Abstract
Reports on experimentally measured K-shell photoionisation cross sections of tin, tantalum, gold, lead and thorium (Z=50-90) targets at gamma-ray energies of 514, 661.6, 765.8 and 1115.5 keV. The K X-ray-photoelectron coincidence method developed by Ranganath et al. has been used for this purpose. Good agreement is observed between the present cross sections and the theoretical predictions of Schmickley and Pratt and Scofield.