Coulomb Excitation of 142Ce and 144Nd

The N = 84 nuclei 142Ce and 144Nd have been Coulomb-excited using 4He, 12C and 160 projectiles. Scattered particles were detected at a mean laboratory angle of 170.6° with an annular silicon surface-barrier detector. The static quadrupole moment f the 2t state was determined for both nuclei. In addition, various electromagnetic transition probabilities involving the 2~, 2~, 1 and 4t states were measured. Taken in conjunction with previous information, the results show that the properties of 142Ce nd 144Nd are well described by the vibrational U(S) limit of IBM-2, and strongly support the proposition that the 2~ level in each nucleus is an essentially pure one d-boson mixed-symmetry state.