Main channels of the decay of the giant dipole resonance in the 20,22Ne nuclei and isospin splitting of the giant dipole resonance in the 22Ne nucleus

Abstract

Data published in the literature on various photonuclear reactions for the 20,22Ne isotopes and for their natural mixture are analyzed with the aim of exploring special features of the decay of giant-dipole-resonance states in these two isotopes. With the aid of data on the abundances of the isotopes and on the energy reaction thresholds, the cross sections for the reactions 20,22Ne[(γ, n)+(γ, np)] and 20,22Ne[(γ, p)+(γ, np)] are broken down into the contributions from the one-nucleon reactions (γ, n) and (γ, p) and the contributions from the reactions (γ, np). The cross sections for the reactions 20,22Ne(γ, n)19,21Ne and 20,22Ne(γ, p)19,21F in the energy range Eγ=16.0–28.0 MeV and the cross sections for the reactions 20,22Ne(γ, np)18,20F in the energy range Eγ=23.3–28.0 MeV are estimated. The behavior of the cross-section ratio r=σ(γ, p)/σ(γ, n) for the 22Ne nucleus as a function of energy is analyzed, and the isospin components of the giant dipole resonance in the 22Ne nucleus are identified. The contributions of the isospin components of the giant dipole resonance in the 22Ne nucleus to the cross sections for various photonuclear reactions are determined on the basis of an analysis of the diagram of the excitation and decay of pure isospin states in the 22Ne nucleus and in nuclei neighboring it, which are members of the corresponding isospin multiplets. The isospin splitting of the giant dipole resonance and the ratio of the intensities of the isospin components are determined to be ΔE=4.57±0.69 MeV and R=0.24±0.04, respectively.