Publication: Search for states with enhanced radii in 20Ne
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2024
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An intensive study of four-nucleon correlations of the Ћ?-cluster type initiated more than 50 years ago established their important role in nuclei. The microscopic Ћ?-cluster models have succeeded in describing the structure of many states in light nuclei, in particular, around the threshold energy of breakup into constituent clusters. Considerable attention has been drawn to the studies of Ћ?-cluster states in 12C, especially the second 0+ state, located at Ex=7.65 MeV, which is 0.38 MeV above the 3Ћ? threshold. This state was called the Hoyle state by the name of the astrophysicist who predicted it. Detailed analysis of the structure of 12C with the microscopic 3Ћ? cluster model was made about 30 years ago. The 3Ћ? generator coordinate method (GCM) and 3Ћ? resonating group method (RGM) calculations showed that the 7.65 MeV 0+2 state in 12C has a loosely coupled 3Ћ? structure and an enlarged radius. Modern microscopic calculations in the framework of cluster models such as the antisymmetrized molecular dynamics (AMD) and the fermionic molecular dynamics (FMD) also predict an increased radius of this above-threshold cluster state. A question naturally arises: do analogs of the Hoyle state exist in more massive 4N nuclei. First possible candidate is the 16O. Our analysis within Modified diffraction model has shown that 0+2 - 0+6 states which were named as possible analogs of the Hoyle state have normal non-increased radii. The next goal is 20Ne. The root mean square radii of 20Ne in the short-lived excited states were estimated for the first time from the analysis of Ћ? + 20Ne diffraction scattering. Differential cross sections of the elastic and inelastic Ћ? + 20Ne scattering in the incident energy range from a few MeV/nucleon up to 100 MeV/nucleon were analyzed by the modified diffraction model. No significant radius enhancement for the members of KЏ? = 01+ and KЏ? = 2ў?? bands in comparison with the ground state was observed. At the same time 20% radius enhancement was obtained for the KЏ? = 01ў?? band members. Moreover, for the 02+ state located above Ћ?-emission threshold increased radius was observed. This result can speak in favor of possible Ћ?-condensate structure of the 02+ state and can be considered as a possible analog of the famous 7.65-MeV 02+ Hoyle state of 12C.
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Search for states with enhanced radii in 20Ne / Demyanova, A. [et al.] // AIP Conference Proceedings. - 2024. - 3020. - № 1. - 10.1063/5.0193498