# $^{21}$Ne level structure in the resonance $^{17}$O+$\alpha$ elastic scattering

## TL;DR

This study investigates the resonance structure of $^{21}$Ne through $^{17}$O+$ extalpha$ elastic scattering using TTIK and R-matrix analysis, revealing new alpha-cluster states and analogs to $^{20}$Ne, with implications for astrophysics.

## Contribution

First observation of broad $l=0$ state in $^{21}$Ne via $^{17}$O+$ extalpha$ scattering, expanding understanding of alpha-cluster states in this nucleus.

## Key findings

- Identified multiple alpha-cluster states in $^{21}$Ne between 9-13 MeV.
- First observation of a broad $l=0$ state in an odd-even nucleus.
- Results aid in refining $^{17}$O($ extalpha$,n) reaction data for astrophysics.

## Abstract

The first study of resonances in $^{17}$O+$\alpha$ elastic scattering was carried out using the Thick Target Inverse Kinematics (TTIK) method. The data were analyzed in the framework of an $\textit{R}$-matrix approach. Many $\alpha$-cluster states were found in the $^{21}$Ne excitation region of the 9-13 MeV excitation energy including the first observation of a broad $\textit{l}$=0 state in an odd-even nucleus, which is likely the analog of the broad 0$^+$ at 8 MeV in $^{20}$Ne. The observed structure in $^{21}$Ne appeared to be strikingly similar to that in $^{20}$Ne populated in the resonance $^{16}$O+$\alpha$ scattering. The results are also useful for refinement of data on an $^{17}$O($\alpha$,$\textit{n}$) reaction important for astrophysics.