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 we re detected using the GAMMASPHERE array at the 88-Inch Cyclotron. Twel ve gamma-ray transitions have been observed directly linking three mem bers of the Pb-194 yrast superdeformed band to low-lying normal deform ed 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 pr iori assumptions J(pi) = 6(+) and E-x = 4878.4(3) keV have been unambi guously assigned to the lowest-lying observed superdeformed state (the state populated by the 170-keV intraband transition). The intensity o f the observed primaries accounts for 21(2)% of the superdeformed band population.