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arXiv · nucl-ex/0608035

New insight into the low-energy $^9$He spectrum

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
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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.

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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. 2006-08-17. New insight into the low-energy $^9$He spectrum. https://doi.org/10.1103/physrevc.76.021605

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