Electron scattering on the Hoyle state and carbon production in stars

High-resolution inelastic electron scattering experiments were performed at the S-DALINAC for a precise determination of the partial pair width Γπ of the second Jπ = 0+ state, the so-called Hoyle state, in 12C. Results for the monopole matrix element (directly related to Γπ) from a nearly model-independent analysis based on an extrapolation of low-q data to zero momentum transfer are presented. Additionally, a Fourier-Bessel analysis of the transition form factor is discussed. The combined result of both methods leads to a pair width Γπ62.2(10) μeV.