Abstract
K-shell ionisation cross sections sigma K have been measured for a Ta target for incident proton energies of 1.1-3.8 MeV and for incident deuteron energies of 1.2-3.2 MeV. The absolute sigma K values have been determined by normalisation to the known Coulomb excitation cross section sigma C of the target nucleus. The experimental results are compared with the predictions of different theoretical models. The sigma p/ sigma d and sigma alpha /4 sigma d ratios of the cross sections are also compared with theoretical model predictions by using the results for alpha particles taken from the literature.