New Measurement of the Direct 3α Decay from the ^{12}C Hoyle State. 
Excited states in certain atomic nuclei possess an unusual structure, where the dominant degrees of freedom are those of α clusters rather than individual nucleons.  It has been proposed that the diffuse 3α system of the ^{12}C Hoyle state may behave like a Bose-Einstein condensate, where the α clusters maintain their bosonic identities.  By measuring the decay of the Hoyle state into three α particles, we obtained an upper limit for the rare direct 3α decay branch of 0.047%.  This value is now at a level comparable with theoretical predictions and could be a sensitive probe of the structure of this state.