Application of Geant4 in routine close geometry gamma spectroscopy for environmental samples

•Corrections due to self-absorption and coincidence summing are investigated.•Underestimates classically found in experimental efficiency curves are fixed.•Significant reduction in relative errors is achieved.•The method can be reliably used in everyday routine measurements in busy labs.•We minimize the need for acquiring new calibration standards.

This work examines the utilization of Geant4 to practically achieve crucial corrections, in close geometry, for self-absorption and true coincidence summing in gamma-ray spectrometry of environmental samples, namely soil and water. After validation, different simulation options have been explored and compared. The simulation was used to correct for self-absorption effects, and to establish a summing-free efficiency curve, thus overcoming limitations and uncertainties imposed by conventional calibration standards. To be applicable in busy laboratories, simulation results were introduced into the conventional software Genie 2000 in order to be reliably used in everyday routine measurements.