Validation of TOPAS MC for modelling the efficiency of an extended-range coaxial p-type HPGe detector

Highlights: • TOPAS Monte Carlo software is used for gamma-ray spectrometry applications. • The efficiency of a High Purity Germanium detector was modelled with TOPAS Monte Carlo software. • Agreement of the TOPAS model with experimental data for a gamma-ray energy range of 46–2734 keV. TOPAS MC software was used to model the efficiency of a coaxial p-type HPGe detector, type GX9023 from Canberra. The model was validated by comparing experimental efficiencies with efficiencies calculated by TOPAS MC simulations. Three different geometries of radionuclide sources, placed at different heights from the detector endcap, were used to validate the model. The imposed criteria of 5% relative difference was met for a range of radionuclides and gamma-ray energies. As a result, the created detector model with TOPAS MC was considered validated.