L-subshell ionisation studies of Ta, W and Pt with protons

L-subshell ionisation cross-sections for Ta, W and Pt by proton impact in t he energy range of 2-5.2 MeV have been determined from the experimental dat a on X-ray production cross-section and the currently available radiative t ransition probabilities, fluorescence and Coster-Kronig factors of Krause, Werner and Jitschin and Xu. The measured ionisation cross-sections and thei r ratios are compared with the results of ECPSSR and RPWBA-BC theoretical c alculations and previously reported experimental results. The deviations in the various L subshell ionisation cross-sections with three sets of decay yield parameters are found to be less than 20%, Our results of absolute L-s ubshell ionisation cross-sections and their ratios are in better agreement with the theoretical calculations as compared to previously reported experi mental results. The L-subshell. coupling effects are found to be weak for t he elements of Ta, W and Pt in the energy region 2-5.2 MeV by proton impact . (C) 2000 Elsevier Science B.V. All rights reserved.