Evolution of the nuclear spin-orbit splitting explored via the 32Si(d,p)33Si reaction using SOLARIS
J. Chen, B. P. Kay, C. R. Hoffman, T. L. Tang, I. Tolstukhin, D. Bazin, R. S. Lubna, Y. Ayyad, S. Beceiro-Novo, B. J. Coombes, S. J. Freeman, L. P. Gaffney, Rajiv Garg, H. Jayatissa, A. N. Kuchera, Patrick T. MacGregor, A. J. Mitchell, W. Mittig, B. Monteagudo, A. Muñoz-Ramos, C. Müller-Gatermann, F. Recchia, N. Rijal, C. Santamaria, M. Z. Serikow, D. K. Sharp, J. F. Smith, Juliette K. Stecenko, G. L. Wilson, A. H. Wuosmaa, Cenxi Yuan, J. C. Zamora, Y.N. Zhang
Abstract
The spin-orbit splitting between neutron 1p orbitals at 33Si has been deduced using the single-neutron-adding (d,p) reaction in inverse kinematics with a beam of 32Si, a long-lived radioisotope. Reaction products were analyzed by the newly implemented SOLARIS spectrometer at the reaccelerated-beam facility at the National Superconducting Cyclotron Laboratory. The measurements show reasonable agreement with shell-model calculations that incorporate modern cross-shell interactions, but they contradict the prediction of proton density depletion based on relativistic mean-field theory. The evolution of the neutron 1p-shell orbitals is systematically studied using the present and existing data in the isotonic chains of N=17, 19, and 21. In each case, a smooth decrease in the separation of the 1p3/2-1p1/2 orbitals is seen as the respective p-orbitals approach zero binding, suggesting that the finite nuclear potential strongly influences the evolution of nuclear structure in this region.