L-SUBSHELL IONIZATION OF HEAVY-ELEMENTS BY HE-3 AND HE-4 IONS

L shell X-ray production cross sections for selected heavy elements (7 2 less-than-or-equal-to Z2 less-than-or-equal-to 83) have been measure d by He-3+ and He-4+ ions impact. The corresponding L subshell ionizat ion cross sections have been extracted from data and compared with the predictions of the ECPSSR and SCA theories by expressing graphically the ratio sigma(exp)/sigma(theory) as a function of the corrected redu ced velocity parameter xi(Li)r. Strong underestimation of experimental data by the ECPSSR and SCA theories has been observed for the lowest energies, especially for the L2 subshell, up to a factor of 3 and 4 fo r He-3 and He-4 ions. respectively. Possible reasons for observed disa greement are discussed.