Computational modeling of a high purity germanium (HPGe) detector using MCNPX code

The efficiency of a detection system is crucial to determine the real activity of a radioactive source. When it's possible, the system's calibration should be performed using a standard source. Unfortunately, there are only a few cases that it can be done this way, considering the difficulty of obtaining appropriate standard sources for each type of measurement. In such cases, computer simulations can be performed to assist in calculating of the efficiency of the system with a similar configuration. This work aims to create, using the MCNPX code, a computer model of a high purity germanium (HPGe) detector belonged to the Radiometry Laboratory of Instituto Militar de Engenharia (IME), adapted for the calculation of the full-energy peak efficiency of {sup 137}Cs. The model was created representing in details an experimental arrangement assembled in IME considering the HPGe detector and measuring a {sup 137}Cs source. The calculated results are being compared with those obtained experimentally and the model is in process of validation. (author)