The d(He-3,p)He-4 cross section has been measured at E = 4.2 to 13.8 keV us
ing 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 p
ower of the He-3 ions in the D-2 target is in good agreement with the stand
ard compilation. Using these stopping power values the data lead to an elec
tron-screening potential energy U-e = 132 +/- 9 eV, which is significantly
higher than the estimated value of 65 eV from an atomic-physics model. Publ
ished by Elsevier Science B.V.