Calculation of the HPGe Detector Efficiency for Volume Sources

Full text: The excellent capability of HPGe detectors for the quantitative assay of almost all radionuclides generates a demand to make measurements for many different geometrical arrangements. For each arrangement it is necessary to know the peak efficiency as a function of energy in a certain interval, let say from 60 keV up 2 MeV or according to needs. The efficiency is usually determined experimentally by means of suitable calibrated radioactive sources emitting photons with energies, which acceptably cover the required interval. As so as these sources are expensive and in case of non-standard shape not quickly available the possibility to replace experimental determination of the peak efficiency by the calculation was thoroughly studied. In the contribution the results obtained with the well-known Monte Carlo code MCNP will be presented. Special attention will be paid to the adjustment of the detector parameters and their influence on the result. (author)