Electron-loss cross-section measurement of ³He ions by the attenuation method

We have measured single-electron loss cross sections of ³He¹⁺ ions for various solid targets such as C, Al, V, Cr, Cu, Ge, Nb, Ag, Sn and Au at 72 MeV by using the attenuation method. In this method residual ³He¹⁺ fractions after charge-changing collisions were measured with a ³He¹⁺ incident beam. Concentrations of contaminating atoms in the target were determined by an independent RBS measurement. It was found that surfaces of almost all the targets were covered with thin oxygen layers by which ³He¹⁺ fractions were reduced by about 10%. Corrections of the observed loss cross sections are made for the surface oxygen layers.