Fig. 1: Overview schematic diagram.
From: Neutron-upscattering enhancement of the triple-alpha process

This details the steps involved in the triple-alpha process, showing the contribution of neutron upscattering to the decay width to bound states. A low-energy neutron interacts with the Hoyle state leaving carbon-12 in the ground-state (or first-excited state) and the extra energy is carried away with the neutron.