Abstract: The accurate calibration of different energy detection efficiency in γ spectrum analysis is an important factor affecting the accuracy of measurement results. In this paper, based on domestic efficiency calibration software Gammacalib, soil samples with different densities were modeled to calculate the corresponding detection efficiency, and compared with the value measured by standard sources to verify the accuracy of Gammacalib. According to the calibration results of Gammacalib, the relative detection efficiency with soil density was analyzed, and the ε~ρ regression equation was obtained. Results for standard soil sources, the relative deviation between active efficiency and Gammacalib ranged from -7.6% to 8.1%, and efficiency was positively correlated with density, with the correlation coefficient between 0.938 and 0.992. The relative deviation of detection efficiency between the calculation results of Gammacalib and standard source can be acceptable. Gammacalib, the domestic efficiency calibration software, can meet the requirements of daily radiation environment monitoring and nuclear accident emergency monitoring, and the applicability of ε~ρ regression equation is good, which can provide reference for different density and efficiency correction.

Key words: γ spectrum analysis, detection efficiency, correlation, sourceless efficiency calculation, experimental calibration