K-X RAY PRODUCTION CROSS SECTIONS OF HEAVY LANTHANIDES OVER THE ENERGY RANGE OF 3–40 MeV/amu

Partial K-x ray production cross sections of dysprosium, erbium and lutetium by proton and ³He-ion impact have been measured over the incident energy range of 3-40 MeV/amu. It is found that the measured ionization cross sections become larger in comparison with the prediction of PWBA theory and agree well with the ECPSSR theory in the wide energy region. This fact means that relativistic effect of inner-shell electrons is the most predominant among many effects such as the energy loss and the Coulomb deflection of the projectile and also the effects of polarization and increased binding energy of orbital electrons in the perturbed stationary states.