5n)Pb-194 reaction at E-beam = 130 MeV. Decay gamma rays were detected using the GAMMASPHERE array at the 88-Inch Cyclotron. Twelve gamma-ray transitions have been observed directly linking three members of the Pb-194 yrast superdeformed band to low-lying normal deformed levels. Anisotropy measurements indicate that these linking decays include E1, M1, and mixed M1/E2 multipolarities. The radiative widths deduced are very inhibited, typically B(E1)similar to 10(-8) Weisskopf units (W.u.) and B(M1)similar to 10(-5) W.u. Without recourse to a priori assumptions J(pi) = 6(+) and E-x = 4878.4(3) keV have been unambiguously assigned to the lowest-lying observed superdeformed state (the state populated by the 170-keV intraband transition). The intensity of the observed primaries accounts for 21(2)% of the superdeformed band population.