Two-neutron Sequential Decay of $^{24}$O

A recent experiment performed at the NSCL populated a two-neutron unbound excited state in $^{24}$O through a (d,d') reaction at 82 MeV/nucleon. Using invariant mass spectroscopy, a three-body state was observed in the $^{22}$O + $2n$ system at E = $750^{+100}_{-100}$ keV and $\Gamma = 100^{+300}_{-100}$ keV, placing it at $\sim$7.68 MeV with respect to the ground state of $^{24}$O. Three-body correlations for the decay of $^{24}$O $\rightarrow$ $^{22}$O + $2n$ were examined and found to show strong evidence for a sequential decay through an intermediate state in $^{23}$O. A di-neutron or phase-space model for the three-body breakup is unable to describe these correlations.