Optimization of lead shielding design for NaI(Tl) gamma spectroscopy system using Monte Carlo simulation

The background-reduction shielding system in nuclear analysis systems helps to reduce the influence of gamma rays not released from the sample on the measured results. Background radiation comes from naturally occurring or artificially produced radioactive nuclides in the environment or from cosmic sources. This paper describes the process of optimizing the design of a background-reduction lead shielding system for an environmental analysis system that utilizes a 3"×3" NaI(Tl) scintillation detector. MCNP-5 simulation software was used to create a model of the measuring system, which included a scintillation detector and a lead shielding system. The capacity of the proposed system to minimize background radiation is calculated with thicknesses ranging from 1.5cm to 5cm. After shielding in the energy range of 20 to 2160 keV, the total count of the measuring system is lowered by 30.06 times for the chosen design. (author)