First observation ofα-cluster states in the14O + 4Heinteraction

Abstract

We measured ${}^{14}\mathrm{O}+{}^{4}\mathrm{He}$ excitation functions for elastic scattering which demonstrate, for the first time, a well developed $\ensuremath{\alpha}$-cluster structure in the proton rich nucleus, ${}^{18}\mathrm{Ne}$. We present the excitation energies and estimates of the spins for the dominant resonances using an R-matrix approach. A resonance at 9.2 MeV excitation energy in ${}^{18}\mathrm{Ne}$ is particularly interesting. The spin-parity of the state is found to be ${3}^{\ensuremath{-}}$ and the $\ensuremath{\alpha}$ particle reduced width for the state appears to be comparable to the single particle limit. We have found indications for unusually large size of the observed $\ensuremath{\alpha}$-cluster configuration.