Extreme alpha-clustering in the 18O nucleus

TL;DR

This study investigates the alpha-cluster structure of the 18O nucleus at high excitation energies, revealing significant alpha clustering and unusual states with large reduced widths, differing from neighboring nuclei.

Contribution

It provides new experimental evidence of extreme alpha-clustering in 18O and discusses its implications for understanding cluster phenomena in light nuclei.

Findings

Identification of states with large alpha reduced widths

Observation of a 0+ state exceeding the single particle limit

Alpha-cluster structures differ from those in 16O and 20Ne

Abstract

The structure of the 18O nucleus at excitation energies above the alpha decay threshold was studied using 14C+alpha resonance elastic scattering. A number of states with large alpha reduced widths have been observed, indicating that the alpha-cluster degree of freedom plays an important role in this N not equal Z nucleus. However, the alpha-cluster structure of this nucleus is very different from the relatively simple pattern of strong alpha-cluster quasi-rotational bands in the neighboring 16O and 20Ne nuclei. A 0+ state with an alpha reduced width exceeding the single particle limit was identified at an excitation energy of 9.9+/-0.3 MeV. We discuss evidence that states of this kind are common in light nuclei and give possible explanations of this feature.