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The unbound isotopes 9,10He

Authors :: Johansson, H.T.
Aksyutina, Yu.
Aumann, T.
Boretzky, K.
Borge, M.J.G.
Chatillon, A.
Chulkov, L.V.
Cortina-Gil, D.
Datta Pramanik, U.
Emling, H.
Forssén, C.
Fynbo, H.O.U.
Geissel, H.
Ickert, G.
Jonson, B.
Kulessa, R.
Langer, C.
Lantz, M.
LeBleis, T.
Mahata, K.
Source :: Nuclear Physics A. Oct2010, Vol. 842 Issue 1-4, p15-32. 18p.
Publication Year :: 2010
Abstract: Abstract: The unbound nuclei 9He and 10He have been produced in proton-knockout reactions from a 280 MeV/u 11Li beam impinging on a liquid hydrogen target at the ALADIN-LAND setup at GSI. Information on their nuclear structure has been obtained from the relative-energy spectra, and , employing reaction models incorporating the structure of 11Li. The relative-energy spectrum is dominated by a strong peak-like structure at low energy, which may be interpreted within the effective-range approximation as the result of an s-wave interaction with a neutron scattering length of . This spectrum also shows evidence for resonance states at and at 2.4 MeV above the threshold. It is argued that the s-state might not be the 9He ground state. For , the analysis of the relative-energy spectrum gives two alternative possibilities for an interpretation: either a narrow resonance at () superimposed on a correlated background, or two overlapping resonances, a ground state at 1.54(11) MeV () together with an excited state at 3.99(26) MeV (). The two possible interpretations are discussed. [Copyright &y& Elsevier]