Abstract
The extremely neutron-rich system was studied in the direct transfer reaction with a 26 secondary beam [Bezbakh et al., Phys. Rev. Lett. 124, 022502 (2020)]. The missing mass spectrum and center-of-mass angular distributions of , as well as the momentum distribution of the fragment in the frame, were constructed. In addition, we carried out another experiment with the same beam but a modified setup, which was cross-checked by the study of the reaction. A solid experimental evidence is provided that two resonant states of are located in its spectrum at 2.2(5) and relative to the decay threshold. Also, there are indications that the resonant states at 7.5(3) and are present in the measured spectrum. Based on the energy and angular distributions, obtained for the studied reaction, the weakly populated 2.2(5)-MeV peak is ascribed to the ground state. It is highly plausible that the firmly ascertained 5.5(3)-MeV state is the member of the excitation doublet, built on the configuration of valence neutrons. The supposed 7.5-MeV state can be another member of this doublet, which could not be resolved in Bezbakh et al. [Phys. Rev. Lett. 124, 022502 (2020)]. Consequently, the two doublet members appeared in the spectrum of in the work mentioned above as a single broad 6.5-MeV peak.
8 More- Received 31 October 2020
- Accepted 11 March 2021
DOI:https://doi.org/10.1103/PhysRevC.103.044313
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