The status of theoretical L-shell x-ray production cross sections by protons based on their revised universal empirical fit

The present status of theoretical L-shell x-ray production cross sections is gauged by an updated and revised fit to 5771 measurements in elements ranging from Cr-24 to Am-95 in ionization by 0.035 to 1000 MeV protons. Both the theory and the fit are cast with a single scaling variable v(1)/v(2L), which is the ratio of proton velocity to the orbital velocity of the L-shell electron. A review of possible theories shows that the ECUSAR theory extended to relativistic protons provides for the most comprehensive choice for comparison with empirical fit to the compiled data. Both the fit and the theory are in excellent agreement with the compiled data except for cross sections reported at v(1)/v(2L), < 0.09 in just two articles from four decades ago.