One-neutron knockout of 23 O

. Breakup reactions were used to study the ground-state configuration of the neutron-rich isotope 23 O. The 22 O fragments produced in one-nucleon removal from 23 O at 938 MeV/nucleon in a carbon target were detected in coincidence with de-exciting γ rays, allowing to discern between 22 O ground-state and excited-states contributions. From the comparison of exclusive experimental momentum distributions for the one-neutron removal channel to theoretical momentum distributions calculated in an Eikonal model for the knockout process, and spin and parity assignment of I π = 1/2 + was deduced for the 23 O ground state. This result solved the existent experimental discrepancy.