COULOMB EXCITATION AND REORIENTATION OF OCTUPOLE STATE IN PB-208

The static quadrupole moment (Q) of the 2.614-MeV 3- level in Pb208 has been measured by observing the angular distribution of inelastically scattered He4 and O16 ions following E3 Coulomb excitation. The reduced matrix element for the E3 transition from the ground state to the 3- state, B(E3) was also obtained. Distributions were taken over the range 80°-170°, using a multiple solid-state-detector array, at particle energies of 19, 18, and 17.5 MeV, and at an oxygen energy of 69.1 MeV. Differential inelastic cross sections were in the range 10-40 b/sr for s and 200-300 b/sr for oxygen. The 19-MeV data showed strong interference between the Coulomb-excitation amplitude and an amplitude resulting from direct nuclear excitation. The remaining three sets of data showed no such intereference and were analyzed simultaneously using the symmetrized semiclassical Coulomb-excitation theory of Alder et al.: The fitted parameters B(E3) and Q are correlated, with best-fit values of B(E3)0.58±0.04 e2 b3 and Q=-1.3±0.6 b. The data are not very sensitive to Q and yet are essential to the result, for the analysis of the and oxygen data together limits the acceptable parameter range much more than if the oxygen data alone are used. © 1969 The American Physical Society.