Gamma-spectrum analysis of neutron activated sand samples

Resumo

Espírito Santo state has an extensive anomalous area that stretches from the coast of Rio de Janeiro to the coast of Bahia state, with a high concentration of rare earth elements and thorium. One of those responsible for such a condition is the presence of the monazite mineral. Gamma spectrometry is a non-destructive technique that allows to identify and quantify the concentrations of radionuclides emitting gamma radiation present in a sample. Also, the neutron activation technique is based on nuclear processes where the elements that make up the sample, when irradiated by neutrons, become excited and emit gamma radiation. This work aims to apply the gamma spectrometry technique to determine the activity concentrations of the elements K-40, Ra-226 and Ra-228 and compare the activity concentration values and associated effective dose with the literature. Moreover, this work intends to apply the neutron activation technique to identify and quantify rare earth and other elements present in the samples. To characterize this material and quantify the rare earth elements, whose concentration is globally unique, is of relevance. In this work, sand samples were collected at Guarapari’s beaches. The places of samples collecting were georeferenced with the use of GPS. The samples were dried in an oven at 40 °C for 48 hours, sieved with a 2 mm nylon sieve, placed in 120 ml polyethylene flasks, sealed and stored for 30 days to achieve secular balance. The next step is to neutron-activate these samples in the Argonauta research reactor.