Structure of 13Be probed via secondary-beam reactions

G. Randisi*, A. Leprince, H. Al Falou, N. A. Orr, F. M. Marqués, N. L. Achouri, J. C. Angélique, N. Ashwood, B. Bastin, T. Bloxham, B. A. Brown, W. N. Catford, N. Curtis, F. Delaunay, M. Freer, E. De Góes Brennand, P. Haigh, F. Hanappe, C. Harlin, B. LaurentJ. L. Lecouey, A. Ninane, N. Patterson, D. Price, L. Stuttgé, J. S. Thomas

*Corresponding author for this work

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24 Citations (Scopus)


The low-lying level structure of the unbound neutron-rich nucleus 13Be has been investigated via breakup on a carbon target of secondary beams of 14,15B at 35 MeV/nucleon. The coincident detection of the beam velocity 12Be fragments and neutrons permitted the invariant mass of the 12Be+n and 12Be+n+n systems to be reconstructed. In the case of the breakup of 15B, a very narrow structure at threshold was observed in the 12Be+n channel. Analysis of the 12Be+n+n events demonstrated that this resulted from the sequential decay of the unbound 14Be(2+) state rather than a strongly interacting s-wave virtual state in 13Be, as had been surmised in stable beam fragmentation studies. Single-proton removal from 14B was found to populate a broad low-lying structure some 0.7 MeV above the neutron-decay threshold, in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)ℏω shell-model calculations, the low-lying structure is concluded to arise from closely spaced Jπ=1/2+ and 5/2+ resonances (Er=0.40±0.03 and 0.85+0.15-0.11 MeV), while the broad higher-lying feature is a second 5/2+ level (Er=2.35±0.14 MeV). Taken in conjunction with earlier studies, the results suggest that the lowest 1/2+ and 1/2- levels lie relatively close together below 1 MeV.

Original languageEnglish
Article number034320
Number of pages13
JournalPhysical Review C
Issue number3
Publication statusPublished - 26 Mar 2014

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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