Abstract
The 4 pi gamma-counting system is a well suited for the analysis of small amounts of environmental samples of low activity, as it can combine both low background and high detection efficiency due to the 4 pi solid angle. In the present work, a new numerical simulation method (NSM) is proposed to calculate the full-energy peak, the total efficiencies and to correct the coincidence summing effect for the HPGe well-type detector geometry. This method is based on the calculation of the solid angle subtended by the well-type detector at a non-axial point extended to cylindrical sources measured inside detector cavity. The attenuation of the photon within the source material itself (self-attenuation), the source container and the detector's end-cap and dead layer materials is also included in this method. Low activity aqueous solution gamma-ray sources contain (Co-60 and Y-88) in small vials are usually used in the Belgium Nuclear Research Center (SCK.CEN), Boeretang 200, B-2400 Mol, Belgium, to calibrate the gamma-ray p-type HPGe well-type detectors in the energy range from 60 up to 1836 keV in the laboratory of gamma-spectroscopy. The measured efficiency values are in good agreement with those obtained by the numerical simulation method.