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Abstract. The spectroscopic structure of 19 C, a prominent one-neutron halo nucleus, has been studied with a 20 C secondary beam at 290 MeV/nucleon and a carbon target. Neutron-unbound states populated by the one-neutron knockout reaction were investigated by means of the invariant mass method. The preliminary relative energy spectrum and parallel momentum distribution of the knockout residue, 19 C * , were reconstructed from the measured four momenta of the 18 C fragment, neutron, and beam. Three resonances were observed in the spectrum, which correspond to the states at E x = 0.62(9), 1.42(10), and 2.89(10) MeV. The parallel momentum distributions for the 0.62-MeV and 2.89-MeV states suggest spin-parity assignments of 5/2 + and 1/2 − , respectively. The 1.42-MeV state is in line with the reported 5/2 + 2 state. a

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International audienc

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