Incoherent scattering of gamma-rays by K-shell electrons of platinum

Abstract

The differential cross-section dσK for the incoherently scattered gamma-rays of energy 662 keV, coming from a 6.0 Curie Caesium-137 source, by K-shell electrons of platinum was studied by experiment. The scattered gamma-rays were selected in coincidence with the accompanying K X-rays from the scatterer, using the NaI (Tl) Scintillation detectors and fast-slow coincidence method. The differential cross-section dσK was compared with that of Klein-Nishina cross-section dσF for free and stationary electrons at a scattering angle of 30° for different thicknesses of platinum scatterers. The ratio is found to be fairly constant (0.52) at thicknesses less than 20 mgm/cm2. The differential cross-section ratio dσK/dσF for the thinnest target is compared with different experimental and theoretical values. The agreement is satisfactory. The cross-section ratio is found to be less than unity because of small momentum transfer to the K-shell electrons at small angles of scattering. The energy spectrum of the gamma-rays scattered by K-shell electrons, displayed on a twenty-channel analyser, is also presented.