Projectile charge and mass dependence of large angle K-shell ionization probabilities on copper

The dependence on the scattering angle of the K-shell ionization probability has been measured with 0.5 MeV H⁺, 1 MeV D⁺ and 2 MeV He⁺ on copper targets. The experimental values are compared to SCA calculations corrected for binding, retardation and relativistic effects. The angular dependences are in good agreement with the theoretical predictions if the rapid variation of the nuclear relative velocity at the distance of closet approach is correctly taken into account (“hair-spin curve” effect).