One-proton knockout reaction of $^{20}\mathrm{N}$

Nuclear structure away from stability can change drastically due to the re-ordering of shell-model orbitals. In particular, near the neutron drip line, the neutron $1s_{1/2}$ orbital and $0d_{5/2}$ orbitals may become degenerate or even inverted. In order to study the trend of these orbitals across the $N=13$ isotones, a one-proton knockout reaction from $^{20}$N has been performed. The cross section is sensitive to states in $^{19}$C as well as the ground state in $^{20}$N. The experiment was performed at the NSCL with a beam of $^{20}$N at 70 MeV/nucleon. Gamma rays in coincidence with the $^{19}$C fragments were measured with GRETINA to determine exclusive cross sections, and the momentum of $^{19}$C recoils were recorded by the S800. Results will be compared to reaction calculations in the eikonal model.