L-subshell ionization by proton and alpha-particle bombardment of Ta, Au, and Bi

Cross sections for ionization of the $L_{\mathrm{I}}$, $L_{\mathrm{II}}$, and $L_{\mathrm{III}}$ subshells in Ta, Au, and Bi have been measured for proton energies from 1.0 to 5.5 MeV and $\alpha$-particle energies from 1.0 to 11.0 MeV. X-ray spectra recorded with a Si(Li) detector were used to deduce the subshell ionization cross sections: $L\alpha$ components give $L_{\mathrm{III}}$ subshell ionization cross sections ${\sigma }_{L_3}$, and $L\gamma$ components were computer analyzed into $L{\gamma }_5$, $L{\gamma }_1$, $L{\gamma }_{2+3}$, and $L{\gamma }_4$ to give the $L_{\mathrm{II}}$ and $L_{\mathrm{I}}$ subshell ionization cross sections, ${\sigma }_{L_2}$ and ${\sigma }_{L_1}$, respectively. The data are compared with simple model calculations. The necessity of including some small but significant additional effects in the plane-wave Born-approximation treatment, particularly wave functions more realistic than the normally assumed hydrogenic forms, is discussed.