Inner-shell ionization of silver by 100- 400-keV electrons and positrons

$K\alpha$ and total $L$ x rays resulting from $K$- and $L$-shell ionization in silver by electron and positron impact at 100, 150, 200, 300, and 400 keV have been measured using a Si(Li) x-ray detector. Within an experimental uncertainty ± 10% the $K\alpha$ x-ray production cross section by electrons, ${\sigma }_{K\alpha }^{-}$, and that by positrons, ${\sigma }_{K\alpha }^{+}$, were found to be the same in the impact-energy region higher than 200 keV, but in the region below this energy it was discovered that the ratio $\frac{{\sigma }_{K\alpha }^{-}}{{\sigma }_{K\alpha }^{+}}$ increases as the impact energy decreases. As for the $L$ x-ray production, no difference between electron and positron impact was found over the whole energy region studied in the present work, although the experimental uncertainty was rather large. Some discussion is included concerning the implications of the present experimental results.