Nuclear structure of 189Tl states studied via \( \beta^{{+}}_{}\) /EC decay and laser spectroscopy of 189m+gPb

The \( \beta^{{+}}_{}\) /EC decay of 189m, gPb has been studied at the ISOLDE facility using nuclear spectroscopy and in-source laser spectroscopy. A level scheme of 189Tl has been built from \( \gamma\) -\( \gamma\) coincidence relationships and information on the feeding of some excited levels of 189Tl provided by the hyperfine spectra obtained from laser ionization. The half-lives of both the 13/2+ and 3/2- 189Pb isomers have been estimated to be T 1/2 = 50±3 s and T 1/2 = 39±8 s, 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 189Tl nucleus.