K-shell X-ray fluorescence cross-sections and yields measurements in 12 elements from Zr to Yb at 122 keV

K X-rays for the elements Zr, Mo, Ag, Sn, Cs, Ba, Ce, Nd, Gd, Dy, Er and Yb were measured following ionization by 122 keV gamma-rays from a Co-57 annular source. From these measurements K-shell fluorescence cross-sections were calculated and K-shell fluorescence yields were extracted from present experimental cross-sections with theoretical K-shell photoionization cross-sections. The obtained results for X-ray fluorescence cross-sections are compared with the theoretical estimates based on relativistic Dirac-Hartree-Slater theory. Measurement of K X-ray fluorescence yields for these elements are compared theoretical predictions, literature experimental values and semiempirical fits.