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Fortune, H. T.

doi:10.1103/physrevc.91.034314

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…In contrast, a very recent theoretical work connecting states in 9 He to states in 10 He [13] argues that the J π = 1/2 + state cannot exist below 1.0 MeV (otherwise 10 He must be neutron-bound) relative to the neutron threshold.…”

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confidence: 92%

“…Seth et al [2] noted surprisingly good agreement between the energies of the peaks in the observed spectrum of π + -mesons and the predictions of a shell model, attributing a J π = 1/2 − spin assignment to the 1.13 MeV peak. Shortly thereafter, the 9 He ground state was populated using the 9 Be( 13 C, 13 O) and 9 Be( 14 C, 14 O) reactions [3][4][5] and its energy was revised to 1.27±0.10 MeV. It appeared to be a narrow resonance with width of only 100±60 keV in the first high resolution study [5].…”

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confidence: 99%

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Nuclear structure beyond the neutron drip line: The lowest energy states in 9 He via their T = 5/2 isobaric analogs in 9 Li

et al. 2016

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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 J π = 1/2 + and J π = 1/2 − and widths on the order of hundreds of 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 J π = 1/2 + state in 9 He located approximately 3 MeV above the neutron decay threshold.

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confidence: 92%

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confidence: 99%

Nuclear structure beyond the neutron drip line: The lowest energy states in 9 He via their T = 5/2 isobaric analogs in 9 Li

et al. 2016

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“…The same phenomenon is found in 10 Li [30][31][32][33][34], making it quite natural to hypothesize that the same trend continues for 9 He. Both experimental [35][36][37][38][39][40][41][42][43][44][45][46][47] and theoretical [48][49][50][51][52][53][54][55][56][57][58][59][60][61] efforts have been dedicated in the past to probe this hypothesis. Experimentally the situation is still under debate and a detailed history of the experimental studies on 9 He can be found in Ref.…”

Section: Introductionmentioning

confidence: 99%

Structure of the exotic He9 nucleus from the no-core shell model with continuum

et al. 2018

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Background: The exotic 9 He nucleus, which presents one of the most extreme neutron-to-proton ratios, belongs to the N = 7 isotonic chain famous for the phenomenon of ground-state parity inversion with decreasing number of protons. Consequently, it would be expected to have an unnatural (positive) parity ground state similar to 11 Be and 10 Li. Despite many experimental and theoretical investigations, its structure remains uncertain. Apart from the fact that it is unbound, other properties including the spin and parity of its ground state and the very existence of additional low-lying resonances are still a matter of debate. Purpose: In this work we study the properties of 9 He by analyzing the n+ 8 He continuum in the context of the ab initio no-core shell model with continuum (NCSMC) formalism with chiral interactions as the only input. Methods: The NCSMC is a state-of-the-art approach for the ab initio description of light nuclei. With its capability to predict properties of bound states, resonances, and scattering states in a unified framework, the method is particularly well suited for the study of unbound nuclei such as 9 He. Results: Our analysis produces an unbound 9 He nucleus. Two resonant states are found at the energies of ∼1 and ∼3.5 MeV, respectively, above the n+ 8 He breakup threshold. The first state has a spin-parity assignment of J π = 1/2 − and can be associated with the ground state of 9 He, while the second, broader state has a spin-parity of 3/2 − . No resonance is found in the 1/2 + channel, only a very weak attraction. Conclusions: We find that the 9 He ground-state resonance has a negative parity and thus breaks the parity-inversion mechanism found in the 11 Be and 10 Li nuclei of the same N = 7 isotonic chain.

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“…In l0-l2Be and 14J6C, differences in calculated and experim ental energies w ere in the range o f 100-300 keV. For l4Be [3] and l()He [4], the model was used to discover inform ation about the single-particle energies (spe's) in l3Be and 9He. Briefly, for (sd )2 states in an A + 2 nucleus, w here A is a p-shell core, the model takes as s and d spe's the experim ental 1 / 2 + and 5 /2 + energies in the A + 1 nucleus.…”

Section: Introductionmentioning

confidence: 99%