Incoherent scattering of 137Cs gamma rays in the rare earth elements Nd, Sm, Gd, Dy, Er and Yb

The differential incoherent scattering cross sections for 661.6 keV photons have been measured with an HPGe detector in the momentum range 4⩽x⩽46Å-1 for the rare earth elements Nd, Sm, Gd, Dy, Er and Yb. The incoherent scattering functions were evaluated from the measured cross sections and compared with the NRHF values of Hubbel et al. [1975, J. Phys. Chem. Ref. Data 4, 471], the recent DHFR values of Kahane [1998, At. Data Nucl. Data Tables 68, 323] and other measured values. The present experimental values are systematically lower than the theoretical predictions, but show a good agreement within the experimental errors except for the momentum transfers of 30.59, 34.29 and 37.72 Å−1 for Nd, 43.69 Å−1 for Gd and 22.54 and 26.66 Å−1 for Dy, which show deviations at the two sigma level.