Proton Spectra from 3He + T and 3He + 3He Fusion at Low Center-of-Mass Energy, with Potential Implications for Solar Fusion Cross Sections

Few-body nuclear physics often relies upon phenomenological models, with new efforts at the ab initio theory reported recently; both need high-quality benchmark data, particularly at low center-of-mass energies. We use high-energy-density plasmas to measure the proton spectra from He-3 + T and He-3 + He-3 fusion. The data disagree with R-matrix predictions constrained by neutron spectra from T + T fusion. We present a new analysis of the He-3 + He-3 proton spectrum; these benchmarked spectral shapes should be used for interpreting low-resolution data, such as solar fusion cross-section measurements.