Secondary Electron Emission from Al, Cu, Ag and Au Metal Targets under Proton Bombardment

The secondary electron emission coefficients, γ, forin-situvacuum-deposited targets of Al, Cu, Ag and Au are measured under proton bombardment in the energy range 4–12 MeV at a pressure of 1–2×10-8Torr. The values of γ for Al are only half of those obtained experimentally by Aarsetet al.The ratios between γ and the electronic stopping powers for protons in these four materials are independent of the incident energy. The values of the ratios are almost equal to those reported by Baragiolaet al.for the same target materials in the much lower energy region below 50 keV. The ratio for Al is theoretically calculated. The theoretical ratio is also independent of the incident energy, but is only half of the experimental one.