Using γγ-coincidence spectroscopy to detect natural radiation in soils near the Mississippi River

Naturally radioactive nuclides, present in soils, contain background radiation that humans are exposed to everyday. Previous research suggests that there are some High Background Radiation Areas (HBRA), caused by climate, geography, wind and water currents that accumulate a higher concentration of these radionuclides. An investigation of one of these HBRA, Nile Delta, confirms the presence of minerals rich in U and Th from Monazite minerals, concluding that some locations have higher concentrations of radionuclides than accepted internationally.^[1] One of the similarities between the Nile and the Mississippi River Delta includes that they are both undergoing erosion. The present work is a search for monazite in the Great River Road State Park, near the Mississippi River. The samples were measured with a low-background NaI(Tl) spectrometer and digital data acquisition system. Using γγ-coincidence spectroscopy to reduce background, we were able to apply coincidence gates of known gamma-ray energies originating from ²³⁸U and ²³²Th decay chains to identify the presence of the radionuclides in the soil samples. We were able to confirm that there is an accumulation of minerals containing ²³⁸U and ²³²Th near the river.

^[1] Mubarak, Fawzia, et al. Scientific Reports, vol. 7, no. 1, 2017.