The Energy Loss of Protons in Metallic Foils and Mica

The rate of loss of energy of 500- to 1300-kev protons in various metals and mica has been determined. Foils of Be, Al, Cu, and Au were prepared by evaporation techniques, and the density of the foil was determined by weighing the amount of metal deposited on a known area. The energy loss rate $\frac{\Delta E}{\Delta x}$ was measured with a standard deviation of <3 percent. The energy loss curve was found to join smoothly to the previously measured curve for lower energy protons ($50 \mathrm{kev}<E<\mathrm{}350\mathrm{} \mathrm{kev}$), and to approach the theoretical curves of Bethe and Bloch at the high energy end.