Relationship between soil bulk density and PVR of in situ γ spectra

This paper presents the specific relationship between soil bulk density and peak-to-valley ratio (PVR) of natural radionuclides in in situ γ spectra, by theoretical deduction, Monte Carlo simulation and experimental research. Results show that for an infinite half-space volume source, PVR is a constant independent of the diverse soil bulk density. But for a limited-scale volume source, PVR would decrease slowly with an increase in soil bulk density, and the smaller the source scale, the larger the PVR variation with soil bulk density. However, the PVR variation with bulk density is very small in general. For field measurements, the volume source thickness is uncontrollable in practice, and the volume source radius should not be as small as needed for the limitation of low detection efficiency. Hence the soil bulk density could not be determined through the information from PVR of field in situ γ spectra.