Problems with interpretation of ${}^{10}$He ground state

Abstract

The continuum of ${}^{10}$He nucleus is studied theoretically in a three-body ${}^8$He+$n$+$n$ model basing on the recent information concerning ${}^9$He spectrum [Golovkov, \textit{et al.}, Phys. Rev. C \textbf{76}, 021605(R) (2007)]. The ${}^{10}$He ground state (g.s.) candidate with structure $[p_{1/2}{]}^2$ for new g.s. energy of ${}^9$He is predicted to be at about $2.0-2.3$ MeV. The peak in the cross section associated with this state may be shifted to a lower energy (e.g. $\sim 1.2$ MeV) when ${}^{10}$He is populated in reactions with ${}^{11}$Li due to peculiar reaction mechanism. Formation of the low-energy ($E<250$ keV) ``alternative'' ground state with structure $[s_{1/2}{]}^2$ is highly probable in ${}^{10}$He in the case of considerable attraction (e.g. $a<-5$ fm) in the s-wave ${}^9$He channel, which properties are still quite uncertain. This result either questions the existing experimental low-energy spectrum of ${}^{10}$He or place a limit on the scattering length in ${}^9$He channel, which contradicts existing data.

Comments: 14 pages, 13 figures, 1 table