A measurement of the absolute photon yield of characteristic carbon K radiation produced by direct electron bombardment of a target is described. The carbon K emission is produced by a simple and economical source. The radiation is detected with a commercially available proportional counter, using both commercially available windows and thinner windows made at this laboratory. A method for determining gas absorption efficiency of the counter and transmission of the counter window is described. The pulse height distributions obtained from the proportional counter vary in shape with target voltage indicating the presence of a bremsstrahlung continuum as well as characteristic K radiation. The continuum contribution is subtracted from the total counting rate to obtain the photon yield of characteristic K radiation as a function of target voltage. The results of this determination are used in the calibration of a grazing incidence grating spectrometer at 44 Å.
A. J. Caruso and W. M. Neupert, "Absolute Calibration and Use of a Soft X-Ray Source of Characteristic Carbon Radiation," Appl. Opt. 4, 247-251 (1965)