Experimental investigation on the effect of high Z front layer on saturation thickness for radiation shielding materials

Abstract

Measurement of number and energy albedo of backscattered gamma rays has wide applications in the design of gamma ray shield involving the use of nuclear radiations. In these applications the characteristic parameter which gives an integral measurement of gamma ray scattering is the albedo of the material involved. Albedo measurements were initiated at the end of the fifth decade of the present century, just after the 2nd World War. Large number of workers worked in different fields such as (i) measurement of angular and energy distributions of backscattered in photons by applying Monte Carlo technique, (ii) experimental investigations of backscattering gamma rays by scintillation spectrometer, Uniform Sensitivity Photon Counter, Proportional Response Photon Counter etc. However, the literature on the effect of high atomic number (Z) front layer on the saturation thickness of a gamma radiation shield is almost nil. In view of the above discussions attempts have been made in the present investigation to extend the scope for optimisation of saturation thickness of a radiation shield by placing a high Z front layer material of varying thickness. Measurements of energy albedo for a homogeneous shield with and without a front layer of different high Z material of varying thickness for two energies namely 662 keV and 1250 keV have been carried out and a careful analysis is presented in the present investigation. From a detailed analysis of the present investigation the following conclusions can be drawn : (i) Anisotroplc distributions of photons as function of emerging angle. (ii) Total energy albedo values of different shielding materials decrease when high Z material is used in front of the shielding material. (iii) Saturation thickness of scattering combinations depends on Z values of the front layer. (iv) The total energy albedo values decrease exponentially as the increase in thickness of the high Z material of the front layer. (v) This experiment not only throws lights on the shielding property but also reduces...