Accurate calculation of well-type detector geometrical efficiency using sources with different shapes and geometries

The well-type detectors are widely used to determine the low level activity in small samples, thus the absolute detector efficiency is required. The calculation of the absolute efficiency of well-type HPGe or NaI(Tl) detectors depends mainly on the value of the geometrical efficiency. The geometrical efficiency depends on the solid angle subtended by various sources situated at different locations from the detector surface. The present work is essentially concerned to introduce a numerical simulation method (NSM) to calculate the geometrical efficiency and give the ability to use it in the theoretical calibration process of gamma-ray well-type detectors for using isotropic radiating gamma-ray (point, disk or volumetric) sources. The results are compared with some published data to show the approach validity and shows how much this work is important in the efficiency calibration process for the complicated gamma-ray detection system.