The Polarization of X-Rays from Thin Targets

Abstract

By the use of Ross' method of balanced foils and a modification of the 90° scattering method, the polarization of the portion of the continuous x-ray spectrum between the $K$ limits of tantalum and tungsten has been measured for targets of aluminum foil (0.7μ) and silver foil (0.17μ), at voltages from the quantum limit up to 120 kv. For both elements, the polarization is complete at the quantum limit, and decreases as the tube voltage is raised above the quantum voltage for the spectrum band. The decrease is more rapid for silver than for aluminum, and in the case of the latter the decrease is greater than that predicted by Sommerfeld. A method is described whereby the finite thickness of the target may be taken into account. The resulting correction, however, is too small to account for the discrepancy between theory and experiment.