De-excitation of high spin isomers in the Pb-191 isotope

The Pb-191 isotope, produced through different A(b,xn)Pb-191 reactions, whe re b stands for nuclei such as O-16, Ne-20, and P-31, is studied. The half- life of some excited levels being greater than 10 ns, the recoil catcher me thod is suitable to look into the de-excitation gamma ray and conversion el ectron spectra of these states. The conversion coefficients are deduced and e(-)-gamma and gamma-gamma coincidence measurements lead to the part of th e level scheme de-exciting these isomers. This level scheme is compared to theoretical predictions obtained through a microscopic calculation in a thr ee quasiparticle approximation, using a surface delta interaction with a re duced pairing component. The conclusions are very similar to those previous ly obtained for Pb-193. (C) 1999 Elsevier Science B.V.