Inelastic scattering of 59.5 keV photons by elements with 13⩽ Z⩽82

Abstract

Inelastic scattering differential cross-sections for 59.5 keV photons at an angle of 121° have been measured in 18 elements with 13⩽ Z⩽82. The measurements were performed using an annular source of 241Am radioisotope as photon source and a planar Si(Li) detector. The measurements were performed under vacuum ∼10 −2 Torr. The contribution due to photons scattered from the surroundings was minimized by placing the target and annular source assembly in a Pb housing, and using a vacuum chamber made of glass lined inside with Pb. Thin targets have been used to minimize the contribution of multiple scattered photons to the inelastic scattered peak. The product of the intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K X-ray yields from targets of different elements with 30⩽ Z⩽69 excited by the 59.5 keV photons from 241Am source and from the knowledge of K X-ray fluorescence cross-sections. A calibrated 241Am radioactive point source was also used for this purpose. The measured inelastic scattering cross-sections are found to be in good agreement with those calculated using the Klein–Nishina cross-section for Compton scattering by stationary free electrons and the nonrelativistic Hartree–Fock incoherent scattering function S( x, Z).