The unbound excited states of the neutron drip-line isotope 24O have been investigated via the 24O(p,p')23O+n reaction in inverse kinematics at a beam energy of 62 MeV/nucleon. The decay energy spectrum of 24O* was reconstructed from the momenta of 23O and the neutron. The spin-parity of the first excited state, observed at Ex = 4.65 +/- 0.14 MeV, was determined to be Jpi = 2+ from the angular distribution of the cross section. Higher lying states were also observed. The quadrupole transition parameter beta2 of the 2+ state was deduced, for the first time, to be 0.15 +/- 0.04. The relatively high excitation energy and small beta2 value are indicative of the N = 16 shell closure in 24O.
@article{arxiv.1205.5657,
title = {The N = 16 spherical shell closure in 24O},
author = {K. Tshoo and Y. Satou and H. Bhang and S. Choi and T. Nakamura and Y. Kondo and S. Deguchi and Y. Kawada and N. Kobayashi and Y. Nakayama and K. N. Tanaka and N. Tanaka and N. Aoi and M. Ishihara and T. Motobayashi and H. Otsu and H. Sakurai and S. Takeuchi and Y. Togano and K. Yoneda and Z. H. Li and F. Delaunay and J. Gibelin and F. M. Marqués and N. A. Orr and T. Honda and M. Matsushita and T. Kobayashi and Y. Miyashita and T. Sumikama and K. Yoshinaga and S. Shimoura and D. Sohler and T. Zheng and Z. X. Cao},
journal= {arXiv preprint arXiv:1205.5657},
year = {2015}
}