UNISOR project

The decay of the members of the A = mass chain beginning with 188Tl has been studied by obtaining gamma and conversion electron multiscaled singles spectra, and gamma-gamma and conversion electron-gamma coincidence data. Data confirm a shift in the Yrast cascade in both 184Hg and 186Hg and provide evidence for band crossing in 188Hg. Under investigation are the A = 189 chain beginning with thallium and the A = 191 chain beginning with lead. General features of these decay chains are discussed. The excited states of 189Au and 191Au have also been studied through decay of the corresponding mercury parent. Positron decay Q values have been measured for some neutron deficient Tl, Hg, Xe, and I isotopes. Results are tentative. In addition, study of deformation effects in the mass 190 region has been extended to thallium by lead decays and a value has been obtained for the half life of the 193Pb high spin isomer. (8 figures, 1 table) (U.S.)