Influence of the detector on calculation of self-attenuation correction factor of volume sources.

Using Monte Carlo simulation and experiment, this study shows that the self-attenuation correction factors (SACFs) for identical samples measured with different detectors are not equal. The Geant4 toolkit is used to study and the following conclusions are drawn: compared with the unattenuated case, when γ-rays with different energies are attenuated by the matrix and container, the distribution of γ-rays on the surface of the entrance window of the detector is distorted. As a consequence, the SACF should be modified to account for both the self-attenuation of the sample, and the corresponding changes in detector efficiency as a result of the changes in the spatial distribution and to the energy spectra caused by the self-attenuation of the source matrix. This paper demonstrates that within certain energy ranges, and for a certain range of detectors, the required SACF modifications are not negligible. Detector parameters should therefore be considered and included when calculating the SACF.