Angular dependence of multiple scattered photons and saturation thickness for certain elements by gamma scattering method

摘要

Multiple scattering of gamma photons obtained from 0.215 GBq Cs-137 source in both forward and backward hemisphere for 4 elements viz., carbon, aluminium, iron and copper are detected by a 76 mm x 76 mm Nal(Tl) scintillation detector. The variation of saturation thicknesses of 4 elements are studied experimentally at 60 degrees, 80 degrees, 90 degrees, 100 degrees, 120 degrees and 135 degrees. Monte Carlo N-Particle (MCNP) simulation of multiple scattering and variation in saturation thicknesses is carried out for 40 degrees, 60 degrees, 80 degrees, 90 degrees, 100 degrees, 120 degrees, 135 degrees, 160 degrees and 180 degrees for four elements. The variation of the intensity of multiple scattered photons in different scattering angles is found to be different in forward and backward hemispheres. The intensity of multiple scattered photons is found to be minimum at around 90 degrees. Saturation thicknesses for 40 degrees and 60 degrees are found to be less than saturation thicknesses for 80 degrees, 90 degrees, 100 degrees, 120 degrees, 135 degrees, 160 degrees and 180 degrees in spite of the fact that the scattered energy is more for lower scattering angles. The behaviour of variation of saturation thicknesses as a function of scattering angles obtained from MCNP simulation agrees well with experimentally obtained values. (C) 2015 Elsevier Ltd. All rights reserved.