Estimation of direct components of the decay of the Hoyle state

Abstract

A high-statistics, high-resolution, complete kinematical measurement has been performed to estimate the quantitative contributions of various direct 3$\ensuremath{\alpha}$ decay mechanisms in the decay of the famous Hoyle state, the ${0}_{2}^{+}$ resonant excited state of ${}^{12}$C at an excitation energy of 7.654 MeV, using inelastic scattering of 60-MeV $\ensuremath{\alpha}$ particles on ${}^{12}$C. The present observation of nonzero branching ratios of various direct 3$\ensuremath{\alpha}$ decay modes, which have been extracted using $\ensuremath{\sim}$20$\phantom{\rule{0.16em}{0ex}}$000 fully detected (4$\ensuremath{\alpha}$) Hoyle events, is expected to remove the ambiguities among various previous estimates, extracted from fewer ($\ensuremath{\lesssim}$5000) events.