Indirect Production of X-Ray Line Radiation

It has been shown experimentally by Webster and by Hansen and Stoddard that there is a constant ratio between the number of $K$ electrons ejected directly by cathode rays and the number ejected by the resulting bremsstrahlung radiation. Their work on thick anodes of silver and palladium extended over a wide range of energy. In the present work, a new technique has been used to reexamine the problem. It was found that a copper anode operating at low energies gives the same results, thus showing, as one might expect from theory, that the said ratio is independent of the anode material. Although indirect ionization is a contributing factor in thick targets, it has been observed that the line emission from extremely thin anodes is caused by direct collisions.