Empirical Formulae to Calculate Full-Energy Peak Attenuation Coefficients of Well-Type NaI (Tl) Detectors

NaI (Tl) detectors have been widely used during the recent years based on their response to γ-rays, which is significant mainly for the elemental analysis of neutron-induced prompt γ-rays. The detector functions significantly influence the analysis results, especially the detector efficiency. The present study focused on this problem and has been made of the contribution of the full-energy peak attenuation in the calculation of the detector efficiency. An empirical formula has been derived to calculate the full-energy peak attenuation for 3″×3″ NaI (Tl) well-type detector using isotropic radiating axial point sources. The measured efficiency values are used in this method to find the peak attenuation coefficient for this particular source-to-detector geometry. In addition, the obtaining values were used to calculate the detector full-energy peak efficiency, and compared it with the measured ones. The calculated values of the detector efficiency are found to be in a good agreement with experimental data. This gives indication about the ability to extend the calculated efficiency values to build an efficiency curve as a function of γ-ray energy as not many radioactive sources exist for the standardization process.