New Analytical Approach to Calculate the Full Energy Peak Efficiency for NaI (Tl) Gamma-Ray Detector Using the Effective Solid Angle Method

In this work the Full-Energy Peak Efficiency (FEPE) of NaI(Tl) - scintillation detectors (5.08x5.08 cm2and 7.62x7.62 cm2) values are calculated for coaxial cylindrical sources with radii greater than the detectors faces radii. This was calculated by the effective solid angle method, taking into account the source self-attenuation effect. In the experiments the gamma sources that contain several radionuclides covering the energy range from 59.52 to 1408.01 keV were used. By comparison, it was found that the theoretical and the experimental FEPE values are in a good agreement.