High spin structure of Ar39 and the FSU cross-shell interaction

High-spin states in Ar-39 were populated using the Al-27(C-14, pn) reaction at 25.6 MeV. The de-exciting gamma rays were measured with the FSU gamma detector array along with evaporation protons in a Si E-Delta E telescope. The known high-spin level scheme was extended up to over 11 MeV with a dozen new levels above the neutron decay threshold. The decay pattern appears somewhat atypical for heavy-ion fusion-evaporation reactions. The structure of Ar-39 is discussed in terms of the new FSU cross-shell spsdpf interaction fitted to a wide range of nuclei. This interaction has proved quite successful in accounting for the level scheme of Ar-39, including the previously suggested fully aligned pi f(7)(/2) circle times nu f(7/2) 17/2(+) state and previously discovered analogs of the lowest states in Cl-39.