K shell ionizations of carbon, nitrogen, oxygen, fluorine and neon by proton and alpha particle bombardments

The K Auger electron spectra have been measured for carbon, nitrogen, oxygen, fluorine and neon excited by protons and alpha particles of 0.5-2.6 MeV. In comparison with the spectra obtained by electron impact, the satellite lines have grown more intensively as projectiles become heavier. This indicates the presence of a contribution of simultaneous L shell ionization. A quantitative analysis has been made for the created L vacancies of nitrogen due to N+p and N+α collisions. The ionization cross sections derived from the Auger yields have been compared with the theories of Born approximation and binary encounter approximation. The deviations from the theories found in O+α, F+α and Ne+α collisions might be explained by a shielding action of L shell electrons against nuclear charge of projectiles.