DEVIATION FROM 1ST-ORDER PERTURBATION-THEORY OBSERVED AT INTERMEDIATERELATIVISTIC VELOCITIES FOR THE IONIZATION OF HIGHLY-CHARGED HEAVY PROJECTILES

Projectile K-shell ionization cross sections were measured for 80-200 MeV u-1 H- and He-like Bi ions incident on thin C, Al and Ni targets. The results are compared with predictions of first-order perturbation theories, RSCA and PWBA, as well as with experimental results publishe d for Xe and U ions at similar ratios eta of projectile velocity to K- shell electron velocity. All experimental data lie a factor of 1.5 abo ve theory for 0.6 < eta < 1.5.