Enhanced triple-α reaction reduces proton-rich nucleosynthesis in supernovae.

The rate of the triple-α reaction that forms C affects the synthesis of heavy elements in the Ga-Cd range in proton-rich neutrino-driven outflows of core-collapse supernovae. Initially, these outflows contain only protons and neutrons; these later combine to form α particles, then C nuclei via the triple-α reaction, and eventually heavier nuclei as the material expands and cools. Previous experimental work demonstrated that despite the high temperatures encountered in these environments, the reaction is dominated by the well characterized Hoyle state resonance in C nuclei.