A high-statistics, high-resolution, complete kinematical measurement has been performed to estimate the quantitative contributions of various direct 3$\alpha$ 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 $\alpha$ particles on ${}^{12}$C. The present observation of nonzero branching ratios of various direct 3$\alpha$ decay modes, which have been extracted using $\sim$20$$000 fully detected (4$\alpha$) Hoyle events, is expected to remove the ambiguities among various previous estimates, extracted from fewer ($\lesssim$5000) events.

• Received 10 May 2013
• Publisher error corrected 21 August 2013

DOI:https://doi.org/10.1103/PhysRevC.88.021601