An external beam technique for proton-induced X-ray emission analysis

A method for proton irradiation of targets in free air is described. A 7.6 μm beryllium foil used as a proton exit window causes negligible energy loss for as low as 2 MeV protons and can withstand high currents for extended periods of time without vacuum problems. Proton-induced X-rays from thin and thick samples are detected using Si(Li) and intrinsic Ge detectors. A detailed comparison of X-ray spectra obtained both with external and internal bombardment, for a variety of samples, is presented and these results clearly demonstrate the superior performance of the external beam technique for elemental microanalysis. (Auth.)