Backward Secondary Electron Emission Yield of Thick Targets Induced by MeV Ions

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.The measured results for H+(1MeV≤E≤5MeV)on carbon are proportional to the electronic stopping power.Our experimental data and fitting formula of yields for H+(1 MeV≤E≤4.5MeV)impacting Au are compared with the theoretical expectation.The influence of the collective field and the charge state of ions on the secondary electron emission yield is discussed.