Measurement of the C 12 (C 12,p) Na 23 cross section near the Gamow energy

The fusion reaction C12(C12,p)Na23 has been studied from E=2.00 to 4.00 MeV by particle spectroscopy. The data reveal broad resonances above E=3.00 MeV and are compatible with previously reported resonance structure around E=2.1 MeV. The data were limited at low energies by low count rates as well as possible background contributions. This experiment extends the previously achieved low-energy measurement by charged particle spectroscopy to 2 MeV, which corresponds to the high-energy side of the astrophysically relevant temperature. Present knowledge of level structures and nonresonant contribution cannot explain the results of the present experiment, which may change the C12+C12 reaction rate significantly. Despite the progress decreasing the low-energy limit, any extrapolation into the astrophysical energy range remains highly uncertain based on available experimental data.