  One-neutron knockout from 24O leading to the first excited state in 23O has
been measured for a proton target at a beam energy of 62 MeV/nucleon. The decay
energy spectrum of the neutron unbound state of 23O was reconstructed from the
measured four momenta of the 22O fragment and emitted neutron. A sharp peak was
found at Edecay=50$\pm$3 keV, corresponding to an excited state in 23O at
2.78$\pm$0.11 MeV, as observed in previous measurements. The longitudinal
momentum distribution for this state was consistent with d -wave neutron
knockout, providing support for a J{\pi} assignment of 5/2+. The associated
spectroscopic factor was deduced to be C2S(0d5/2)=4.1$\pm$0.4 by comparing the
measured cross section (View the MathML source) with a distorted wave impulse
approximation calculation. Such a large occupancy for the neutron 0d5/2 orbital
is in line with the N=16 shell closure in 24O.
