Particle-induced X-ray emission using high energy ions with respect to microprobe application

Cross-sections for continuous and characteristic X-ray emission from heavy elements induced by 16 MeV protons and 70 MeV carbon ions are measured. The K- and L-line emission cross-sections are significantly increased compared to those of lower proton energies. The data are in satisfactory agreement with semi-empirical calculations for the proton beams while the experimenta l cross-sections for the 70 MeV carbon ions are up to one order of magnitud e lower as calculated. The continuous X-ray background for protons can also be well described by theory taking into account the various sources of X-r ay production by bremsstrahlung whereas again for carbon ions the backgroun d is overestimated by scaled theory. The sensitivity for particle-induced X -ray emission (PIXE) using high energy ions is within the same order of mag nitude as that for the commonly used 1-3 MeV protons. However, 16 MeV proto n beams may be better suited for PIXE analysis with submicron-sized beams d ue to the lower ion currents necessary from the increased X-ray production cross-sections and because the sample damage and lateral spread are reduced . (C) 2001 Elsevier Science B.V. All rights reserved.