A method for considering the spatial variations of dead layer thickness in HPGe detectors to improve the FEPE calculation of bulky samples

A method for considering the spatial variation of deal layer (DL) thickness at the lateral and top surfaces of HPGe detectors is proposed. Instead of considering the exact variation of DL thickness at detector surface, the lateral surface is divided into 12 segments, assuming each segments covers 30 degrees of the detector lateral surface and has a different DL thickness. Then, using Am-241 source at 12 positions on lateral surface and also on top surface of a HPGe detector, the nearest DL thickness for each segment can be selected through estimation of Full Energy Peak Efficiency (FEPE). This is the case in both experimental and simulation sides. The proposed detector can be used for FEPE calculation of bulk samples geometries such as Marinelli beaker containers. In order to check the suitability of proposed detector for bulky samples, a Marinelli beaker containing a set of standard radiation source solution with specified activities is considered. The experimental and simulation results of FEPE show good agreement with minimum 2% to maximum 6% relative difference from low (59.5 keV) to high energy (1.33 MeV) gamma ray.