Projectile charge dependence of electron emission from foils - art. no. 052901

We have precisely measured the secondary-electron-emission yield (gamma) fr om thin Al, Ag, and Au foils with a thickness of 1 mu m on exposure to full y stripped 6 MeV/n heavy ions (H, He, C, N, O, Ne, Si, and Ar). The depende nce of the forward and backward yields on the projectile nuclear charge (z) showed a proportionality to the square of the effective charge (z(eff)(2)) and an oscillatory behavior with atomic number z; the yields were comparat ively low for exposures to He2+ and Ne10+ beams. The forward enhancement wa s significant for Al foil (light metal), depending on z; in contrast, it wa s small for Ag and Au foils (heavy metals). The accuracy of the gamma value s was evaluated by determination of z(eff) (+/-5%) and the surface reproduc ibility of the foil (+/-2-3%).