Ratio ofLKX-Ray Intensities in Thallium-204 Decay

Abstract

The ratio of $L$ and $K$ x-rays of mercury resulting from orbital-electron capture in high-specific-activity sources of 4-year ${\mathrm{Tl}}^{204}$ has been measured with a gas proportional counter and NaI(Tl) scintillation spectrometer. The intensity ratio was found to be $\frac{I_L}{I_K}=0.46\mathrm{}\pm 0.04$. If one accepts a value of 0.524 for the $\frac{L}{K}$ electron capture ratio from the theoretical results of Brysk and Rose, the mean $L$-fluorescence yield of mercury becomes ${\overline{\omega }}_L=0.34\mathrm{}\pm 0.04$. A study was made of the possible effect of fluorescent x-ray excitation owing to the noncarrier-free nature of the source; among sources of equal radioactive strength ranging in superficial density from 0.54 to 2.21 mg/${\mathrm{cm}}^2$ in inert thallium nitrate solids, no appreciable change in the x-ray intensities was detected.