Observation of a two-neutron cascade from a resonance in 24O

A new resonance having a relative decay energy of similar to 0.6 MeV has been observed above the two-neutron separation energy in O-24 at an excitation energy of similar to 7.5 MeV. The new level was found to directly feed the first excited state in O-23, an E = 0.045(2)-MeV resonance, through the measurement of neutron-neutron correlations. Energy level comparisons with O-23 suggest that this new level in O-24 is dominated by an unpaired neutron in the nu 0d(3/2) single-particle orbital coupled to a single hole in the nu 0d(5/2) single-particle orbital. Establishment of this two-neutron discrimination technique provides a means for investigating high-lying excited states in neutron-rich nuclei.