Behaviors of Impurity Elements at Beryllium Target Surface Bombarded by Alpha Particles

A beryllium target has been bombarded by an energetic beam of alpha particles and the RBS measurements have been applied to know the behaviors of impurity elements, especially of carbon and oxygen, under various dose and temperature conditions. Carbon compounds initially attached are easily removed by heating up but a deposition of carbon atoms decomposed from oil vapors follows. Oxygen atoms are accumulated on a heated target, which come from decomposed water molecules. During a heavy and long bombardment, diffusion of both atoms becomes dominant and this suggests carbonization and oxidation of beam-excited beryllium atoms.