Precise measurement of the γ-decay probability of the Hoyle state with a new triple coincidence-detection method

We measured the γ-decay probability of the Hoyle state with a new method of triple coincidence detection of a scattered α particle, a recoil 12C nucleus, and a γ ray in inelastic alpha scattering on 12C. This method successfully enabled a low-background measurement and a precise determination of the γ-decay probability of the Hoyle state as Γγ/Γ=[4.00±0.22(sta.)±0.18(sys.)]×10−4, which is consistent with the previous literature value. Therefore, we concluded that the literature value can be reliably used in the study of nucleosynthesis in the universe.