HIGH-RESOLUTION STUDY OF ION-INDUCED K-ALPHA(1,2) X-RAY-SPECTRA FROM HIGH-Z ELEMENTS

The K alpha(1,2), x rays emitted from La, TD, Ta, and U targets induce d by proton nitrogen, and neon ion bombardment at incident energies be tween 15 and 28 MeV/nucleon have been measured with a high-resolution crystal spectrometer. The spectra reflect the decay of a K vacancy in the presence of multiple L,, M, N,... shell ''spectator'' vacancies. T he L-shell ionization probabilities for impact parameters in the inter ior of the target's K shell are extracted from the measured spectra an d compared with extensive theoretical calculations of ionization proba bilities, based on the semiclassical separate-atom perturbation theory [semiclassical approximation (SCA)]. The projectile velocity varies f rom 60% to 125% of the target L electron velocity, so we can compare e xperimental data with theoretical predictions as a function of the rel ative velocity. We find that wave-function effects play an important r ole for an accurate calculation of the ionization probability. The exp erimental results agree well with the SCA predictions when Hartree-Foc k-type wave functions are used [variationally determined optimized pot ential (SCA-OPM)]. Relativistic hydrogenic wave functions (SCA-HYD) pr ovide a reliable description of experimental data only in the case of the uranium target. The influence of electron capture and intrashell c oupling is also calculated and discussed. An independent comparison of theoretical constructed spectra with the experimental ones confirms t he validity of the SCA-OPM. The hole-hole angular momentum coupling be tween ''active'' and ''spectator'' holes has been observed as predicte d.[S1050-2947(98)05699-1].