Wallace, G. 2001 Energy-dispersive Compton backscatter of gamma radiation . Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 2001/03 19 p.
Abstract: Compton scatter, the inelastic interaction by which some energy of an incident gamma ray photon is transferred to an atomic electron, has the capability to non-invasively measure the density of the scattering material. This is easily done for homogenous materials. However, the use of gamma rays for imaging normally requires tight geometric collimation that severely limits the number of scattered photons that can be detected. As a consequence, ther are very few imaging applications based on Compton scatter. This investigation examines a novel geometry that has potential to relieve the tight collimation constraint, and therefore avoid the need for high strengths of gamma ray sources. The work was directed at the scattering from light matrices of 60 keV gamma rays from 241Am radiosotopic sources. Although the simplicity of the technique was demonstrated, practical difficulties in dealing with the multiple scatter inherent with real samples caused major difficulties. As the only recourse seemed to be the reintroduction of restrictions in the angular spreads of incident and scattered gamma rays, the technique was abandoned. It was concluded that it would offer no advantages over conventional collimation. (auth)