Determination of stopping power for ions by backscattering from thin targets

Abstract

A new procedure is presented for extracting the stopping power from the widths of a number of backscattering spectra. It can be applied irrespectively of the magnitude of the kinematic factor. For this method we introduce a function dependent on four parameters, the shape of which is sufficiently adaptable not to cause a relevant bias. This is demonstrated by fitting this function to the proton stopping power tables of Janni: for all 92 elements we list the fit parameters together with the mean and the maximum deviation. By computer simulation it is shown that the projectile energies in the backscattering measurements have to cover a certain range — depending on the kinematic factor — to give the correct stopping cross section. Finally, we applied this procedure to the measurement of the stopping cross section of Al for He-ions.