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.

• Received 13 March 2013

DOI:https://doi.org/10.1103/PhysRevC.87.064316