Invariant Mass Spectroscopy of 23 O via the ( p , p ′) Reaction in Inverse Kinematics

The neutron-rich oxygen isotope 23 O has been investigated via proton inelastic scattering on a liquid hydrogen target at 63.5 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum. A sharp resonance state was observed at 42(5) keV above the neutron threshold. A comparison of the differential cross section leading to this state with a microscopic DWBA calculation allowed a J π assignment of 5/2 + for this state.