First observation of unbound $^{11}$O, the mirror of the halo nucleus $^{11}$Li

Abstract

The structure of the extremely proton-rich nucleus 11 8 O3, the mirror of the two-neutron halo nucleus 11 3 Li8, has been studied experimentally for the first time. Following two-neutron knockout reactions with a 13 O beam, the 11 O decay products were detected after two-proton emission and used to construct an invariant-mass spectrum. A broad peak of width 3.4 MeV was observed. Within the Gamow coupled-channel approach, it was concluded that this peak is a multiplet with contributions from the four-lowest 11 O resonant states: J π =3/2 − 1 , 3/2 − 2 , 5/2 + 1 , and 5/2 + 2 . The widths and configurations of these states show strong, non-monotonic dependencies on the depth of the p-9 C potential. This unusual behavior is due to the presence of a broad threshold resonant state in 10 N, which is an analog of the virtual state in 10 Li in the presence of the Coulomb potential. After optimizing the model to the data, only a moderate isospin asymmetry between ground states of 11 O and 11 Li was found.

2018 update of the discoveries of nuclides

“…Other than these isotopes there is only one possible candidate listed in the table: 11 O, posted on the arXiv and submitted for publication in December 2018. 25 If indeed only a few new isotopes are reported during the present year, another update of the discoveries of nuclides at the end of 2019 will not be warranted. The most current status will continue to be posted on the discovery project website.…”

“…The table contains five new isotopes: 24 N and 25 N were the subject of the Ph.D. thesis of Deshayes, 24 11 O was posted on the arXives by Webb et al, 25 and 79 Co and 84 Cu were reported in the most recent RIKEN Annual Report. 26 An additional three isotopes were presented at conferences and mentioned in the corresponding abstracts.…”