A new FSA approach for in situ $\gamma$-ray spectroscopy

Abstract

An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, $\gamma$-spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the identification and quantitative determination of $\gamma$-ray emitting radioisotopes, reducing time and costs. Both for geological and civil purposes not only ${}^{40}$K, ${}^{238}$U, and ${}^{232}$Th have to be measured, but there is also a growing interest to determine the abundances of anthropic elements, like ${}^{137}$Cs and ${}^{131}$I, which are used to monitor the effect of nuclear accidents or other human activities. The Full Spectrum Analysis (FSA) approach has been chosen to analyze the $\gamma$-spectra. The Non Negative Least Square (NNLS) and the energy calibration adjustment have been implemented in this method for the first time in order to correct the intrinsic problem related with the ${\chi }^2$ minimization which could lead to artifacts and non physical results in the analysis. A new calibration procedure has been developed for the FSA method by using in situ $\gamma$-spectra instead of calibration pad spectra. Finally, the new method has been validated by acquiring $\gamma$-spectra with a 10.16 cm x 10.16 cm sodium iodide detector in 80 different sites in the Ombrone basin, in Tuscany. The results from the FSA method have been compared with the laboratory measurements by using HPGe detectors on soil samples collected in the different sites, showing a satisfactory agreement between them. In particular, the ${}^{137}$Cs isotopes has been implemented in the analysis since it has been found not negligible during the in-situ measurements.

accepted by Science of Total Environment: 8 pages, 10 figures, 3 tables

References in corpus (1)

• NNLC: Non-Negative Least Chi-square minimization and application to HPGe detectors

Cited by in corpus (10)

• Accuracy of Flight Altitude Measured with Low-Cost GNSS, Radar and Barometer Sensors: Implications for Airborne Radiometric Surveys
• Investigating the potentialities of Monte Carlo simulation for assessing soil water content via proximal gamma-ray spectroscopy
• A multivariate spatial interpolation of airborne γ-ray data using the geological constraints
• Detection of Nuclear Sources in Search Applications using Dynamic Quantum Clustering of Spectral Data
• Modeling Aerial Gamma-Ray Backgrounds using Non-negative Matrix Factorization
• Uranium distribution in the Variscan Basement of Northeastern Sardinia
• Airborne Radiometric Surveys and Machine Learning Algorithms for Revealing Soil Texture
• Development and validation of a high-fidelity full-spectrum Monte Carlo model for the Swiss airborne gamma-ray spectrometry system
• Training Future Engineers to Be Ghostbusters: Hunting for the Spectral Environmental Radioactivity
• Full-spectrum modeling of mobile gamma-ray spectrometry systems in scattering media