Energy Loss by Low-Energy Protons in Gold

An experiment employing a new method of measuring stopping power at low energies is described, and results are given for protons on gold. Values of $\frac{\mathrm{dE}}{\mathrm{dx}}$ for protons on gold have been obtained from measurements of the reponse of a silicon surface-barrier detector, covered with a surface layer of gold, to protons of energy below 50 keV. The response of the detector to $\mathrm{H}_2^{}{}_{}{}^{+}$ and $\mathrm{H}_3^{}{}_{}{}^{+}$ ions in the same energy range has been used to determine backscattering cross sections for protons on gold.