Experimental Measurements and GEANT4 Simulation of NaI(Tl) Scintillator Detector

Abstract

Thallium-doped sodium iodide NaI(Tl) is one of the major scintillators that have been used for radiation detection. In this study, 2"x1.5" cylindrical NaI(Tl) detector was modelled using Monte Carlo simulation code GEANT4 in order to reproduce experimental results using standard point-like gamma sources ( 60 Co, 22 Na, 137 Cs) emitting mono-energetic gammas in the photon energy range 511-1332.5 keV. The modelled NaI(Tl) detector has been used to calculate the absolute and intrinsic efficiencies, as well as the mass attenuation coefficients for three different absorbers: lead (Pb), aluminum (Al), and copper (Cu) at various energies and thicknesses. The experimental and simulated data showed good agreement with a correlation coefficient (R 2 ) of 0.9522 and a mean absolute error (MAE) of 2.03%, confirming the robustness of the simulation models implemented in the GEANT4 simulation toolkit and validate its use for accurately modeling the performance of NaI(Tl) detectors. The findings provide a reliable framework for extending the application of GEANT4 simulations in nuclear instrumentation, radiation protection, and medical physics.