Calibration transfer from HPGe to NaI(Tl) detectors for radionuclides quantification

Gamma-ray spectrometry is a non-destructive technique that may be employed on several types of samples to perform radiation measurements and radionuclide quantification. Different kinds of detectors may present different efficiencies and resolutions, which may lead to difficulties in measuring and quantifying particular radionuclides. To compensate for these difficulties, this work focuses on the feasibility of applying a calibration transfer methodology between a NaI(Tl) and a HPGe detector. The method employed was Target Transformation Factor Analysis, and its performance was evaluated using Root Mean Squared Error and Mean Absolute Error. Both coefficients indicated that the calculated transformation matrix performs well, and this kind of methodology is suitable for gamma-ray spectrometry measurements. Moreover, ⁷Be, ⁴⁰K, ¹³⁷Cs, ²⁰⁸Tl and ²¹⁴Bi were quantified in all 41 soil samples using the HPGe, NaI(Tl), and transformed spectra. The comparison of the results obtained with the three sets of spectra revealed statistically insignificant differences. Furthermore, the Mean Difference, Mean Absolute Error, and Mean Bias Error between the transformed and HPGe spectra indicate that the application of TTFA significantly enhances the results in comparison with the original NaI(Tl) spectra.