# Nucleus $^{26}$O: A Barely Unbound System beyond the Drip Line

Abstract : The unbound nucleus 26O has been investigated using invariant-mass spectroscopy following one-proton removal reaction from a 27F beam at 201  MeV/nucleon. The decay products, 24O and two neutrons, were detected in coincidence using the newly commissioned SAMURAI spectrometer at the RIKEN Radioactive Isotope Beam Factory. The 26O ground-state resonance was found to lie only 18±3(stat)±4(syst)  keV above threshold. In addition, a higher lying level, which is most likely the first 2+ state, was observed for the first time at 1.28+0.11−0.08  MeV above threshold. Comparison with theoretical predictions suggests that three-nucleon forces, pf-shell intruder configurations, and the continuum are key elements to understanding the structure of the most neutron-rich oxygen isotopes beyond the drip line.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-01285922
Contributor : Michel Lion <>
Submitted on : Thursday, March 10, 2016 - 8:39:24 AM
Last modification on : Tuesday, February 19, 2019 - 11:13:19 AM

### Citation

Y. Kondo, T. Nakamura, R. Tanaka, R. Minakata, S. Ogoshi, et al.. Nucleus $^{26}$O: A Barely Unbound System beyond the Drip Line. Physical Review Letters, American Physical Society, 2016, 116 (10), pp.102503. ⟨10.1103/PhysRevLett.116.102503⟩. ⟨in2p3-01285922⟩

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