A detailed procedure to simulate an HPGe detector with MCNP5

• This work describes a detailed procedure to simulate an HPGe detector.
• The use of Monte Carlo simulation to calculate the response function is effective.
• No need for several isotopes standard, saving time, financial resources and effort.
• The efficiency curves are free of peak sum effect.

Due to its high resolution, HPGe detectors are widely used for analysis of gamma emitters radioisotopes. The determination of the response curves for this type of detector is not easy and demands a large number of gamma emitters in order to account for the energy range of interest. For volumetric geometries, a standard solution of a mix of radionuclides is commonly used, but requires one standard solution for each counting geometry of interest. The Monte Carlo method can be used to determine the detector's response curves, making it easier and cheaper. This work presents a detailed description of the procedure to simulate and calibrate co-axial HPGe detectors. It also presents a complete input file for the MCNP5 computer code. The comparison of the simulated and the experimental data showed very good agreement and the discrepancies are mainly due to the uncorrected peak sum effect of the experimental data.