Nuclear structure beyond the neutron drip line: The lowest energy states in 9 He via their T = 5/2 isobaric analogs in 9 Li
E. Uberseder (Department of Physics & Astronomy, Cyclotron Institute, Texas A&M; University, College Station, TX, 77843, USA); G.V. Rogachev (Department of Physics & Astronomy, Cyclotron Institute, Texas A&M; University, College Station, TX, 77843, USA); V.Z. Goldberg (Department of Physics & Astronomy, Cyclotron Institute, Texas A&M; University, College Station, TX, 77843, USA); E. Koshchiy (Department of Physics & Astronomy, Cyclotron Institute, Texas A&M; University, College Station, TX, 77843, USA); B.T. Roeder (Department of Physics & Astronomy, Cyclotron Institute, Texas A&M; University, College Station, TX, 77843, USA); et al - Show all 13 authors
The level structure of the very neutron rich and unbound 9 He nucleus has been the subject of significant experimental and theoretical study. Many recent works have claimed that the two lowest energy 9 He states exist with spins Jπ=1/2+ and Jπ=1/2− and widths on the order of 100–200 keV. These findings cannot be reconciled with our contemporary understanding of nuclear structure. The present work is the first high-resolution study with low statistical uncertainty of the relevant excitation energy range in the 8 He+n system, performed via a search for the T=5/2 isobaric analog states in 9 Li populated through 8 He+p elastic scattering. The present data show no indication of any narrow structures. Instead, we find evidence for a broad Jπ=1/2+ state in 9 He located approximately 3 MeV above the neutron decay threshold.
