Coulomb excitation of vibrational triplet states and octupole states in the even cadmium nuclei

Abstract

Oxygen-16 ions with energies of 42 to 49 MeV have been used to Coulomb excite higher states in the even cadmium isotopes. Double E2 excitation of the 0 + state at 1133 keV in 144Cd has been observed. The E2 transition between the excited 0′ + state and the first 2 + state is strongly enhanced, i.e., B( E2, 0′ → 2) B( E2, 2 → 0) = 0.85±0.17 . The second 2 + state and the 4 + state in 116Cd are degenerate to within 5 keV at 1222 keV excitation. The values obtained for the ratio B( E2, 4 → 2) B( E2, 2 → 0) are 1.42±0.19, 1.82±0.23, 1.80±0.23 and 1.63±0.36, respectively for 110Cd, 112Cd, 114Cd and 116Cd. States at 2051±16, 1968±16, 1945±16 and 1900±16 keV are excited in 110Cd, 112Cd, 114Cd and 116Cd, respectively. If these states are interpreted to be the result of direct E3 Coulomb excitation, the B(E3, 0 → 3) are 10.3, 10.6, 9.0, and 7.5×10 4 e 2fm 6 with an accuracy of ±20% provided the branching ratio of cascades to crossover from the 3 − state is large compared to unity. These B(E3) values represent enhancement of 13 to 20. They are 3 to 6 times smaller than the results derived from yield measurements with 14–15 MeV α particles at Copenhagen.