Abstract
-shell x-ray production cross sections, x-ray intensity ratios and and x-ray energy shifts have been determined for thin solid targets of , , , , , , , , , and for 4-38-MeV ion bombardment. Comparisons of the cross sections were made to direct Coulomb ionization and electron-capture theories by means of fluorescence yields corrected for multiple-ionization effects. The dominant contribution to -vacancy production for these projectile-target combinations is believed to be direct ionization. Electron capture is expected to be important only for the lighter target elements and then primarily at the higher velocities. The direct-ionization theories employed were the binary-encounter approximation and the plane-wave Born approximation (PWBA) both of which overestimated the experimental data especially at the lower incident ion velocities. The PWBA was modified for increased target-electron binding, Coulomb deflection of the incident ion, polarization of the target-electron wave functions due to the passage of the incident ion, and relativistic target-electron velocities. The experimental data were found to agree quite well with the sum of the theoretical predictions of the modified PWBA and electron capture.
- Received 27 December 1977
DOI:https://doi.org/10.1103/PhysRevA.18.380
©1978 American Physical Society