comitants. [*aequationes mathematicae*]{} [**1970**]{}, [*4*]{}, 127-138.

D. Lovelock. Degenerate Lagrange densities involving geometric objects . [*Arch. Ration. Mech. Anal.*]{} [**1970**]{}, [*36*]{}, 293-304.

[^1]: Electronic address: `aimericcx@yahoo.fr`


---
abstract: |
    The spectrum of $^9$He was studied by means of the $^8$He($d$,$p$)$^9$He reaction at a lab energy of 25 MeV/n and small center of mass (c.m.) angles. Energy and angular correlations were obtained for the $^9$He decay products by complete kinematical reconstruction. The data do not show narrow states at $\sim $1.3 and $\sim $2.4 MeV reported before for $^9$He. The lowest resonant state of $^9$He is found at about 2 MeV with a width of $\sim $2 MeV and is identified as $1/2^-$. The observed angular correlation pattern is uniquely explained by the interference of the $1/2^-$ resonance with a virtual state $1/2^+$ (limit on the scattering length is obtained as $a
    > -20$ fm), and with the $5/2^+$ resonance at energy $\geq 4.2$ MeV.
author:
- 'M.S. Golovkov'
- 'L.V. Grigorenko'
- 'A.S. Fomichev'
- 'A.V. Gorshkov'
- 'V.A. Gorshkov'
- 'S.A. Krupko'
- 'Yu.Ts. Oganessian'
- 'A.M. Rodin'
- 'S.I. Sidorchuk'
- 'R.S. Slepnev'
- 'S.V. Stepantsov'
- 'G.M. Ter-Akopian'
- 'R. Wolski'
- 'A.A. Korsheninnikov'
- 'E.Yu. Nikolskii'
- 'V.A. Kuzmin'
- 'B.G. Novatskii'
- 'D.N. Stepanov'
- 'S. Fortier'
- 'P. Roussel-Chomaz'
- 'W. Mittig'
date: '. [File: he9-11.tex ]{}'
title: 'New insight into the low-energy $^9$He spectrum'
---

*Introduction.* — Since the first observation of $^9$He in the experiment [@set87] it was studied in relatively small number of works compared to the neighbouring exotic neutron dripline nuclei. This can be connected, on one hand, to the facts that technical difficulty of the precision measurements rapidly grows with move away from the stability line. On the other hand, already in the first experiment (pion double charge exchange on the $^9$Be nucleus [@set87]) several narrow resonances were observed above the