At the ALADIN-LAND setup at GSI the unbound nucleus 13 Be has been produced in one-neutron knockout reactions from a 304 MeV/nucleon relativistic beam of 14 Be ions impinging on a liquid hydrogen target. An analysis of the data including all available information about 13 Be, and in particular recent data from a similar experiment performed at RIKEN, has been performed. A consistent description is reached. It is found that the excitation spectrum is dominated by s-waves at low energy, which solves problems from previous seemingly contradictory interpretations. A possible interference between two s-states in 13 Be is also discussed. The results indicate that the ground-state wave function of 14 Be is dominated by valence neutrons in the s-shell contributing with 60-75% of the total neutron knockout cross section.

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