Year: 2022
Type: article
Abstract: The spectra of mass-11 nuclei are unusual, and so pose a challenge for nuclear-structure theory. Relating to nucleon emission, the set of isobars range from being well-bound ( $$^{11}$$ 11 B, $$^{11}$$ 11 C) through weakly bound ( $$^{11}$$ 11 Li, $$^{11}$$ 11 Be), to being proton unstable ( $$^{11}$$ 11 N, $$^{11}$$ 11 O). To add complexity, the weakly bound $$^{11}$$ 11 Li takes the form of a two-nucleon halo nucleus. A self-consistent approach to understand this set of nuclei is especially important as the mirror pair $$^{11}$$ 11 Be- $$^{11}$$ 11 N exhibit a parity-inverted ground state compared to their neighboring nuclei. Herein, the Multi-Channel Algebraic Scattering method (MCAS) has been used to describe the low excitation spectra of those isobars in terms of nucleon-nucleus clusters. A collective model description of the low-excitation states of the mass-10 mass-10 core nuclei has been used to form the coupled-channel interactions required in the method. For comparison, and to understand the underlying configurations, a shell model approach has been used to obtain those spectra with no-core $$(0+2+4)\hbar \omega $$ ( 0 + 2 + 4 ) ħ ω and $$(0+2)\hbar \omega $$ ( 0 + 2 ) ħ ω shell-model spaces for the mass 10 and mass 11 nuclei respectively. The results of the calculations suggest the need of a strong coupling in the collective coupled-channel vibrational model. In particular, the strong coupling of the collective $$2^+_1$$ 2 1 + state of $$^{10}$$ 10 Be to the valence neutron plays a decisive role in forming the positive parity ground state in $$^{11}$$ 11 Be; an effect confirmed by the shell-model results.
Source: The European Physical Journal A
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,390
Funder: University of Melbourne
OpenAlex ID: W4296448343