$R$-matrix analysis of ${}^{22}\mathrm{Ne}$ states populated in ${}^{18}\mathrm{O}(\alpha ,\alpha )$ resonant elastic scattering

The properties of resonances in the ${}^{18}\mathrm{O}+\alpha$ interaction are important for analyses of astrophysical processes and for understanding of the development of the $\alpha$-cluster structure with addition of neutrons to 4N nuclei. Previous high-energy resolution measurements have not been treated using the contemporary $R$-matrix approach. We have performed an $R$-matrix analysis of the resonant data [D. Powers, J. K. Bair, J. L. C. Ford, Jr., and H. B. Willard, Phys. Rev. 134, B1237 (1964)] and obtained new data on 15 levels in the excitation region of 11.7–12.5 MeV ${}^{22}\mathrm{Ne}$. It appears that the model calculations did not predict the observed tendency in the ${}^{20–22}\mathrm{Ne}$ $\alpha$ clustering. This paper is the first step of our program of investigation of the ${}^{22}\mathrm{Ne}$ spectrum in resonant reactions.

Figure 1

An example of the excitation functions for the $\alpha +{}^{18}\mathrm{O}$ elastic scattering from Ref. [4] in comparison with data [5]. A bold line is the fit [4].

Figure 2

$R$-matrix fit for the excitation functions for the $\alpha +{}^{18}\mathrm{O}$ elastic scattering [4] and the total cross section for the ${}^{18}\mathrm{O}(\alpha ,n$) reaction [10] (bottom panel).

Figure 3

$l=0$, 1 resonances in ${}^{22}\mathrm{Ne}$ in comparison with those in ${}^{20,21}\mathrm{Ne}$ [2, 10] and ${}^{19}\mathrm{F}$ [12]. The dash (red) lines are for $l=0$, the solid (blue) lines for $l=1$. See more explanations in the text.