Coulomb excitation of the lead isotopes with α and 16O beams

Abstract The lead isotopes were Coulomb excited with α-particles of 15 and 18 MeV and 16 O ions of 70 and 80 MeV. By measuring the absolute yields of the de-excitation γ-rays very accurately, B ( Eλ ) values for the first 2 + states in 204 Pb and 206 Pb, the 3 − states in 206 Pb and 208 Pb and of four states in 207 Pb were obtained. The E2 transition strengths to the two first excited states of 207 Pb are well described by coupling these states to a quadrupole core excitation of 208 Pb. The B (E3) values for the excitation of the ( 3 − ⊗p 1 2 ) doublet show only slight deviations from the weak coupling value, yet the lifetimes of the two states, which were determined with the Doppler-shift attenuation method, are different from model predictions. The M1 transition rate of the 3 2 − state to ground as determined from the lifetime of 0.17 ps agrees with the value obtained from the B (E2) and the mixing ratio measurement.