IMPACT-PARAMETER DEPENDENCE OF K-VACANCY PRODUCTION IN CU-NI COLLISIONS

We have measured the impact-parameter (b) dependent probabilities (P) for the production of Ni (and Cu) K x rays in the bombardment of thin nickel foils by 50- and 65.5-MeV Cu beams. The shape of P(b) is found to be independent of nickel-foil thickness (t) and of the presence of a pre-exciting carbon layer, but the magnitude scale of both P(b) and of the total K-x-ray cross section is quite dependent upon t and on the presence of the carbon. The data suggest that 2p σ vacancies are being produced via 2p π-2p σ rotational coupling preceded by preparation of the necessary projectile 2p vacancies in both single- and multiple-collision processes. The shape of P(b) is only qualitatively similar to that expected for the rotational-coupling process, however. © 1979 The American Physical Society.