Peak-to-Valley Ratio Method to Determine Depth Distribution of ¹³⁷Cs in Soil by In-Situ γ Spectrometry

The peak-to-valley ratio (PVR) method was approached to determine the depth distribution of ¹³⁷Cs in soil by in-situ γ spectrometry. Theoretical calculations show that the variation of PVR is much sensitive with the dissimilarity of radioactive depth distribution, and the influence of soil density uncertainty to PVR is slight and can be neglected when the variation of soil density is within 10%. Field experiments were performed to justify the theories as correctness. The results show that the maximum relative deviation of in-situ γ spectrometry is about 31% relative to the samples analysis in laboratory, which indicates that PVR method of in-situ γ spectrometry is correct for the determination of radioactive depth distribution in soil.