High-spin levels in the 109Pb and 200Pb isotopes

The de-excitation of the 200Pb and 199Pb isotopes, produced through the 186W(18O, 4n, 5n) reactions, is investigated using γ-ray and conversion electron spectroscopy. The conversion coefficients are measured and the multipolarities deduced for a great number of transitions. The e-γ- and γγ-coincidences and the half-life measurements lead to several new levels in both level schemes; the 200Pb one is extended up to nearly 7 MeV, where an isomer is found. The experimental results are compared to those of microscopic calculations, performed in a two or three quasi-particle approximation, using a surface delta interaction with a reduced pairing component. (orig.)