L X-ray intensity ratios for proton impact on selected rare-earth elements

L X-rays excited by 75-300 keV protons impacting thick targets of Gd, Tb, Dy, Ho, Er, Tm and Yb were measured with a high-resolution Si(Li) detector equipped with an ultra-thin window. The intensities of the L-alpha(L3M4,(5)) and L-beta 2,(15)(L3N4,(5)) X-rays relative to the L-l(L3M1) X-rays were compared with theoretical predictions. Discrepancies in the results are attributed to multiple vacancy production by various mechanisms. M-4,(5) and N-4,(5) ionization probabilities in these collisions are deduced from the results. (c) 2007 Elsevier B.V. All rights reserved.