LIFETIMES OF THE 21(-)/2-STATE AND 29(+)/2-STATE IN AT-211 AND THEIR IMPLICATION FOR EFFECTIVE CHARGES AND QUADRUPOLE-MOMENTS

The lifetimes of the 21(-)/2 state (1416 keV) and the 29(+)/2 state (2641 keV) in At-211 were measured to be tau(m) = 50.7(10) ns and tau(m) = 73.3(10) ns, respectively, using the gamma gamma-time technique. Using these lifetime measurements a value for the quadrupole moment of the 29(+)/2 state was derived. The explicit inclusion of octupole coupling effects into a description of the configuration for the 29(+)/2 level allows the extraction of an orbital independent effective charge of e(eff) = 1.5e. From this a nominal value for the quadrupole moment of the pi i(13/2) orbital can be deduced. New levels identified have allowed a determination of the strength of the pi i(13/2)-pi f(7/2) residual interaction.