Proton hole
= Proton hole
A missing <proton> relative to a filled <nuclear shell>. In a closed-core approximation a single hole in a $j$ orbital has the same total <angular momentum> $j$ and orbital <parity> as the removed particle. For example, removing a $p_{1/2}$ <proton> from a spin-zero closed core gives $J^P=1/2^-$.