The unbound isotopes 9,10He

doi:10.1016/j.nuclphysa.2010.04.006

Nuclear Physics A

Volume 842, Issues 1–4, 15 October 2010, Pages 15-32

https://doi.org/10.1016/j.nuclphysa.2010.04.006 Get rights and content

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, ${}^{8}{He} + n$ and ${}^{8}{He} + 2 n$ , employing reaction models incorporating the structure of ¹¹Li.

The ${}^{8}{He} + n$ 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 $- 3.17 (66) fm$ . This spectrum also shows evidence for resonance states at $1.33 (8) MeV$ and at 2.4 MeV above the ${}^{8}{He} + n$ threshold. It is argued that the s-state might not be the ⁹He ground state.

For ${}^{8}{He} + n + n$ , the analysis of the relative-energy spectrum gives two alternative possibilities for an interpretation: either a narrow resonance at $1.42 (10) MeV$ ( $Γ = 1.11 (76) MeV$ ) superimposed on a correlated background, or two overlapping resonances, a ground state at 1.54(11) MeV ( $Γ = 1.91 (41) MeV$ ) together with an excited state at 3.99(26) MeV ( $Γ = 1.64 (89) MeV$ ). The two possible interpretations are discussed.

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Nuclear Physics A

Abstract

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