Properties of the odd-A samarium nuclei

Beams of 6-11 MeV α particles and 38-48 MeV 16O ions obtained from the ANU EN tandem accelerator were used to study 147Sm and 148Sm via the Coulomb excitation process. This work has provided information on the energies, branching ratios, transition probabilities and spin and parity assignments for the low lying states of these nuclei. B(E2) values of greater than 20 single particle units were measured for several states in each nucleus. With neutron numbers N=85 and 87, the odd mass Sm nuclei provide a test for model predictions of the properties of transitional odd-A nuclei. Coupling of a single particle to the vibrational core represented by the even-even neighbour fails to reproduce the observed level sequence for the strongly collective states in these nuclei. Since, in a shell model framework, 147Sm and 149Sm correspond to (2f7/2)3 and (2f7/2)-3 neutron configurations respectively, it is reasonable to postulate that the low lying states of these nuclei derive their overall energy and spin structure from the (2f7/2)+-3 recoupling scheme whilst the collective nature exhibited in the observed B(E2) strengths arises from rather large phonon admixtures in the wave functions of these states. A multiparticle-vibration coupling model calculation was applied to the N=84 to 88 Sm isotopes and is found in good overall agreement with experimental level schemes and E2 transition probabilities. (author)