Stopping powers of Ag and Au for 0. 3--2. 0-MeV /sup 4/He ions

The stopping powers of Ag and Au for /sup 4/He ions have been measured in the energy region from 0.3 to 2.0 MeV with accuracy (standard deviation) +- 1%. The energy losses of He ions were determined from the backscattering spectra. The target films were vapor-deposited on silicon wafers and the areal densities were absolutely determined by weighing. The present results are for both elements above 500 keV within 2% of the best-fit values in a recent compilation by Ziegler. The agreement is worse below 500 keV where the present results lie consistently above the best-fit values.