Efficiency transfer in HPGe gamma spectrometry with Monte Carlo method

Efficiency transfer method is nowadays widely used in HPGe gamma spectrometry technique to calibrate the detectors for samples which are significantly different in geometry and/or density from the calibration standard. The efficiency transfer method is based on a physical principle called the Moens concept and is usually applied through the use of the idea of the effective solid angle which can be calculated by Monte Carlo method or by numerical integration. The efficiency transfer method is known to be not accurate at low emission energy (less than few ke Vs). In this work we show that the efficiency transfer at low energy using pure Monte Carlo technique is more accurate when using the total efficiencies than when using the detection efficiencies relative to the detection configurations in question. To illustrate and discuss that fact we calibrated an HPGe detector with point gamma ray sources and cylindrical reference soil samples containing the isotope Pb²¹⁰