Backward secondary electron emission yield of thick targets induced by MeVions

The backward secondary electron emission yields of MeV ions (H+, He+, He++, Cl, Si, and Cu) impinging on thick carbon and gold targets are studied. Th e measured results for Hf (1MeV less than or equal to E less than or equal to 5 MeV) on carbon are proportional to the electronic stopping power. Our experimental data and fitting formula of yields for H+ (1 MeV less than or equal to E less than or equal to 4.5 MeV) impacting Au are compared with th e theoretical expectation. The influence of the collective field and the ch arge state of ions on the secondary electron emission yield is discussed.