An empirical expression for the full energy peak efficiency of an N-type high purity germanium detector

An empirical expression for the full energy peak efficiency (ε) in terms of the gamma-ray energy (E) and the vertical distance from the detector surface (z) (i.e.,ε=ε(z,E)) has been obtained for an N-type high purity germanium (HPGE) detector using an extended mixed standard radionuclide solution. Comparison of the calculated efficiencies and the experimentally measured values for the energy range of 59.5–1332.5 keV and a source-to-detector distance of 1.2–7.2 cm showed that the theoretical values agree with that of the experiment within 1.5–3.7% standard deviations. This shows a good agreement between the theory and the experiment.