K-FLUORESCENCE YIELD MEASUREMENTS IN RARE-EARTH AND HEAVY-ELEMENTS

K fluorescence yields were measured for 16 elements Cu, Mo, Ag, Cd, Sn , Pr, Sm, Gd, Dy, Ho, Yb, Ta, W, Pb, Th and U using a HPGe low energy photon detector employing the reflection geometry set-up. The target a toms were excited using 59.5 keV and 279.2 keV gamma rays from Am-241 and Hg-203 radioactive sources of strengths 20 mCi and 40 mCi respecti vely An effective shielding arrangement was used to minimize the backg round and multiple scattering. Elemental foils of uniform aerial densi ty and purity better than 99.9% were used as targets. The data were re corded in a 4K multichannel analyser. Among the K fluorescence yields measured in this work nine cases constitute the first measurement. The results are compared with the literature experimental values for avai lable cases and also with the semiempirical fits and theoretical predi ctions.