Multiple backscattering on monoelemental materials and albedo factors of 279, 320, 511 and 662 keV gamma photons

Abstract

The energy and intensity distributions of multiple backscattering of 279, 320, 511 and 662 keV gamma photons emerging from targets of different elements are observed as a function of the target thickness. To characterize the backscattering, probabilities of gamma photons of different energies interacting with different atomic number (Z), energy (AE), number (An) and dose (AD) albedos are experimentally evaluated. The number and energy albedos are plotted as a function of incident gamma photon energy and atomic number (Z) of the target. The numbers of these multiple backscattered events show an increase with increasing target thickness and then saturate for a particular thickness of the target (the saturation thickness (depth)). The energy albedo is found to decrease with increasing incident gamma photon energy. The response function converts the observed pulse-height distribution of a NaI(Tl) detector to a true photon spectrum. Monte Carlo calculations support the present experimental results. The present measurements are carried out to study how the entities the gamma photon number albedo and the energy albedo vary as a function of the incident energy of the gamma photons, and the atomic number and thickness of an irradiated target.