K-shell ionization induced by 4.5 MeV/u 40Ar ions undergoing fusion reactions

K X-ray spectra of 40Ar+51V, 59Co, 62Ni fusion evaporation residues are measured in coincidence with γ-rays, protons and α-particles. The spectra are separated into prompt components due to ionization of the target atom by the projectile (PI) and delayed components due to internal conversion of γ-rays deexciting the residues (IC). K-shell ionization probabilities in half-trajectory collisions, P1/2PI, are deduced. The results are compared with numerical evaluation of two mechanisms producing K-shell vacancies during the collision: The direct ionization of the target atom by the projectile and the transfer of the K-shell vacancy from the projectile to the K-shell of the united atom. The elemental distribution of cross sections for nuclear reaction products were determined as a by-product from the yields of the PI K X-ray components. (orig.)