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Physics Letters B 718 (2012) 441-446
New excited states in the halo nucleus 6He
X. Mougeot1, V. Lapoux1, W. Mittig2, N. Alamanos1, F. Auger1, B. Avez1, D. Beaumel3, Y. Blumenfeld3, R. Dayras1, A. Drouart1, C. Force2, L. Gaudefroy4, A. Gillibert1, J. Guillot3, H. Iwasaki1, T. Al Kalanee2, N. Keeley, L. Nalpas1, E.C. Pollacco1, T. Roger2, P. Roussel-Chomaz2, D. Suzuki, K.W. Kemper, T.J. Mertzimekis, A. Pakou, K. Rusek, J.-A. Scarpaci3, C. Simenel1, I. Strojek, R. Wolski

The low-lying spectroscopy of 6He was investigated via the 2-neutron transfer reaction p(8He, t) with the 8He beam delivered by the SPIRAL facility at 15.4 A MeV. The light charged particles produced by the direct reactions were measured using the MUST2 Si-strip telescope array. Above the known 2+ state, two new resonances were observed: at E∗ = 2.6±0.3 MeV (width Γ = 1.6±0.4 MeV) and at 5.3±0.3 MeV with Γ = 2 ± 1 MeV. Through the analysis of the angular distributions, they correspond to a 2+ state and to an L = 1 state, respectively. These new states, challenging the nuclear theories, could be used as benchmarks for checking the microscopic inputs of the newly improved structure models, and should trigger development of models including the treatments of both core excitation and continuum coupling effects.
1 :  IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers (ex DAPNIA)
2 :  GANIL - Grand Accélérateur National d'Ions Lourds
3 :  IPNO - Institut de Physique Nucléaire d'Orsay
4 :  DAM/DIF - DAM Île-de-France
Physique/Physique Nucléaire Expérimentale
8He(p – t) – Transfer reaction – Borromean nucleus – Resonant states