Onset of Collectivity in Neutron Deficient $^{196,198}$Po

Bernstein, L. A.; Cizewski, J. A.; Jin, H. -Q.; Younes, W.; Henry, R. G.; Farris, L. P.; Charos, A.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Bearden, I. G.; Ye, D.; Becker, J. A.; Henry, E. A.; Brinkman, M. J.; Hughes, J. R.; Kuhnert, A.; Wang, T. F.; Stoyer, M. A.; Diamond, R. M.; Stephens, F. S.; Deleplanque, M. A.; Macchiavelli, A. O.; Lee, I. Y.; Cederwall, B.; Oliveira, J. R. B.; Burde, J.; Fallon, P.; Duyar, C.; Draper, J. E.; Rubel, E.; Vo, D. T.

Onset of Collectivity in Neutron Deficient $^{196,198}$Po

Authors

Description

We have studied via in-beam $γ$-ray spectroscopy $^{196}$Po and $^{198}$Po, which are the first neutron-deficient Po isotopes to exhibit a collective low-lying structure. The ratios of yrast state energies and the E2 branching ratios of transitions from non-yrast to yrast states are indicative of a low-lying vibrational structure. The onset of collective motion in these isotopes can be attributed to the opening of the neutron i$_{13/2}$ orbital at N$\approx$112 and the resulting large overlap between the two valence protons in the h$_{9/2}$ orbital and the valence neutrons in the i$_{13/2}$ orbital.
(accepted by Phys. Rev. C, in press) 18 pages, revtex 3.0, Five figs. available upon request