Lα x-ray production efficiency from Z=50–82 thick target elements by electron impacts from threshold energy to 30 keV

Thick target yields of Lα x rays (x rays/str electron) under electron bombardments from around threshold energy to 30 keV are presented for pure elements of Sn, Sm, Ta, W, Pt, Au, and Pb. The calculation of K x-ray yields by Green and Cosslett has been applied to the deduction of Lα x-ray yields and observed data have been compared with the calculation. A good agreement has been obtained for high Z elements. An empirical formula for observed Lα x-ray yields ILα (x rays/str electron) has been found to be expressed by ILα =1.3×10−7×Z1.3(UL3−1)1.46 ×0.938[ln(UL3−1)]2 in impact energies less than 30 keV, where UL3 is the overvoltage ratio defined by the ratio of electron impact energy to L3 shell ionization energy.