Title: Structure of $^{20}$Ne states in the resonance $^{16}$O+$α$ elastic scattering,
Abstract: Background
The nuclear structure of the cluster bands in $^{20}$Ne presents a challenge
for different theoretical approaches. It is especially difficult to explain the
broad 0$^+$, 2$^+$ states at 9 MeV excitation energy. Simultaneously, it is
important to obtain more reliable experimental data for these levels in order
to quantitatively assess the theoretical framework.
Purpose
To obtain new data on $^{20}$Ne $\alpha$ cluster structure. Method Thick
target inverse kinematics technique was used to study the $^{16}$O+$\alpha$
resonance elastic scattering and the data were analyzed using an \textit{R}
matrix approach. The $^{20}$Ne spectrum, the cluster and nucleon spectroscopic
factors were calculated using cluster-nucleon configuration interaction model
(CNCIM).
Results
We determined the parameters of the broad resonances in
\textsuperscript{20}Ne: 0$^+$ level at 8.77 $\pm$ 0.150 MeV with a width of 750
(+500/-220) keV; 2$^+$ level at 8.75 $\pm$ 0.100 MeV with the width of 695
$\pm$ 120 keV; the width of 9.48 MeV level of 65 $\pm$ 20 keV and showed that
9.19 MeV, 2$^+$ level (if exists) should have width $\leq$ 10 keV. The detailed
comparison of the theoretical CNCIM predictions with the experimental data on
cluster states was made.
Conclusions
Our experimental results by the TTIK method generally confirm the adopted
data on $\alpha$ cluster levels in $^{20}$Ne. The CNCIM gives a good
description of the $^{20}$Ne positive parity states up to an excitation energy
of $\sim$ 7 MeV, predicting reasonably well the excitation energy of the states
and their cluster and single particle properties. At higher excitations, the
qualitative disagreement with the experimentally observed structure is evident,
especially for broad resonances.