K-shell ionization of heavy atoms by 40-110-MeV alpha -particles

Cross sections for K-shell ionization of Ho, Tm, Lu, Ta, W, Pt, Au, Pb, and Bi by alpha -particle impact have been measured in the projectile energy range 40-110 MeV. The results are compared with a number of theoretical predictions, in particular those of Amundsen (1976), which take account of relativistic effects. Measured intensity ratios are in agreement with previous observations. X-ray satellites, arising from ionization following nuclear reactions were observed and, in the case of Ho, an attempt was made to relate the ionization and nuclear cross sections. Small peaks in the Au, Pb and Bi spectra are tentatively attributed to double K-shell ionization.