MEASUREMENT OF K-SHELL IONIZATION CROSS SECTIONS OF AL AND MG FOR 1-MEV TO 5-MEV ALPHA PARTICLES

The K-shell ionization cross sections of Al and Mg for 1- to 5-MeV α particles have been obtained from measurements of the fluorescent x-ray yields of thin foils irradiated by α particles. The results for Al range from (0.36 ± 0.31) × 10-20 cm2 at 1.0 MeV to (13.47 ± 0.77) × 10-20 cm2 at 5.0 MeV, and for Mg from (1.04 ± 0.25) × 10-20 cm2 at 1.0 MeV to (16.61 ± 0.56) × 10-20 cm2 at 5.0 MeV. The energy dependence is stronger than predicted by the Born approximation. The data are compared with theoretical calculations and with other experimental results for protons, He3, and α particles. © 1969 The American Physical Society.