Spectroscopy of neutron-unbound $^{27,28}$F
  The ground state of $^{28}$F has been observed as an unbound resonance $2\underline{2}0$ keV above the ground state of $^{27}$F. Comparison of this result with USDA/USDB shell model predictions leads to the conclusion that the $^{28}$F ground state is primarily dominated by $sd$-shell configurations. Here we present a detailed report on the experiment in which the ground state resonance of $^{28}$F was first observed. Additionally, we report the first observation of a neutron-unbound excited state in $^{27}$F at an excitation energy of $25\underline{0}0 (2\underline{2}0)$ keV. 
G. Christian, N. Frank, S. Ash, T. Baumann, P. A. DeYoung, J. E.   Finck, A. Gade, G. F. Grinyer, B. Luther, M. Mosby, S. Mo...
nucl-ex