The well-known shell structure of stable atomic nuclei has been observed to change insystems with extreme proton-neutron ratios. Understanding this changing structure canprovide insight into the underlying forces between nucleons, and how they can lead to shellstructure. The N = 28 shell gap, which disappears in the region of the nuclear chart centeredon 42Si, is an interesting case because this gap is the first gap which requires the assumptionof a strong spin-orbit splitting in the shell-model framework.Previous experimental work on the breakdown of the N = 28 shell gap has generally uti-lized collective observables which have then been interpreted though theoretical calculationsin terms of changing shell structure. In this work, one-proton and one-neutron knockoutreactions are used to obtain a complimentary, single-particle picture of this region, focusingon the neutron-rich silicon isotopes 36Si, 38Si, and 40Si. This isotopic chain connects theclosed-shell nucleus 34Si to 42Si, which does not reflect a good shell closure. Level schemesof knockout residues 35,37,39Si and 35,37,39Al are constructed, with new levels identified foreach nuclide. These results, in conjunction with large-scale shell model and eikonal reactionmodel calculations, generally support the interpretation developed to explain the collectiveobservables. They further emphasize and illuminate the importance of excitations acrossboth the N = 20 and N = 28 shell gaps for describing nuclides in this region, and provideadditional guidance for shell model effective interactions in describing this region.In addition, an empirical method is introduced to model the asymmetry observed in themomentum distributions by utilizing inelastic scattering reactions to approximate the dissi-pative effects of target breakup, producing good agreement with the measured distributions.
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