The apparent splitting between orbitals that are spin-orbit partners can be substantially influenced by the effects of finite binding. In particular, such effects can account for the observed decrease in separation of the neutron $1p_{ 3/2}$ and $1p_{ 1/2}$ orbitals between the $^{ 41}$Ca and $^{ 35}$Si isotopes. This behavior has been the subject of recent experimental and theoretical works and cited as evidence for a proton "bubble" in $^{ 34}$Si causing an explicit weakening of the spin-orbit interaction. The results reported here suggest that the change in the separation between the $1p_{ 3/2}$ and $1p_{ 1/2}$ partners occurs dominantly because of the behavior of the energies of these $1p$ neutron states near zero binding.
Categories: nucl-th nucl-ex