Monte Carlo simulation of the full energy peak efficiency of an HPGe detector

This paper presents a Monte Carlo method to obtain the full energy peak efficiency (FEPE) curve for a High Purity Germanium (HPGe) detector, as it is difficult and time-consuming to measure the FEPE curve experimentally. The Geant4 simulation toolkit was adopted to establish a detector model since detector specifications provided by the nominal manufacturer are usually insufficient to calculate the accurate efficiency of a detector. Several detector parameters were optimized. FEPE curves for a given HPGe detectors over the energy range of 59.50-1836keV were obtained and showed good agreements with those measured experimentally. FEPE dependences on detector parameters and source-detector distances were investigated. A best agreement with experimental result was achieved for a certain detector geometry and source-detector distance.