Low-lying excited states of the neutron-rich calcium isotopes 48−52Ca have been studied via γ-ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA γ-ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.
@article{arxiv.1604.08624,
title = {Octupole strength in the neutron-rich calcium isotopes},
author = {L. A. Riley and D. M. McPherson and M. L. Agiorgousis and T. R. Baugher and D. Bazin and M. Bowry and P. D. Cottle and F. G. DeVone and A. Gade and M. T. Glowacki and S. D. Gregory and E. B. Haldeman and K. W. Kemper and E. Lunderberg and S. Noji and F. Recchia and B. V. Sadler and M. Scott and D. Weisshaar and R. G. T. Zegers},
journal= {arXiv preprint arXiv:1604.08624},
year = {2016}
}