Magnetic rotation in Pb-197 and Pb-198

High-spin states in Pb-197 and Pb-198 were populated in the W-186(O-18, xn) reactions. In-beam gamma -ray coincidences were measured in two experiment s using the GAMMASPHERE and the EUROGAM Il spectrometer arrays, respectivel y. In both nuclei new bands of enhanced magnetic dipole transitions were fo und and the known cascades were partly reordered and extended to higher spi ns. In most cases, gamma -ray transitions connecting the magnetic rotationa l bands to lower-lying states have been identified. Configuration assignmen ts are suggested for the bands. The systematic behavior confirms the shears mechanism. An effective interaction between the main high-spin proton and neutron orbitals is derived. (C) 2001 Elsevier Science B.V. All rights rese rved.