Investigation into the B(E2) anomaly in Nd144 using Coulomb excitation

The ratio of B(E2) strengths between the lowest lying members of the ground state band in Nd144, B4/2=B(E2;41+→21+)/B(E2;21+→01+), which is used to quantify collectivity in nonmagic nuclei, has been remeasured by means of Coulomb excitation. Ambiguities in literature values for this ratio have been resolved. The results are discussed in terms of the interplay of collective and single-particle degrees of freedom, and in the context of the formation of collective structures in the A=140 mass region, and more generally near (sub)shell closures. In addition, the B4/2 ratio of Sm148 has been remeasured, and the quadrupole moment of the 41+ state is found to be on the order of 1eb. © 2008 The American Physical Society