Overview of 12C(α,γ)16O

This talk will review the current status as well as some history of the ¹²C(α,γ)¹⁶O reaction and the level structure of ¹⁶O. This reaction is essential for our understanding of helium burning in massive stars and also subsequent nucleosynthesis. The R-matrix method will be reviewed, as this approach is utilized to predict the cross section at astrophysical energies based upon experimental inputs. In addition to ¹²C(α,γ)¹⁶O data, modern analyses consider many reaction channels including ¹²C(α,α), ¹²C(α,α')¹²C(4.4 MeV), and ¹²C(α,p)¹⁵N as well as information from beta decay and transfer reactions. Much of the recent improvement in the constraint on the low-energy ¹²C(α,γ)¹⁶O S factor has come from extending the data set considered and analysis to higher energies and from indirect methods. Some recent experimental results on ¹²C(α,γ)¹⁶O from TRIUMF and fits to ¹⁵N(p,α) data will be presented. The talk will conclude with a discussion of potential areas for future experimental and theoretical progress on this important reaction.