The 10.15 MeV resonance in 10Be has been probed via resonant 6He+4He elastic scattering. It is demonstrated that it is the Jpi=4+ member of a rotational band built on the 6.18 MeV 0+ state. A Gammaalpha of 0.10-0.13 MeV and Gammaalpha/Gamma=0.35-0.46 were deduced. The corresponding reduced alpha width, gamma2alpha, indicates one of the largest alpha-cluster spectroscopic factors known. The deformation of the band, including the 7.54 MeV, 2+ member, is large (h2/2I=200 keV). Such a deformation and the significant degree of clusterization signals a well-developed alpha:2n:alpha molecular structure.

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The low-lying level structure of the unbound neutron-rich nucleus 13 Be has been investigated via breakup on a carbon target of secondary beams of 14 B was found to populate a broad lowlying 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) ω shell-model calculations, the low-lying structure is concluded to arise from closely spaced J π =1/2 + and 5/2 + resonances (Er=0.40±0.03 and 0.85−0.11 MeV), whilst the broad higher-lying feature is a second 5/2 + level (Er=2.35±0.14 MeV). Taken in conjunction with earlier studies, it would appear that the lowest 1/2 + and 1/2 − levels lie relatively close together below 1 MeV.

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