Experimental and simulated validation of the energy dependence of saturation thickness of multiple scattered gamma rays

Abstract

Abstract:Saturation thickness for multiple scattering gamma rays from multiple sources has been measured experimentally and simulated using the Monte Carlo N-Particle (MCNP) Code. Experimental measurements were performed using a collimated beam of gamma-rays from 57 Co, 203 Hg, 133 Ba, 22 Na, 137 Cs, 65 Zn and 60 Co sources. The gamma rays were directed at rectangular aluminium targets of varying thickness. A NaI (Tl) scintillation detector placed at a backscattering angle of 180 • was used to detect the scattered photons. The measured and calculated saturation thickness increases with increasing energy of incident gamma-rays. Experimental and simulated values are compared and are in good agreement.

Evaluation of Multiple Backscattering and Saturation Thickness of Gamma Rays

“…This behaviour is in agreement with experimental results obtained from the works of Sabharwal et al [1,3,6,14]. The values of the saturation thicknesses, being compared with experiment and MCNP [2], are presented in Table I. Differences at low energies observed in Table I between results of this study and experimental and MCNP calculated ones [2] can be arisen due to utilization of fit function of cross-sections for aluminium in the written code.…”

“…The values of the saturation thicknesses, being compared with experiment and MCNP [2], are presented in Table I. Differences at low energies observed in Table I between results of this study and experimental and MCNP calculated ones [2] can be arisen due to utilization of fit function of cross-sections for aluminium in the written code. The similarity between the experimental and the simulated response functions, and the compatible results for saturation thicknesses demonstrate that the simulation code offers a reliable estimate of the true spectrum of backscattered photons from the target and analysis of this spectrum.…”

“…2) by experimentally one observed by Eshwarappa et al [2]. In the second step, to extract useful information about multiple backscattering processes, number of multiply backscattered events for 123, 279, 360, 511, 662, 1115, and 1250 keV incident gamma rays as a function of target thickness has been obtained.…”

“…When gamma rays are allowed to interact with thick targets, they undergo multiple scattering incidents within the dimensions of the target before they escape from it [2]. These gamma photons continue to decrease in energy as the number of scatterings increases in the target.…”

“…The backscattering of gamma rays from various materials has been the subject of experimental investigation by many studies [1][2][3][4][5][6][7][8][9][10]. Because of the large number of experimental parameters that must be followed by Monte Carlo simulations, these become both unwieldy and time consuming, in addition to the unavoidable increase in statistical errors that follow this type of correction procedure [5].…”