X-Ray Line Intensities and Cathode-Ray Retardation in Thick Targets of Silver

Abstract

$K$-line intensities from thick silver targets have been measured in arbitrary units for voltages up to 180 kv, with emergence angles from 1 to 25\ifmmode^\circ\else\textdegree\fi{}. A practical use of these data is the determination of the voltage which will give the maximum efficiency of line emission at any emergence angle. At 1\ifmmode^\circ\else\textdegree\fi{} the best voltage is 70 kv but at 25\ifmmode^\circ\else\textdegree\fi{} it is well above 180 kv. These data are also used in conjunction with data on thin targets to get information as to the retardation of cathode rays in silver. For this purpose the thick-target data are corrected to eliminate the effects of target absorption, indirect production of line rays through fluorescence and loss of cathode rays by rediffusion. The loss of energy per unit distance along the path of a cathode ray varies as the -1.4 power of the speed, just as it does in light elements according to more direct evidence collected by E. J. Williams.