Stopping power, electron screening and the astrophysical S(E) factor of d(He-3,p)He-4

The d(He-3,p)He-4 cross section has been measured at E = 4.2 to 13.8 keV using the LUNA underground accelerator facility. The experiment was performed to determine the magnitude of the atomic screening effect and to establish values for the energy loss used in data reduction. The observed stopping power of the He-3 ions in the D-2 target is in good agreement with the standard compilation. Using these stopping power values the data lead to an electron-screening potential energy U-e = 132 +/- 9 eV, which is significantly higher than the estimated value of 65 eV from an atomic-physics model. Published by Elsevier Science B.V.