Nuclear Structure Of Tl-189 States Studied Via Beta(+)/Ec Decay And Laser Spectroscopy Of Pb189m+G

The beta(+)/EC decay of Pb-189m,Pb-g has been studied at the ISOLDE facility using nuclear spectroscopy and in-source laser spectroscopy. A level scheme of T-189 has been built from gamma-gamma coincidence relationships and information on the feeding of some excited levels of Tl-189 provided by the hyperfine spectra obtained from laser ionization. The half-lives of both the 13/2(+) and 3/2(-) Pb-189 isomers have been estimated to be T-1/2 = 50 +/- 3s and T-1/2 = 39 +/- 8s, respectively. Calculations have been performed for different oblate and prolate nuclear deformations using an axial-rotor coupled to one-quasiparticle model, a structure has been suggested for the low-lying levels of the Tl-189 nucleus.