Neutron-hole states in Sn and spin-orbit splitting in neutron-rich nuclei

Orlandi, R.  ; Pain, S. D.*; Ahn, S.*; Jungclaus, A.*; Schmitt, K. T.*; Bardayan, D. W.*; Catford, W. N.*; Chapman, R.*; Chipps, K. A.*; Cizewski, J. A.*; Gross, C. G.*; Howard, M. E.*; Jones, K. L.*; Kozub, R. L.*; Manning, B.*; Matos, M.*; Nishio, Katsuhisa   ; O' Malley, P. D.*; Peters, W. A.*; Pittman, S. T.*; Ratkiewicz, A.*; Shand, C.*; Smith, J. F.*; Smith, M. S.*; Fukui, Tokuro*; Tostevin, J. A.*; Utsuno, Yutaka   

Low-lying neutron-hole states in Sn were populated via the Sn(d,t) reaction at Oak Ridge National Laboratory. The triton angular distributions were compared to DWBA calculations and revealed spectroscopic factors compatible with a single-hole nature of the states populated. The data permit to determine the spin-orbit splitting of the strongly bound and neutron orbits below the shell gap, which was compared to the splitting of the weakly bound 3 and 2 orbits above the gap. The comparison revealed a smaller energy splitting of the 3 orbits. All splittings were reproduced using Woods-Saxon calculations, and the lower splitting of the 3 orbits was explained to arise from the large radial extent of the wavefunction and small value of the amplitude at the surface. This result is important to understand at a fundamental level the spin-orbit interaction, and its effects on neutron-rich nuclei.