Abstract
The structure of the extremely proton-rich nucleus , the mirror of the two-neutron halo nucleus , has been studied experimentally for the first time. Following two-neutron knockout reactions with a beam, the decay products were detected after two-proton emission and used to construct an invariant-mass spectrum. A broad peak of width was observed. Within the Gamow coupled-channel approach, it was concluded that this peak is a multiplet with contributions from the four lowest resonant states: , , , and . The widths and configurations of these states show strong, nonmonotonic dependencies on the depth of the - potential. This unusual behavior is due to the presence of a broad threshold resonant state in , which is an analog of the virtual state in in the presence of the Coulomb potential. After optimizing the model to the data, only a moderate isospin asymmetry between ground states of and was found.
- Received 20 December 2018
- Revised 23 February 2019
DOI:https://doi.org/10.1103/PhysRevLett.122.122501
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