Monte Carlo simulation by GEANT 4 and GESPECOR of in situ gamma-ray spectrometry measurements

• Application of GEANT 4 and GESPECOR for in situ gamma-ray spectrometry.
• Variance reduction techniques were implemented in GESPECOR resulting in a very fast computation.
• The specific depth profile of activity was incorporated in GESPECOR.
• Procedures for evaluating the effect of non-homogeneous activity distribution were developed.
• The results obtained with GESPECOR are consistent with GEANT 4 simulations and with published experimental data.

The application of GEANT 4 and GESPECOR Monte Carlo simulation codes for efficiency calibration of in situ gamma-ray spectrometry was studied. The long computing time required by GEANT 4 prevents its use in routine simulations. Due to the application of variance reduction techniques, GESPECOR is much faster. In this code specific procedures for incorporating the depth profile of the activity were implemented. In addition procedures for evaluating the effect of non-homogeneity of the source were developed. The code was validated by comparison with test simulations carried out with GEANT 4 and by comparison with published results.