Combination of nonlinear function and mixing method for fitting HPGe efficiency curve in the 59–2754 kev energy range

A nonlinear function in combination with the method of mixing activity-calibrated and uncalibrated gamma-ray sources is applied for fitting the experimental peak efficiency of HPGe spectrometers in the 59–2754 keV energy range. In addition, a step function was developed for fitting the gamma-ray background under the peak. Calibrated 241Am, 133Ba,137Cs, 152Eu, 60Co and 88Y sources, as well as one 24Na source (treated as uncalibrated) were used for obtaining the experimental peak efficiency curve. The results were compared to the conventional linear polynomial fitting. From the fitted parameters, the 24Na activity was determined and compared with the result obtained from absolute measurements in a 4πβ–γ coincidence system.