12C(α, β)16O studied with the Karlsruhe 4π BaF2 detector.

The 12C(α, γ)16O reaction is one of the most important in nuclear astrophysics since it determines the ratio of 12C to 16O during stellar helium burning. Experimental data, however, are still subject to large uncertainties due to the almost vanishing cross section at stellar energies. So far, most measurements have been performed with germanium detectors. To compensate for their low efficiency, the highest beam currents had to be used, resulting in target degradation and beam-induced backgrounds. Instead, the present measurement was performed with high-efficiency detectors and low beam currents, using the Karlsruhe 4π BaF2 detector and the pulsed 3.7-MV Van de Graaff accelerator at Karlsruhe Institute of Technology. The 12C(α, γ)16O cross sections have been measured at center-of-mass energies E between 1002 and 1510 keV, and the E1 and E2 components were derived with an accuracy comparable to the previous best data obtained with HPGe detectors. [ABSTRACT FROM AUTHOR]