KX-Ray Fluorescence Yield of Argon

Reported values of the $K$ x-ray fluorescence yield of argon lie in two distinct groups, viz., low values (about 0.07) and high values (about 0.13). A new measurement herein reported gives 0.14±0.014. This measurement was made from the "escape peak" in the pulse-height distribution of a flow proportional counter with monochromatic rays. An ${\mathrm{Fe}}^{55}$ radio-isotope was used as the source of primary x rays. Corrections were made for the $L$ and $M$ ionizations in the argon gas, for the reabsorption of the $K$ fluorescent x rays, and for background counts.