L-subshell ionization cross sections for tungsten at low electron energies

The L-subshell ionization cross sections for tungsten have been measured for incident electron beams of low energies. The electron energy was in the range of 1<EIL4. The values of the three L-subshell cross sections L1, L2, and L3 were deduced from the thick-target yields of L23, L1, and L1 x rays of tungsten. A differential method was employed in the deduction procedures. The x-ray spectra were obtained by an improved version of a single-crystal, high-angle goniometer. The shape of the energy dependence of the measured cross sections deviates from the predictions given by McGuire's scaling result as well as Gryzinski's classical scaling result.