A study on activity determination of volume sources using point-like standard sources and Monte Carlo simulations

•The activities were determined using point-like sources and MC simulations.•Ratios of efficiency were calculated by MC simulations based on GEANT4 codes.•The obtained activities were in good agreement with the reference values.

In this paper, the activities of volume sources were determined using point-like sources and Monte Carlo simulations. Three point-like sources (137Cs, 60Co and 152Eu) were measured as standard at the different distances from the detector window, and two volume sources, one containing 137Cs and 60Co, and another containing 152Eu, were measured directly on the detector window. After the ratios of efficiency between point-like sources and volume sources were calculated by Monte Carlo simulations based on GEANT4 codes, the activities of two volume sources were determined. Experimental verifications had shown that the activities obtained by this method for volume sources were in good agreement with the reference values.