One-neutron knockout from Ni-57

The single-particle structure of $^{57}\mathrm{Ni}$ and level structure of $^{56}\mathrm{Ni}$ were investigated with the $^{9}\mathrm{Be}$ ($^{57}\mathrm{Ni}$,$^{56}\mathrm{Ni}+\ensuremath{\gamma}$)$X$ reaction at 73 MeV/nucleon. An inclusive cross section of 41.4(12) mb was obtained for the reaction, compared to a theoretical prediction of 85.4 mb, hence only 48(2)% of the theoretical cross section is exhausted. This reduction in the observed spectroscopic strength is consistent with that found for lighter well-bound nuclei. One-neutron removal spectroscopic factors of 0.58(11) to the ground state and 3.7(2) to all excited states of $^{56}\mathrm{Ni}$ were deduced.